Cultured Milk Products Chapter 7

**Chapter 7.** **Cultured Milk Products** Fermented or cultured milks are milk products that have undergone lactic acid fermentation (e.g., yoghurt) or a mix of this and yeast fermentation (e.g., Kefir). Cultured milk, a term used to describe products like yoghurt, kefir, buttermilk, filmjölk (Sc...

**Chapter 7.** **Cultured Milk Products** Fermented or cultured milks are milk products that have undergone lactic acid fermentation (e.g., yoghurt) or a mix of this and yeast fermentation (e.g., Kefir). Cultured milk, a term used to describe products like yoghurt, kefir, buttermilk, filmjölk (Scandinavian sour milk), cream, and koumiss (a product based on mares' milk), is produced by inoculating milk with a starter culture that converts lactose into lactic acid. This process produces carbon dioxide, acetic acid, diacetyl, acetaldehyde, and other substances, giving the products a fresh taste and aroma. The production of kefir and koumiss also produces ethyl alcohol. Originating from the Near East, cultured milk gained popularity in Eastern and Central Europe. The first example was likely accidentally produced by nomads, who accidentally turned the milk sour and coagulated under certain micro-organisms. **A Legend** ------------ The legend of yoghurt and kefir, originating from Mount Elbrus in the Caucasus range, explains that micro-organisms landed in a pitcher of milk at the right temperature and found symbiosis. The Turks called this \"Yogurut,\" which was introduced in the 8th century and later changed to yoghurt in the 11th century. Yogurt is believed to act as a \"preservative\" against human aging, as a Cossack may be 130 to 140 years old. Kefir, on the other hand, was created by a mixture of micro-organisms that thrive at 25-28°C and may be derived from the Turkish language. The name \"kefir\" may be derived from the first syllable, \"kef,\" meaning pleasurable, which likely reflects the shepherd\'s initial comment on the flavor. Kefir contains various types of micro-organisms, with yeast being the most famous, capable of forming alcohol, with a maximum alcohol content of about 0.8%. **General Requirements for Cultured Milk Production** ----------------------------------------------------- Cultured milk is a type of milk that is partially broken down by bacterial enzymes, resulting in a low pH that prevents the growth of harmful bacteria and prolongs its shelf life. However, it also poses a risk to yeasts and moulds, which can cause off-flavours. Some people lack the lactase enzyme, preventing them from consuming large amounts of ordinary milk. To produce cultured milk, optimal growth conditions are created through heat treatment and temperature control. The milk must be cooled quickly to stop fermentation, and the correct appearance and consistency are determined by pre-processing parameters. Adequate heat treatment and homogenization, sometimes combined with methods to increase MSNF (milk solids-not-fat) content, are essential \"foundation-stones\" for the construction of the coagulum during the incubation period. Some of the most important cultured milk products include yoghurt, but the production technique for other products is similar, with the focus on the production stages that differ from those in yoghurt production. The process descriptions for other products focus primarily on the production stages that differ from those in yoghurt production. **Yoghurt** =========== **YOGHURT** is a popular cultured-milk product globally, particularly in countries around the Mediterranean, Asia, and Central Europe. Its consistency, flavor, and aroma vary across regions, with some producing a viscous liquid and others a softer gel. Yoghurt is also produced in frozen form for desserts or drinks. Its flavor and aroma differ from other acidified products, with volatile aromatic substances including acetic acid and acetaldehyde. Photo by Cookidoo Yogurt is often classed as follows: 1. **Set-type.** Set-type yogurt is a type of yogurt that is made through a specific fermentation method, resulting in a thicker and creamier texture. This thickening is achieved through a controlled fermentation process and specific strains of lactic acid bacteria, such as *Lactobacillus bulgaricus* and *Streptococcus thermophilus*. These bacteria consume lactose in milk, producing lactic acid that thickens and flavors the yogurt. The milk is heated and cooled to a specific temperature range, usually around 110-115°F (43-46°C), to activate the bacterial culture. The mixture is then allowed to ferment for 4-8 hours, transforming the milk into yogurt. Set-type yogurt does not require stirring to achieve its desired texture, as it sets firmly in its container during the fermentation process. 2. **Stirred-type**. Stirred-type yogurt, also known as \"stirred yogurt\" or \"European-style yogurt,\" is a type of yogurt preparation method that differs from set-type yogurt, which sets without stirring. It is made by introducing specific bacterial cultures into milk, such as *Lactobacillus bulgaricus* and *Streptococcus thermophilus*, which convert lactose into lactic acid, thickening and flavoring the yogurt. The milk and bacterial culture mixture are heated and fermented at a specific temperature for 4-8 hours. After the initial fermentation period, the yogurt is cooled and stirred or mixed to achieve the desired creamy consistency. Stirred yogurt is popular among those who prefer the creamy and smooth texture of traditional yogurt and is commonly found in grocery stores. 3. **Drinking type**. Drinking yogurt, also known as drinkable yogurt or yogurt drink, is a liquid yogurt product that offers a convenient and refreshing way to enjoy the taste and health benefits of yogurt. It is similar to the stirred form, but the coagulum is \"broken down\" to a liquid before packing. It is made by introducing *Lactobacillus bulgaricus* and *Streptococcus thermophilus* into milk to initiate fermentation, converting lactose into lactic acid. Drinking yogurt is a good source of protein, calcium, and probiotics, promoting digestive health and supporting the immune system. It is a popular choice for individuals who enjoy the convenience and portability of a yogurt beverage. 4. **Frozen type**. Frozen yogurt, also known as \"froyo,\" is a popular frozen dessert made from yogurt, milk, sugar, and often flavorings, stabilizers, and probiotics. It is similar to traditional ice cream but is typically lower in fat content. It can be produced in various flavors like fruit, chocolate, and vanilla and can be fat-free or low-fat. Frozen yogurt has a creamy texture similar to ice cream, but can vary in creaminess based on fat content and processing methods. It is sweetened with sugar or sweeteners for a sweeter taste.  5. **Strained Yoghurt**. Strained yogurt, also known as Greek yogurt, strained Greek yogurt, or yogurt cheese, is a type of yogurt that has been processed to remove whey content, resulting in a thicker and creamier texture. This process involves straining regular yogurt through a cloth or paper filter, which can take several hours or longer depending on the desired thickness. Strained yogurt has a thicker consistency, similar to sour cream or yogurt cheese. **Factors Affecting the Quality of Yoghurt** -------------------------------------------- During the manufacturing process, numerous factors must be carefully controlled to ensure high-quality yoghurt with desired flavor, aroma, consistency, appearance, whey separation freedom, and long shelf life. 1. **Choice of Milk** Yogurt production requires high-quality, low-bacterial milk from approved producers, free from antibiotics, bacteriophages, and sterilizing agents, and meticulous analysis at the dairy to ensure optimal yoghurt culture development. 2. **Milk Standardization** Milk fat and dry solids content are generally integrated in accordance with the FAO/WHO code and the principles outlined below. Yogurt can have a fat content ranging from 0 to 10%. However, a fat level of 0.5 - 3.5% is the most common. According to the FAO/WHO code and principles, yoghurt can be categorized into the following groups: Yoghurt Min. milk fat 3% --------------------------- --------------- ---------------- Partially skimmed yoghurt Max. milk fat Less than 3% Min. milk fat More than 0.5% Skimmed yoghurt Max. milk fat 0.5% The FAO/WHO guideline and principles require a minimum MSNF of 8.2%. Increased total DM content, notably the amount of casein and whey proteins, results in a firmer yoghurt coagulum and a reduced susceptibility to whey separation. The following are the most common methods for standardizing DM content: - Evaporation (usually 10 - 20% of the milk volume is evaporated). - Addition of skimmilk powder, usually up to 3%. - Addition of milk concentrate. - Addition of UF retentate from skimmilk. 3. **Milk Additives** Yogurt production can incorporate sugar, sweeteners, and stabilizers as additives. *Sugar or sweetener*. Sucrose or glucose can be added to milk to satisfy dieters, particularly diabetics, who prefer sweeteners. These sweeteners have no nutritive value but are sweet even in small doses. The fruit usually contains about 50% sugar or a corresponding amount of sweetener, so adding 12-18% fruit can provide the required sweetness. However, adding more than 10% sugar before incubation can negatively affect fermentation conditions by changing the osmotic pressure of the milk. *Stabilizers*. Hydrophilic colloids in yoghurt increase viscosity and prevent whey separation. Manufacturers must experimentally determine the type and rate of stabilizer addition. The wrong stabilizer or excess can cause a rubbery consistency. Natural yoghurt requires no stabilizers, as a firm, fine gel with high viscosity occurs naturally. Stabilizers (0.1 - 0.5%), such as gelatin, pectin, starch, and agar-agar, are commonly used in fruit yoghurts and pasteurized yoghurt. 4. **Deaeration** The milk used to manufacture cultured milk products should have as low aeration content as possible. However, some air admixture is unavoidable if the MSNF level is increased by adding milk powder. If this is done, the milk should be deaerated before further processing. Deaeration occurs as part of the process of increasing the MSNF content by evaporation. The following are the benefits of deaeration: - Enhanced homogenizer\'s operating conditions - Reduced fouling risk during heat treatment. - Increased yoghurt\'s stability and viscosity. - Deodorization (removal of volatile off-flavors). 5. **Homogenization** Homogenization is a process used to prevent creaming during incubation and ensure uniform distribution of milk fat in cultured milk production. It improves the stability and consistency of cultured milks, even those with low fat content. The viscosity of cultured milk is significantly influenced by homogenisation pressure and heating temperature. The homogenisation temperature is typically 90-95°C for 5 minutes, and the viscosity is measured using a simple viscosimeter. High-temperature heat treatment makes the product more viscous. The recommended homogenisation pressure is 20-25 MPa and the temperature is 65-70°C. Homogenisation is often used in low-fat cultured milk production, and the choice of single or double stage homogenisation depends on the design of the homogenisation system and the homogenizer head. 6. **Heat Treatment** Before being infected with the starter, the milk is heat treated to: - enhance the qualities of milk as a medium for bacteria cultivation. - ensure the coagulum of the finished yoghurt is firm. - lessen the possibility of whey separation in the finished product. Heat treatment at 90-95°C and a 5-minute holding time yields optimal results in yoghurt. This process denatures 70-80% of whey proteins, particularly b-lactoglobulin, which interacts with k-casein for a stable \"body.\" However, UHT treatment and sterilization do not significantly affect viscosity. 7. **Choice of Culture** Advanced procedures are currently used in culture facilities to create customized yoghurt cultures to meet specific flavor and viscosity criteria. Some examples of end-product properties that can be achieved are: - High viscosity with low acetaldehyde content and a reasonably high final pH, for example.  - Low viscosity with medium acetaldehyde content, acceptable for sipping yoghurt, for example. 8. **Culture Preparation** The handling of starters for yoghurt production requires precision and hygiene. Concentrated, frozen, and freeze-dried cultures are becoming more widely used, saving costs on separate culture rooms and storage facilities. Direct inoculation of milk with a concentrated culture minimizes contamination risk, as intermediate stages of propagation are excluded. However, subscription costs and storage facilities must be offset against these savings. 9. **Plant Design** The coagulum produced during fermentation is highly susceptible to mechanical treatment, necessitating careful selection and dimensioning of various equipment. **Probiotic Milk** ================== Probiotic milk is a type of milk made by introducing specific probiotic strains, like Lactic Acid Bacteria (LAB), into milk. These cultures ferment the milk, converting lactose into lactic acid, which thickens the milk. The key characteristic of probiotic milk is the presence of live, beneficial bacteria, which can improve gut health by promoting the balance of microorganisms in the digestive system. Probiotics can enhance digestion, maintain gut health, support the immune system, and be better tolerated by individuals with lactose intolerance. They may also help manage certain conditions like irritable bowel syndrome and diarrhea. **Types of Probiotic Strains in Milk** -------------------------------------- Probiotic milk can contain various strains of beneficial bacteria, with each strain potentially offering specific health benefits. The most common probiotic strains found in probiotic milk and dairy products include: 1. *Lactobacillus acidophilus*: This is one of the most well-known and widely used probiotic strains. It is known for its ability to maintain a healthy balance of beneficial bacteria in the gut and may help with various digestive issues. 2. *Bifidobacterium lactis*: *B. lactis* is commonly found in probiotic milk products. It is known for its potential to support digestive health and enhance the immune system. 3. *Lactobacillus casei*: *L. casei* is believed to aid in digestion and may have potential benefits in reducing the risk of certain digestive problems. 4. *Bifidobacterium bifidum*: *B. bifidum* is often found in probiotic products for its potential to promote a balanced gut microbiome and support digestive health. 5. *Streptococcus thermophilus*: While this bacterium is not considered a traditional probiotic, it is often used in the fermentation of yogurt and other dairy products. It can contribute to the production of lactic acid, which helps to create a sour taste and thicken the milk. 6. *Lactobacillus bulgaricus*: Like *S. thermophilus, L. bulgaricus* is used in yogurt fermentation and contributes to the yogurt-making process. 7. *Saccharomyces boulardii*: *S. boulardii* is a yeast strain that is sometimes included in probiotic milk products. It is known for its potential to support digestive health, particularly in cases of diarrhea. 8. *Bifidobacterium breve*: *B. breve* is associated with the promotion of gut health and may be beneficial for those with digestive issues. 9. *Lactococcus lactis*: This bacterium is used in the fermentation of dairy products and can contribute to the development of probiotic cultures in some types of milk products. When selecting probiotic milk products, read the label to identify specific strains and quantities, as different strains may offer varying health benefits. The viability of these strains is crucial, so check the product\'s shelf-life and storage recommendations. This allows you to choose a product that suits your specific health goals and needs. **Probiotic Milk vs. Regular Milk** ----------------------------------- Probiotic milk and regular milk are two distinct types of dairy products with differences in their composition, health benefits, and potential effects on digestive health. Here\'s a comparison between probiotic milk and regular milk: **Probiotic Milk** ------------------ 1. Beneficial Bacteria: Probiotic milk is enriched with specific strains of beneficial bacteria, known as probiotics. These live cultures can contribute to improved gut health when consumed in adequate amounts. 2. Health Benefits: Probiotic milk is associated with several potential health benefits, such as enhanced digestion, better gut health, potential immune system support, and improved tolerance for individuals with lactose intolerance. 3. Digestive Support: The live probiotic cultures in probiotic milk can help maintain a balanced gut microbiome, potentially reducing the risk of digestive issues. 4. Flavors and Varieties: Probiotic milk is available in various flavors, including plain, fruit-flavored, and sweetened options. Some products may also be fortified with additional probiotic strains and nutrients. 5. Dietary Considerations: Probiotic milk is available in low-fat, fat-free, and lactose-free versions, catering to different dietary preferences and restrictions. **Regular Milk** ---------------- 1. Composition: Regular milk is typically pure milk with no added probiotics or live bacterial cultures. It contains the natural nutrients found in milk, such as protein, calcium, vitamins, and minerals. 2. Taste and Texture: Regular milk has the traditional taste and texture of milk, with no added sourness or tanginess associated with probiotics. 3. Versatility: Regular milk is a staple ingredient in cooking and baking, used in a wide range of recipes, from breakfast cereals and coffee to sauces and baked goods. 4. Nutritional Benefits: Regular milk is a good source of essential nutrients, including calcium, vitamin D, and protein, which are important for bone health and overall nutrition. 5. Lactose Content: Regular milk contains lactose, a natural sugar found in milk. Some individuals may have lactose intolerance and may experience digestive discomfort when consuming regular milk. 6. Shelf Life: Regular milk has a specific shelf life, and its freshness can deteriorate over time. It is typically refrigerated to maintain its quality. In summary, probiotic milk and regular milk differ primarily in the presence of live probiotic cultures. Probiotic milk is enhanced with specific beneficial bacteria that can have potential benefits for digestive health, while regular milk is in its natural form and provides essential nutrients without the probiotic content. The choice between the two depends on individual dietary preferences and health goals. Some individuals may choose probiotic milk to support gut health, while others may prefer regular milk for its versatility and nutritional content. **Kefir** ========= Kefir is one of the earliest fermented milk products. It comes from the Caucasus region. The raw source is goat, sheep, or cow milk. Kefir is produced in numerous nations, but Russia consumes the most - an annual total of roughly 5L per capita. Kefir should be viscous and homogeneous, with a shining surface. The flavor should be mild and acidic, with a hint of yeast. The pH of the product is normally between 4.3 and 4.4. Kefir is produced using a unique culture known as Kefir grain. The grains are made up of proteins, polysaccharides, and a variety of microorganisms, including yeasts, aroma and lactic-acid forming bacteria. Yeasts make up roughly 5 to 10% of the overall microflora. **Production of Starter Culture** --------------------------------- Kefir culture is usually derived from milk with varying fat levels, however skimmilk and reconstituted skimmilk have recently been used to improve control of the microbial makeup of the kefir grains. To inactivate bacteriophages, the milk substrate must be properly heat-treated, just like starting cultures for other cultured milk products. The production is broken down into two stages. The underlying reason for this is that kefir grains are bulky and difficult to manage; little amounts of mother culture are easier to regulate. Figure 7.10 illustrates the various steps of the process. The prepared substrate is infected with active kefir grains in the first stage. The incubation temperature is around 23°C, and the grain proportion is about 5% (1 part grains to 20 parts substrate) or 3.5% (1 part grains to 30 parts milk). The incubation duration is approximately 20 hours; however, because the grains tend to sink to the bottom, intermittent stirring for 10 - 15 minutes every 2 - 5 hours is recommended. When the appropriate pH value (say, 4.5) is obtained, the culture is agitated before the grains, now known as filtrate, are filtered out from the mother culture. The holes in the strainer are 3 - 4 mm in diameter. In the strainer, the grains are washed with boiled and cooled water (sometimes skimmilk). They can be reused in order to start a new batch of mother culture. Since the microbial population expands by around 10% per week during incubation, the grains must be weighed and any excess eliminated before the batch may be reused. In the second stage, if the filtrate needs to be kept for a few hours before use, it can be cooled to about 10°C. If a significant amount of kefir is to be made, the filtrate can be directly inoculated into the prepared milk intended as the substrate for the bulk starter. The dosage is 3 - 5% of the substrate volume. After around 20 hours of incubation at 23°C, the bulk starter is ready for inoculation into the kefir milk. **Production of Kefir** ----------------------- The stages of production are similar to those of most cultured milk products, with the following combination being typical for traditional kefir production: 1. **Fat Standardization**. Kefir\'s fat content has been reported to range between 0.5% and 6%. Raw milk is frequently used with its original fat content. However, fat contents ranging from 2.5 to 3.5% are commonly defined. 2. **Homogenization**. Following any fat standardization, the milk is homogenized at 65 - 70°C and 17.5 - 20 MPa (175 - 200 bar). 3. **Heat Treatment**. The heat treatment program for yoghurt and most cultured milks is the same: 90 - 95°C for 5 minutes. 4. **Inoculation**. After heat treatment, the milk is cooled to inoculation temperature, which is usually around 23°C, and 2 - 3% starter is added. 5. **Incubation**. Incubation is often separated into two stages: acidulation and ripening. 6. **The Acidulation Stage**. The acidulation stage continues until a pH of 4.5 is obtained, or until an acidity of 85 - 100°Th (35 - 40°SH) has produced. This takes approximately 12 hours. While still in the tank, the coagulum is gently stirred and pre-cooled. At 14 - 16°C, cooling is stopped and agitation is turned off. 7. **The Ripening Stage**. During the next 12 - 14 hours, the distinctive slightly \"yeasty\" flavor develops. When the acidity reaches 110 - 120°Th (pH around 4.4), final cooling begins. 8. **Cooling**. In a heat exchanger, the product is rapidly cooled to 5 - 8°C. This prevents any additional pH decrease; therefore, it is important that the product be handled gently when cooled and throughout subsequent packing. Mechanical agitation in pumps, pipes, and filling machines must be reduced. Air entrainment must also be prevented as it raises the likelihood of syneresis in the product. **Cultured Cream** ================== Cultured cream, also known as sour cream or clotted cream, is a dairy product made by fermenting cream with lactic acid bacteria. This process thickens and sours the cream, giving it a tangy flavor and a thicker consistency. Cultured cream has a creamy and smooth texture, making it versatile for various dishes. It is used in various culinary applications, such as as a condiment, topping for baked potatoes, tacos, or chili, and as an ingredient in dips, dressings, and baked goods. Cultured cream comes in different fat content options, including full-fat, reduced-fat, and fat-free, which can affect its richness and creaminess. It has been used for years in some countries and forms the basis of many dishes, similar to yoghurt. It can have a fat content of 10 -- 12% or 20 -- 30%. The starter culture contains *Streptococcus lactis* and Str. cremoris, while *Str. diacetylactis* and *Leuconostoc citrovorum* bacteria are used for aroma. Cultured cream has a bright, uniform structure, and is relatively viscous, with a mild and slightly acidic taste. It has a limited shelf life and requires strict hygiene to maintain product quality. Extended storage can lead to the development of yeast and molds on the surface of the cream, which can cause it to become bitter and lose its flavor due to the diffusion of carbon dioxide and other aromatic substances. **Production of Cultured Cream** -------------------------------- The cultured cream production process line contains equipment for standardizing fat content, homogenization and heat treatment of the cream, as well as inoculation and packing. 1. **Homogenization**. The homogenization pressure for cream with 10 - 12% fat is generally 15 - 20 MPa (150 - 200 bar) at 60 - 70°C. An increase in homogenisation temperature increases uniformity up to a point. Since there is insufficient protein (casein) to form membranes on the larger total fat surface, the homogenisation pressure for cream with 20 - 30% fat should be reduced, 10 - 12 MPa (100 - 120 bar). 2. **Heat Treatment**. Normally, the homogenized cream is heated for 5 minutes at 90°C. If the homogenisation procedure is precisely matched to the heat treatment, other time/temperature combinations can be used. 3. **Inoculation and Packing**. The prepared cream is cooled to 18 - 21°C inoculation temperature. Then 1 - 2% of bulk starting culture is introduced. Inoculation can occur in a tank or in packets. Fermentation takes 18 to 20 hours. When fermentation is finished, the cultured cream is promptly cooled to prevent further pH lowering. The viscosity of fermented cream may be extremely high, making packing difficult. Despite safeguards, the mechanical treatment that the cultured cream undergoes during stirring, pumping, and packaging produces a minor deterioration in the product\'s consistency - it will become thinner. To prevent mechanical treatment, the cream is occasionally infected, bottled, and fermented in the containers. Following cream inoculation and subsequent packing, the product is held at 20°C until the acidity of the fat-free phase reaches 85°Th, which takes approximately 16 - 18 hours. The packages are then carefully transferred to the refrigerated store, where they are maintained at a temperature of roughly 6°C for at least 24 hours until distribution. **Buttermilk** ============== Buttermilk is a by-product of butter production from sweet or fermented cream, with a 0.5% fat content and high membrane material content, including lecithin. Its shelf life is short due to oxidation of membrane material content, and whey separation from fermented cream makes product defects difficult to prevent. Buttermilk is a unique dairy product with a distinct taste and texture, produced by the liquid left over after churning butter. Traditional buttermilk and cultured buttermilk are two primary types of buttermilk. Here's the overview of both: ### **Traditional Buttermilk** Traditional buttermilk is a byproduct of butter-making, produced after churning from cream. It has a slightly tangy flavor and is thinner than regular milk, with a less creamy and watery consistency. Although less commonly used in modern cooking and baking, it can still be found in Southern-style buttermilk biscuits and cornbread. Traditional buttermilk is lower in fat and contains protein, calcium, and other dairy-related nutrients. In some regions, it is allowed to ferment naturally, creating a more pronounced tangy flavor and thicker consistency, known as \"old-fashioned buttermilk.\" ### **Cultured Buttermilk** Cultured buttermilk, also known as buttermilk, is a fermented low-fat or skim milk made with lactic acid bacteria like *Lactococcus lactis* and *Lactococcus cremoris*. It has a mild, tangy flavor and a slightly thicker consistency, similar to traditional buttermilk. It is a versatile ingredient in cooking and baking, used in recipes like pancakes, waffles, muffins, salad dressings, marinades, and tenderizing meats, especially in Southern fried chicken. Cultured buttermilk contains probiotics, which can benefit gut health, and provides essential nutrients like protein and calcium. It is often available in low-fat or fat-free versions, making it a healthier option for those looking to reduce their fat intake. **References** ============== Meiji Yogurt Library. n.d. Different types of yogurt (online). Retrieved from https://www.meiji.co.jp/yogurtlibrary/en/laboratory/yogurt/04/\#:\~:text=Classification%20of%20yogurts%20by%20production%20method&text=Most%20plain%20yogurt%20and%20hard,a%20distinctive%20texture%20and%20flavor. Tetra Pak. nd. Dairy Processing Handbook. Lund, Sweden Zhang, Y. 2022. Classification and Characterization of Yogurt. *Research & Reviews: Journal of Food and Dairy Technology* DOI: 10.4172/2321-6204.10.4.005