ES2331827B1 - PROCEDURE FOR THE ELABORATION OF MILK FERMENTED WITH ELEVATE CONTAINED IN PREBIOTIC OLIGOSACARIDS, MILK FERMENTED AS SO OBTAINED. - Google Patents

Abstract

Milk making procedure fermented with high content of prebiotic oligosaccharides, fermented milk thus obtained.

The present invention describes a process of elaboration of new dairy products of fermented milk (yogurt, kefir or yogurt with bifidobacteria) high in prebiotic carbohydrates originated during a process of Enzymatic hydrolysis of lactose prior to the fermentation process. The resulting product provides, in addition to the qualities of fermented milk, the prebiotic properties of galactooligosaccharides originated since the amounts of these present in the final product ranges from 1.5 to 3.0 g / 100 ml, which which means tripling the usual content in milks traditional fermented. Said galactooligosaccharide content allows a consumption of fermented milk in moderate quantities Provide a prebiotic effect.

Description

Milk making procedure fermented with high content of prebiotic oligosaccharides, fermented milk thus obtained.

Technical sector

The present invention falls within the sector of functional foods and the dairy industry, more specifically to obtain fermented milks with high Prebiotic content.

State of the art

Currently the interest of consumers for foods that provide beneficial health effects, In addition to the supply of nutrients they contain, it has led to dairy industry to the development of fermented milks to which they incorporate functional ingredients. Among those ingredients, the so-called prebiotics stand out, defined as those ingredients that are not digested and reach the colon where they stimulate the growth or activity of a limited number of bacteria which are considered beneficial for health (Gibson G.R, Roberfroid, M.B Dietary modulation of the human colonic microflora- introducing the concept of prebiotics. Journal of Nutrition 125, 1402-1412, 1995).

Among the wide variety of ingredients Prebiotics fructoologosaccharides and galactooligosaccharides they are the most studied and currently the only ones on which there is scientific evidence of its beneficial properties (Goulas, A., Tzortzis, G., Gibson, G.R. Development of a process for the production and purification of \ alpha and β-galactooligosaccharides from Bifidobacterium bifidum NCIMB 41171. Int. Dairy J., 17, 648-656, 2007). These ingredients, when taken in the diet in amounts of 5-20 g / day have clearly shown, in studies in humans, a prebiotic effect since stimulate the growth of beneficial bacteria such as bifidobacteria and lactobacilli (Parvez S., Malik, KA, Kang SA, Kim, HY, Probiotics and their fermented products are beneficial for health. Journal of Applied Microbiology, 100 (6) 1171-1185, 2006).

Other properties have also been described. healthy such as hypocholesterolemic effect, prevention of colon cancer and promoting calcium absorption (Sako, T., Matsumoto, K., & Tanaka, R. Recent progress on research and applications of non-digestible galacto-oligosaccharides. International Dairy Journal, 9, 69-80,1999; Perugino, G., Trincone, A., Rossi, M., & Moracci, M., Oligosaccharide synthesis by glycosynthases. Trends in Biotechnology, 22, 31-37, 2004; Tuohy, K. M., Rouzaud, G. C. M., Brück, W. M., & Gibson, G. R. Modulation of the human gut flora towards improved health using prebiotics- Assessment of efficacy. Current Pharmaceutical Design, 11, 75-90, 2005).

Fermented milks are dairy products obtained through the fermentation of milk, which can have been made from products obtained from milk with or without modifications in its composition by the action of suitable microorganisms and resulting in reduction pH with or without coagulation (isoelectric precipitation). Being able be the cultures of viable, active microorganisms used and abundant in the products until the date of minimum duration depending on whether they have suffered or not, a heat treatment after of the fermentation process.

The types of fermented milk differ in function of the crop (or specific crops) used for fermentation, such as:

- Yogurt : Symbiotic cultures of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus

- Yogurt Based on Alternative Crops: Crops of Streptococcus thermophilus and all species Lactobacillus .

- Acidophilus milk : Lactobacillus acidophilus .

- Kefir : Culture prepared from granules of kefir, Lactobacillus kefir , species of the genus Leuconostoc , Lactococcus and Acetobacter that grow in a close specific relationship.

Kefir granules constitute both lactose fermenting yeasts ( Kluyveromyces marxianus ) and fermentation yeasts without lactose ( Saccharomyces unisporus , Saccharomyces cerevisae and Saccharomyces exiguus ).

- Kumys : Lactobacillus delbrueckii subsp. bulgaricus and Kluyveromyces marxianus .

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Other microorganisms may be added apart from those that constitute the specific crop (or crops specific) specified above.

In turn, there are two subtypes of milk fermented concentrated and flavored. The first is a kind of fermented milk whose protein content has a minimum of 5.6% This group includes traditional products such as Stragisto (strained yogurt), Labneh, Ymer and Ylette.

Fermented flavored milks contain a  maximum 50% (w / w) of non-dairy ingredients (such as nutritional and non-nutritional carbohydrates, fruits and vegetables as well as juices, purees, pasta, preparations and preservatives derivatives thereof, cereals, honey, chocolate, nuts, coffee, spices and other natural and harmless flavoring foods) and / or flavors. Non-dairy ingredients can be added before or after fermentation (CODEX STAN 243-2003). During the elaboration of fermented milks, they originate prebiotic galactooligosaccharides in amounts ranging from 0.26 and 0.71% depending on the microorganisms used (Joung HK, Cheong WJ, Simultaneous quantitative determination of mono-, di-, tri-, tetra-, and pentasaccharides in yogurt products by a simple HPLC system with a refractive index detector. Bull. Korean Chem. Soc. 22, 1, 123-126, 2001; Lamoureux L., Roy, D., Gauthier S. F., Production of oligosaccharides in yogurt containing Bifidobacteria and yogurt cultures. J. Dairy Sci. 85, 1058-1069, 2002; Yadav, H., Jain, S, Sinha P.R .. Formation of oligosaccharides in skim milk fermented with mixed dahi cultures, Lactococcus lactis ssp. diacetylactis and probiotic strains of lactobacilli. Journal of Dairy Research, 74, 1-6. 2007. These contents are considered insufficient for moderate consumption of fermented milk (250 ml / day) provide a prebiotic effect.

In this regard and to increase the content of oligosaccharides in fermented milks that exist in the market, the procedure described in the present invention has been carried out, whereby before carrying out the fermentation process for processing of fermented milk, a process of enzymatic hydrolysis of lactose under conditions that give rise to the formation of estimated amounts of oligosaccharides, so that a moderate consumption of fermented milk (250 ml) provides a Prebiotic effect appreciable.

Description of the invention brief description

An object of the present invention constitutes it a procedure for obtaining a fermented milk with high oligosaccharide content, characterized by understanding the following stages:

a) preparation of concentrated milk with a lactose content of at least 80 g / L,

b) pasteurization,

c) cooling, preferably up to 60 ° C,

d) hydrolysis with a lactase and stirring,

e) adding liquid milk and adjusting the extract dry,

f) homogenization,

g) pasteurization,

h) addition of lactic acid ferment and / or  bifidobacteria,

i) maintenance at 40-45 ° C preferably until the desired pH is reached.

A particular case of the invention is that in the hydrolysis step of the procedure a lactase of Natural origin, from a microorganism.

Another more particular case of the invention is that the origin of lactase is a fungus, preferably Aspergillus oryzae .

Another more particular case of the invention is that the origin of lactase is a yeast, preferably Kluyveromyces lactis .

Another particular case of the invention is that in The added ferment comprises a mixture of Lactobacilli and / or Streptococci and / or bifidobacteria.

Another object of the present invention is a fermented milk made according to the process of the invention, characterized by presenting an amount of galactooligosaccharides in the final product that ranges between 1.5 and 3.0 g / 100 ml.

Detailed description

The present invention consists essentially in a new procedure to obtain a high content in oligosaccharides during the preparation of new products Fermented milk dairy (yogurt, kefir or yogurt with bifidobacteria), whose novelty lies in a hydrolysis process enzymatic prior to the fermentation process. In said hydrolysis the lactose is degraded from a commercial lactase from from different natural origins, thus freeing a D-glucose molecule and D-galactose

The advantages of the procedure of the  invention is that on the one hand, it is an economically process viable, since commonly used commercial enzymes are used in the dairy industry and the product resulting from said procedure, provides the qualities of fermented milk and the prebiotic properties of galactooligosaccharides originated after said process, since the amount of galactooligosaccharides present in the final product is greater than 1.5 g / 100 ml, which means tripling the milk content commercial fermented.

Lactase has glycosidase activities and transglycosidase so that by breaking the bond β- (1-4) between galactose and glucose due to the β-galactosidase activity, part of the released galactose binds to other lactose molecules giving place to the formation of galactooligosaccharides with activity prebiotic

To carry out the process of this invention a well concentrated milk is prepared by dissolution  of powdered milk in liquid milk or by evaporation of milk liquid so that the lactose content of the mixture is equal or greater than 80 g / L and then undergoes a process of pasteurization. Once the milk is pasteurized, it cools to reach temperatures below 60 ° C and the enzyme is added (lactase), keeping under stirring for several hours, until achieve maximum oligosaccharide production.

Once the mixture is hydrolyzed, liquid milk is added to adjust the dry extract to the percentages required according to the type of fermented milk desired, homogenized and then pasteurized. To the cooled mixture are added starter cultures whose nature will depend on the type of fermented milk that is intended to be made. In the case of traditional yogurt, commercial crops composed of Lactobacillus bulgaricus and Streptococcus thermophilus are used although other lactic bacteria such as Lactococcus casei , Lactobacillus acidophilus and different species of bifidobacteria can also be used. It is then incubated at 40-45 ° C for several hours until a pH value ranging from 4.8-3.8 is reached and taken to a cold store where it is stored at temperatures between 2-7 ° C.

The amount of galactooligosaccharides present in the final product it ranges between 1.5 and 2.0 g / 100 ml, which it means tripling the usual content in fermented milks Traditional

The main feature of this innovation is that before carrying out the fermentation process for processing of fermented milk, a process of enzymatic hydrolysis of lactose under conditions that give rise to the formation of appreciable amounts of oligosaccharides, so that a moderate consumption of fermented milk (250 ml) provides a prebiotic effect

Examples of embodiment of the invention Example 1

Powdered milk is dissolved in liquid milk until reaching a lactose content in the mixture of 250 g / L. The mixture is pasteurized at 72 ° C for 20 seconds and once cooled, 2.5 U / ml of Lactozym ( Kluyveromyces lactis lactase) is added and kept under stirring for 1.5 hours at 40 ° C. Liquid milk is then added until the total solids content is adjusted to an approximate value of 13%, homogenized and pasteurized again. Once cooled, it is inoculated with 1.5% of a culture composed of Lactobacillus bulgaricus and Streptococcus thermophilus in a 1: 1 ratio and incubated at 43 ° C for 4 hours after which it is refrigerated at 5 ° C. The content of galactooligosaccharides in the final product is 2.0 g / 100 ml.

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Example 2

The mixture of liquid milk and milk powder is prepared as in the previous example but with a final content of 200 g / L of lactose. Once pasteurized and cooled, 2.5 U / ml of Lactozym ( Kluyveromyces lactis lactase) is added and kept under stirring for 2 hours at 40 ° C. Liquid milk is then added until the total solids content is adjusted to an approximate value of 13%, homogenized and pasteurized again. Once cooled, it is inoculated with 1.5% of a culture composed of Lactobacillus bulgaricus and Streptococcus thermophilus in a 1: 1 ratio and incubated at 43 ° C for 4 hours after which it is refrigerated at 5 ° C. The content of galactooligosaccharides in the final product is 1.75 g / 100 ml.

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Example 3

Liquid milk is evaporated to a third of its initial volume and pasteurized as in the previous example. Once pasteurized and cooled, 2 U / ml of Lactozym ( Kluyveromyces lactis lactase) are added and kept under stirring for 2 hours at 40 ° C. Liquid milk is then added until the total solids content is adjusted to an approximate value of 13%, homogenized and pasteurized again. Once cooled, it is inoculated with 1.5% of a culture composed of Lactobacillus bulgaricus and Streptococcus thermophilus in a 1: 1 ratio and incubated at 43 ° C for 4 hours after which it is refrigerated at 5 ° C. The content of galactooligosaccharides in the final product is 1.50 g / 100 ml.

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Example 4

A mixture of liquid milk and milk powder with a content of 200 g / L of lactose is pasteurized and once cooled, 2.5 U / ml of lactase (from Aspergillus oryzae ) is added and kept under stirring for 2 hours at 40 ° C . Liquid milk is then added until the total solids content is adjusted to an approximate value of 13%, homogenized and pasteurized again. Once cooled, it is inoculated with 1.5% of a culture composed of Lactobacillus bulgaricus , Streptococcus thermophilus and Bifidobacterium bifidum and incubated at 43 ° C for 4 hours after which it is refrigerated at 5 ° C. The content of galactooligosaccharides in the final product is 1.70 g / 100 ml.

Claims (6)

1. Procedure for obtaining a fermented milk with high oligosaccharide content, characterized by comprising the following steps: a) preparation of concentrated milk with a lactose content of at least 80 g / L, b) pasteurization, c) cooling, preferably up to 60 ° C, d) hydrolysis with a lactase and stirring, e) adding liquid milk and adjusting the extract dry, f) homogenization, g) pasteurization, h) addition of lactic acid ferment and / or  bifidobacteria, i) maintenance at 40-45 ° C for 3-4 hours, until reaching the desired pH, preferably in the range 4.8-3.8.

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2. Method according to claim 1 characterized in that in the hydrolysis step of d) a lactase of natural origin is used, preferably from a microorganism. 3. Method according to claim 2 characterized in that the origin of the lactase is a fungus, preferably Aspergillus oryzae . Method according to claim 2, characterized in that the origin of lactase is a yeast, preferably Kluyveromyces lactis . 5. Method according to claims 1 to 4, characterized in that the ferment of h) comprises a mixture of Lactobacilli and / or Streptococci and / or bifidobacteria. 6. Fermented milk made according to the procedure of claims 1 to 5, characterized in that the amount of galactooligosaccharides present in the final product ranges from 1.5 to 3.0 g / 100 ml.