JP6018948B2

JP6018948B2 - Method for producing concentrated fermented milk containing bifidobacteria

Info

Publication number: JP6018948B2
Application number: JP2013032567A
Authority: JP
Inventors: 篤茂藤田
Original assignee: Morinaga Milk Industry Co Ltd
Current assignee: Morinaga Milk Industry Co Ltd
Priority date: 2013-02-21
Filing date: 2013-02-21
Publication date: 2016-11-02
Anticipated expiration: 2033-02-21
Also published as: JP2014161237A

Description

本発明はビフィズス菌入り濃縮発酵乳の製造方法、および該製造方法で得られるビフィズス菌入り濃縮発酵乳に関する。 The present invention relates to a method for producing concentrated fermented milk containing bifidobacteria, and a concentrated fermented milk containing bifidobacteria obtained by the production method.

近年、食生活の多様化はますます進み、例えば健康に寄与する目的等により、ヨーグルト等の発酵乳の消費量が増加している。ヨーグルトの種類も豊富になり、プレーンタイプの他にも、フルーツを混合したもの、寒天やゼラチンを用いて重い食感が得られるようにしたもの、ドリンク様のもの、発酵後に濃縮することで濃厚な食感を楽しめるようにした濃縮発酵乳などが発売されている。
特に濃縮発酵乳は、乳原料のみで製造した場合でも際立った濃厚な食感と、良好な風味が得られ、高濃度のタンパク質を含むことで栄養価も高いことから注目されている。 In recent years, the diversification of eating habits has been further advanced, and the consumption of fermented milk such as yogurt is increasing, for example, for the purpose of contributing to health. A variety of yogurts are also available. In addition to plain types, fruits mixed, agar and gelatin are used to provide a heavy texture, drinks, and concentrated by fermentation. Concentrated fermented milk that allows you to enjoy a fresh texture is on sale.
In particular, concentrated fermented milk has been attracting attention because it has an outstandingly rich texture and good flavor even when it is produced only from milk raw materials, and has a high nutritional value because it contains a high concentration of protein.

濃縮発酵乳の製造方法として、特許文献１には、乳原料を含む発酵ミックスに、乳酸菌、ビフィズス菌、酵母等を１種または２種以上含むスターターを接種し、発酵させた後、膜処理を行うことによって１．５倍程度に濃縮する方法が記載されている。膜処理時の発酵乳温度については１〜５０℃との記載があり、例えば３〜２０℃の低温域では発酵乳が高粘度で発酵がほとんど進行しない状態にあり、それよりも高温域では発酵乳の粘度が低くなって透過流速が増すが、発酵が進行する状態にあることが記載されている。 As a method for producing concentrated fermented milk, Patent Document 1 discloses that a fermentation mix containing milk raw materials is inoculated with a starter containing one or more lactic acid bacteria, bifidobacteria, yeasts, etc., fermented, and then subjected to membrane treatment. A method for concentration by about 1.5 times is described. The fermented milk temperature at the time of membrane treatment is described as 1 to 50 ° C., for example, in a low temperature range of 3 to 20 ° C., the fermented milk is in a state of high viscosity and fermentation hardly proceeds, and fermentation is performed in a higher temperature range. It is described that the viscosity of milk is lowered and the permeation flow rate is increased, but the fermentation is in progress.

また非特許文献１には、乳原料を６０℃に予備加熱して均質化した後、９５℃に昇温し５分間保持して加熱殺菌し、４０〜４５℃に降温して発酵させた後に、５８〜６０℃で３分間の加熱処理を行い、４０℃に降温して２〜４段の限外濾過（ＵＦ）により濃縮し、２０℃に冷却して容器に充填して最終製品とする方法が記載されている。
このように発酵物を加熱処理してから限外濾過（ＵＦ）を行うことによって濾過流束を大きくできる。 In Non-Patent Document 1, after milk material is preheated to 60 ° C. and homogenized, it is heated to 95 ° C., held for 5 minutes, sterilized by heating, lowered to 40-45 ° C. and fermented. , Heat treatment at 58-60 ° C. for 3 minutes, drop the temperature to 40 ° C., concentrate by 2-4 stages of ultrafiltration (UF), cool to 20 ° C. and fill the container to make the final product A method is described.
Thus, a filtration flux can be enlarged by performing ultrafiltration (UF) after heat-treating fermented material.

特許第４２４１４９４号公報Japanese Patent No. 4241494

Ａ．Ｙ．Ｔａｍｉｍｅ，Ｒ．Ｋ．Ｒｏｂｉｎｓｏｎ著 “ＷｏｏｄｈｅａｄＰｕｂｌｉｓｈｉｎｇｉｎＦｏｏｄＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ，ＹｏｇｈｕｒｔＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙ，ｓｅｃｏｎｄｅｄｉｔｉｏｎ” （発行国：Ｅｎｇｌａｎｄ，ＵＳＡ、発行所：ＷｏｏｄｈｅａｄＰｕｂｌｉｓｈｉｎｇＬｉｍｉｔｅｄ，ＣＲＣＰｒｅｓｓＬＬＣ、１９９９年発行）ｐ．３３２A. Y. Tamime, R.A. K. By Robinson, “Woodpublishing in Food Science and Technology, Yoghurt Science and Technology, cd. 332

一方、乳酸菌やビフィズス菌がアレルギー症状の緩和や免疫力の向上などをもたらすことが認知されてきており、発酵乳に含まれる乳酸菌、ビフィズス菌への関心も高まっている。
しかしながら本発明者等は、ビフィズス菌を含有する濃縮発酵乳を従来の方法を用いて製造しようとすると下記のような問題が生じる場合があることを知見した。
例えば、特許文献１に記載されている方法を用いて、スターターにビフィズス菌を含有させて発酵させた後に、膜処理して濃縮すると、製造直後のビフィズス菌の生菌数は高くても、保存中に該生菌数が低下しやすい。
さらに、非特許文献１に記載されている手法を採用して、スターターにビフィズス菌を含有させて発酵させた後に、加熱処理して濃縮すると、製造直後のビフィズス菌の生菌数が低くなってしまう。 On the other hand, it has been recognized that lactic acid bacteria and bifidobacteria can alleviate allergic symptoms and improve immunity, and interest in lactic acid bacteria and bifidobacteria contained in fermented milk is also increasing.
However, the present inventors have found that the following problems may occur when an attempt is made to produce concentrated fermented milk containing bifidobacteria using conventional methods.
For example, by using the method described in Patent Document 1 and fermenting bifidobacteria in a starter and then performing membrane treatment and concentrating, even if the viable count of bifidobacteria immediately after production is high, it is preserved The viable count tends to decrease.
Furthermore, when the method described in Non-Patent Document 1 is adopted, the starter is fermented by containing bifidobacteria, and then heat-treated and concentrated, the viable count of bifidobacteria immediately after production becomes low. End up.

本発明は前記事情に鑑みてなされたもので、ビフィズス菌を高い生菌数で含み、保存中における該生菌数の低下が抑制された、ビフィズス菌入り濃縮発酵乳を提供することを目的とする。 The present invention has been made in view of the above circumstances, and an object thereof is to provide a concentrated fermented milk containing bifidobacteria containing bifidobacteria in a high viable count and suppressing a decrease in the viable count during storage. To do.

前記課題を解決するために、本発明のビフィズス菌入り濃縮発酵乳の製造方法は、
ビフィズス菌を含む濃縮発酵乳を製造する方法であって、乳原料を含む殺菌調乳液に乳酸菌スターターを添加して発酵させる発酵工程と、前記発酵により得られた発酵物を加熱処理する加熱処理工程と、前記加熱処理後の発酵物を膜分離法により濃縮する濃縮工程を有し、
前記加熱処理工程の条件を、加熱温度５３〜６５℃、加熱時間１分間以上、該加熱処理後の乳酸菌数が１×１０^７ＣＦＵ／ｍｌ以上、かつ該加熱処理後に４５℃で４時間保温する保温試験を行ったときのｐＨが４．１０〜４．４６であって、該加熱処理を行わずに該保温試験を行ったときのｐＨよりも高くなる条件とし、前記加熱処理工程の後、前記濃縮工程の前に、前記加熱処理後の発酵物にビフィズス菌を添加することを特徴とする。

In order to solve the above problems, the method for producing concentrated fermented milk containing bifidobacteria of the present invention,
A method for producing concentrated fermented milk containing bifidobacteria, a fermentation process in which a lactic acid bacteria starter is added to a sterilized milky solution containing a milk raw material and fermented, and a heat treatment process in which a fermented product obtained by the fermentation is heat-treated And a concentration step of concentrating the fermented material after the heat treatment by a membrane separation method ,
The conditions of the heat treatment step are as follows: a heating temperature of 53 to 65 ° C., a heating time of 1 minute or more, a number of lactic acid bacteria after the heat treatment of 1 × 10 ⁷ CFU / ml or more, and a heat treatment at 45 ° C. for 4 hours after the heat treatment. The pH when the heat retention test is performed is 4.10 to 4.46, and the condition is higher than the pH when the heat retention test is performed without performing the heat treatment, and after the heat treatment step, Before the concentration step, bifidobacteria are added to the fermented product after the heat treatment.

前記発酵工程において前記殺菌調乳液に添加する乳酸菌数が１×１０^５〜１×１０^１０ＣＦＵ／ｍｌであることが好ましい。
前記濃縮工程において、遠心分離法または膜分離法を用いて濃縮を行うことが好ましい。
前記ビフィズス菌入り濃縮発酵乳を、製造後１０℃で１４日間保存したときの、ビフィズス菌数が１×１０^６ＣＦＵ／ｍｌ以上であることが好ましい。
前記ビフィズス菌が、ビフィドバクテリウム・ロンガムＡＴＣＣＢＡＡ−９９９株であることが好ましい。
本発明は、本発明の製造方法で得られるビフィズス菌入り濃縮発酵乳を提供する。 It is preferable that the number of lactic acid bacteria added to the sterilized milky lotion in the fermentation step is 1 × 10 ⁵ to 1 × 10 ¹⁰ CFU / ml.
In the concentration step, concentration is preferably performed using a centrifugal separation method or a membrane separation method.
The number of bifidobacteria when the concentrated fermented milk containing bifidobacteria is stored at 10 ° C. for 14 days after production is preferably 1 × 10 ⁶ CFU / ml or more.
The Bifidobacterium is preferably Bifidobacterium longum ATCC BAA-999 strain.
The present invention provides concentrated fermented milk containing bifidobacteria obtained by the production method of the present invention.

本発明のビフィズス菌入り濃縮発酵乳の一実施形態の工程図である。It is process drawing of one Embodiment of the concentrated fermented milk containing a bifidobacterium of this invention. 試験例１の工程図である。5 is a process diagram of Test Example 1. FIG. 試験例２の結果を示すグラフである。6 is a graph showing the results of Test Example 2. 比較例１、４の工程図である。It is process drawing of the comparative examples 1 and 4. FIG. 比較例２、５の工程図である。6 is a process diagram of Comparative Examples 2 and 5. FIG. 比較例３、６の工程図である。It is process drawing of the comparative examples 3 and 6. 実施例１および比較例１〜３の結果を示すグラフである。It is a graph which shows the result of Example 1 and Comparative Examples 1-3. 実施例１および比較例１〜３の結果を示すグラフである。It is a graph which shows the result of Example 1 and Comparative Examples 1-3. 実施例２および比較例４〜６の結果を示すグラフである。It is a graph which shows the result of Example 2 and Comparative Examples 4-6. 実施例２および比較例４〜６の結果を示すグラフである。It is a graph which shows the result of Example 2 and Comparative Examples 4-6.

＜発酵乳＞
「乳及び乳製品の成分規格等に関する省令」（乳等省令と略す）において、発酵乳とは「乳又はこれと同等以上の無脂乳固形分を含む乳等を乳酸菌又は酵母で発酵させ、糊状又は液状にしたもの又はこれらを凍結したもの」と定義されており、その成分規格は、無脂乳固形分８％以上、乳酸菌数又は酵母数（１ｍｌ当り）１，０００万（１×１０^７、１．００Ｅ＋０７と表記することもある。）以上、大腸菌群陰性と定められている。乳酸菌数の単位はＣＦＵ（ｃｏｌｏｎｙｆｏｒｍｉｎｇｕｎｉｔ；コロニー形成単位）である。
発酵乳に含まれる乳酸菌数（生菌数）の測定方法は、乳等省令の別表に規定されていて、ＢＣＰ（ｂｒｏｍ−ｃｒｅｓｏｌｐｕｒｐｌｅ）を含んだ標準寒天培地（ｐｌａｔｅｃｏｕｎｔａｇａｒ）で通常の混釈培養を３５〜３７℃で７２時間行い、黄変するコロニーを数えることによって測定される。 <Fermented milk>
In the "Ministerial Ordinance on Component Standards of Milk and Dairy Products" (abbreviated as the Ordinance of Milk etc.), fermented milk is "fermented milk or milk containing non-fat milk solids equal to or higher than this with lactic acid bacteria or yeast, It is defined as “a paste-like or liquid-made one or a product obtained by freezing them”, and its component standards are non-fat milk solid content of 8% or more, the number of lactic acid bacteria or yeast (per ml) 10 million (1 × 10 ⁷ , 1.00E + 07 may be indicated.) As described above, it is determined that the coliform group is negative. The unit of the number of lactic acid bacteria is CFU (colony forming unit).
The method for measuring the number of lactic acid bacteria (viable bacteria) contained in fermented milk is stipulated in a separate table of the Ordinance of the Ministry of Milk, etc., and is normally mixed with a standard agar medium (plate count agar) containing BCP (brom-cresol purple). The incubation is performed at 35-37 ° C. for 72 hours and measured by counting the yellowing colonies.

＜乳原料＞
乳原料は乳由来の原料であり、発酵乳の製造において用いられる公知の乳原料を用いることができる。例えば生乳、牛乳、水牛乳、やぎ乳、羊乳、馬乳、濃縮乳、脱脂濃縮乳、脱脂粉乳、クリーム、バター、乳清蛋白質濃縮物（ＷＰＣ）、乳清蛋白質分離物（ＷＰＩ）、乳蛋白質濃縮物（ＭＰＣ）、ミセラカゼインアイソレート（ＭＣＩ）、ミルクプロテインアイソレート（ＭＰＩ）等が挙げられる。これらは１種を単独で用いてもよく、２種以上を混合して用いてもよい。 <Milk ingredients>
The milk raw material is a milk-derived raw material, and known milk raw materials used in the production of fermented milk can be used. For example, raw milk, cow milk, water buffalo milk, goat milk, sheep milk, horse milk, concentrated milk, defatted concentrated milk, defatted powdered milk, cream, butter, whey protein concentrate (WPC), whey protein isolate (WPI), milk Examples include protein concentrate (MPC), micellar casein isolate (MCI), and milk protein isolate (MPI). These may be used alone or in combination of two or more.

＜殺菌調乳液＞
殺菌調乳液は、これに乳酸菌を作用させて発酵させるものであり、乳原料および必要に応じて水を含む。これら以外のその他の成分を含んでもよい。水以外の成分が乳原料のみであってもよい。
その他の成分として、例えば、砂糖、オリゴ糖等の糖類、植物性脂肪、安定剤、香料、甘味料等、発酵乳の製造において添加される公知の成分を適宜含有させることができる。安定剤として、例えば寒天、ゼラチン、及びペクチン等が挙げられる。
殺菌調乳液における全固形分（水分以外の成分の合計）の含有量は６〜２４質量％が好ましく、８〜２２質量％がより好ましい。
殺菌調乳液における無脂乳固形分の含有量は６〜１６質量％が好ましく、８〜１４質量％がより好ましい。該無脂乳固形分の含有量が上記範囲の下限値以上であると濃縮に適した発酵物が得られやすく、上限値以下であると風味の良い濃縮発酵乳が得られやすい。 <Bactericidal formula>
The sterilized milky lotion is prepared by allowing lactic acid bacteria to act on this and fermenting it, and contains milk raw materials and water as required. Other components other than these may be included. Components other than water may be only milk raw materials.
As other components, for example, sugars such as sugars and oligosaccharides, vegetable fats, stabilizers, fragrances, sweeteners and the like, which are known components added in the production of fermented milk, can be appropriately contained. Examples of the stabilizer include agar, gelatin, and pectin.
6-24 mass% is preferable and, as for content of the total solid (total of components other than a water | moisture content) in a bactericidal formula, 8-22 mass% is more preferable.
The content of nonfat milk solid content in the sterilized milky preparation is preferably 6 to 16% by mass, and more preferably 8 to 14% by mass. A fermented product suitable for concentration is easily obtained when the content of the non-fat milk solid content is at least the lower limit of the above range, and concentrated fermented milk having a good flavor is easily obtained when the content is less than the upper limit.

［ビフィズス菌入り濃縮発酵乳の製造方法］
図１に本発明のビフィズス菌入り濃縮発酵乳の一実施形態の工程図を示す。
＜殺菌調乳液の調製＞
まず、乳原料、および必要に応じた水、その他の成分等を混合し、好ましくは均質化処理を行い、加熱殺菌処理する。均質化処理および加熱殺菌処理は常法により行うことができる。
加熱殺菌処理は、例えば、プレート式殺菌機、チューブラー式殺菌機、直接加熱式殺菌機、ジャケット付きタンク等の加熱殺菌装置を用いて行うことができる。殺菌条件は、８５〜９５℃で５〜１５分間が好ましい。
加熱殺菌後に、タンク等に保存する場合１０℃以下に冷却することが好ましい。 [Production method of concentrated fermented milk containing bifidobacteria]
FIG. 1 shows a process diagram of an embodiment of the concentrated fermented milk containing bifidobacteria of the present invention.
<Preparation of sterilized milky lotion>
First, milk raw materials, water as required, other components, etc. are mixed, preferably homogenized, and heat sterilized. Homogenization treatment and heat sterilization treatment can be performed by conventional methods.
The heat sterilization treatment can be performed using, for example, a heat sterilizer such as a plate sterilizer, a tubular sterilizer, a direct heat sterilizer, or a jacketed tank. The sterilization condition is preferably 85 to 95 ° C for 5 to 15 minutes.
After heat sterilization, when storing in a tank or the like, it is preferable to cool to 10 ° C. or lower.

＜発酵工程＞
殺菌調乳液に乳酸菌スターターを添加（接種）し、所定の発酵温度に保持して発酵させ、発酵物を得る。発酵によりカードが形成される。
乳酸菌スターターとしては、例えば、ラクトバチルス・ブルガリクス（Ｌ．ｂｕｌｇａｒｉｃｕｓ）、ラクトコッカス・ラクチス（Ｌ．ｌａｃｔｉｓ）、ストレプトコッカス・サーモフィラス（Ｓ．ｔｈｅｒｍｏｐｈｉｌｕｓ）等のヨーグルト製造に通常用いられている乳酸菌を用いることができる。
上記に例示した乳酸菌スターターを用いる場合の発酵温度は３７〜４０℃が好ましい。乳酸菌を添加（接種）する前に、予め殺菌調乳液の温度を発酵温度に調整しておくことが好ましい。
乳酸菌スターターの添加量は、殺菌調乳液に対する乳酸菌数が１×１０^５〜１×１０^１０ＣＦＵ／ｍｌが好ましく、１×１０^６〜１×１０^９ＣＦＵ／ｍｌがより好ましい。
乳酸菌による発酵においては酸が生成されるため、発酵が開始された後の殺菌調乳液のｐＨは経時的に低下する。発酵時間は、該殺菌調乳液のｐＨが４．６〜４．８に到達する時間に設定することが好ましい。発酵工程における到達ｐＨが前記の範囲であると、組織がなめらかで良好なカードが形成されやすい。
ｐＨが目標の値に達したら、形成されたカードを撹拌により破砕し、１０℃以下に冷却して発酵物を得る。
１０℃以下に冷却することにより、乳酸菌の活性を低下させて酸の生成を抑制することができる。カードの破砕は冷却中に行ってもよく、冷却後に行ってもよい。
具体的には、例えばタンク内で発酵を行い、タンク内に形成されたカードを、撹拌しながら冷却し、または冷却後に撹拌して破砕する。撹拌は公知の方法で行うことができる。
このようにカードの破砕を行うと撹拌型発酵乳が得られる。 <Fermentation process>
A lactic acid bacteria starter is added (inoculated) to the sterilized milky lotion, and fermented by maintaining the fermentation temperature at a predetermined fermentation temperature. A card is formed by fermentation.
As the lactic acid bacteria starter, for example, lactic acid bacteria usually used for producing yogurt such as Lactobacillus bulgaricus (L. bulgaricus), Lactococcus lactis (L. lactis), Streptococcus thermophilus (S. thermophilus) are used. Can do.
As for the fermentation temperature in the case of using the lactic acid bacteria starter illustrated above, 37-40 degreeC is preferable. Before adding (inoculating) lactic acid bacteria, it is preferable to adjust the temperature of the sterilized milky lotion to the fermentation temperature in advance.
The amount of lactic acid bacteria starter added is preferably 1 × 10 ⁵ to 1 × 10 ¹⁰ CFU / ml, and more preferably 1 × 10 ⁶ to 1 × 10 ⁹ CFU / ml, with respect to the sterilized milk solution.
In the fermentation by lactic acid bacteria, an acid is generated, so that the pH of the sterilized milky lotion after the fermentation is started decreases with time. The fermentation time is preferably set to a time for the pH of the sterilized milky solution to reach 4.6 to 4.8. When the ultimate pH in the fermentation process is in the above range, a smooth card and a good card are easily formed.
When the pH reaches the target value, the formed curd is crushed by stirring and cooled to 10 ° C. or lower to obtain a fermented product.
By cooling to 10 ° C. or lower, the activity of lactic acid bacteria can be reduced and the production of acid can be suppressed. The crushing of the card may be performed during cooling or after cooling.
Specifically, for example, fermentation is performed in a tank, and the card formed in the tank is cooled with stirring, or stirred and crushed after cooling. Stirring can be performed by a known method.
When the curd is crushed in this way, stirred fermented milk is obtained.

＜加熱処理工程＞
次いで、発酵工程で得られた発酵物を加熱処理して加熱後発酵物（加熱処理後の発酵物）を得る。発酵物を適度に加熱することにより、加熱後発酵物中の乳酸菌による酸の生成を抑えることができる。これによって、その後の製造工程中および／またはビフィズス菌入り濃縮発酵乳の保存中のｐＨの低下を抑えることができ、その結果、ビフィズス菌の生残性を向上させることができる。
また発酵物を加熱することにより、カードとホエーの分離を生じさせて、濃縮効率を向上させることができる。 <Heat treatment process>
Next, the fermented product obtained in the fermentation process is heat-treated to obtain a post-heated fermented product (fermented product after the heat treatment). By appropriately heating the fermented product, acid production by lactic acid bacteria in the fermented product after heating can be suppressed. Thereby, the fall of pH during the subsequent manufacturing process and / or preservation | save of the concentrated fermented milk containing a bifidobacterium can be suppressed, As a result, the survival property of a bifidobacterium can be improved.
Further, by heating the fermented product, separation of the curd and whey can be caused and the concentration efficiency can be improved.

加熱処理工程における加熱温度は５３℃以上が好ましい。５３℃以上であると、加熱処理によって乳酸菌による酸の生成を抑制する効果が得られやすい。後述の実施例に示されるように、加熱後発酵物にビフィズス菌を添加して濃縮して得られるビフィズス菌入り濃縮発酵乳の、ｐＨの経時的低下が抑制されると、ビフィズス菌の生残性が向上する。
一方、加熱温度が高すぎると、加熱処理によって乳酸菌の生菌数が大きく低下するため、加熱温度は６５℃以下が好ましい。乳等省令で規定されている、乳酸菌数が１×１０^７ＣＦＵ／ｍｌ以上を満たすビフィズス菌入り濃縮発酵乳を得るためには、加熱後発酵物中における乳酸菌数が１×１０^７ＣＦＵ／ｍｌ以上であることが好ましい。加熱処理工程における加熱温度が６５℃を超えると、加熱後発酵物中における乳酸菌数が１×１０^７ＣＦＵ／ｍｌを下回ってしまう。
加熱処理工程における加熱時間は１分間以上が好ましい。５３〜６５℃の温度で１分間以上加熱処理を行うと、濃縮前にホエーを分離させて濃縮効率を向上させる効果が充分に得られやすい。加熱温度が高いほど、または加熱時間が長いほど、分離するホエーの量が多くなる。 The heating temperature in the heat treatment step is preferably 53 ° C. or higher. The effect which suppresses the production | generation of the acid by lactic acid bacteria by heat processing as it is 53 degreeC or more is easy to be acquired. As shown in the examples below, when the pH-related decrease in time of concentrated fermented milk containing bifidobacteria obtained by adding bifidobacteria to the fermented product after heating and concentrating is suppressed, the survival of bifidobacteria Improves.
On the other hand, if the heating temperature is too high, the number of viable lactic acid bacteria is greatly reduced by the heat treatment, and thus the heating temperature is preferably 65 ° C. or lower. In order to obtain a concentrated fermented milk containing bifidobacteria satisfying the number of lactic acid bacteria of 1 × 10 ⁷ CFU / ml or more, which is specified by an ordinance of milk, etc., the number of lactic acid bacteria in the fermented product after heating is 1 × 10 ⁷ CFU / ml. The above is preferable. If the heating temperature in the heat treatment step exceeds 65 ° C., the number of lactic acid bacteria in the fermented product after heating is less than 1 × 10 ⁷ CFU / ml.
The heating time in the heat treatment step is preferably 1 minute or longer. When the heat treatment is performed at a temperature of 53 to 65 ° C. for 1 minute or longer, the effect of improving the concentration efficiency by separating whey before the concentration can be sufficiently obtained. The higher the heating temperature or the longer the heating time, the more whey is separated.

加熱処理工程の条件は、上記の範囲内であって、加熱後発酵物中の乳酸菌による酸の生成を抑制できるように設定することが好ましい。かかるｐＨの低下を抑制する効果は、加熱温度が高いほど、または加熱時間が長いほど大きい。
かかる加熱後発酵物中の乳酸菌による酸の生成量は、該加熱後発酵物が１０℃程度の低温で保存された場合よりも、その後の工程で加温された場合の方が多くなる。例えば、膜処理法で濃縮を行う場合の温度条件を想定して、加熱処理後に４５℃で４時間保温する保温試験を行ったときのｐＨ（４５℃）が、該加熱処理を行わずに同じ保温試験を行ったときのｐＨ（４５℃）よりも高くなる条件が好ましく、０．０２以上高くなる条件がより好ましく、０．０３以上高くなる条件がさらに好ましい。
また、加熱処理後に４５℃で４時間保温する保温試験を行ったときのｐＨ（４５℃）が４．１０〜４．４６となるように、加熱処理工程の条件を設定することが好ましい。該保温試験後のｐＨが上記の範囲内であれば、加熱後発酵物にビフィズス菌を添加して濃縮して得られるビフィズス菌入り濃縮発酵乳における、良好なビフィズス菌の生残性が得られやすい。 The conditions for the heat treatment step are preferably set so as to be within the above-mentioned range and to suppress the production of acid by lactic acid bacteria in the fermented material after heating. The effect of suppressing such a decrease in pH is greater as the heating temperature is higher or the heating time is longer.
The amount of acid produced by the lactic acid bacteria in the fermented product after heating is greater when the heated fermented product is heated in the subsequent process than when the fermented product is stored at a low temperature of about 10 ° C. For example, assuming a temperature condition when concentrating by a membrane treatment method, the pH (45 ° C.) when performing a heat insulation test for 4 hours at 45 ° C. after the heat treatment is the same without performing the heat treatment. Conditions that are higher than the pH (45 ° C.) when the heat retention test is performed are preferable, conditions that increase 0.02 or more are more preferable, and conditions that increase 0.03 or more are more preferable.
Moreover, it is preferable to set the conditions of the heat treatment step so that the pH (45 ° C.) when the heat retention test is carried out at 45 ° C. for 4 hours after the heat treatment is 4.10 to 4.46. If the pH after the heat retention test is within the above range, good survival of bifidobacteria can be obtained in concentrated fermented milk containing bifidobacteria obtained by adding and concentrating bifidobacteria to the fermented product after heating. Cheap.

加熱処理工程を実施する方法は、特に限定されない。例えば発酵工程で得られた発酵物をプレート式殺菌機、チューブラー式殺菌機、直接加熱式殺菌機、ジャケット付きタンク等の加熱殺菌装置を用いて、所定の条件で加熱することができる。
所定の条件で加熱処理した後は、濃縮工程における被濃縮物の温度にまで冷却することが好ましい。 The method for performing the heat treatment step is not particularly limited. For example, the fermented product obtained in the fermentation process can be heated under predetermined conditions using a heat sterilizer such as a plate sterilizer, a tubular sterilizer, a direct heating sterilizer, a jacketed tank, or the like.
After heat treatment under predetermined conditions, it is preferable to cool to the temperature of the concentrate in the concentration step.

＜ビフィズス菌の添加工程＞
次いで、加熱処理工程で得られた加熱後発酵物に、ビフィズス菌を添加する。
ビフィズス菌の中でも、ビフィドバクテリウム・ロンガム（Ｂｉｆｉｄｏｂａｃｔｅｒｉｕｍｌｏｎｇｕｍ）を用いることが好ましい。ビフィドバクテリウム・ロンガムは、発酵乳によく用いられているビフィズス菌の一つであり、また免疫力の向上という点で注目されている。またビフィドバクテリウム・ロンガムは、他のビフィズス菌に比べて熱や酸による影響を受けやすく、濃縮発酵乳中での良好な生残性を得ることが難しいため、本発明を適用することによる効果が大きい。 <Bifidobacteria addition process>
Next, bifidobacteria are added to the post-heating fermentation product obtained in the heat treatment step.
Among the Bifidobacteria, it is preferable to use Bifidobacterium longum. Bifidobacterium longum is one of the bifidobacteria often used in fermented milk, and has attracted attention in terms of improving immunity. Bifidobacterium longum is more susceptible to heat and acid than other bifidobacteria, and it is difficult to obtain good survival in concentrated fermented milk. Great effect.

ビフィドバクテリウム・ロンガムは、公知の菌株を適宜用いることができる。特に食品への汎用性が高く、機能性が期待できる点でビフィドバクテリウム・ロンガムＡＴＣＣＢＡＡ−９９９株が好ましい。
ビフィドバクテリウム・ロンガムを添加する際の加熱後発酵物の温度は１０〜５０℃が好ましく、１０〜４５℃がより好ましい。該加熱後発酵物の温度が上記の上限値以下であるとビフィズス菌の生残性が良好である。
ビフィドバクテリウム・ロンガムの添加量は、加熱後発酵物に対して１×１０^７〜１×１０^１１ＣＦＵ／ｍｌが好ましく、１×１０^８〜１×１０^１０ＣＦＵ／ｍｌがより好ましい。 As Bifidobacterium longum, known strains can be appropriately used. In particular, the Bifidobacterium longum ATCC BAA-999 strain is preferred because of its high versatility in food and the expectation of functionality.
10-50 degreeC is preferable and, as for the temperature of the fermented material after a heating at the time of adding Bifidobacterium longum, 10-45 degreeC is more preferable. When the temperature of the fermented product after heating is not more than the above upper limit value, the viability of bifidobacteria is good.
The amount of Bifidobacterium longum added to the fermented product after heating is preferably 1 × 10 ⁷ to 1 × 10 ¹¹ CFU / ml, more preferably 1 × 10 ⁸ to 1 × 10 ¹⁰ CFU / ml.

＜濃縮工程＞
加熱後発酵物にビフィズス菌を添加した後、濃縮を行う。濃縮工程は公知の濃縮方法を適宜用いて行うことができる。例えば遠心分離法または膜分離法を用いることができる。
濃縮前の質量を、濃縮後の質量で除した値で表される濃縮倍率は１．５〜４．５倍が好ましく、２〜４倍がより好ましい。
濃縮工程で得られるビフィズス菌入り濃縮発酵乳の１０℃における粘度は５００〜１５０００ｍＰａ・ｓが好ましく、２０００〜１２０００ｍＰａ・ｓがより好ましい。
該ビフィズス菌入り濃縮発酵乳の粘度は、Ｂ型粘度計にて、回転数６０ｒｐｍでＮｏ．２〜４ローターを使用して測定したときの、測定開始から１０秒後の値（単位：ｍＰａ・ｓ）である。 <Concentration process>
After the heating, the bifidobacteria are added to the fermented product and then concentrated. A concentration process can be performed using a well-known concentration method suitably. For example, a centrifugal separation method or a membrane separation method can be used.
The concentration ratio represented by a value obtained by dividing the mass before concentration by the mass after concentration is preferably 1.5 to 4.5 times, and more preferably 2 to 4 times.
The viscosity at 10 ° C. of the concentrated fermented milk containing bifidobacteria obtained in the concentration step is preferably 500 to 15000 mPa · s, more preferably 2000 to 12000 mPa · s.
The concentrated fermented milk containing the bifidobacteria has a viscosity of No. It is a value (unit: mPa · s) after 10 seconds from the start of measurement when measured using 2 to 4 rotors.

遠心分離法では、被濃縮物（ビフィズス菌が添加された加熱後発酵物）中のホエーが除去されて、固形分濃度が高められたビフィズス菌入り濃縮発酵乳が得られる。遠心分離する際の被濃縮物の温度は１０〜５０℃が好ましく、４０〜４５℃がより好ましい。該被濃縮物の温度が上記の上限値以下であるとビフィズス菌の生残性が十分に得られ、下限値以上であると濃縮効率が良い。 In the centrifugal separation method, whey in the product to be concentrated (fermented product after heating to which bifidobacteria are added) is removed, and concentrated fermented milk containing bifidobacteria with an increased solid content concentration is obtained. 10-50 degreeC is preferable and the temperature of the to-be-concentrated substance at the time of centrifuging has more preferable 40-45 degreeC. If the temperature of the concentrate is below the above upper limit, the viability of bifidobacteria is sufficiently obtained, and if it is above the lower limit, the concentration efficiency is good.

膜分離法としては、例えば限外ろ過膜を用いる方法、精密濾過膜を用いる方法等が挙げられる。膜分離法で濃縮する際の被濃縮物の温度は１０〜５０℃が好ましく、４０〜４５℃がより好ましい。該被濃縮物の温度が上記の上限値以下であるとビフィズス菌の生残性が十分に得られやすく、下限値以上であると濃縮効率が良い。
濃縮後は、２０℃以下に冷却することが好ましい。 Examples of the membrane separation method include a method using an ultrafiltration membrane and a method using a microfiltration membrane. 10-50 degreeC is preferable and, as for the temperature of the to-be-concentrated material at the time of concentrating with a membrane separation method, 40-45 degreeC is more preferable. If the temperature of the concentrate is below the above upper limit, the viability of bifidobacteria can be obtained sufficiently, and if it is above the lower limit, the concentration efficiency is good.
After concentration, it is preferable to cool to 20 ° C or lower.

［ビフィズス菌入り濃縮発酵乳］
こうして得られるビフィズス菌入り濃縮発酵乳は、保存中におけるｐＨの経時的な低下が小さく、ビフィズス菌の生残性が良好である。ビフィズス菌入り濃縮発酵乳の賞味期間中にビフィズス菌数が充分に高く維持されるという点で、１０℃で１４日保存後のビフィズス菌の生菌数が１×１０^６ＣＦＵ／ｍｌ以上であることが好ましい。
また、ビフィズス菌入り濃縮発酵乳のｐＨは、濃縮工程で得られた直後のｐＨ（１０℃）が４．４〜５であり、１０℃で１４日保存後のｐＨ（１０℃）が４．２〜５であることが好ましい。 [Concentrated fermented milk with bifidobacteria]
The concentrated fermented milk containing bifidobacteria thus obtained has a small decrease in pH over time during storage, and the viability of bifidobacteria is good. The viable count of bifidobacteria after storage for 14 days at 10 ° C. is 1 × 10 ⁶ CFU / ml or more in that the bifidobacteria count is maintained sufficiently high during the shelf life of the concentrated fermented milk containing bifidobacteria It is preferable.
The pH of the concentrated fermented milk containing bifidobacteria is 4.4 to 5 immediately after being obtained in the concentration step (10 ° C.), and the pH after storage at 10 ° C. for 14 days (10 ° C.) is 4. It is preferable that it is 2-5.

以下に実施例を用いて本発明をさらに詳しく説明するが、本発明はこれら実施例に限定されるものではない。以下において、含有割合を表す「％」は特に断りのない限り「質量％」である。
＜試験例１＞
本試験例の手順を図２に示す。本例では発酵物に対して、表１に示す条件で加熱処理を行った後に保温試験を行い、発酵物のｐＨへの影響を調べた。保温試験後のｐＨの値が低いほど、保温試験（４５℃・４時間）中における乳酸菌による酸の生成量が多いことを意味する。用いた原料は以下の通りである。
（乳原料）
・脱脂粉乳：森永乳業社製、脂肪含量１．０％、蛋白質含量３４．０％、無脂乳固形分９５．２％。
・クリーム：森永乳業社製、脂肪含量４５．５％、蛋白質含量１．６％、無脂乳固形分４．５％。
（乳酸菌）
・乳酸菌スターター：森永乳業社製。ラクトバチルス・ブルガリクス（Ｌ．ｂｕｌｇａｒｉｃｕｓ）とストレプトコッカス・サーモフィラス（Ｓ．ｔｈｅｒｍｏｐｈｉｌｕｓ）の混合培養物。生菌数：５×１０^８ＣＦＵ／ｍｌ。脂肪含有量０．１％、蛋白質含量４．１％、無脂乳固形分１０％。
（ビフィズス菌）
・ビフィズス菌：森永乳業社製。ビフィドバクテリウム・ロンガム（ＡＴＣＣＢＡＡ−９９９株）菌培養物。生菌数：３×１０^９ＣＦＵ／ｍｌ。 Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to these examples. In the following, “%” representing the content ratio is “% by mass” unless otherwise specified.
<Test Example 1>
The procedure of this test example is shown in FIG. In this example, the heat treatment was performed on the fermented product under the conditions shown in Table 1, and then a heat retention test was performed to examine the influence on the pH of the fermented product. It means that the lower the pH value after the heat retention test, the greater the amount of acid produced by the lactic acid bacteria during the heat retention test (45 ° C., 4 hours). The raw materials used are as follows.
(Milk ingredients)
Nonfat dry milk: manufactured by Morinaga Milk Industry Co., Ltd., fat content 1.0%, protein content 34.0%, nonfat milk solid content 95.2%.
-Cream: manufactured by Morinaga Milk Industry Co., Ltd., fat content 45.5%, protein content 1.6%, non-fat milk solid content 4.5%.
(Lactic acid bacteria)
・ Lactic acid bacteria starter: Made by Morinaga Milk Industry. Lactobacillus bulgaricus (L. bulgaricus) and Streptococcus thermophilus (S. thermophilus) mixed culture. Viable count: 5 × 10 ⁸ CFU / ml. Fat content 0.1%, protein content 4.1%, non-fat milk solids 10%.
(Bifidobacterium)
・ Bifidobacteria: manufactured by Morinaga Milk Industry. Bifidobacterium longum (ATCC BAA-999 strain) bacterial culture. Viable count: 3 × 10 ⁹ CFU / ml.

［殺菌調乳液の調製］
乳原料として脱脂粉乳３８０ｇおよびクリーム１４０ｇを用いた。これらを水３４５６ｇに添加し、６５℃に加温して溶解した後、１５ＭＰａの圧力で均質化した。得られた溶液を９０℃で１０分間加熱殺菌し、１０℃に冷却して殺菌調乳液を得た。
殺菌調乳液における全固形分は１０．９質量％、無脂乳固形分は９．２質量％である。
［乳酸菌添加および発酵工程］
得られた殺菌調乳液を予め３８℃付近に加温しておき、これに乳酸菌スターター２４ｇを接種し、３８℃でｐＨ４．７になるまで発酵させた。殺菌調乳液に対する乳酸菌の添加量は３×１０^６ＣＦＵ／ｍｌである。
発酵により生成したカードを破砕し、１０℃に冷却して発酵物約３０００ｇを得た。発酵温度（３８℃）に達してから、ｐＨ４．７になるまでの発酵時間は、約６時間であった。得られた発酵物の乳酸酸度は０．６％、ｐＨ（１０℃）は４．７であった。
得られた発酵物を、蓋付きガラス管に２０ｍｌ／本ずつ分注して発酵物サンプルとした。 [Preparation of sterilized milky lotion]
380 g of skim milk powder and 140 g of cream were used as milk raw materials. These were added to 3456 g of water, heated to 65 ° C. to dissolve, and then homogenized at a pressure of 15 MPa. The obtained solution was sterilized by heating at 90 ° C. for 10 minutes and cooled to 10 ° C. to obtain a sterilized milky lotion.
The total solid content in the sterilized milky lotion is 10.9 mass%, and the non-fat milk solid content is 9.2 mass%.
[Lactic acid bacteria addition and fermentation process]
The obtained sterilized milky lotion was preheated to around 38 ° C., inoculated with 24 g of lactic acid bacteria starter, and fermented at 38 ° C. until pH 4.7. The amount of lactic acid bacteria added to the sterilized milky lotion is 3 × 10 ⁶ CFU / ml.
The card | curd produced | generated by fermentation was crushed, and it cooled at 10 degreeC, and obtained about 3000 g of fermented products. The fermentation time from reaching the fermentation temperature (38 ° C.) to pH 4.7 was about 6 hours. The obtained fermented product had a lactic acid acidity of 0.6% and a pH (10 ° C.) of 4.7.
The obtained fermented product was dispensed into a glass tube with a lid at a rate of 20 ml / tube to obtain a fermented product sample.

［加熱処理工程・保温試験］
得られた発酵物サンプルを表１に示す加熱条件で加熱処理し、一旦１０℃に冷却した。加熱方法は８０℃の温湯中で撹拌しながら昇温させた後、各保持温度の温湯で所定の加熱時間だけ保持した後、氷水中で１０℃に急冷させる方法で行った。得られた加熱後発酵物を、４５℃で４時間保温して１０℃に冷却し、ｐＨ（１０℃）を測定した。結果を表１に示す。
［対象試験］
対象試験として、発酵物サンプルに加熱処理を施さず、４５℃で４時間保温した後１０℃に冷却した。冷却後のｐＨ（１０℃）は４．００であった。 [Heat treatment process and heat insulation test]
The obtained fermented product sample was heat-treated under the heating conditions shown in Table 1 and once cooled to 10 ° C. The heating was carried out by heating in 80 ° C. hot water with stirring, holding the hot water at each holding temperature for a predetermined heating time, and then rapidly cooling to 10 ° C. in ice water. The obtained fermented product after heating was kept at 45 ° C. for 4 hours, cooled to 10 ° C., and pH (10 ° C.) was measured. The results are shown in Table 1.
[Target test]
As a target test, the fermented material sample was not subjected to heat treatment, kept at 45 ° C. for 4 hours, and then cooled to 10 ° C. The pH after cooling (10 ° C.) was 4.00.

表１の結果より、加熱温度が５３℃の場合は、加熱時間が１〜３分間では対象試験と同じｐＨとなるが、５分間以上の加熱で、対象試験よりも保温試験後のｐＨが高くなり、加熱することによって発酵物中における酸の生成を抑制する効果が得られることがわかる。
加熱温度が５５℃の場合、加熱時間が１分間では対象試験と同じｐＨとなるが、３分間以上の加熱で、対象試験よりも保温試験後のｐＨが高くなり、加熱することによって発酵物中における酸の生成を抑制する効果が得られることがわかる。
加熱温度が高いほど、また加熱時間が長いほど、保温試験後のｐＨがより高くなり、発酵物中における酸の生成がより抑制されることがわかる。 From the results in Table 1, when the heating temperature is 53 ° C., the same pH as the target test is obtained when the heating time is 1 to 3 minutes, but the heating after the heat retention test is higher than the target test by heating for 5 minutes or more. It turns out that the effect which suppresses the production | generation of the acid in fermented material is acquired by heating.
When the heating temperature is 55 ° C., the same pH as that of the target test is obtained when the heating time is 1 minute, but the pH after the heat retention test becomes higher than that of the target test by heating for 3 minutes or more. It turns out that the effect which suppresses the production | generation of the acid in is obtained.
It can be seen that the higher the heating temperature and the longer the heating time, the higher the pH after the heat retention test, and the generation of acid in the fermented product is further suppressed.

＜試験例２＞
試験例１と同様の手順で、発酵物に対する加熱処理による、発酵物中の乳酸菌数への影響を調べた。ただし本例では、表２に示す条件で加熱処理を行い、保温試験は行わず、加熱処理直後の発酵物（加熱後発酵物）中の乳酸菌数を測定した。
すなわち、試験例１と同様にして殺菌調乳液の調製、乳酸菌添加および発酵工程を行い、得られた発酵物を、蓋付きガラス管に２０ｍｌ／本ずつ分注して発酵物サンプルとした。
得られた発酵物サンプルに、表２に示す加熱条件で加熱処理を施した後に１０℃に冷却した加熱後発酵物について、下記の方法で乳酸菌の生菌数（乳酸菌数）を測定した。
結果を表２に示すとともに、図３のグラフに示した。このグラフにおいて、縦軸は発酵物サンプル中の乳酸菌数（単位：ＣＦＵ／ｍｌ）であり、横軸は加熱処理温度である。 <Test Example 2>
In the same procedure as in Test Example 1, the influence of the heat treatment on the fermented product on the number of lactic acid bacteria in the fermented product was examined. However, in this example, the heat treatment was performed under the conditions shown in Table 2, the heat retention test was not performed, and the number of lactic acid bacteria in the fermented product (fermented product after heating) immediately after the heat treatment was measured.
That is, preparation of a sterilized milky lotion, addition of lactic acid bacteria and fermentation process were performed in the same manner as in Test Example 1, and the obtained fermented product was dispensed into a glass tube with a lid by 20 ml / tube to obtain a fermented product sample.
The obtained fermented product sample was subjected to a heat treatment under the heating conditions shown in Table 2, and then the heated fermented product cooled to 10 ° C. was measured for the number of viable lactic acid bacteria (the number of lactic acid bacteria) by the following method.
The results are shown in Table 2 and shown in the graph of FIG. In this graph, the vertical axis represents the number of lactic acid bacteria in the fermented product sample (unit: CFU / ml), and the horizontal axis represents the heat treatment temperature.

表２および図３の結果より、加熱温度が６５℃を超えると加熱時間を短くしても、乳酸菌数が、乳等省令の規定を満たすのに好ましい１×１０^７ＣＦＵ／ｍｌを下回ってしまうことがわかる。
また表１、２の結果より、加熱処理後の乳酸菌数を１×１０^７ＣＦＵ／ｍｌ以上に維持しつつ、発酵物のｐＨの経時低下を抑えるために好ましい加熱処理条件の下限値は５３℃以上５５℃未満で５分間以上、５５℃以上５８℃未満で３分間以上、５８℃以上６５℃未満で１分間以上、６５℃で１分間である。上限値は、それぞれの温度において加熱処理後の乳酸菌数が１×１０^７ＣＦＵ／ｍｌ以上となる加熱時間に設定すればよく、製造効率の点からは５分間以下が好ましい。 From the results of Table 2 and FIG. 3, when the heating temperature exceeds 65 ° C., the number of lactic acid bacteria falls below 1 × 10 ⁷ CFU / ml, which is preferable for satisfying the provisions of the Ministerial Ordinance such as milk, even if the heating time is shortened. I understand that.
In addition, from the results of Tables 1 and 2, the lower limit of the preferred heat treatment condition is 53 ° C. in order to suppress the aging of the pH of the fermented product while maintaining the number of lactic acid bacteria after the heat treatment at 1 × 10 ⁷ CFU / ml or more. It is 5 minutes or more at 55 ° C or less, 3 minutes or more at 55 ° C or less and less than 58 ° C, 1 minute or more at 58 ° C or more and less than 65 ° C, and 1 minute at 65 ° C. The upper limit may be set to a heating time at which the number of lactic acid bacteria after the heat treatment at each temperature is 1 × 10 ⁷ CFU / ml or more, and is preferably 5 minutes or less from the viewpoint of production efficiency.

＜実施例１＞
図１に示す手順でビフィズス菌入り濃縮発酵乳（以下、単に濃縮発酵乳ということもある。）を製造した。加熱後発酵物を得るまでの手順は試験例１、２と同じである。本例では、濃縮工程において遠心分離法を用いて濃縮を行った。
［殺菌調乳液の調製］
乳原料として脱脂粉乳３８０ｇおよびクリーム１４０ｇを用いた。これらを水３３３２ｇに添加し、６５℃に加温して溶解した後、１５ＭＰａの圧力で均質化した。得られた溶液を９０℃で１０分間加熱殺菌し、１０℃に冷却して殺菌調乳液を得た。
殺菌調乳液における全固形分は１０．９質量％、無脂乳固形分は９．２質量％である。
［乳酸菌添加および発酵工程］
得られた殺菌調乳液を予め３８℃付近に加温しておき、これに乳酸菌スターター２４ｇを接種し、３８℃でｐＨ４．７になるまで発酵させた。殺菌調乳液に対する乳酸菌の添加量は３×１０^６ＣＦＵ／ｍｌである。
発酵により生成したカードを破砕し、１０℃に冷却して発酵物約３８７６ｇを得た。発酵温度（３８℃）に達してから、ｐＨが４．７になるまでの発酵時間は、約５時間であった。得られた発酵物のｐＨ（１０℃）は４．７であった。
得られた発酵物を、ポリプロピレン製５０ｍｌ遠沈管に３８．７６ｇ／本ずつ取り分けた。 <Example 1>
Concentrated fermented milk containing bifidobacteria (hereinafter sometimes simply referred to as concentrated fermented milk) was produced by the procedure shown in FIG. The procedure for obtaining a fermented product after heating is the same as in Test Examples 1 and 2. In this example, concentration was performed using a centrifugal separation method in the concentration step.
[Preparation of sterilized milky lotion]
380 g of skim milk powder and 140 g of cream were used as milk raw materials. These were added to 3332 g of water, heated to 65 ° C. to dissolve, and then homogenized at a pressure of 15 MPa. The obtained solution was sterilized by heating at 90 ° C. for 10 minutes and cooled to 10 ° C. to obtain a sterilized milky lotion.
The total solid content in the sterilized milky lotion is 10.9 mass%, and the non-fat milk solid content is 9.2 mass%.
[Lactic acid bacteria addition and fermentation process]
The obtained sterilized milky lotion was preheated to around 38 ° C., inoculated with 24 g of lactic acid bacteria starter, and fermented at 38 ° C. until pH 4.7. The amount of lactic acid bacteria added to the sterilized milky lotion is 3 × 10 ⁶ CFU / ml.
The curd produced by fermentation was crushed and cooled to 10 ° C. to obtain about 3876 g of a fermented product. The fermentation time from reaching the fermentation temperature (38 ° C.) until the pH reached 4.7 was about 5 hours. The pH (10 ° C.) of the obtained fermented product was 4.7.
The obtained fermented product was dispensed 38.76 g / piece into a 50 ml centrifuge tube made of polypropylene.

［加熱処理工程］
こうして遠沈管に収容された発酵物を、試験例１と同じ加熱方法で６０℃、２分間の加熱条件で加熱処理した後、１０℃に冷却して加熱後発酵物を得た。
［ビフィズス菌の添加］
得られた加熱後発酵物（１０℃）に対して、ビフィズス菌を、遠沈管１本（加熱後発酵物３８．７６ｇ）当たり１．２４ｇ添加して撹拌混合した。加熱後発酵物に対するビフィズス菌の添加量は１×１０^８ＣＦＵ／ｍｌである。
［濃縮工程］
上記でビフィズス菌が添加された加熱後発酵物に対して、遠心分離機（ｅｐｐｅｎｄｏｒｆ社製、製品名：Ｃｅｎｔｒｉｆｕｇｅ５８０４Ｒ）を用いて、遠心力４０００（単位：×ｇ）、１０分間の条件で遠心分離を行った。
これにより遠沈管１本（加熱後発酵物４０ｇ）当たり、ホエー２６．７ｇが分離除去され、ビフィズス菌入り濃縮発酵乳１３．３ｇが得られた。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．５５、ビフィズス菌の生菌数（ビフィズス菌数）は１．９８×１０^８ＣＦＵ／ｍｌであった。 [Heat treatment process]
The fermented material thus housed in the centrifuge tube was heat-treated at 60 ° C. for 2 minutes under the same heating method as in Test Example 1, and then cooled to 10 ° C. to obtain a fermented product after heating.
[Addition of bifidobacteria]
1.24 g of bifidobacteria per 1 centrifuge tube (38.76 g of fermented product after heating) was added to the obtained fermented product after heating (10 ° C.) and mixed with stirring. The amount of bifidobacteria added to the fermented product after heating is 1 × 10 ⁸ CFU / ml.
[Concentration process]
The centrifuge (product name: Centrifuge 5804R) is used to centrifuge the fermented material to which bifidobacteria have been added as described above using a centrifuge (product name: Centrifuge 5804R) for 10 minutes. Separation was performed.
As a result, 26.7 g of whey was separated and removed per one centrifuge tube (40 g of fermented product after heating), and 13.3 g of concentrated fermented milk containing bifidobacteria was obtained. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.55, and a viable count of bifidobacteria (bifidos The number of bacteria) was 1.98 × 10 ⁸ CFU / ml.

［評価：保存試験］
得られた濃縮発酵乳を１０℃のインキュベーターで保存した。製造日の１日後、７日後、１４日後、２１日後、２８日後のそれぞれの時点で、ｐＨ（１０℃）を測定し、またビフィズス菌の生菌数を下記の方法で測定した。
ビフィズス菌の生菌数（ビフィズス菌数）の測定結果を図７に示し、ｐＨの測定結果を図８に示す（比較例１〜３も同様。）。 [Evaluation: Storage test]
The obtained concentrated fermented milk was stored in an incubator at 10 ° C. The pH (10 ° C.) was measured at each time point 1 day, 7 days, 14 days, 21 days, and 28 days after the production date, and the viable count of bifidobacteria was measured by the following method.
The measurement result of the viable count of bifidobacteria (the number of bifidobacteria) is shown in FIG. 7, and the measurement result of pH is shown in FIG. 8 (the same applies to Comparative Examples 1 to 3).

［ビフィズス菌の生菌数の測定方法］
ビフィズス菌入り濃縮発酵乳に含まれるビフィズス菌数の測定方法は、ＴＯＳプロピオン酸寒天平板培地（ヤクルト薬品工業社製）を用い、嫌気条件下で混釈培養を３７℃で７２時間行い、ビフィズス菌のコロニーを数えることによって測定した。 [Measurement method of viable count of bifidobacteria]
The method for measuring the number of bifidobacteria contained in the concentrated fermented milk containing bifidobacteria is TOS propionate agar plate (manufactured by Yakult Yakuhin Kogyo Co., Ltd.). Was measured by counting the number of colonies.

＜比較例１＞
図４に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が実施例１と大きく異なる点は、発酵物に加熱処理を行わずにビフィズス菌を添加した点である。
すなわち、実施例１と同様にして得られた発酵物（１０℃）をポリプロピレン製５０ｍｌ遠沈管に３８．７６ｇ／本ずつ取り分けた。
これに、ビフィズス菌を、遠沈管１本（発酵物３８．７６ｇ）当たり１．２４ｇ添加して撹拌混合した。
こうしてビフィズス菌が添加された発酵物（加熱処理なし）に対して、実施例１と同じ遠心分離機を用いて遠心分離を行った。本例では遠心分離条件を遠心力４０００（単位：×ｇ）、１０分間とした。遠沈管１本（発酵物４０ｇ）当たり、ホエー２６．７ｇが除去され、ビフィズス菌入り濃縮発酵乳１３．３ｇが得られた。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．５６、ビフィズス菌の生菌数（ビフィズス菌数）は２．５４×１０^８ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例１と同様にして保存試験を行った。 <Comparative Example 1>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. This example is significantly different from Example 1 in that bifidobacteria were added to the fermented product without heat treatment.
That is, the fermented material (10 ° C.) obtained in the same manner as in Example 1 was separately placed in a polypropylene 50 ml centrifuge tube at 38.76 g / tube.
To this, 1.24 g of bifidobacteria per one centrifuge tube (fermented product 38.76 g) was added and mixed with stirring.
The fermented product thus added with bifidobacteria (no heat treatment) was centrifuged using the same centrifuge as in Example 1. In this example, the centrifugal separation conditions were a centrifugal force of 4000 (unit: xg) and 10 minutes. 26.7 g of whey was removed per centrifuge tube (fermented product 40 g), and 13.3 g of concentrated fermented milk containing bifidobacteria was obtained. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.56, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 2.54 × 10 ⁸ CFU / ml.
About the obtained concentrated fermented milk, the storage test was done like Example 1. FIG.

＜比較例２＞
図５に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が実施例１と大きく異なる点は、発酵工程前にビフィズス菌を添加し、加熱処理工程後はビフィズス菌を添加しなかった点である。
［殺菌調乳液の調製］
乳原料として脱脂粉乳３８４．８ｇおよびクリーム１４０ｇを用いた。これらを水３３７９．２ｇに添加し、６５℃に加温して溶解した後、１５ＭＰａの圧力で均質化した。得られた溶液を９０℃で１０分間加熱殺菌し、１０℃に冷却して殺菌調乳液を得た。
殺菌調乳液における全固形分は１１質量％、無脂乳固形分は９．３質量％である。
［乳酸菌添加および発酵工程］
得られた殺菌調乳液に乳酸菌スターター２４ｇ、およびビフィズス菌７２ｇを接種し、３８℃でｐＨ４．７になるまで発酵させた。殺菌調乳液に対する乳酸菌の添加量は３×１０^６ＣＦＵ／ｍｌ、ビフィズス菌の添加量は３×１０^７ＣＦＵ／ｍｌである。
発酵により生成したカードを破砕し、１０℃に冷却して発酵物約４０００ｇを得た。発酵時間は約４時間であった。得られた発酵物のｐＨ（１０℃）は４．７であった。
得られた発酵物を、ポリプロピレン製５０ｍｌ遠沈管に４０ｇ／本ずつ取り分けた。
［加熱処理工程］
こうして遠沈管に収容された発酵物を、試験例１と同じ加熱方法で６０℃、２分間の加熱条件で加熱処理した後、１０℃に冷却して加熱後発酵物を得た。
［濃縮工程］
得られた加熱後発酵物に対して、実施例１と同じ遠心分離機を用いて、遠心力４０００（単位：×ｇ）、１０分間の条件で遠心分離を行った。これにより遠沈管１本（加熱後発酵物４０ｇ）当たり、ホエー２６．７ｇが分離除去され、ビフィズス菌入り濃縮発酵乳１３．３ｇが得られた。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．５５、ビフィズス菌の生菌数（ビフィズス菌数）は１．８３×１０^６ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例１と同様にして保存試験を行った。 <Comparative example 2>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. This example is significantly different from Example 1 in that bifidobacteria were added before the fermentation step and no bifidobacteria were added after the heat treatment step.
[Preparation of sterilized milky lotion]
As the milk raw material, 384.8 g of skim milk powder and 140 g of cream were used. These were added to 3379.2 g of water, heated to 65 ° C. to dissolve, and then homogenized at a pressure of 15 MPa. The obtained solution was sterilized by heating at 90 ° C. for 10 minutes and cooled to 10 ° C. to obtain a sterilized milky lotion.
The total solid content in the sterilized milky lotion is 11% by mass, and the non-fat milk solid content is 9.3% by mass.
[Lactic acid bacteria addition and fermentation process]
The obtained sterilized milky lotion was inoculated with 24 g of lactic acid bacteria starter and 72 g of bifidobacteria and fermented at 38 ° C. until pH 4.7. The amount of lactic acid bacteria added to the sterilized milky lotion is 3 × 10 ⁶ CFU / ml, and the amount of bifidobacteria added is 3 × 10 ⁷ CFU / ml.
The card | curd produced | generated by fermentation was crushed, it cooled at 10 degreeC, and about 4000 g of fermented products were obtained. The fermentation time was about 4 hours. The pH (10 ° C.) of the obtained fermented product was 4.7.
The obtained fermented product was divided into 40 ml / tube in a polypropylene 50 ml centrifuge tube.
[Heat treatment process]
The fermented material thus housed in the centrifuge tube was heat-treated at 60 ° C. for 2 minutes under the same heating method as in Test Example 1, and then cooled to 10 ° C. to obtain a fermented product after heating.
[Concentration process]
The obtained fermented material after heating was centrifuged using the same centrifuge as in Example 1 under a centrifugal force of 4000 (unit: xg) for 10 minutes. As a result, 26.7 g of whey was separated and removed per one centrifuge tube (40 g of fermented product after heating), and 13.3 g of concentrated fermented milk containing bifidobacteria was obtained. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.55, and a viable count of bifidobacteria (bifidos The number of bacteria) was 1.83 × 10 ⁶ CFU / ml.
About the obtained concentrated fermented milk, the storage test was done like Example 1. FIG.

＜比較例３＞
図６に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が比較例２と大きく異なる点は、発酵物に加熱処理を行わずに濃縮工程を行った点である。
すなわち、比較例２と同様に、乳酸菌とビフィズス菌を添加した後に発酵を行って得られた発酵物（１０℃）をポリプロピレン製５０ｍｌ遠沈管に４０ｇ／本ずつ取り分けた。
こうして得られた発酵物（加熱処理なし）に対して、実施例１と同じ遠心分離機を用いて遠心分離を行った。本例では遠心分離条件を遠心力４０００（単位：×ｇ）、１０分間とした。遠沈管１本（発酵物４０ｇ）当たり、ホエー２６．７ｇが除去され、ビフィズス菌入り濃縮発酵乳１３．３ｇが得られた。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．５０、ビフィズス菌の生菌数（ビフィズス菌数）は２．４０×１０^８ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例１と同様にして保存試験を行った。 <Comparative Example 3>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. The point that this example is greatly different from Comparative Example 2 is that the concentration step was performed without performing the heat treatment on the fermented product.
That is, as in Comparative Example 2, 40 g / piece of fermented material (10 ° C.) obtained by fermentation after adding lactic acid bacteria and bifidobacteria was placed in a polypropylene 50 ml centrifuge tube.
The fermented material thus obtained (without heat treatment) was centrifuged using the same centrifuge as in Example 1. In this example, the centrifugal separation conditions were a centrifugal force of 4000 (unit: xg) and 10 minutes. 26.7 g of whey was removed per centrifuge tube (fermented product 40 g), and 13.3 g of concentrated fermented milk containing bifidobacteria was obtained. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.50, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 2.40 × 10 ⁸ CFU / ml.
About the obtained concentrated fermented milk, the storage test was done like Example 1. FIG.

＜結果＞
図７、８の結果より、実施例１では１４日間の保存期間中におけるビフィズス菌数の減少はわずかであり、２８日間の保存後も、１×１０^６ＣＦＵ／ｍｌ以上のビフィズス菌数を維持していた。またｐＨは１４日後までは比較的高く、４．４以上に維持されていた。これらの結果より、保存中における乳酸菌による酸の生成が抑制された結果、ビフィズス菌の良好な生残性が得られたと考えられる。
比較例１は、発酵工程後に加熱処理工程を行わずにビフィズス菌を添加した例である。７日間の保存期間であればビフィズス菌数の減少はわずかであるが、１４日後にはビフィズス菌数が大きく低減した。またｐＨは、保存開始から７日後には４．０以下にまで大きく低下した。これらの結果より、保存開始後から乳酸菌による酸生成量が多くてｐＨの低下が大きいために、ビフィズス菌数の減少が生じやすかったと考えられる。
比較例２は、発酵前に乳酸菌とビフィズス菌を添加し、発酵後に加熱処理して濃縮工程を行った例であるが、製造直後の状態で既にビフィズス菌数が低く、７日後には１．０×１０^４ＣＦＵ／ｍｌにまで低下した。ｐＨの推移は実施例１とほぼ同等であった。保存中における乳酸菌による酸の生成は抑制されたものの、加熱処理工程においてビフィズス菌の減少が生じたと考えられる。
比較例３は、発酵前に乳酸菌とビフィズス菌を添加し、発酵工程後に加熱処理工程を行わずに濃縮した例である。７日間の保存期間であればビフィズス菌数の減少はわずかであるが、１４日後にはビフィズス菌数が大きく低減した。またｐＨは、保存開始から７日後には４．０付近にまで大きく低下した。保存開始後から乳酸菌による酸生成量が多くてｐＨの低下が大きいために、ビフィズス菌数の減少が生じやすかったと考えられる。 <Result>
From the results of FIGS. 7 and 8, in Example 1, the decrease in the number of bifidobacteria during the storage period of 14 days was slight, and the number of bifidobacteria of 1 × 10 ⁶ CFU / ml or more was maintained even after 28 days of storage. Was. The pH was relatively high until 14 days later and was maintained at 4.4 or higher. From these results, it is considered that good survival of Bifidobacteria was obtained as a result of the suppression of acid production by lactic acid bacteria during storage.
Comparative Example 1 is an example in which bifidobacteria were added without performing a heat treatment step after the fermentation step. Although the decrease in the number of bifidobacteria was slight during the storage period of 7 days, the number of bifidobacteria was greatly reduced after 14 days. Further, the pH greatly decreased to 4.0 or less after 7 days from the start of storage. From these results, it is considered that the number of bifidobacteria was likely to decrease because the amount of acid produced by lactic acid bacteria was large after the start of storage and the pH was greatly reduced.
Comparative Example 2 is an example in which lactic acid bacteria and bifidobacteria were added before fermentation, and heat treatment was performed after fermentation to perform a concentration step. However, the number of bifidobacteria was already low in the state immediately after production, and after 7 days, 1. Reduced to 0 × 10 ⁴ CFU / ml. The change in pH was almost the same as in Example 1. Although the production of acid by lactic acid bacteria during storage was suppressed, it is considered that the reduction of bifidobacteria occurred in the heat treatment process.
Comparative Example 3 is an example in which lactic acid bacteria and bifidobacteria were added before fermentation and concentrated without performing a heat treatment process after the fermentation process. Although the decrease in the number of bifidobacteria was slight during the storage period of 7 days, the number of bifidobacteria was greatly reduced after 14 days. In addition, the pH greatly decreased to around 4.0 after 7 days from the start of storage. Since the amount of acid produced by lactic acid bacteria is large after the start of storage and the pH is greatly lowered, it is considered that the number of bifidobacteria is likely to decrease.

＜実施例２＞
本例では、濃縮工程において膜分離法を用いて濃縮を行った。その他の工程は実施例１と同様の手順（図１）で、ビフィズス菌入り濃縮発酵乳を製造した。
［殺菌調乳液の調製］
乳原料として脱脂粉乳２６６０ｇおよびクリーム９８０ｇを用いた。これらを水２３３２４ｇに添加し、６５℃に加温して溶解した後、１５Ｍｐａの圧力で均質化した。得られた溶液を９０℃で１０分間加熱殺菌し、１０℃に冷却して殺菌調乳液を得た。
殺菌調乳液における全固形分は１０．９質量％、無脂乳固形分は９．２質量％である。
［乳酸菌添加および発酵工程］
得られた殺菌調乳液を予め３８℃付近に加温しておき、これに乳酸菌スターター１６８ｇを接種し、３８℃でｐＨ４．７になるまで発酵させた。殺菌調乳液に対する乳酸菌の添加量は３×１０^６ＣＦＵ／ｍｌである。
発酵により生成したカードを破砕し、１０℃に冷却して発酵物約２７１３２ｇを得た。発酵時間は約６時間であった。得られた発酵物のｐＨ（１０℃）は４．７であった。 <Example 2>
In this example, concentration was performed using a membrane separation method in the concentration step. The other steps were the same procedure as in Example 1 (FIG. 1) to produce concentrated fermented milk containing bifidobacteria.
[Preparation of sterilized milky lotion]
Non-fat dry milk 2660 g and cream 980 g were used as milk raw materials. These were added to 23324 g of water, dissolved by heating to 65 ° C., and then homogenized at a pressure of 15 Mpa. The obtained solution was sterilized by heating at 90 ° C. for 10 minutes and cooled to 10 ° C. to obtain a sterilized milky lotion.
The total solid content in the sterilized milky lotion is 10.9 mass%, and the non-fat milk solid content is 9.2 mass%.
[Lactic acid bacteria addition and fermentation process]
The obtained sterilized milky lotion was preheated to around 38 ° C., inoculated with 168 g of lactic acid bacteria starter, and fermented at 38 ° C. until pH 4.7. The amount of lactic acid bacteria added to the sterilized milky lotion is 3 × 10 ⁶ CFU / ml.
The card | curd produced | generated by fermentation was crushed, it cooled at 10 degreeC, and about 27132g of fermented materials were obtained. The fermentation time was about 6 hours. The pH (10 ° C.) of the obtained fermented product was 4.7.

［加熱処理工程］
得られた発酵物をバットに入れ、８０℃の温湯中にバットを浸し、撹拌しながら昇温することにより、６０℃、２分間の加熱条件で加熱処理した後、４５℃まで冷却して加熱後発酵物を得た。
［ビフィズス菌の添加］
得られた加熱後発酵物（４５℃）約２７１３２ｇに対して、ビフィズス菌８６８ｇを添加して撹拌混合した。加熱後発酵物に対するビフィズス菌の添加量は１×１０^８ＣＦＵ／ｍｌである。
［濃縮工程］
上記でビフィズス菌が添加された加熱後発酵物に対して、限外ろ過膜（Ａｌｆａ−ｌａｖａｌ社製、分画分子量２５０００Ｄａ）を用い、液温が４０〜４５℃の状態で限外ろ過処理を行い、得られたビフィズス菌入り濃縮発酵乳８５００ｇを１０℃まで冷却した。
濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．４２、ビフィズス菌の生菌数（ビフィズス菌数）は８．２×１０^７ＣＦＵ／ｍｌであった。
［評価：保存試験］
得られたビフィズス菌入り濃縮発酵乳について、実施例１と同様にして保存試験を行った。製造日の１日後、７日後、１４日後のそれぞれの時点で、ｐＨ（１０℃）を測定し、またビフィズス菌の生菌数を下記の方法で測定した。 [Heat treatment process]
Put the obtained fermented material in a vat, immerse the vat in hot water at 80 ° C., heat up with stirring, heat treatment under heating conditions of 60 ° C. for 2 minutes, then cool to 45 ° C. and heat A post-fermented product was obtained.
[Addition of bifidobacteria]
868 g of bifidobacteria were added to about 27132 g of the obtained fermented product (45 ° C.) after heating, and mixed with stirring. The amount of bifidobacteria added to the fermented product after heating is 1 × 10 ⁸ CFU / ml.
[Concentration process]
For the post-heating fermented product to which bifidobacteria have been added as described above, an ultrafiltration membrane (manufactured by Alfa-laval, fractional molecular weight 25000 Da) is used, and ultrafiltration treatment is performed in a state where the liquid temperature is 40 to 45 ° C. Then, 8500 g of the concentrated fermented milk containing bifidobacteria obtained was cooled to 10 ° C.
The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.42, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 8.2 × 10 ⁷ CFU / ml.
[Evaluation: Storage test]
The obtained fermented milk containing bifidobacteria was subjected to a storage test in the same manner as in Example 1. The pH (10 ° C.) was measured at 1 time, 7 days, and 14 days after the production date, and the viable count of bifidobacteria was measured by the following method.

＜比較例４＞
図４に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が実施例２と大きく異なる点は、発酵物に加熱処理を行わずにビフィズス菌を添加した点である。
すなわち、実施例２と同様にして得られた発酵物を４５℃に加温したもの２７１３２ｇに対して、ビフィズス菌８６８ｇを添加して撹拌混合した。発酵物に対するビフィズス菌の添加量は１×１０^８ＣＦＵ／ｍｌである。
こうしてビフィズス菌が添加された発酵物（加熱処理なし）に対して、実施例２と同じ限外ろ過膜を用い、液温が４０〜４５℃の状態で限外ろ過処理を行い、得られたビフィズス菌入り濃縮発酵乳８５００ｇを１０℃まで冷却した。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．１８、ビフィズス菌の生菌数（ビフィズス菌数）は１．２９×１０^８ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例２と同様にして保存試験を行った。 <Comparative example 4>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. This example is significantly different from Example 2 in that bifidobacteria were added to the fermented product without heat treatment.
That is, 868 g of bifidobacteria were added to 27132 g of the fermented product obtained in the same manner as in Example 2 and heated to 45 ° C., and stirred and mixed. The amount of bifidobacteria added to the fermented product is 1 × 10 ⁸ CFU / ml.
Thus, with respect to the fermented product (without heat treatment) to which bifidobacteria were added, the same ultrafiltration membrane as in Example 2 was used, and ultrafiltration treatment was performed in a state where the liquid temperature was 40 to 45 ° C. 8500 g of concentrated fermented milk containing bifidobacteria was cooled to 10 ° C. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.18, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 1.29 × 10 ⁸ CFU / ml.
The obtained concentrated fermented milk was subjected to a storage test in the same manner as in Example 2.

＜比較例５＞
図５に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が実施例２と大きく異なる点は、ビフィズス菌を発酵工程前に添加し、加熱処理工程後はビフィズス菌を添加しなかった点である。
［殺菌調乳液の調製］
乳原料として脱脂粉乳２６９３ｇおよびクリーム９８０ｇを用いた。これらを水２３６５４ｇに添加し、６５℃に加温して溶解した後、１５ＭＰａの圧力で均質化した。得られた溶液を９０℃で１０分間加熱殺菌し、１０℃に冷却して殺菌調乳液を得た。
殺菌調乳液における全固形分は１１質量％、無脂乳固形分は９．３質量％である。
［乳酸菌添加および発酵工程］
得られた殺菌調乳液に乳酸菌スターター１６８ｇ、およびビフィズス菌５０４ｇを接種し、３８℃でｐＨ４．７になるまで発酵させた。殺菌調乳液に対する乳酸菌の添加量は３×１０^６ＣＦＵ／ｍｌ、ビフィズス菌の添加量は３×１０^７ＣＦＵ／ｍｌである。
発酵により生成したカードを破砕し、１０℃に冷却して発酵物約２８０００ｇを得た。発酵時間は約５時間であった。得られた発酵物のｐＨ（１０℃）は４．７であった。
［加熱処理工程］
こうして得られた発酵物を、実施例２と同じ加熱方法で６０℃、２分間の加熱条件で加熱処理した後、４５℃に冷却して加熱後発酵物を得た。
［濃縮工程］
得られた加熱後発酵物に対して、実施例２と同じ限外ろ過膜を用い、液温が４０〜４５℃の状態で限外ろ過処理を行い、得られたビフィズス菌入り濃縮発酵乳８４００ｇを１０℃まで冷却した。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．４２、ビフィズス菌の生菌数（ビフィズス菌数）は４．５×１０^３ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例１と同様にして保存試験を行った。 <Comparative Example 5>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. This example is significantly different from Example 2 in that bifidobacteria were added before the fermentation process and no bifidobacteria were added after the heat treatment process.
[Preparation of sterilized milky lotion]
As the milk raw material, 2673 g of skim milk powder and 980 g of cream were used. These were added to 23654 g of water, heated to 65 ° C. and dissolved, and then homogenized at a pressure of 15 MPa. The obtained solution was sterilized by heating at 90 ° C. for 10 minutes and cooled to 10 ° C. to obtain a sterilized milky lotion.
The total solid content in the sterilized milky lotion is 11% by mass, and the non-fat milk solid content is 9.3% by mass.
[Lactic acid bacteria addition and fermentation process]
The obtained sterilized milky lotion was inoculated with 168 g of lactic acid bacteria starter and 504 g of bifidobacteria and fermented at 38 ° C. until pH 4.7. The amount of lactic acid bacteria added to the sterilized milky lotion is 3 × 10 ⁶ CFU / ml, and the amount of bifidobacteria added is 3 × 10 ⁷ CFU / ml.
The card | curd produced | generated by fermentation was crushed, and it cooled at 10 degreeC, and obtained about 28000g of fermented products. The fermentation time was about 5 hours. The pH (10 ° C.) of the obtained fermented product was 4.7.
[Heat treatment process]
The fermented product thus obtained was heat-treated at 60 ° C. for 2 minutes under the same heating method as in Example 2, and then cooled to 45 ° C. to obtain a fermented product after heating.
[Concentration process]
For the obtained fermented product after heating, the same ultrafiltration membrane as in Example 2 was used, and ultrafiltration was performed in a state where the liquid temperature was 40 to 45 ° C., and 8400 g of concentrated fermented milk containing bifidobacteria obtained. Was cooled to 10 ° C. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.42, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 4.5 × 10 ³ CFU / ml.
About the obtained concentrated fermented milk, the storage test was done like Example 1. FIG.

＜比較例６＞
図６に示す手順でビフィズス菌入り濃縮発酵乳を製造した。本例が比較例５と大きく異なる点は、発酵物に加熱処理を行わずに濃縮工程を行った点である。
すなわち、比較例５と同様に、乳酸菌とビフィズス菌を添加した後に発酵を行って得られた発酵物を４５℃に加温したものに対して、実施例２と同じ限外ろ過膜を用い、液温が４０〜４５℃の状態で限外ろ過処理を行い、得られたビフィズス菌入り濃縮発酵乳８４００ｇを１０℃まで冷却した。濃縮倍率は約３倍である。
得られたビフィズス菌入り濃縮発酵乳の無脂乳固形分は１５．８％、粘度（１０℃）は４０００ｍＰａ・ｓ以上、ｐＨ（１０℃）は４．１４、ビフィズス菌の生菌数（ビフィズス菌数）は２．３×１０^７ＣＦＵ／ｍｌであった。
得られた濃縮発酵乳について、実施例１と同様にして保存試験を行った。 <Comparative Example 6>
Concentrated fermented milk containing bifidobacteria was produced by the procedure shown in FIG. The point that this example is greatly different from Comparative Example 5 is that the concentration step was performed without performing the heat treatment on the fermented product.
That is, as in Comparative Example 5, the same ultrafiltration membrane as in Example 2 was used for the fermented product obtained by performing fermentation after adding lactic acid bacteria and bifidobacteria to 45 ° C. Ultrafiltration was performed in a state where the liquid temperature was 40 to 45 ° C, and 8400 g of the concentrated fermented milk containing bifidobacteria thus obtained was cooled to 10 ° C. The concentration factor is about 3 times.
The obtained concentrated fermented milk containing bifidobacteria has a solid content of non-fat milk of 15.8%, a viscosity (10 ° C.) of 4000 mPa · s or more, a pH (10 ° C.) of 4.14, and a viable count of bifidobacteria (bifidos). The number of bacteria) was 2.3 × 10 ⁷ CFU / ml.
About the obtained concentrated fermented milk, the storage test was done like Example 1. FIG.

＜結果＞
図９、１０の結果より、実施例２では７日間の保存期間中においてビフィズス菌数の減少はなく、１４日間の保存後も、１×１０^６ＣＦＵ／ｍｌ以上のビフィズス菌数を維持していた。これらの結果より、保存中における乳酸菌による酸の生成が抑制された結果、ビフィズス菌の良好な生残性が得られたと考えられる。
比較例４は、発酵工程後に加熱処理工程を行わずにビフィズス菌を添加した例である。保存開始直後からビフィズス菌数が減少した。またｐＨは、保存開始から７日後には３．９．０にまで大きく低下した。これらの結果より、保存開始後から乳酸菌による酸生成量が多くてｐＨの低下が大きいために、ビフィズス菌数の減少が生じやすかったと考えられる。
比較例５は、発酵前に乳酸菌とビフィズス菌を添加し、発酵後に加熱処理して濃縮工程を行った例であるが、製造直後の状態で既にビフィズス菌数が低い。ｐＨの推移は実施例２とほぼ同等であった。保存中における乳酸菌による酸の生成は抑制されたものの、加熱処理工程においてビフィズス菌の減少が生じたと考えられる。
比較例６は、発酵前に乳酸菌とビフィズス菌を添加し、発酵工程後に加熱処理工程を行わずに濃縮した例である。保存開始直後からビフィズス菌数が減少した。またｐＨは、保存開始から１日後には４．０付近にまで大きく低下していた。ｐＨの低下が大きく、ビフィズス菌数の減少が生じやすかったと考えられる。また比較例６は比較例３と比べて保存開始直後のｐＨの値が低い。比較例６では、膜処理法による濃縮工程において加熱後発酵物が４０〜４５℃で２時間程度加温されたため、該濃縮工程でのｐＨ低下が大きかったためと考えられる。 <Result>
9 and 10, in Example 2, there was no decrease in the number of bifidobacteria during the storage period of 7 days, and the number of bifidobacteria of 1 × 10 ⁶ CFU / ml or more was maintained even after storage for 14 days. It was. From these results, it is considered that good survival of Bifidobacteria was obtained as a result of the suppression of acid production by lactic acid bacteria during storage.
Comparative Example 4 is an example in which bifidobacteria were added without performing the heat treatment step after the fermentation step. The number of bifidobacteria decreased immediately after the start of storage. Further, the pH was greatly reduced to 3.9.0 after 7 days from the start of storage. From these results, it is considered that the number of bifidobacteria was likely to decrease because the amount of acid produced by lactic acid bacteria was large after the start of storage and the pH was greatly reduced.
Comparative Example 5 is an example in which lactic acid bacteria and bifidobacteria were added before fermentation, and heat treatment was performed after fermentation to perform the concentration step. However, the number of bifidobacteria is already low immediately after production. The change in pH was almost the same as in Example 2. Although the production of acid by lactic acid bacteria during storage was suppressed, it is considered that the reduction of bifidobacteria occurred in the heat treatment process.
Comparative Example 6 is an example in which lactic acid bacteria and bifidobacteria were added before fermentation and concentrated without performing a heat treatment process after the fermentation process. The number of bifidobacteria decreased immediately after the start of storage. The pH was greatly reduced to around 4.0 one day after the start of storage. It is thought that the decrease in pH was large and the number of bifidobacteria was likely to decrease. Comparative Example 6 has a lower pH value immediately after the start of storage than Comparative Example 3. In Comparative Example 6, since the fermented material after heating was heated at 40 to 45 ° C. for about 2 hours in the concentration step by the membrane treatment method, it is considered that the pH drop in the concentration step was large.

＜官能試験＞
実施例２、比較例４〜６で得られたビフィズス菌入り濃縮発酵乳を紙カップに充填した後、１０℃で７日間保管して安定させたものを官能評価用の試料とした。該試料をパネル８人に試食してもらい、酸味、ビフィズス菌臭、美味しさに関して、それぞれ１０段階（１点〜１０点）で評価点をつけた。各試料について８人の評価点の平均点を算出した。
結果を表３に示す。
（酸味の評価点の基準）
「強い酸味」：１０点。
「弱い酸味」：１点。
（ビフィズス菌臭の評価点の基準）
「ビフィズス菌臭が強い」：１０点。
「ビフィズス菌臭が弱い」：１点。
（美味しさの評価点の基準）
「美味しい」：１０点。
「美味しくない」：１点。 <Sensory test>
After filling the fermented milk containing bifidobacteria obtained in Example 2 and Comparative Examples 4 to 6 into a paper cup, the sample was stored and stabilized at 10 ° C. for 7 days to obtain a sample for sensory evaluation. The panel was sampled by 8 panelists and scored in 10 stages (1 to 10 points) for acidity, bifidobacterial odor and taste. The average score of 8 evaluation points was calculated for each sample.
The results are shown in Table 3.
(Criteria for evaluation of acidity)
“Strong acidity”: 10 points.
"Weak acidity": 1 point.
(Criteria for evaluation score of bifidobacterial odor)
“Strong bifidobacterial odor”: 10 points.
“Bifidus odor is weak”: 1 point.
(Standard of evaluation point of deliciousness)
“Delicious”: 10 points.
"It's not delicious": 1 point.

表３の結果より、実施例２で得られたビフィズス菌入り濃縮発酵乳は、風味が良好であり、美味しさも良好であった。
これに対して、発酵後に加熱処理を行わなかった比較例４、６で得られたビフィズス菌入り濃縮発酵乳は、酸味が強く、ビフィズス菌臭が強く、美味しさが劣る。
またビフィズス菌を発酵前に添加し、発酵後に加熱処理を行った比較例５で得られたビフィズス菌入り濃縮発酵乳は、図９に示されるように、実施例２よりもビフィズス菌数が少ないにもかかわらず、実施例２よりビフィズス菌臭が強く、美味しさが劣る。 From the results in Table 3, the concentrated fermented milk containing bifidobacteria obtained in Example 2 had good flavor and good taste.
On the other hand, the concentrated fermented milk containing bifidobacteria obtained in Comparative Examples 4 and 6 in which heat treatment was not performed after fermentation has a strong acidity, a strong bifidobacteria odor, and a poor taste.
In addition, the concentrated fermented milk containing bifidobacteria obtained in Comparative Example 5 in which bifidobacteria were added before fermentation and heat-treated after fermentation had a smaller number of bifidobacteria than Example 2 as shown in FIG. Nevertheless, the bifidobacteria odor is stronger than in Example 2 and the taste is inferior.

Claims

A method for producing concentrated fermented milk containing bifidobacteria,
A fermentation process in which a lactic acid bacteria starter is added to a sterilized milky lotion containing milk ingredients and fermented;
A heat treatment step of heat-treating the fermented product obtained by the fermentation;
A concentration step of concentrating the fermented material after the heat treatment by a membrane separation method ;
The conditions of the heat treatment step are as follows: a heating temperature of 53 to 65 ° C., a heating time of 1 minute or more, a number of lactic acid bacteria after the heat treatment of 1 × 10 ⁷ CFU / ml or more, and a heat treatment at 45 ° C. for 4 hours after the heat treatment. The pH when the heat retention test is performed is 4.10 to 4.46, and the condition is higher than the pH when the heat retention test is performed without performing the heat treatment,
A method for producing concentrated fermented milk containing bifidobacteria, wherein bifidobacteria are added to the fermented product after the heat treatment after the heat treatment step and before the concentration step.

2. The method for producing concentrated fermented milk containing bifidobacteria according to claim 1, wherein the number of lactic acid bacteria added to the sterilized formula in the fermentation step is 1 × 10 ⁵ to 1 × 10 ¹⁰ CFU / ml.

The concentrated fermented milk containing bifidobacteria according to claim 1 or 2 , wherein the number of bifidobacteria when the concentrated fermented milk containing bifidobacteria is stored at 10 ° C for 14 days after production is 1 x 10 ⁶ CFU / ml or more. Manufacturing method.

The method for producing concentrated fermented milk containing bifidobacteria according to any one of claims 1 to 3 , wherein the bifidobacteria is Bifidobacterium longum ATCC BAA-999 strain.