JPH06245692A - Production of frozen fruit having fresh taste - Google Patents

Abstract

PURPOSE:To obtain a fruit product capable of retaining texture of fresh fruit without freezing the fruit hard like ice even at freezing temperature by making sugar content permeate into the fruit. CONSTITUTION:Fruit is immersed in a neutral or acidic aqueous solution of sugar containing an organic acid and/or its salt under normal pressure without heating and then frozen to produce the objective frozen fruit.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention provides a freshness that does not freeze as hard as ice even when it is frozen and maintains appropriate flexibility, and therefore can be easily used in the frozen state without thawing. The present invention relates to a method for producing a frozen fruit having various raw fruit shapes, textures and flavors. The frozen fruit can be used as it is or as a food material for various frozen desserts.

[0002]

2. Description of the Related Art There are various techniques for using fruits as food materials, but when fruits are used together with frozen desserts such as ice cream and sorbet, conventionally,
Crush fruit juice and pulp and mix with other food ingredients,
For example, it was made into a strawberry puree or a fruit sauce after being subjected to a treatment such as concentration. Or something like strawberry jam or orange marmalade using pulp. However, all of these processed fruit products have lost the original form of the fruit, and their texture and flavor are completely different from those of fresh raw fruit.

On the other hand, in order to make the best use of the original shape, flavor and texture of fruits, for example, fresh strawberries may be sliced into thin pieces and coexist with frozen desserts. Except when eaten immediately after cooking, such as a handmade product, in this case, raw strawberries contain about 85 to 90% by weight of water like other fruits, so they are frozen together with freezing and extremely frozen like ice. Although it becomes hard and its shape can be retained, it cannot be chewed with teeth as it is, and the texture and physical properties of the surrounding frozen dessert become remarkably uncomfortable. Even if frozen fruits are mixed in frozen desserts such as sherbet where ice and water coexist, the fruits will thaw and produce a large amount of drip. It has a soft texture. Therefore, there is a drawback in that the original flavor and texture of the fruit cannot be fully utilized even if the fruit is used as a raw or frozen product for a frozen dessert.

By the way, it is known that the freezing temperature of a solution containing a high concentration of solute such as saccharide or electrolyte is lowered by its freezing point lowering action. Many products utilizing this principle are found in the food field. For example, the above-mentioned purees, jams, and candied foods also contain a large amount of sugars, so that the freeze resistance is improved. These foods and food ingredients are
It can be regarded as belonging to the intermediate moisture region,
Generally, normal fruits have a sugar content (Brix, the same below) of 5 to 2
0, water content is 75 to 90% by weight, while sugar content is about 4
It is 0 or more, and the water content is reduced to 30 to 60% by weight. Such high-sugar and low-moisture fruit products have various freeze-resistant properties such as contamination prevention and spoilage prevention, have freezing resistance to maintain fluidity even at low temperatures, or maintain fruit shape, and are used for various purposes. However, the original color tone, flavor, texture, and freshness of the fruit are almost completely lost, such as the fact that the sweetness is extremely increased and the texture becomes softer than that of the fruit itself, and the artificial fruit that is a natural product is used. Has a strong image as a processed product.

Regarding the method for producing foods containing a high concentration of sugar as described above, for example, Japanese Patent Publication No. 4-7183, JP-A-58-36365, and US Pat. No. 5,075,12.
No. 4, for example. According to Japanese Patent Publication No. 4-7183, sugar-injected fruit products having a water-soluble solid content of about 32 to 58% by weight are obtained by immersing fruits in a heated sugar aqueous solution having a constant concentration. In 58-36365, a fruit is immersed in an aqueous sugar solution in multiple stages to inject sugar, and a water-soluble solid content is about 32 to 55% by weight, and an amorphous product is obtained even at -18 ° C. However, such a product has the above-mentioned drawbacks and lacks the original freshness of the fruit.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a fruit product in which sugar content is infiltrated into a fruit and the texture of raw fruit is retained without being frozen hard like ice even at a freezing temperature. To aim.

[0007]

According to the present invention, it is possible to efficiently solve the above problems by immersing fruit in a specific sugar aqueous solution to which an organic acid and / or its salt is added without heating and then freezing. It was made based on the knowledge of. That is, the present invention relates to a frozen fruit characterized by immersing the fruit under normal pressure without heating in a neutral or acidic aqueous sugar solution containing an organic acid and / or a salt thereof, and then freezing the same. Providing a manufacturing method.

In the present invention, the fruit used as a raw material may be raw fresh ripe fruit or frozen fruit generally distributed, regardless of the variety, and may be in the form or form not heat-treated. There is no particular limitation as long as it is not broken or processed into an appropriate form other than paste. Specific fruits include berries such as strawberries, melons, blueberries, raspberries, cranberries, pineapple, papaya, mango, mangosteen, durian,
Examples include kiwi, banana, peach (yellow peach, white peach), cherry, apricot, apple, pear, loquat, orange, grapefruit and the like. Especially, strawberries, melons and berries are preferable. Such fruits, in order to facilitate the permeation treatment of sugar components, etc., as appropriate, remove the skin, stem and core, or scratch the surface with needle holes or slits, or slice or cut into a desired size, It is preferable to remove foreign substances and other germs by a usual method for food production, for example, a treatment such as washing. Further, in the case of frozen fruits, the frozen fruits can be thawed at room temperature or refrigeration temperature or by other appropriate thawing means, and the generated drip can be separated or used without separation.

Next, the present invention is characterized in that such a fruit is immersed under normal pressure in a neutral or acidic aqueous sugar solution containing an organic acid and / or a salt thereof without heating. The types of sugar that can be used include glucose (glucose), fructose, galactose, arabinose, xylose and other monosaccharides, maltose (maltose),
There are disaccharides such as sucrose (sucrose) and lactose (lactose), various oligosaccharides such as malto or isomaltooligosaccharides, xylooligosaccharides, polysaccharides and their decomposition products (dextrin, raffinose, stachyose, etc.). In addition, alcohol-based substances such as polyhydric alcohols such as glycerin, pentaerythritol, mannitol, xylitol, and sorbitol or sugar alcohols can be included therein. Such saccharides may be used alone or in combination of two or more, preferably in an aqueous solution having a sugar concentration of 30 to 90% by weight, more preferably 50 to 75% by weight. For example,
Commercial glucose dextrose fructose syrup (fructose: 42% in addition to glucose and oligosaccharides, Brix 70) and fructose glucose syrup (fructose: 55% in addition to glucose and oligosaccharides,
Brix 75) and the like can be preferably used in the present invention.

In the present invention, the pH of the sugar aqueous solution is adjusted to neutral or acidic. The pH may be adjusted using an appropriate means, but preferably using an organic acid and / or a salt thereof used in food production, or together with a buffer, preferably pH 1 to 7, desirably pH 2.0 to 4,
More preferably pH 2.0 to 3.9, most preferably p
Adjust to H2.5-3.5. Various organic acids can be used as the organic acid. Of these, carboxylic acids having 3 to 6 carbon atoms such as lactic acid, succinic acid, fumaric acid, malic acid, tartaric acid and citric acid are preferable. Examples of salts of organic acids include sodium, potassium, calcium, magnesium and the like. Among these, sodium salt or potassium salt of lactic acid, malic acid, tartaric acid or citric acid is preferable. Further, a part of the constituent carboxylic acid is esterified, and the organic acid may be, for example, a lower alcohol ester,
Further, a salt of the ester may be used. The amount of such organic acid and / or salt thereof added is 0.01 to 20% by weight, preferably 0.1, in view of the object of the present invention.
It may be added to the sugar aqueous solution so as to have a concentration of 10% by weight.

In the present invention, an aqueous solution of neutral or acidic sugar containing an organic acid and / or a salt thereof may further contain an interfacial tension reducing agent. The interfacial tension reducing agent referred to here is one that dissolves or disperses in the sugar aqueous solution, has an action of promoting the wetting of the fruit tissue by the sugar aqueous solution and accelerating the penetration of the solute component into the fruit tissue,
Ethanol or hydrophilic surfactants can be used. In addition to drinking ethanol, liqueur liquor, sherry liquor, wine and various fruit liquors may be used as ethanol. Further, as the hydrophilic surfactant, sucrose fatty acid ester, polyglycerin fatty acid ester (average degree of polymerization:
4-15, preferably 6-10) can be used, and those having an HLB of 10 or more are preferable. Specific examples include sucrose monostearate, sucrose monopalmitate, sucrose monolaurate, sucrose monooleate, sucrose dioleate, etc., and tetraglycerin monolaurate, hexaglycerin monopalmitate, hexaglycerin monooleate, deca. Examples thereof include glycerin monostearate, decaglycerin dilaurate, decaglycerin distearate and decaglycerin dioleate. Such an interfacial tension lowering agent takes into account its action and role,
It may be added to the sugar aqueous solution so as to have a concentration of 01 to 10% by weight, preferably 0.1 to 5% by weight. 0.01
If it is less than 10% by weight, the desired effect cannot be expected, and if it exceeds 10% by weight, the flavor of the product is adversely affected.

The basic steps according to the present invention are generally as described below, but these are merely examples and do not limit the present invention. First, fresh fruit or frozen fruit as it is or if necessary, the above-mentioned washing treatment,
It is cut into dies and other shapes, surface-treated, thawed, drip-separated, removed, etc., and used as the raw material. This is immersed in an appropriate container (bath) filled with an aqueous solution having a sugar concentration of 30 to 90 wt% whose pH is adjusted to neutral or acidic by adding an organic acid and / or a salt thereof,
If necessary, appropriate treatments such as shaking and stirring promote the water from the fruit, the exudation of the extract into the solution, and the penetration of solutes (sugars, organic acids, salts thereof, etc.) into the fruit tissue. The soaking treatment generally impregnates a large amount of solute into the fruit if it is carried out at high temperature for a long time, but at the same time, the water content in the fruit is exuded more than necessary due to the osmotic pressure of the solution, which causes the so-called contraction phenomenon of the fruit volume. Wake up. This phenomenon is not an exception as in the case where the whole fruit is used as a raw material as it is, and it is not preferable for the purpose of the present invention to obtain a fruit product having a fresh flavor.

Therefore, the immersion treatment of the present invention is carried out under normal pressure without heating the raw material and the sugar aqueous solution. The immersion time is generally 0.5 to 20 hours, preferably 1 to 10 hours, although it is affected by the form of the raw material, the temperature of the aqueous solution, the solute concentration, and the like. The sugar aqueous solution containing the interfacial tension reducing agent is effective in shortening the immersion time. When the soaking time exceeds 20 hours, for example, when strawberry is used as a raw material, solute is most difficult to be impregnated, that is, one whole strawberry is used as a raw material and treated at 0 ° C. with an aqueous solution having a sugar concentration of 40% by weight. However, the sugar content of the obtained frozen strawberries is 30
Which is unfavorable since it impairs the fresh flavor of raw strawberries. After the immersion treatment, the immersion product and the aqueous solution of the bath are separated by a conventional method, and the immersion product can be frozen by, for example, a method such as IQF (individual quick freezing) treatment to obtain the frozen fruit intended by the present invention. . In this way, the sugar content is 2
0-30, water content 65-75% by weight and thickness 7
It is preferable to obtain a frozen fruit having a physical property that the hardness of the frozen fruit of mm is 0.5 to 2 kg as a cutting load as measured by a rheometer. Next, the present invention will be described with reference to examples.

[0014]

【Example】

Example 1 Freshly harvested ripe strawberries (10 kg) obtained by removing the cores and cores were used as raw materials and had a citric acid content of 0.5% by weight.
Glucose-fructose syrup having a sugar content of 70% by weight, the H of which was adjusted to 2.2 (manufactured by Nippon Shokuhin Kogyo Co., Ltd., "Fuji Cract F-1"
00 ", sugar content (Brix, the same applies below): 70, fructose: 45% as a sugar component, and glucose and oligosaccharides) in 10 liters of an aqueous solution under normal pressure at room temperature for 5 hours. During the dipping treatment, the solution was stirred gently to make the concentration distribution of the solute in the bath solution as uniform as possible. Then, the soaked product and the sugar aqueous solution were separated to obtain 7.5 kg of the soaked product, and this was further rapidly frozen at -40 ° C to produce frozen strawberries.
The frozen strawberry maintains the shape of the whole raw strawberry used as a raw material and can be easily scraped or scooped with a spoon. Sugar content: 25, water content: 70% by weight, hardness: 1.
It was 0 kg (sugar content of raw material: 7.1, moisture content: 9
0.1% by weight, hardness: 0.8 kg at room temperature). The sugar content is measured by a conventional method using a refractometer, the water content is calculated by measuring the loss on drying (treatment at 110 ° C. for 3 hours) of the sample, and the hardness is measured by a rheometer (“Fudo Kogyo Co., Ltd.”). Hood rheometer J type ") at room temperature using a toothed push rod adapter (fixed blade with a blade edge angle of 45 ° C) and a freezer (-18
Frozen strawberries or fresh strawberries immediately after being taken out from (.degree. C.) are sliced to a thickness of 7 mm, the sample table on which the sliced pieces are placed is raised at a speed of 6 cm / min, and the load when the sample is cut by the fixed blade Was measured. In addition, when the product of the present invention (frozen strawberries) and fresh raw strawberries were compared by a sensory test by 10 expert panels, the product of the present invention showed that sweetness, sourness, color tone, texture and flavor were similar to those of raw strawberries. It was evaluated and revealed to have excellent suitability as a food or food material.

Example 2 1 kg of frozen strawberries, which had been stored by freezing the strawberry halved in the longitudinal direction at -18 ° C, was thawed at 0 ° C for about 8 hours, and 300 g of the resulting drip was separated. . The obtained thawed strawberry 700 g was adjusted to pH 7.0 with a phosphate buffer solution containing 8.5% by weight of sodium citrate and 1.5% by weight of sodium lactate, and maltose having a sugar content of 50% by weight: Dextrose = 1: 1 (weight ratio) aqueous solution (sugar content:
50) Immersed in 1 liter under normal pressure at 4 ° C. for 15 hours. The aqueous solution was separated to obtain 650 g of the immersion product. Further, this was subjected to IQF treatment at −30 ° C. for 1 hour to produce a frozen strawberry. The frozen strawberry retains the shape of the raw material, and the pulp portion does not have a texture that is not too soft, but has flexibility that can be scraped off with a spoon. Sugar content measured by the same method as in Example 1: 27, water content The ratio was 68% by weight and the hardness was 1.2 kg. Further, in the same sensory test as in Example 1,
90% of the evaluations were that the color tone, texture and flavor were all comparable to fresh raw strawberry.

Example 3 5 kg of frozen strawberry obtained by freezing and storing strawberry at -18 was thawed in the same manner as in Example 2. Drip caused by this 1.
3 kg, together with 3.7 kg of thawed strawberries, contained 3.5% by weight of sodium malate and 1.0% by weight of tartaric acid, and the pH was adjusted to 5.5. A sorbitol aqueous solution having a sugar content of 80% by weight (sugar content: 80) In addition to 15 liters, under normal pressure, 0
The thawed strawberries were soaked at 20 ° C. for 20 hours. Then, the soaked product and the aqueous sugar solution were separated to obtain 4.5 kg of the soaked product, which was further subjected to IQF treatment at -30 ° C to produce a frozen strawberry. The frozen strawberry retains the form of the raw material and has appropriate flexibility so that it can be easily eaten, and the sugar content is 23 and the water content is 73.
% By weight, hardness: 0.8 kg, and its color tone and texture and flavor when the frozen strawberry was mixed with ice cream were comparable to those of raw strawberry. It was a thing. The measurement of physical properties and sensory evaluation were performed by the methods described in Example 1.

Example 4 In Example 3, hexaglycerin monooleate (HLB-10.5, Taiyo Kagaku Co., Ltd., "polyglycerin ester Q-17F") was further added to the sorbitol aqueous solution.
1.5% by weight added (pH 5.5, sugar content: 80)
In the same manner, under normal pressure, soaked at 0 ° C. for 15 hours.
Frozen strawberries were produced by QF treatment. This one has a sugar content of 2
4. Moisture content: 72% by weight, hardness: 0.7 kg, it had appropriate flexibility, and the color tone, texture and flavor were similar to those of raw strawberry.

Example 5 In Example 2, the aqueous sugar solution was treated with tripotassium citrate.3.
5% by weight and 1.0% by weight of sucrose extremely hardened beef tallow fatty acid monoester (HLB = 19.0, "DK Ester SS" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) were prepared and the pH was adjusted to 7.0. Was replaced with a maltose: dextrose = 1: 1 (weight ratio) aqueous solution (sugar content: 50) having a sugar content of 50% by weight, and the thawed strawberry was similarly immersed under atmospheric pressure at 4 ° C. for 11 hours, and I
Frozen strawberries were produced by QF treatment. This one has a sugar content of 2
8. Water content: 68% by weight, hardness: 1.2 kg, which had appropriate flexibility, color tone, texture and flavor similar to those of fresh raw strawberries.

Comparative Example 1 In the procedure described in Example 1, no citric acid was added,
Using glucose-fructose syrup with the same sugar content without adjusting the pH,
The raw strawberry was soaked under the same conditions except that it was soaked for 24 hours, and the frozen strawberry was manufactured by the same rapid freezing process. It retains its shape and can be easily scooped with a spoon, but the pulp is extremely soft and has a sugar content of 4
It increased to 0, the water content decreased to 54% by weight, and the hardness was only 0.5 kg or less. Moreover, when compared with fresh raw strawberries by sensory evaluation, it was found that the sweetness was too strong and there was no appropriate sourness, and there was no answer to evaluate freshness in terms of flavor and texture.

Example 6 A peeled pineapple was peeled, cored and sliced to a thickness of 8 mm, 1 kg was weighed, and this contained 0.2% by weight of citric acid and the pH was adjusted to 3.5. It was immersed at room temperature for 6 hours in 1 liter of a sugar aqueous solution (sugar content: 65) having a content of 65% by weight (details: glucose: 60% by weight, sugar: 5% by weight). During the dipping treatment, gentle stirring was appropriately performed in order to make the sugar concentration distribution of the aqueous solution as uniform as possible.
Then, the sugar aqueous solution was separated to obtain 800 g of the immersion product. This was subjected to IQF treatment at -40 ° C to prepare frozen pineapple, which was further stored in a freezer at -18 ° C. The frozen pineapple retained the form of the raw material, had a sugar content of 24, a water content of 71% by weight, and a hardness of 1.5 kg, and had such a softness that it could be immediately eaten without being thawed from the freezer. Moreover, the color tone, texture and flavor were about the same level of preference as compared with the raw materials.

Example 7 1 kg of frozen melon balls (a melon molded into a spherical shape and frozen) contained 0.5% by weight of malic acid and had a pH of 3.
After adjusting to 0, decaglycerin monolaurate (HL
B: 15.5, "polyglycerin ester Q-12S" (manufactured by Taiyo Kagaku Co., Ltd.) 3.5% by weight was added, and a dissolved sugar content of 75% by weight of fructose glucose liquid sugar (manufactured by Nippon Shokuhin Kako Co., Ltd.) , "Fuji Cruct H-100", sugar content: 75,
Fructose as sugar component: 55%, and glucose and oligosaccharides were included in 1 liter of an aqueous solution. During the dipping treatment, gentle stirring was appropriately performed in order to make the sugar concentration distribution of the aqueous solution as uniform as possible. Then, the sugar aqueous solution was separated to obtain 800 g of the immersion product. This-
IQF treatment was performed at 40 ° C., and further stored in a freezer at −18 ° C. The frozen melon balls retained the form of the raw material, had a sugar content of 26, a water content of 71% by weight, and a hardness of 1.1 kg, and had such softness that it could be taken out from the freezer and immediately eaten without thawing. Moreover, the color tone, texture and flavor were about the same level of preference as compared with the raw materials.

Example 8 In Example 7, when decaglycerin monolaurate was not added and the other conditions were the same, the immersion time was 7 hours and the yield of the immersion product was 835 g and the sugar content was 2
3, water content 74% by weight, hardness: 1.8 kg, when immersion time: 10 hours, yield of immersion product: 805 g, sugar content:
26, water content 71% by weight, hardness: 1.2 kg.

Example 9 1 kg of frozen blueberries contains 1.5% by weight of succinic acid and 5.0% by weight of sodium succinate, and has a pH of 2.5.
After adjusting to 0.2% by weight of drinking alcohol and sucrose extremely hardened beef tallow fatty acid monoester (HLB = 19.
0, "DK Ester SS" manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
0.3 wt% was added, and the mixture was immersed in 2 liters of an aqueous solution of maltooligosaccharide having a sugar content of 50 wt% (sugar content: 50) under normal pressure at room temperature for 9 hours. During the dipping treatment, gentle stirring was appropriately performed in order to make the sugar concentration distribution of the aqueous solution as uniform as possible. Then, the sugar aqueous solution was separated to obtain 900 g of the immersion product. This was subjected to IQF treatment at -40 ° C and further stored in a freezer at -18 ° C. The frozen blueberries retain the form of the raw material, sugar content: 25, water content: 70% by weight, hardness: 2.
The weight was 0 kg, which was so soft that it could be taken out from the freezer and immediately eaten without thawing. In addition, the color tone and texture were almost the same as those of the raw materials. When the alcohol and the sucrose extremely hardened beef tallow fatty acid monoester were not added and the other treatment conditions were the same, a dipping time of 13 hours was required to obtain the same sugar content and water content.

[0024]

EFFECTS OF THE INVENTION The frozen fruit obtained by the method of the present invention maintains its original form and has a freezing temperature (-18 ° C).
Despite being cooled to the vicinity, it is soft enough not to freeze like ice, for example, it can be crushed even immediately after taking it out from the freezer,
It can be easily cut with a spoon and used for food.
Further, the product of the present invention has an appropriate sweetness (sugar content: 20 to 30) that is not too sweet even when mixed in a frozen dessert, and has a water content of 65 to 7
5% by weight, less than the water content of raw fruits (eg about 90% by weight for raw strawberries) but much higher than conventional sugar infusions (eg 40-60% by weight), Regarding the texture, for example, a hardness of 7 mm is 0.5 to 2 kg as a cutting load with a rheometer, and a hardness of raw fruits (for example, a cutting load of 0.8 to 0.8 at the room temperature of raw strawberry).
1.3 kg), and its flavor and color were very similar to those of fresh raw fruits.

Claims (7)

[Claims] 1. A process for producing a frozen fruit, which comprises immersing the fruit under normal pressure without heating it in a neutral or acidic aqueous sugar solution containing an organic acid and / or a salt thereof, and then freezing the same. . 2. The method according to claim 1, wherein the fruit is obtained by thawing frozen fruit and removing drip. 3. The method according to claim 1 or 2, wherein the organic acid is one or more selected from the group consisting of lactic acid, malic acid, tartaric acid and citric acid. 4. The method according to claim 1, wherein the aqueous sugar solution has a pH of 2.0 to 3.9. 5. The method according to claim 1, wherein the aqueous sugar solution further contains an interfacial tension reducing agent. 6. The interfacial tension reducing agent is ethanol or HLB.
The method according to claim 5, wherein the method is at least one selected from the group consisting of 10 or more sucrose fatty acid esters and HLB of 10 or more polyglycene fatty acid esters. 7. Frozen fruit has a sugar content of 20 to 30 and a water content of 65.
75% by weight and hardness is 0.5 to 2 kg (7 mm thickness) as a cutting load when measured by a rheometer.
7. The method according to any one of 6 to 6.