INSTANT YOGHURT

Field of the invention

The present invention relates to the production of instant yoghurt and the yoghurt itself.

Background of the invention

In US 4066794 is disclosed that an instant yoghurt (yogurt, yoghourt, youghurt or yogourt) composition can be prepared which contains dried milk powder, a de-activated yoghurt powder, a dormant yoghurt culture, sugar, sodium alginate and a sequestrant such as EDTA. The composition is low in fat and free of starch. When reconstituted by admixture with water, the composition exhibits a smooth custard-like texture and possesses nutritional and medicinal properties comparable to that of natural yoghurt.

US 4956185 provides an instant, dry powdered yoghurt formulation which can be reconstituted into either a yoghurt meal or a yoghurt drink, and a process for making same. The formulation of this invention includes a combination of xanthan gum and locust bean gum. This combination is important in making the formulation suitable to produce either a high quality meal or drink. A Lactobacillus culture, whey, and dehydrated yoghurt powder are also included in the formulation. A process for preparing the formulation is described. Thus in many of the instant yoghurt described in the literature or being on the market, a non-dairy ingredient like a hydro-colloid is used for getting a texture which is close to that of the natural yoghurts.

Another way of producing instant yoghurt is, producing yoghurt according to traditional methods and subsequently drying yoghurt to preserve it in a shelf-stable powdered form without a need for refrigeration. Such powder can be prepared by various methods, such as freeze-drying, spray-drying, microwave-drying and vacuum drying. The production of an instant yoghurt powder would, thus, provide benefits of shelf-life extension and convenience of preparation and storage. However, the drying of such

products is difficult due to low pH, which causes stickiness in drier chambers and makes powder recovery difficult. Furthermore, key flavour components formed by fermentation such as acetaldehyde and diacetyl which contribute to the unique flavour of natural yoghurt are sensitive to heat and easily lost during spray-drying.

Summary of the invention

The present invention relates to a process to prepare an instant yoghurt composition on basis of dairy based ingredients. Another aspect of the invention is an instant yoghurt composition which comprises milk powder, dry rennet enzyme and a dried lactic acid culture.

Also the present invention relates to the process to produce yoghurt from the instant yoghurt composition by adding water to the composition or adding the composition to water. The present invention also provides a container which comprises a dry instant yoghurt composition in amount to produce yoghurt in a volume of between 20 ml and 2 litre, preferably between 50 ml and 1 litre. The container is preferably a plastic container and may optionally also comprise paper or card-board parts.

Detailed description of the invention

Dry instant yoghurt of the invention comprises dry milk product, dried rennet enzyme and a dried lactic acid bacterium. In general the dry instant yoghurt will comprise 75 to 98 wt%(on dry matter) of dry milk products, 5 to 200, preferably 10 to 100 IMCU of rennet enzyme per gram dry instant yoghurt and 10 ⁵ to 10 ⁹ , preferably 10 ⁷ to 10 ⁸ CFU (colony forming units) per gram dry instant yoghurt. Optionally others ingredients are present. These other ingredients may comprise taste compounds. The dry instant yoghurt will in general contain for 95 to 99 wt% of dry matter. To the dry instant yoghurt water is added. The temperature of the added water is preferably between 10 and 40 ⁰ C, more preferably between 15 and 30 ⁰ C.

In general after the addition of water, the formed yoghurt is allowed to rest for 5 to 60 minutes, preferably 10 to 40 minutes. Resting can be done at room temperature, for example 20 ⁰ C or under cooled conditions for example at a temperature between 3 and 15 ⁰ C, preferably at a temperature between 5 and 10 ⁰ C.

The resulting yoghurt will contain between 5 and 20 wt% dry matter (DM), preferably between 7 and 15 wt% dry matter and most preferably between 8 and 12 wt% dry matter.

Surprisingly we have found that by using rennet to coagulate milk ingredients it is possible to obtain a structure which is yoghurt-like. By using rennet, the use of non-dairy ingredients for the structure of the yoghurt can be avoided.

Suitable milk powder By dry milk powder is meant dry milk powders like skim milk powder, fat free milk powder, low lactose milk powder, butter milk powder, powder mixtures which contain of casein and whey, or mixtures thereof. So dry milk powder will comprise whey and casein proteins of milk and is not only the casein fraction which is separated from the whey fraction. Milk protein can be divided into two classes based on relative solubility in acid: whey (acid soluble) and casein (acid insoluble). Cow's milk contains about 20% of whey protein and 80% of casein protein. The preferred dry milk powder is dry cow's milk powder.

The weight protein ratio of casein to whey in the dry milk powder (and in the instant dry yoghurt) is preferably less than 9, more preferably less than 8, even more preferably less than 7, and most preferably less than 6. The weight protein ratio of casein to whey in the dry milk powder (and in the instant dry yoghurt) is preferably more than 0.3, more preferably more than 1 , even more preferably more than 3, and most preferably more than 3.5. In general the weight protein ratio of casein to whey in the dry milk powder (and in the instant dry yoghurt) is between 1 and 8, preferably between 3 and 7 and most preferably between 3.5 and 6.

In GB 1 ,032,587 creamy liquids are produced by adding water to a composition obtained by drying a liquid of cream, rennet and a lactic acid culture. Before drying the liquid, coagulation takes place by the presence of the rennet. Moreover the whey proteins (serum) are removed before the liquid is dried. So in GB 1 ,032,587, not a dry milk powder is present in the dried composition but rather the coagulated casein fraction of milk whereby the whey proteins are removed.

US 3,963,837 and US 5,554,397 disclose a dry product which can be converted into cheese by adding water. The dry product is made from a liquid ultrafiltered (UF) milk fraction to which a lactic starter and rennet are added. Subsequently renneting of the

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liquid ultrafiltered (UF) milk takes place (see for example column 4 lines 60 to 68) and thereafter drying takes place. The UF-step will remove the whey proteins. The liquid ultrafiltered (UF) milk as well as the final dry product will therefore contain coagulated casein and no whey proteins. So in the dry products disclosed in GB 1 ,032,587, US 3,963,837 and US

5,554,397 the milk fraction present will be coagulated casein whereby the whey proteins are removed. The dry product of the present invention relates to a dry composition which comprises non-coagulated milk proteins. Moreover the dry product of the present invention contains whey. Especially the presence of the whey proteins is important in order to obtain a product which has the appearance of yoghurt.

In general a dry product such as a powder can be prepared by various methods, such as freeze-drying, spray-drying, microwave-drying and vacuum drying. Spray-drying is the preferred option to produce the milk powder

In general dry instant yoghurt of the invention will comprise 75 to 98 wt% of dry milk powder and preferably between 80 to 97 wt% of dry milk powder.

Suitable rennet enzymes

By rennet enzyme in this text is meant a proteolytic enzyme (protease) that coagulates the milk. The enzyme can be a microbial coagulating enzyme or an animal protease such as chymosin (EC 3.4.23.4). Rennet or rennet composition will contain as active coagulating enzyme, a rennet enzyme and may also comprise other enzymes in it, e.g., pepsin or lipase. Rennet may be used as source for the addition of rennet enzyme. Non-animal sources, such as microbial or animal sources can be used for the production of rennet or rennet enzyme. Animal rennet enzyme or animal rennet may be obtained by extracting from suitable animal tissue according to methods well-known in the art. Optionally the animal rennet or animal rennet enzyme is subsequently purified. Another possibility is the production of animal rennet enzyme by fermentation of host cells which are transformed using r-DNA techniques to produce this rennet enzyme. Microbial rennet enzymes are produced in fermentation process of natural producing microooragnisms or microorganisms which are transformed using r-DNA techniques to produce this rennet enzyme. The enzyme produced in a fermentation process can be isolated and purified according to methods known in the art.

In general dried rennet enzyme is present as a powder or granulate and can be prepared by various methods, such as freeze-drying, spray-drying, fluidized-bed drying, microwave-drying and vacuum drying. Spray-drying is the preferred option to produce dried rennet. Optionally the rennet enzyme is granulated. An example of a suitable animal rennet enzyme is chymosin which is commercially available, for example DSM sells commercially the product Maxiren ™.

Examples of microbial rennet enzymes are rennet enzymes of Mucor miehei (for example Fromase ™ or Rennilase ™ both from DSM, The Netherlands or Hannilase ™ Chr. Hansen, Denmark). Also microbial rennet from Mucor pusillus, for example Cuajo™ from Rhodia, France, can be used. Another suitable rennet is produced by Cryphonectria (Endothia) parasitica, (for example Suparen™ from DSM, The Netherlands). Animal rennets that can be used in the present invention are chymosin or chymosin/pepsin mixtures (for example Delvoren™ from DSM, The Netherlands or Naturen from Chr. Hansen, Denmark) or fermentation derived chymosin products (FPC) for example chymosin produced in K. lactis: Maxiren ™ of DSM, The Netherlands.

In general 5 to 200, preferably 10 to 100 IMCU per gram dry instant yoghurt is present in the dry instant yoghurt. More preferably 20 to 90 IMCU and most preferably 30 to 80 IMCU per gram dry instant yoghurt is present in the dry instant yoghurt.

The activity of a rennet enzyme is given in IMCU units. IMCU stands for International Milk Clotting Units and is determined according to the IDF standard 176:1996.

Suitable yoghurt producing lactic acid bacteria

Suitable lactic acid bacteria which can be used in the process of the present invention are Lactococcus spp. including Lactococcus lactis subsp. lactis and

Lactococcus lactis subsp. cremoris, Streptococcus spp including Streptococcus thermophilus or Streptococcus salivarius ssp. Thermophilus, Lactobacillus spp. Including

Lactobacillus delbrueckii ssp. bulgaricus, Leuconostoc spp., Weissella spp.,

Propionibacterium spp., Bifidobacterium spp., Brevibacterium spp., Enterococcus spp., Pediococcus spp. or mixtures thereof.

The product of the invention comprises preferably the bacterial strains Streptococcus salivarius ssp. thermophilus and/or Lactobacillus delbrueckii ssp. bulgaricus. Preferably yoghurt is produced by adding water to the dry instant yoghurt composition contains live bacteria.

Often these Streptococcus salivarius ssp. thermophilus and/or Lactobacillus delbrueckii ssp. bulgaricus are both present with other lactic acid bacteria for taste or health effects (for example for a probiotic effect). The latter include L. acidophilus, L. casei and Bifidobacterium species. In general 10 ⁵ to 10 ⁹ CFU (colony forming units) per gram dry instant yoghurt which corresponds to cell counts of dried lactic acid bacteria are present in the dry instant yoghurt. Preferably 10 ⁶ to 5 x 10 ⁸ CFU and more preferably 10 ⁷ to 10 ⁸ CFU per gram dry instant yoghurt are present in the dry instant yoghurt.

The enumeration of LAB (in CFU) is performed with pour plates in Rogosa agar (Oxoid) incubated at 30 ⁰ C for 3 days.

In general it is possible to add other lactic acid bacteria for taste or health effects (for example a probiotic bacterium). These include L. acidophilus, L. casei and Bifidobacterium species. The additional bacteria are included in dry form. An example thereof is the DELVO-YOG™ cultures (DSM, The Netherlands) which have been classified into traditional yoghurt cultures (TY), classic yoghurt cultures (CY) and mild yoghurt cultures (MY). The mild yoghurt cultures also include various probiotic strains.

In general dried lactic acid bacteria are present as powder or granulate and can be prepared by various methods, such as freeze-drying, spray-drying or fluidized-bed drying. Freeze-drying is the preferred option to produce dried lactic acid bacteria. Dried lactic acid bacteria are commercially available.

Additional components of the dry instant yoghurt

These other ingredients of the dry instant yoghurt may comprise taste compounds. Examples of taste ingredients are natural acids, for example citric acid, and sweeteners such as sugars or artificial sweeteners.

In general these additional components are present in dried form.

Other dry food products may be added to the dry instant yoghurt to give it a more differentated taste, like pieces of dried fruit; chocolate; or cereals.

Containers suitable to comprise the dry instant yoghurt

The present invention also provides a container which comprises a dry instant yoghurt composition in amount to produce yoghurt in a volume of between 20 ml and 2 litre, preferably between 50 ml and 1 litre. The container is preferably a plastic container, such as a plastic bag, pouch or stick and may optionally also comprise paper or card-

board parts. The container comprising the dry instant yoghurt composition is emptied in another container which is suitable to contain water, such as a cup, bowl or bottle, and water is added to the instant dry yoghurt composition. In another embodiment of the invention the dry instant yoghurt composition is packaged in a container which is suitable to contain liquid and which can be a disposable as well as a collectable. After opening of this container, water is added to the instant yoghurt composition present in this container.

Examples of yoghurts produced according to the process of the invention To offset its natural sourness, yoghurt can be sold sweetened, flavoured, or in containers with fruit or fruit jam on the bottom. It can also be used as carrier for different minerals, vitamins or any other functional food ingredient like probiotics etc. If the fruit has been stirred into the yoghurt before purchase, it is commonly referred to as Swiss- style. Most yoghurt in the United States have added pectin or gelatine. Some specialty yoghurts have a layer of fermented fat at the top. Fruit jam is used instead of raw fruit pieces in fruit yoghurts to allow storage for weeks. "Strained" yoghurt is the concentrated residue (described as a sort of "yoghurt cheese") produced by filtering plain yoghurt that is without flavourings, gelatine, pectin, or other additives through a paper or cloth filter, and allowing water and whey to drain away. Strained yoghurts, which include Greek Yoghurt (yiaourti), Dahi and Bulgarian

Yoghurt are types of yoghurt which are strained through a cloth or paper filter, traditionally made of muslin, to remove the whey, giving a much thicker consistency, and a distinctive, slightly tangy taste. Some types are boiled in open vats first, so that the liquid content is reduced. The popular East Indian dessert, Mishti Dahi, is a variation of traditional Dahi, offers a thicker, more custard-like consistency, and is usually sweeter than western yoghurts.

Dadiah sold in Bukittinggi Market. Dadiah, or Dadih, is traditional West Sumatran yoghurt made from water buffalo milk. It is fermented in bamboo tubes.

Labneh yoghurt of Lebanon is thickened yoghurt used for sandwiches. Olive oil, cucumber slices, olives, and various green herbs may be added. It can be thickened further and rolled into balls, preserved in olive oil, and fermented for a few more weeks. It is sometimes used with onions, meat, and nuts as a stuffing for a variety of Lebanese pies or Kebbeh balls.

Tarator/cacik is a popular cold soup made from yoghurt, popular during summertime in Bulgaria, Macedonia, and Turkey. It is made with Ayran, cucumbers, dill, salt, olive oil, and optionally garlic and ground walnuts in Bulgaria, and generally without walnuts in Turkey. Rahmjoghurt, a creamy yoghurt with much higher milkfat content (10%) than most yoghurts offered in English-speaking countries (Rahm is German for cream), is available in Germany and other countries.

Caspian Sea Yoghurt is believed to have been introduced into Japan in 1986 by researchers returning from a trip to the Caucasus region in Georgia. This variety, called Matsoni, is started with Lactococcus lactis subsp. cremoris and Acetobacter orientalis species and has a unique, viscous, honey-like texture. It is milder in taste than other varieties of yoghurts. Ideally, Caspian Sea yoghurt is made at home because it requires neither special equipment nor unobtainable culture. It can be made at room temperature (20-30 ⁰ C) in 10 to 15 hours. In Japan, freeze-dried starter cultures are sold in department stores and online, although many people obtain starter cultures from friends. Jameed is yoghurt which is salted and dried to preserve it. It is popular in Palestine and Jordan. Yoghurt Drinks

Bihidasu, a Japanese edible brand of Ayran.Ayran is a yoghurt-based, salty drink popular in Turkey, Azerbaijan, Bulgaria, Macedonia, Kazakhstan and Kyrgyzstan. It is made by mixing yoghurt with water and adding salt. The same drink is known as tan in

Armenia, "Laban Ayran" in Syria and Lebanon, "Shenina" in Jordan, "Moru" in South

India, and "Laban Arbil" in Iraq. A similar drink, doogh, is popular in the Middle East between Lebanon and Afghanistan; it differs from ayran by the addition of herbs, usually mint, and is carbonated, usually with seltzer water. In the United States, yoghurt-based beverages are often marketed under names like "yoghurt smoothie" or "drinkable yoghurt". They are also popular in Ecuador where the primary form of yoghurt is "bebida de yoghurt", which literally means drink of yoghurt.

Lassi is a yoghurt-based beverage originally from the Indian subcontinent that is usually slightly salty or sweet. Much like a smoothie, the sweet version is typically flavored with coconut, rosewater, lemon, mango or other fruit juice. Salty lassi is usually flavored with ground, roasted cumin and chili peppers.

Yop a fruity French yoghurt coming from the Yoplait Dairy Company, is popular in France, Canada and the UK.

Kefir is a fermented milk drink originating in the Caucasus. A related Central Asian Turco-Mongolian drink made from mare's milk is called kumis, or airag in Mongolia. Some American dairies have offered a drink called "kefir" for many years with fruit flavours but without carbonation or alcohol. As of 2002, names like "drinkable yoghurt" and "yoghurt smoothie" have been introduced.

(source of the yoghurt information: http://en.wikipedia.org/wiki/Yoghurt) The term dietary supplement as used herein denotes a product taken by mouth that contains a "dietary ingredient" intended to supplement the diet. The "dietary ingredients" in these products may include: vitamins, minerals, herbs or other botanicals, amino acids, and substances such as enzymes, organ tissues, glandulars, and metabolites.

A multi-vitamin and mineral supplement may be added to the instant yoghurt of the present invention to obtain an adequate amount of an essential nutrient missing or known to be relatively low in some diets. The multi-vitamin and mineral supplement may also be useful for disease prevention and protection against nutritional losses and deficiencies due to lifestyle patterns and common inadequate dietary patterns sometimes observed in diabetes. Moreover, oxidant stress has been implicated in the development of insulin resistance. Reactive oxygen species may impair insulin stimulated glucose uptake by disturbing the insulin receptor signalling cascade. The control of oxidant stress with antioxidants such as α-tocopherol (vitamin E) ascorbic acid (vitamin C) may be of value in the treatment of diabetes. Therefore, the intake of a multivitamin supplement may be added to the instant yoghurt to maintain a well balanced nutrition.

Furthermore, the instant yoghurt may comprise minerals such as magnesium (Mg ²⁺ ), Calcium (Ca ²⁺ ) and/or potassium (K ⁺ ) which are useful for the improvement of health and the prevention and/or treatment of diseases including but not limited to cardiovascular diseases and diabetes.

It is an object of the invention to provide instant yoghurt which can be used to provide health benefits to a subject consuming it. "Health benefit agent(s)" according to the present invention are materials which provide a health benefit, that is which have a positive effect on an aspect of health or which help to maintain an aspect of good health, when ingested, these aspects of good health being prevention of obesity, body weight control and cardiovascular health

maintenance. "Health benefit" means having a positive effect on an aspect of health or helping to maintain an aspect of good health.

The term "comprising" where used herein is meant not to be limiting to any subsequently stated elements but rather to encompass non-specified elements of major or minor functional importance. In other words the listed steps, elements or options need not be exhaustive. Whenever the words "including" or "having" are used, these terms are meant to be equivalent to "comprising" as defined above.

EXAMPLES

Example 1

In a bowl of 1.5 litres, 100 grams of standard medium heat skim milk powder (Promex from Friesland Food Professional, The Netherlands) is mixed with 3 grams of Fromase™ 2200 TL Granulated (DSM, The Netherlands); 1 gram of Delvo-Yog™ MY 1821 , containing Streptococcus thermophilus, Lactobacillus delbrueckii ssp bulgaricus, Lactobacillus acidophilus, Bifidobacterium sp, Lactobacillus casei (DSM, The Netherlands) and 0.15 grams of citric acid (DSM, The Netherlands) was added. 3 grams of Fromase™ corresponds to 6600 IMCU. After mixing the dry components using a spoon, the mixed dry components are dissolved in 1 liter of tap water of 30 ⁰ C.

Dissolving is done under gentle stirring with a spoon for 5 minutes. The solution is left at rest in a refrigerator at 8°C.

After 10 minutes the solution has become thick, and is ready for consumption.