fermented dairy products
TRANSCRIPT
Fermented Dairy products
Fermented milk products, also known as cultured dairy foods, cultured dairy products, or cultured milk products, are dairy foods that have been fermented with lactic acid bacteria such as Lactobacillus, Lactococcus, and Leuconostoc. The fermentation process increases the shelf-life of the product, as well as adds to the taste and improves the digestibility of milk. There is evidence that fermented milk products have been produced since around 10,000 BC. A range of differentLactobacilli strains has been grown in laboratories allowing for a wide range of cultured milk products with different tastes
Varoius types of dairy products
1. Cheese2. Cultured sour cream3. Filmjolk4. Yogurt5. Kefir6. Kumis 7. Villi8. Cultured buttermilk9. Ac idophilus milk
Comparison chart
Product
Alternative
names
Typicalmilkfatcontent
Typical shelf life
at 4°C
Fermentation agent Description
Acidophilus milk
acidophilus cultured milk
0.5-2%2 weeks
Lactobacillus acidophilus
Thermophilic fermented milk, often lowfat (2%, 1.5%) or nonfat (0.5%), cultured withLactobacillus acidophilus.
Cheese 1-75% variesa variety of bacteria and/or mold
Any number of solid fermented milk products.
Crème fraîche
creme fraiche
30-40%10 days
naturally occurring lactic acid bacteria in cream
Mesophilic fermented cream, originally from France; higher-fat variant of sour cream.
Cultured buttermilk
1–2% 10 days
Lactococcus lactis* (Lactococcus lactis subsp. lactis*, Lactococcus lactis subsp. cremoris, Lactococcus lactis biovar. diacetylactis and
Mesophilic fermented pasteurized milk.
Product
Alternative
names
Typicalmilkfatcontent
Typical shelf life
at 4°C
Fermentation agent Description
Leuconostoc mesenteroides subsp.cremoris)
Cultured sour cream
sour cream[4] 14–18%[4] 4
weeksLactococcus lactis subsp. lactis*
Mesophilic fermented pasteurized cream with an acidity of at least 0.5%. Rennet extract may be added to make a thicker product. Lower fat variant ofcrème fraîche.
Filmjölk fil 0.1-4.5%10–14 days
Lactococcus lactis* andLeuconostoc
Mesophilic fermented milk, originally from Scandinavia.
Kefir kephir, kewra, talai, mudu kekiya, milkkefir, búlgaros
0-4% 10–14 days
Kefir grains, a mixture of bacteriaand yeasts
A fermented beverage, originally from the Caucasus region, made with kefir grains. Can be made with any sugary liquid, such as milk from mammals, soy milk, or fruit
Product
Alternative
names
Typicalmilkfatcontent
Typical shelf life
at 4°C
Fermentation agent Description
juices.
Kumis
koumiss, kumiss, kymys, kymyz, airag, chigee
4%?10–14 days
Lactobacilli and yeasts
A carbonated fermented milk beverage traditionally made from horse milk.
Viili filbunke 0.1-3.5%14 days
Lactococcus lactis subsp. cremoris,Lactococcus lactis* biovar.diacetylactis, Leuconostoc mesenteroides subsp. cremorisand Geotrichum candidum
Mesophilic fermented milk that may or may not contain fungus on the surface. Originally fromSweden but today is a Finnishspecialty.
Yogurtyoghurt, yogourt, yoghourt
0.5–4%35–40 days
Lactobacillus bulgaricus andStreptococcus thermophilus
Thermophilic fermented milk, cultured with Lactobacillus bulgaricus and Streptococcus thermophilus.
* Streptococcus lactis has been renamed to Lactococcus lactis subsp. lactis
Acidophilus milk
Lactobacillus acidophilus (Latin meaning acid-loving milk-bacterium) is a species in the genus Lactobacillus. L. acidophilus is a homofermentativespecies, fermenting sugars into lactic acid, and grows readily at rather low pH values (below pH 5.0) and has an optimum growth temperature of around 37 °C(99 °F). L. acidophilus occurs naturally in the human and animalgastrointestinal tract, mouth, and vagina.[ Some strains of L. acidophilus may be considered to have probiotic characteristics. These strains are commercially used in many dairy products, sometimes together with S. salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus in the production of acidophilus-type yogurt.
Amount Per ServingCalories 110Calories from Fat 22
% Daily Value*
Total Fat 2.5g4%
Saturated Fat 1.5g7%
Cholesterol 15mg5%Sodium 130mg5%Total Carbohydrates 13.0g4%
Sugars 12.0g
Protein 9.0g
Vitamin A 10% • Vitamin C 2%
Calcium 30% • Iron 0%
* Based on a 2000 calorie die
Health effects
Antibiotics taken orally will also kill beneficial bacteria, including L. acidophilus. After a therapy that includes antibiotics, patients are occasionally instructed to take an L. acidophilus treatment in order to recolonize the gastrointestinal tract. To that effect, L.
acidophilus is often sold in health stores in pill or powder form as a nutritional supplement, as well as being available in many yogurts. A part of the claims in favor of such treatment refer to attaining a better digestion thanks to a recovered normal intestinal flora. L. acidophilus LA-5 produces bacteriocin CH5 that is both antibacterial and inhibitory against certain yeasts and moulds and is effective against both Salmonella typhimurium and Campylobacter jejuni. It has been shown to improve bowel regularity and has been shown to have a preventative effect against traveller's diarrhea, as well as antibiotic related bowel issues.
Because of its relation to gut-associated lymphoid tissue (GALT), L. acidophilus LA-5 has been associated with positive effects on the immune system such as increased cytokine, phagocytic activity and antibody production, as well as phagocytosis ofSalmonella, and L. acidophilus NCFM has even been shown to reduce incidence of symptoms of fever, cough and runny nose. Anti-inflammatory effects have also been observed in people consuming L. acidophilus NCFM. Additionally L. acidophilus LA-5 has shown to inhibit growth of breast cancer cells, and positive effects on chemotherapy patients. An improvement of lipid metabolism has also been linked to L. acidophilus LA-5.
Animal studies of NCFM have indicated that it reduces intestinal pain by inducing u-opioid and canabinoid receptors in the intestines (of animals), but this effect has not been sufficiently shown in humans yet.
Other benefits of L. acidophilus include the production of vitamin K and lactase, and some strains may producebacteriocins such as acidolin, acidophilin and lactocidin.
A study published in the Journal of the American College of Nutrition reported that yogurt containing L. acidophilus L1 has the potential to reduce risk for coronary heart disease by 6–10% by reducing serum cholesterol concentration.
Although a study that evaluated the effects of L. acidophilus on the symptoms of Japanese cedar-pollen allergy achieved positive results, this still needs further research.
Side effects
In general, the ingestion of L. acidophilus is safe. However, people with some conditions are discouraged from taking L. acidophilus, including intestinal damage, a weakened immune system, or overgrowth of intestinal bacteria.
Some people complain of discomfort or gas. This condition can be overcome when the individual ingests it continuously.Lactose sensitive people may also experience abdominal discomfort from dairy products that include L. acidophilus.
Infections of heart valves with L. acidophilus have also been reported. The risk may be greater in people with artificial heart valves.
Some women have reported burning of the vagina after using vaginal tablets that contain L. acidophilus
Cheese
Cheese is a generic term for a diverse group of milk-based foodproducts. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms.
Cheese consists of proteins and fat from milk, usually the milk ofcows, buffalo, goats, or sheep. It is produced by coagulation of the milk protein casein. Typically, the milk is acidified and addition of the enzyme rennet causes coagulation. The solids are separated and pressed into final form. Some cheeses have molds on the rind or throughout. Most cheeses melt at cooking temperature.
Hundreds of types of cheese are produced. Their styles, textures and flavors depend on the origin of the milk (including the animal's diet), whether they have been pasteurized, the butterfat content, the bacteria and mold, the processing, and aging. Herbs, spices, or wood smoke may be used as flavoring agents. The yellow to red color of many cheeses is from adding annatto.
For a few cheeses, the milk is curdled by adding acids such asvinegar or lemon juice. Most cheeses are acidified to a lesser degree by bacteria, which turn milk sugars into lactic acid, then the addition of rennet completes the curdling. Vegetarian alternatives to rennet are available; most are produced by fermentation of the fungusMucor miehei, but others have been extracted from various species of the Cynara thistle family.
.
Composition
Fat 18-20% Moisture 60% (approx)Protein 10-12% Added Salt 1.8% Sodium Citrate 2.5% Calorific value : 225 kcal./100g
Nutritional Information
Nutritional Information*
Amount per 100 g
Energy, kcal 225
Energy from Fat, kcal 180
Total Fat, g 20
Saturated fat,g 13.2
Cholesterol, mg 70
Sodium, mg 840
Protein, g 11.2
Not a significant source of Vitamin C, Iron and Dietary fiber.
Shelf Life9 Months from date of packaging
Storage conditionRefrigerated at 4° C or below. Do not deep freeze
Production of cheese
Curdling processA required step in cheesemaking is separating the milk into solid curds and liquidwhey. Usually this is done by acidifying (souring) the milk and adding rennet. The acidification can be accomplished directly by the addition of an acid like vinegar in a few cases (paneer, queso fresco), but usually starter bacteria are employed instead. These starter bacteria convert milk sugars into lactic acid. The same bacteria (and the enzymes they produce) also play a large role in the eventual flavor of aged cheeses. Most cheeses are made with starter bacteria from theLactococci, Lactobacilli, or Streptococci families. Swiss starter cultures also includePropionibacter shermani, which produces carbon dioxide gas bubbles during aging, giving Swiss cheese or Emmental its holes
Curd process
At this point, the cheese has set into a very moist gel. Some soft cheeses are now essentially complete: they are drained, salted, and packaged. For most of the rest, the curd is cut into small cubes. This allows water to drain from the individual pieces of curd.
Some hard cheeses are then heated to temperatures in the range of 35–55 °C (95–131 °F). This forces more whey from the cut curd. It also changes the taste of the finished cheese, affecting both the bacterial culture and the milk chemistry. Cheeses that are heated to the higher temperatures are usually made withthermophilic starter bacteria that survive this step—either Lactobacilli or Streptococci.
Salt has roles in cheese besides adding a salty flavor. It preserves cheese from spoiling, draws moisture from the curd, and firms cheese’s texture in an interaction with its proteins. Some cheeses are salted from the outside with dry salt or brine washes. Most cheeses have the salt mixed directly into the curds.
Other techniques influence a cheese's texture and flavor. Some examples:
Stretching: (Mozzarella, Provolone) The curd is stretched and kneaded in hot water, developing a stringy, fibrous body.
Cheddaring : (Cheddar, other English cheeses) The cut curd is repeatedly piled up, pushing more moisture away. The curd is also mixed (or milled) for a long time, taking the sharp edges off the cut curd pieces and influencing the final product's texture.
Washing: (Edam, Gouda, Colby) The curd is washed in warm water, lowering its acidity and making for a milder-tasting cheese.
Most cheeses achieve their final shape when the curds are pressed into a mold or form. The harder the cheese, the more pressure is applied. The pressure drives out moisture—the molds are designed to allow water to escape—and unifies the curds into a single solid body.
Ripening
A newborn cheese is usually salty yet bland in flavor and, for harder varieties, rubbery in texture. These qualities are sometimes enjoyed—cheese curds are eaten on their own—but normally cheeses are left to rest under controlled conditions. This aging period (also called ripening, or, from the French, affinage) lasts from a few days to several years. As a cheese ages, microbes and enzymes transform texture and intensify flavor. This transformation is largely a result of the breakdown of casein proteins and milkfat into a complex mix of amino acids,amines, and fatty acids.
Some cheeses have additional bacteria or molds intentionally introduced before or during aging. In traditional cheesemaking, these microbes might be already present in the aging room; they are simply allowed to settle and grow on the stored cheeses.
Health effects
Heart disease
Cheese potentially shares other nutritional properties of milk. The Center for Science in the Public Interest describes cheese as America's number one source of saturated fat, adding that the average American ate 30 lb (14 kg) of cheese in the year 2000, up from 11 lb (5 kg) in 1970. Their recommendation is to limit full-fat cheese consumption to 2 oz (57 g) a week. Whether or not cheese's highly saturated fat content actually leads to an increased risk of heart disease is a subject of debate, as epidemiological studies have observed relatively low incidences of cardiovascular disease in populations such asFrance and Greece, which lead the world in cheese consumption (more than 14 oz/400 g a week per person, or over 45 lb/20 kg a year).
Dental health
Some studies claim that cheddar, mozzarella, Swiss and American cheeses can help to prevent tooth decay. Several mechanisms for this protection have been proposed:
The calcium, protein, and phosphorus in cheese may act to protect tooth enamel. Cheese increases saliva flow, washing away acids and sugars.
Effect on sleep
A study by the British Cheese Board in 2005 to determine the effect of cheese upon sleep and dreaming discovered that, contrary to the idea that cheese commonly causes nightmares, the effect of cheese upon sleep was positive. The majority of the two hundred people tested over a fortnight claimed beneficial results from consuming cheeses before going to bed, the cheese promoting good sleep. Six cheeses were tested and the findings were that the dreams produced were specific to the type of cheese. Although the apparent effects were in some cases described as colorful and vivid, or cryptic, none of the cheeses tested were found to induce nightmares. However, the six cheeses were all British. The results might be entirely different if a wider range of cheeses were tested. Cheese contains tryptophan, an amino acid that has been found to relieve stress and induce sleep.
Casein
Like other dairy products, cheese contains casein, a substance that when digested by humans breaks down into several chemicals, including casomorphine, an opioid peptide. In the early 1990s it was hypothesized that autism can be caused or aggravated by opioid peptides. Studies supporting these claims have had significant flaws, so the data are inadequate to guide autism treatment recommendations.
Lactose
Cheese is often avoided by those who are lactose intolerant, but ripened cheeses like Cheddar contain only about 5% of thelactose found in whole milk, and aged cheeses contain almost none. Nevertheless, people with severe lactose intolerance should avoid eating dairy cheese. As a natural product, the same kind of cheese may contain different amounts of lactose on different occasions, causing unexpected painful reactions.
Hypertensive effect
Some people suffer reactions to amines found in cheese, particularly histamine and tyramine. Some aged cheeses contain significant concentrations of these amines, which can trigger symptoms mimicking an allergic reaction: headaches, rashes, andblood pressure elevations.
Pasteurization
A number of food safety agencies around the world have warned of the risks of raw-milk cheeses. The U.S. Food and Drug Administration states that soft raw-milk cheeses can cause "serious infectious diseases including listeriosis, brucellosis,salmonellosis and tuberculosis". It is U.S. law since 1944 that all raw-milk cheeses (including imports since 1951) must be aged at least 60 days. Australia has a wide ban on raw-milk cheeses as well, though in recent years exceptions have been made for Swiss Gruyère, Emmental and Sbrinz, and for French Roquefort. There is a trend for cheeses to be pasteurized even when not required by law.
Compulsory pasteurization is controversial. Pasteurization does change the flavor of cheeses, and unpasteurized cheeses are often considered to have better flavor, so there are reasons not to pasteurize all cheeses. Some say that health concerns are overstated, or that milk pasteurization does not ensure cheese safety.
Pregnant women may face an additional risk from cheese; the U.S. Centers for Disease Control has warned pregnant women against eating soft-ripened cheeses and blue-veined cheeses, due to the listeria risk, which can cause miscarriage or harm to the fetus during birth
Sour cream
Sour cream is a dairy product rich in fats obtained by fermenting a regular creamby certain kinds of lactic acid bacteria. The bacterial culture, which is introduced either deliberately or naturally, sours and thickens the cream. Its name stems from the production of lactic acid by bacterial fermentation, which is called souring. The taste of sour
cream is only mildly sour.
Nutritional Facts
Serving Size 200ml Serving per pack 5
Amount per Serving
Energy 149 Calories Energy from fat 81 calories
% Daily Value*
Total Fat, 9 g 13.5
Saturated Fat, 5.5g 28
Trans Fat, 0.13 g 0
Cholesterol, 24 mg 7.5
Sodium 100 mg 4.6
Total Carbohydrate 10 g 3.3
Sugars 10 g 3.3
Dietary Fibre 0 g 0
Protein, 7g 14
Calcium 300 mg 61
Added Vitamin A 150 µgAdded Vitamin D 1 µg
RE
Not a significant source of Vitamin C & Iron.*Percent daily Values (DV) are based on a 2000 calorie diet.
Traditaonally Sour cream, made out of cream, contains from 18 to 20 percent butterfat–about 14 grams per 4 ounce serving–and gets its characteristic tang from the lactic acidcreated by the bacteria. Commercially produced sour cream often contains additional thickening agents such as gelatin, rennet, guar and carrageen, as well as acids to artificially sour the product.
Sour cream is not fully fermented, and as such must be stored under refrigeration. As with other dairy products, it is usually sold with an expiration date stamped on the container, though whether this is a "sell by" a "best by" or a "use by" date varies with local regulation. Food authorities, such as the USDA, advise that sour cream with visible mold should be discarded, as it may be contaminated below the surface and could contain dangerous mycotoxins and aflatoxin.
Filmjolk
Filmjölk (also known as fil or the older word surmjölk[) is a Nordic dairy product, similar to yoghurt, but using different bacteria which give a different taste and texture.
It can also be described as a mesophilic fermented milk product that is made byfermenting cow's milk with a variety of bacteria from the species Lactococcus lactisand Leuconostoc mesenteroides. The bacteria metabolize lactose, the sugar naturally found in milk, into lactic acid which means people who are lactose intolerant can consume filmjölk. The acid gives filmjölk a sour taste and causesproteins in the milk, mainly casein, to coagulate, thus thickening the final product. The bacteria also produce a limited amount of diacetyl, which gives filmjölk its characteristic taste. Filmjölk is similar to cultured buttermilk, kefir, or yoghurt in consistency, but fermented by different bacteria and thus has a slightly different taste. Compared with yoghurt, filmjölk tastes less sour. In Sweden, it is normally sold in 1-liter packages with live bacteria
Overview
In Nordic countries, filmjölk is commonly eaten during breakfast or as a snack between meals in the same manner as yoghurt, usually from a bowl with a spoon. It can be drunk but is not normally done so since the liquid is fairly thick. Filmjölk is often eaten with breakfast cereal, muesli or crushed crisp bread on top. Since plain filmjölk tastes somewhat sour, many people addsugar, jam, apple sauce, cinnamon, ginger, fruits, and/or berries. In Norwegian it is called surmelk (new Norwegian: surmjølk) (sourmilk) but the official name is kulturmelk (new Norwegian: kulturmjølk).
Manufactured filmjölk is made from pasteurised, homogenised, and standardised cow's milk. Although home made filmjölk has been around for a long time (written records from the 18th century speak of filmjölk-like products, but it has probably been around since the Viking Age or longer), it was first introduced to the Swedish market as a consumer product in 1931 by the Swedish dairy cooperative Arla. The first filmjölk was unflavoured and contained 3% milkfat. Since the 1960s, different varieties of unflavoured filmjölk have been marketed in Swedish grocery stores. Långfil, a more elastic variant of filmjölk was introduced in 1965; lättfil, filmjölk with 0.5% milkfat was introduced in 1967; and mellanfil, filmjölk with 1.5% milkfat was introduced in 1990. In 1997, Arla introduced its first flavoured filmjölk: strawberry flavoured
filmjölk. The flavoured filmjölk was so popular that different flavours soon followed. By 2001, almost one third of the filmjölk sold in Sweden was flavoured filmjölk. Since 2007, variations of filmjölk include filmjölk with various fat content, filmjölk flavoured with fruit, vanilla, or honey, as well as filmjölk with probiotic bacteria
YogurtYogurt or yoghurt a dairy product produced by bacterial fermentation of milk. The bacteria used to make yogurt are known as "yogurt cultures". Fermentation of lactose by these bacteria produces lactic acid, which acts on milk protein to give yogurt its texture and its characteristic tang.
Worldwide, cow's milk is most commonly used to make yogurt, but milk from water buffalo, goats, sheep, camels and yaks is also used in various parts of the world.
Dairy yogurt is produced using a culture of Lactobacillus delbrueckii subsp.bulgaricus and Streptococcus salivarius subsp. thermophilus bacteria. In addition,Lactobacillus acidophilus and bifidobacteria are also sometimes added during or after culturing yogurt.
The milk is first heated to about 80 °C (176 °F) to kill any undesirable bacteria and to denature the milk proteins so that they set together rather than form curds. The milk is then cooled to about 45 °C (112 °F). The bacteria culture is added, and the temperature is maintained for 4 to 7 hours to allow fermentation.
Yogurt, full fat
Nutritional value per 100 g (3.5 oz)
Energy 257 kJ (61 kcal)
Carbohydrates 4.7 g
- Sugars 4.7 g (*)
Fat 3.3 g
- saturated 2.1 g
- monounsaturated 0.9 g
Protein 3.5 g
Vitamin A equiv. 27 μg (3%)
Riboflavin (vit. B 2) 0.14 mg (12%)
Calcium 121 mg (12%)
(*) Lactose content diminishes during storage.Percentages are relative to US recommendations for
adults.
Nutritional value and health benefits
Yogurt is nutritionally rich in protein, calcium, riboflavin, vitamin B6 and vitamin B12. It has nutritional benefits beyond those of milk. People who are moderatelylactose-intolerant can consume yogurt without ill effects, because much of the lactose in the milk precursor is converted to lactic acid by the bacterial culture.
Yogurt containing live cultures has been found effective in a randomized trial at preventing antibiotic-associated diarrhea. The use of probiotics, including some of the common cultures used in yogurt, has been found in a larger, meta-analysis of 25 randomized, controlled trials, to be effective at preventing antibiotic-associated biarrhea, but one culture, Saccharomyces boulardii, not typically contained in yogurt, was found to be effective at treating Clostridium difficileinfection.
Yogurt contains varying amounts of fat. There is non-fat (0% fat), low-fat (usually 2% fat) and plain or whole milk yogurt (4% fat). A study published in the International Journal of Obesity (11 January 2005) also found that the consumption of low-fat yogurt can promote weight loss, especially due to the calcium in the yogurt.
KefirKefir (alternately kefīrs, keefir, kephir,kewra, talai, mudu kekiya, milk kefir, búlgaros) is a probiotic fermented milk drink made with Kefir Grains that originated with shepherds of the North Caucasus region, who discovered that fresh milk carried in leather pouches would occasionally ferment into a carbonated beverage. It is prepared by inoculating cow, goat, or sheep's milk with kefir grains. Traditional kefir was made in skin bags that were hung near a doorway; the bag would be knocked by anyone passing through the doorway to help keep the milk and kefir grains well mixed.
Marco Polo mentions kefir in recounting his travels.
ProductionProduction of traditional kefir requires a starter community of kefir grains which are added to the liquid one wishes to ferment. Kefir grains cannot be produced from scratch, but the grains grow during fermentation, and additional grains are produced. Kefir grains can be bought from or donated by other growers.
The traditional, or artisanal, method of making kefir is achieved by directly adding kefir grains (2–10%) to milk in a loosely covered acid proof container which is traditionally agitated once or more times a day. It is not filled to capacity, allowing room for some expansion as the kefiran and carbon dioxide gas produced causes the liquid level to rise. If the container is not light proof it should be stored in the dark to prevent degradation of vitamins and inhibition of the culture. After a period of fermentation lasting around 24 hours, ideally at 20–25 °C (68–77 °F), the grains are removed from the liquid by sieving and reserved as the starter for a fresh amount of liquid. The temperature during fermentation is not critical as long as it is not above one that will kill the culture (about 40 °C / 104 °F), or much below 4 °C (39 °F) where the process will cease.
The fermented liquid which contains live microflora from the grain, may now be consumed as a beverage, used in recipes, or kept aside for several days to undergo a slower secondary fermentation which further thickens and sours the liquid. Without refrigeration the shelf life is two to three days. The grains will enlarge in the process of kefir production, and eventually split. Grains can be dried at room temperature or lyophilized (freeze-dried) or frozen.
The Russian method permits production of kefir on a larger scale, and uses two fermentations. The first step is to prepare the cultures by incubating milk with grains (2–3%), as just described.
The grains are then removed by filtration and the resulting liquid mother culture is added to milk (1–3%) which is fermented for 12 to 18 hours.
Kefir can be produced using lyophilized cultures commonly available as a powder from health food shops. A portion of the resulting kefir can be saved to be used a number of times to propagate further fermentations but ultimately does not form grains, and a fresh culture must be obtained
Kefir means foam in Turkish. Kefir grains are a combination of bacteria and yeasts in a matrix of proteins, lipids, and sugars, and this symbiotic matrix forms "grains" that resemble cauliflower. For this reason, a complex and highly variable community of lactic acid bacteria and yeasts can be found in these grains.
Kefir grains contain a water soluble polysaccharide known as kefiran, which imparts a rope-like texture and feeling in the mouth; appear in hues ranging from white to yellow; and usually grow to the size of walnuts (although rice-grain-sized grains have been known to develop).
Traditional kefir is fermented at ambient temperatures, generally overnight. Fermentation of the lactose yields a sour,carbonated, slightly alcoholic beverage, with a consistency similar to thin yogurt. Kefir fermented by small-scale dairies early in the 20th century achieved alcohol levels between 1 and 2 percent, but kefir made commercially with modern methods of production has less than 1% alcohol, possibly due to reduced fermentation time.
Variations that thrive in various other liquids exist, and they vary markedly from kefir in both appearance and microbial composition. Water kefir (or kefir d'acqua) is grown in water with sugar (sometimes with added dry fruit such as figs, and lemonjuice) for a day or more at room temperature.
Kumis
Kumis, also spelled kumiss or koumiss in English (or kumys, see othertransliterations and cognate words below under terminology and etymology) is afermented dairy product traditionally made from mare's milk. The drink remains important to the peoples of the Central Asian steppes, of Turkic and Mongol origin: Bashkirs, Kazakhs, Kyrgyz, Yakuts, Mongols and Kalmyks. It was also consumed by Baltic, Hungarian tribes.
Kumis is a dairy product similar to kefir but is produced from a liquid starter culture, in contrast to the solid kefir "grains". Because mare's milk contains more sugars than the cow's or goat's milk fermented into kefir, kumis has a higher, though still mild, alcohol content.
Even in the areas of the world where kumis is popular today, mare's milk remains a very limited commodity. Industrial-scale production of kumis, therefore, generally uses cow's milk, which is richer in fat and protein but lower in lactose than the milk from a horse. Before fermentation, the cow's milk is fortified in one of several ways. Sucrose may be added to allow a comparable fermentation. Another technique adds modified whey in order to better approximate the composition of mare's milk.
Production
A 1982 source reported that 230,000 horses were kept in the USSR specifically for producing milk to make into kumis.
Rinchingiin Indra, writing about Mongolian dairying, says "it takes considerable skill to milk a mare" and describes the technique: the milker kneels on one knee, with a pail propped on the other, steadied by a string tied to an arm. One arm is wrapped behind the mare's rear leg and the other in front. A foal starts the milk flow and is pulled away by another person, but left touching the mare's side during the entire process.
In Mongolia, the milking season for horses traditionally runs between mid-June and early October. During one season, a mare produces approximately 1,000 to 1,200 kilograms of milk, of which about half is left to the foals.
Nutritional propertiesDuring fermentation, the lactose in mare's milk is converted into lactic acid, ethanoland carbon dioxide, and the milk becomes an accessible source of nutrition for people who are lactose intolerant.
Before fermentation, mare's milk has almost 40% more lactose than cow's milk. According to one modern source, "unfermented mare's milk is generally not drunk", because it is a strong laxative. Varro's On Agriculture, from the 1st century BC, also mentions this: "as a laxative the best is mare's milk, then donkey's milk, cow's milk, and finally goat's milk..."; drinking six ounces (190 ml) a day would be enough to give a lactose-intolerant person severe intestinal symptoms.
VilliViili (Finnish viili, Swedish fil) is a type of yogurt (a mesophilic fermented milk) that originated in the Nordic countries. It has a ropey, gelatinous consistency and a pleasantly mild taste resulting from lactic acid. This cultured milk product is the results of microbial action of lactic acid bacteria (LAB) and a surface-growing yeast-like fungus Geotrichum candidum present in milk, which forms a velvet-like surface on viili. In addition, most traditional viili cultures also contain yeast strains such asKluveromyces marxianus and Pichia fermentans. The LAB identified in viili includingLactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar. diacetylactis, Leuconostoc mesenteroides subsp. cremoris. Among those mesophilic LAB strains, the slime-forming Lc. lactis subsp. cremoris produce a phosphate-containing heteropolysaccharide, named viilian. Viilian is similar tokefiran produced by kefir grains. The production of exopolysaccharides (EPS) by the strain forms the consistency character of viili and it has been claimed to have various functional benefits toward the rheological properties of milk products and the health improving potential.
ButtermilkButtermilk refers to a number of dairy drinks. Originally, buttermilk was the liquid left behind after churning butter out of cream. This type of buttermilk is known as traditional buttermilk.
The term buttermilk also refers to a range of fermented milk drinks, common in warm climates (e.g., Middle East, Pakistan, India, and the Southern United States) where unrefrigerated fresh milk otherwise sours quickly, as well as in colder climates such as Germany, Scandinavia and the Netherlands. Thisfermented dairy product known as cultured buttermilk is produced from cow's milk and has a characteristically sour taste caused by lactic acid bacteria. This variant is made using one of two species of bacteria—either Streptococcus lactis or Lactobacillus bulgaricus, which creates more tartness. Buttermilk made with the latter is called Bulgarian buttermilk.
The tartness of buttermilk is due to acid in the milk. The increased acidity is primarily due to lactic acid produced by lactic acid bacteria while fermenting lactose , the primary sugar in milk. As the bacteria produces lactic acid, the pH of the milk decreases and casein, the primary milk protein, precipitates, causing thecurdling or clabbering of milk. This process makes buttermilk thicker than plain milk. While both traditional and cultured buttermilk contain lactic acid, traditional buttermilk tends to be less viscous, whereas cultured buttermilk is more viscous.
Cultured buttermilkCommercially available cultured buttermilk is milk that has been pasteurized and homogenized (if 1% or 2% fat), and theninoculated with a culture of lactic acid bacteria to simulate the naturally occurring bacteria in the old-fashioned product. Some dairies add colored flecks of butter to cultured buttermilk to simulate residual flecks of butter that can be left over from the churning process of traditional buttermilk.
Condensed buttermilk and Dried buttermilk have increased in importance in the food industry. Buttermilk solids are used inice cream manufacture Adding specific strains of bacteria to pasteurized milk allows more consistent production.
In the early 1900s, cultured buttermilk was labeled artificial buttermilk, to differentiate it from traditional buttermilk, which was known as natural or ordinary buttermilk
Acidified buttermilkAcidified buttermilk is a related product made by adding a food-grade acid (such as lemon juice) to milk. It can be produced by mixing 1 tablespoon of vinegar or lemon juice with 1 cup of milk and letting it sit until it curdles, about 10 minutes. Any level of fat content for the milk ingredient may be used, but whole milk is usually used for baking.