Interesting Article on Dairy Products

[Guest guest]

http://www.foodproductdesign.com/articles/2000/03/new-directions-for-cultured-dairy-products.aspx

or

http://tinyurl.com/yhtq2gy

Interesting article on dairy products. Regrettably, the author hadn't

read the Weston-Price information on healthy fats, and still advocates

low-fat dairy, but.....

New Directions for

Cultured Dairy Products

March 2000 -- Design Elements

By: C. Deis, Ph.D.

Contributing Editor

It's an established fact

that milk and other dairy foods play an extremely important role in the

American diet. Milk also provides an ideal substrate for microorganisms

that further improve nutrition, texture and flavor characteristics,

resulting in yogurt, sour cream, buttermilk, cottage cheese, kefir and

fermented cheeses. For this discussion, we'll focus on fermented milks,

outlining their production, characteristics and nutritional benefits.

Fermentation facts

What happens to milk during fermentation? Bacterial cultures are

added to pasteurized milk, which is incubated at 40° to 44°C for several

hours. During this time, the bacterial population grows and produces acid

from lactose, reducing the pH of the milk. This destabilizes the micellar

casein, coagulating the milk. When the target pH (generally 4.1 to 4.6)

has been reached, the product is cooled to slow fermentation.

The bacterial cultures, termed " starter cultures, " are

derived from seven types of lactic acid bacteria: Lactococcus

lactis subspecies (ssp.) cremoris; Lactococcus lactis ssp.

lactis; Lactococcus lactis ssp. lactis biovar diacetylactis;

Leuconostoc mesenteroides ssp. cremoris; Streptococcus

thermophilus; Lactobacillus delbrueckii ssp. bulgaricus and

Lactobacillus helveticus.

The genus Lactococcus is composed of spherical cells that

form pairs or chains. L. lactis ssp. lactis and L.

lactis ssp. cremoris are homofermentative, meaning that from

lactose, they produce only lactic acid, no CO2. L.

lactis ssp. lactis biovar diacetylactis is heterofermentative;

it ferments lactose to lactic acid, but also utilizes citrate to produce

diacetyl and CO2. Lactococci grow at 40°C and in 2% to

4% sodium chloride.

Leuconostoc mesenteroides ssp. cremoris, a

heterofermentative coccus, metabolizes citrate to diacetyl and

CO2. The organisms grow at 20° to 22°C, and must be combined

with a Lactococcus because Leuconostoc grows poorly in

milk, and needs assistance to drop the pH to less than 5.1.

Streptococcus thermophilus grows best at 35° to 41°C, and

will grow in 2.5% salt. It splits lactose to glucose and galactose.

Lactobacillus delbrueckii ssp. bulgaricus is a rod that

grows optimally at 43° to 45°C, and also ferments lactose to glucose plus

galactose. Lactobacillus helveticus is similar to L.

bulgaricus, but acts more readily on galactose at the end of

fermentation, when the other sugars are depleted.

Combinations of all these organisms, plus other probiotic

microorganisms, are used to manufacture fermented milk products. When

choosing a starter culture, keep in mind which are mesophilic and which

are thermophilic, as well as which end products are contributed; i.e.,

what is the target for the final product?

The activity of lactic-acid bacteria has one immediate result - it

improves lactose digestion in lactose-intolerant individuals, who cannot

digest lactose in the small intestine due to lack of the enzyme that

performs this function. This leads to water accumulation in the small

intestine and lactose fermentation in the large intestine, resulting in

mucosal irritation and cramps, flatulence and diarrhea, as well as

potential death for young children.

Fermentation reduces lactose levels by 20% to 30% (from about 4.5%

in raw milk). Lactic-acid bacteria harbor beta-galactosidase (lactase)

while passing through the stomach, after which it becomes available to

hydrolyze lactose in the intestines. The extent of this activity depends

on beta-galactosidase activity in the strain or culture used, rate of

transit through the gastrointestinal tract, and post-fermentation

treatment.

Cultured classes

The use of starter cultures began within the cheese- and

butter-making industries. Prior to the commercial development of starter

cultures, a cheesemaker had three choices - let nature take its course in

the batch; use the previous day's production as a starter; or sour a

small portion, taste it, then use that as a starter. In 1893, the company

that now operates as Chr. Hansen, Inc., Milwaukee, started marketing

cheese cultures, which drastically decreased variability and increased

yield. Previously, the chance of losing a batch was about 50%. These

first liquid cultures, while more predictable than the previous options,

were far from perfect, however.

Air-dried lactic-ferments - cultures dried on sterile cloth strips

- were introduced at the turn of the century. These eventually progressed

to a powdered form, sold in small bottles. Freeze-dried cultures came

along in 1950, followed by frozen cultures in 1960. As dairies grew, they

required larger, faster-starting cultures, along with bigger starter

rooms. Frozen concentrated cultures eliminated the need for a large

inoculum in the mid-1970s, and strain purity improved dramatically. From

the 1980s on, frozen defined-strain starters have been available, so

dairies can use specific strains if desired, or undefined starters, which

are mixtures of the seven types of lactic-acid bacteria. Single-strain

starters are also available, in case of phage attack on one type of

bacteria.

Prior to discussing the benefits of cultured milk products, let's

define the products and how they differ.

Yogurt has become very popular, and is leading the way in

educating consumers about probiotics. Americans consume approximately 5

lbs. of yogurt yearly per person - five times more than in 1970. In the

United States, yogurt is defined (21 CFR 131.200) as a cultured dairy

product made with a characterizing bacterial culture containing L.

bulgaricus and S. thermophilus. Nonfat milk-solids content

must be greater than 8.25%, and is often higher. Final titratable acidity

(TA) must be at least 0.9%, expressed as lactic acid. Other cultures may

be added to the two designated.

In the United States, yogurt is typically prepared in one of two

methods, Swiss-style or sundae-style. Both styles are prepared by

standardizing milk for fat and protein content, then storing, if

necessary, at 40°F. Stabilizers, such as gelatin and starch, and sucrose

and other sweeteners may be added. Aspartame should be added

post-process, generally with fruit, while sucralose and acesulfame K may

be added earlier in the process. The mix is homogenized (2000 psi first

stage, 500 psi second stage), then heat-processed at 180°F for 30 minutes

or 195°F for one minute, and cooled to 110°F.

Pasteurizing yogurt prior to fermentation destroys bacteria, and

increases resistance to " wheying-off. " Homogenization spreads

casein evenly around fat globules, ensuring that fat is evenly

distributed in the final gel structure. In sundae-style products, the gel

formed when the casein coagulates is not disturbed, so the product is

firmer than Swiss-style, where the gel must be broken to package the

product. Either 0.5% gelatin or modified food starch may be added to

re-set the structure.

After the starter culture is added - either to a vat (Swiss-style)

or to the final container (sundae-style) - the mixture is held for three

to four hours at 110°F for fermentation, then cooled to under 39°F. The

yogurt's pH drops as lactic acid is produced during fermentation.

" Recently introduced cultures significantly shorten acidification

time, while maintaining a mild flavor. These cultures also contain

probiotics, " says Marilyn Stieve, market manager, cultured dairy

products, Chr. Hansen, Inc.

L. bulgaricus and S. thermophilus are synergistic,

producing acid and acetaldehyde (optimally at pH less than 5.0). In the

United States, most people do not care for the " nutty " flavor

of acetaldehyde, so sugar, flavor and/or fruit are generally

added.

Fruit can be found in the bottom of the cup (sundae-style) or

distributed throughout the product (Swiss-style). According to Kathleen

Doren, industry manager, sweet group, Haarmann & Reimer Corp.,

Elkhart, IN, " Adults and children are looking for high-impact foods

and flavor combinations. Fruit flavors that give a burst of flavor are in

demand, along with multi-fruit type flavors. "

Culture selection also contributes to flavor. " We have worked

with traditional culture types, " notes Stieve, " blending L.

lactis and L. cremoris with L. diacetylactis to produce

much higher levels of diacetyl - the fresh butter note - than could

previously be achieved. " Higher levels of natural flavors in the

product provide greater impact and a longer shelf life.

Frozen yogurt is produced by a similar process, but at 1.5 to 2.0,

its TA is generally much higher, and the solids level is also higher,

approximately 25%. Frozen yogurt is added at 10% to 15% to a base mix to

obtain the lower TA and a mild flavor. Gel structure is not important for

frozen yogurt, since it is broken up when the product is frozen.

Kefir is a fermented, effervescent milk product produced

from a complex mixture of bacteria and yeast. This product was originally

produced by letting milk sour naturally, resulting in generation of

CO2, alcohol and the aromatic compounds that set kefir apart

from other cultured products. The inoculum is traditionally " kefir

grains, " which are small casein/polysaccharide/microorganism

clusters added to the milk.

Like yogurt, kefir contains much less lactose than milk, and

beta-galactosidase is also harbored by its live organisms. Kefir's TA is

about 1%, and it has an alcohol content of about 0.01% to 0.10%.

Production starts with whole, low-fat or skim milk, adjusted for body

with nonfat milk solids. The milk is pasteurized, then heat-treated at

95°C for 10 to 15 minutes, which totally denatures the whey proteins.

This product is then cooled to 18° to 22°C, and 2% to 5% kefir grains are

added. This mixture is incubated at 18° to 22°C for 24 hours, after which

the kefir grains are sieved out, and the product is chilled and packaged.

Kefir grains can be rinsed and re-used, or dried and stored for later

use. The final kefir product can be flavored in a manner similar to

yogurt.

Lifeway Foods, Inc., Morton Grove, IL, the largest producer of

kefir in the United States, adds a concentrated bovine colostrum product

to some of its kefir products. Colostrum, the first milk produced by a

cow after calving, is loaded with antibody activity. GalaGen Inc. (a name

formed from the combination of the Greek gala, meaning milk, and gen,

meaning birth), St. , MN, provides colostrum's immune components in

Proventra™, a mixture of bioactive proteins, including broad-spectrum

antibodies, lactoferrin, lactoperoxidase, growth factors and cytokines.

Kefir, even without colostrum supplementation, has been linked to

immunological, antitumoral and hypocholesterolemic properties, but

requires much more study to substantiate claims. A number of similar

fermented milks - including kumiss, which is popular in Russia - are

prepared around the world, all popular largely for their health

benefits.

Cottage cheese (21 CFR 133.128) is produced from skim milk

pasteurized at 145°F for 30 minutes or 161°F for 15 seconds.

Pasteurization is minimized to avoid coagulation, which inhibits later

drying. In general, the curd is set at 86° to 92°F for about eight

hours.

Cottage cheese coagulator, an enzyme preparation, is generally

used to form the coagulum. Depending on the size of the curd, the

coagulum is cut at or near casein's isoelectric point (pH 4.7). The cut

curd is heated slowly, then held at 125° to 135°F for 30 minutes. The

curd is drained, then washed with chlorinated (5 ppm available chlorine)

water several times at successively lower temperatures - 80°, 65° and

then 45°F. Cream (5% to 10% fat) is then added to about 40%, and salt at

about 1.0%. The creaming mixture can be flavored by adding a starter to

the cream, or by fermenting skim milk with L. mesenteroides ssp.

cremoris or Lactococcus lactis to form flavor compounds,

then adding this milk as desired to the creaming mixture. " A

two-part culture system is available to reduce make time and maximize

flavor in cottage cheese and sour cream, which improves process times and

efficiency, " notes Stieve.

Buttermilk is usually defined as the liquid product

remaining when fat is removed from milk or cream by churning. It contains

not less than 8.25% nonfat milk solids. Buttermilk is pasteurized at 185°

to 190°F for 30 to 60 minutes, then cooled to 70° to 72°F for

fermentation. Both lactic-acid-producing and flavor-producing strains are

used for culturing.

Fermentation requires about 16 hours, with a targeted TA of 0.75%

to 0.90%, which correlates to a diacetyl content of about 2.0 ppm. This

gives the product an optimum buttery flavor. Viscosity can be increased

by adding stabilizers, nonfat dry milk, or polysaccharide-producing

cultures. Thicker buttermilk is preferred in the southeastern United

States, but for those who prefer it thinner, buttermilk can be thinned by

targeting a higher TA, then diluting with skim milk. After fermentation,

buttermilk is pumped through a screen to smooth the product, then stored

at refrigeration temperature.

Sour cream (21CFR131.160) consists of pasteurized cream

fermented with flavor-producing bacteria. Sour cream must contain 18%

milkfat. Other sour-dairy products might use half-and-half with 10.5%

milkfat, or even no fat. Stabilizers such as gelatin and starch are

required to adjust viscosity. The fermentation process is the same as for

buttermilk, but nonfat milk solids are higher.

Powerful probiotics

According to the National Dairy Council, Chicago, dairy foods are

the most important source of calcium and other nutrients for optimal bone

health and prevention of osteoporosis, which affects 28 million people in

this country. Studies have linked higher intakes of calcium and lactose

with a reduced risk of breast cancer, and calcium intake has also been

linked to control of colon and colorectal cancer. Calcium, lactose,

Vitamin D, conjugated linoleic acid (CLA), sphingomyelin, butyric acid

and protein have all been shown to have anticarcinogenic properties. Whey

proteins contain sulfur amino acids (cysteine, methionine, glutathione),

which also possess anticarcinogenic properties. Given their inherent

healthful benefits, it's a natural extension for fermented dairy products

to be leaders in the functional foods area.

Lactobacillus organisms are commonly considered to be

probiotics, which are defined as live bacteria that improve intestinal

microbial balance and enhance health. Prebiotics, which are

non-digestible food ingredients that selectively stimulate the growth and

activity of probiotics, include starches, dietary fibers, polyols, inulin

and oligofructose.

" Probiotics produce short-chain fatty acids, which are used

by colonocytes as an energy source, maintaining a healthier colon.

Butyric acid, for example, reportedly has anticarcinogenic

properties, " says Mark Izzo, Ph.D., director of technology, ORAFTI

Active Food Ingredients, Malvern, PA. " Probiotics also produce

bacteriocins, which, as natural antibiotics, increase resistance to

infection. Prebiotics such as inulin and oligofructose give these

cultures a chance to work - they synergistically improve the survival of

the probiotic in the intestinal tract.

" With both the pro- and prebiotic in a product, the product

is synbiotic, " continues Izzo. " Synbiotics have been shown to

reduce colon cancer risk in animals, and to increase bacteria in the

feces after drinking acidophilus milk with inulin. "

At this point, not enough well-defined studies exist to

definitively state the benefits of probiotics (or synbiotics) to human

health, but studies certainly indicate a number of favorable effects:

Gastrointestinal well-being, including resistance to infection;

prevention, or fast recovery from, diarrhea; and fewer constipation

difficulties, due to faster transit time. Beneficial roles in immune response. Reduced cancer risk, particularly colon, breast and intestinal,

possibly due to immune-response stimulation, reduction of carcinogenic

enzymes, or modification of the colon environment. Improved tolerance to lactose and milk proteins. This is due

primarily to beta-galactosidase in the bacteria, which helps digest

lactose. It's also possible that probiotics may reduce sensitivity to

milk proteins. Reduced LDL cholesterol. Results are somewhat contradictory at this

point, but one study reports reduced LDL cholesterol in animals after

ingestion of yogurt or cultured milk. It is clear, in any case, that

regular consumption of yogurt does not increase plasma cholesterol

concentration.

Bifidobacteria, first observed and reported in 1900, are strictly

anaerobic, gram-positive rods with the ability to grow slowly in milk.

These probiotics are normal inhabitants of the gastrointestinal tract

from shortly after birth. Identified species are Bifidobacterium

lactis, B. infantis, B. longum and B. animalis. Other

identified probiotics include Lactobacillus casei, L. acidophilus, L.

delbrueckii ssp. bulgaricus, L. paracasei ssp. paracasei,

L. rhamnosus and Streptococcus thermophilus. Stieve notes that

these strains are commercially available as single strains,

multi-strains, and in specific cell counts.

Chr. Hansen has sponsored more than 50 probiotic studies at a

number of hospitals and universities, including s Hopkins,

Pennsylvania State, UCLA, and the University of Minnesota. Researchers

have reported reduced diarrhea, reduced yeast infections, improved

lactose tolerance, lower cholesterol, reduced antibiotic side effects and

enhanced immunity. Researchers at s Hopkins evaluated the

effectiveness of feeding infants S. thermophilus and B.

animalis to prevent rotavirus-induced diarrhea. Results indicated

that probiotics helped prevent infection and its spread via shedding in

the feces. A study at Jewish Medical Center in New York City showed a

three-fold decrease in vaginal yeast infections using probiotics - it

worked so well that the probiotic test group refused to discontinue the

treatment.

Yogurt associates

Yogurt, due to its popularity and easy acceptance of other

ingredients, is a vehicle for numerous health-related modifications. For

example, Schouten USA, Inc., Minneapolis, conducted a study last year to

determine if soy isoflavones could be easily added to yogurt. These

compounds, according to Schouten, help deposit calcium and reduce

osteoporosis. Some differences in the yogurt's color and flavor were

noted, but the isoflavones did not interfere with fermentation.

Oligofructose can, according to studies, increase calcium,

magnesium, and iron absorption. " Oligofructose can be successfully

added to yogurt with no effect on the fermentation, and no significant

difference in color or flavor, " says Izzo. " Two human studies

have shown a positive calcium-absorption effect, with an increase of 26%

(with 15 grams/day of oligofructose, in adolescents) and 58% (with 40

grams/day of inulin in young adults). "

Yogurt and the consumers who ingest it can also gain from added

omega-3 long-chain polyunsaturated fatty acids (LC PUFAs), says Raimund

C. Hoenes, Ph.D., marketing manager, Roche Vitamins, Inc., Parsippany,

NJ. LC PUFAs are instrumental in optimal infant neural and visual

development, and may protect against inflammatory and autoimmune

conditions and cardiovascular disease, in the latter case by lowering

triglyceride levels and maintaining a healthy heartbeat. " Yogurt

allows for a fairly high level of fortification, " notes Hoenes,

" thus providing a potentially excellent source of omega-3 LC PUFAs

per serving.

" It is important to differentiate the long-chain PUFAs from

the other omega-3 oils out there, " continues Hoenes, " since

only the LC PUFAs are associated with the heart-healthy benefits. An

example of an oil with short-chain omega-3s is canola, which does not

have the healthy properties. "

Omega-3 LC PUFAs may be added before homogenization or after

fermentation while stirring - the oil has no effect on fermentation,

according to Hoenes, who suggests using about 1,320 mg of the company's

omega-3 product per serving. At this level, the taste remains unaffected.

" The suggested amount provides 330 mg omega-3 LC PUFAs per 225-gram

serving, " he says. " The British Nutrition Foundation has

recommended 1.25 grams docosahexaenoic acid (DHA) and eicosapentaenoic

acid (EPA) per day. Therefore, 330 mg would provide 26% of the

recommended daily intake. "

The ROPUFA® 30 n-3 food oil marketed by Roche contains at least

25% omega-3 fatty acids as EPA, DHA and docosapentaenoic acid (DPA). The

marine oil is dispersed in gelatin, sucrose and starch stabilized with

mixed tocopherols, ascorbyl palmitate and rosemary extract.

Omega-3 LC PUFA has been self-affirmed as GRAS based on an expert

panel review, and the FDA has determined that menhaden oil is safe as a

direct food ingredient, provided the daily intake of EPA and DHA does not

exceed 3 grams/day.

Horizon Organic Dairy of Boulder, CO, introduced a new synbiotic

yogurt in 1999, combining low-fat blended yogurt with various herbs such

as ginger, chamomile, rose hips, hibiscus, and ginseng, as well as

beta-carotene. The company's line of products is based on certified

organic milk and organic ingredients. Their blended yogurts contain agar

and pectin rather than the traditional gelatin or modified food starch,

as well as five active cultures - L. acidophilus, L. bulgaricus, B.

bifidus, S. thermophilus and L. casei. Their organic sour

creams contain live and active cultures of L. acidophilus and

B. bifidus, as does their cottage cheese. The Dannon Company,

Tarrytown, NY, has introduced Actimel®, a dairy-based beverage sold in

Europe since 1994. Actimel contains a unique combination of active

cultures, including L. casei. The product is supported by

extensive clinical studies that support the company's campaign to educate

consumers about active-culture benefits.

Cultured perspectives

What else can we expect from cultured dairy products? " We

have shown that a diet rich in low-fat dairy foods affects the way in

which fat cells do their job, " said Zemel, Ph.D., department

head and director of nutrition, Nutrition Institute, University of

Tennessee, at the November 1999 North American Association for the Study

of Obesity meeting. " A diet high in low-fat dairy causes fat cells

to make less fat and turns on the machinery to break down fat, which

translates into significantly lower risk of obesity. " This theory is

supported by a two-year study at Purdue University, West Lafayette, IN,

which found that women getting their calcium from dairy foods experienced

greater weight loss than those who used other calcium sources. This could

change the way dieters have generally thought about dairy products, but

this finding requires further examination.

Fermented milks have been associated with health for centuries,

and their gastrointestinal effects were reported around 1900 by E.

Metchnikoff at the Pasteur Institute in Paris. Their proposed effects,

detailed in Paris-based Danone, Inc.'s July 1997 Danone World

Newsletter, are many. (The publication, intended to keep concerned

scientists, regulatory officials and media representatives around the

world up to date on new findings regarding the benefits of yogurt and

fermented milks in nutrition and health, is available at www.danone.com.)

Published health benefits of cultured dairy products include

physiological effects (production of bacteriocins/anti-pathogen

activity); actions on the digestive tract (regulation of intestinal

motility, prevention of intestinal disturbances, stabilization of Crohn's

disease); alterations of intestinal microflora (increase in fecal

bifidobacteria, balance of intestinal bacteria); actions on diarrhea

(treatment of persistent diarrhea, treatment of rotavirus and

antibiotic-associated diarrhea); and systemic effects (immune enhancer,

reduction of serum cholesterol, anti-cancer).

Danone reports, however, that only a few benefits are relatively

well established; i.e., those with several studies and no conflicting

data. These include enhancement of lactose digestion, increase of fecal

bifidobacteria, decrease of certain fecal enzyme activities, decreased

rotavirus diarrhea, and treatment of adolescent persistent

diarrhea.

Obviously, there is more to be done, and research on fermented

milk products continues - with a wide variety of studies underway at

North Carolina State University, Michigan State University, California

Polytechnic State University in San Obispo, State University of New

York in Buffalo, University of Minnesota, University of California at

and University of Tennessee - to name a few. As knowledge continues

to grow, so will the use of cultured dairy products. Health care costs

are escalating, preventive care is of major concern, and consumers are

becoming more informed, not to mention that the food industry is always

interested in new products. All these factors bode well for the future of

cultured foods - traditional products that incorporate new technologies

and new knowledge.

C. Deis, Ph.D., is a consulting food scientist based

in West Chester, PA. He specializes in food ingredient technology and

process/ingredient troubleshooting, and has a strong formulation

background in baked goods and wet systems. He hosts a website at

http://hometown.aol.com/rcdeis/deiswebpage.htm.

—

Marilyn

New

Orleans, Louisiana, USA

Undiagnosed IBS since 1976, SCD since 2001

Darn Good SCD Cook

No Human Children

Shadow & Sunny Longhair Dachshund