Etiket Arşivleri: dairy products
The Importance of Dairy Products
Dairy products are important for building healthy bones and for maintaining a healthy weight. Dairy is also beneficial for your teeth and gums because it can reduce your risk for gum disease. Does anyone know some vitamins or minerals commonly associated with dairy products?
All dairy products belong to the Milk Group of MyPyramid. All milks, yogurts, frozen yogurts, dairy desserts, cheeses (except cream cheese), including lactose-free and lactose-reduced products. Most choices should be fat-free or low-fat. Calcium-fortified soy beverages are an option for those who want a non-dairy calcium source.
What Nutrients are Found in Dairy Products?
We already heard about calcium, but dairy products have many other nutrients other than calcium. They have vitamin D, vitamin A, magnesium, zinc, and protein. All of which are necessary in our daily diet for us to have energy, to grow, and to fight infection.
Calcium is important because our bodies use the calcium we get from dairy products to help build our bones, promote blood clotting, make sure our nerves work well, and help to build strong muscles.
What if I am lactose intolerant?
If you are lactose intolerant, this should still not prevent you from having select dairy foods like yogurt and cheese. Alternate forms are available, such as soy milk and even almond milk. You must make sure that you get enough calcium from other sources such as fruits and vegetables, nuts, and dried beans.
Other Ways to Get Calcium
Green leafy vegetables, such as spinach, turnip greens, and broccoli are excellent sources of Calcium. Use these in addition to dairy products to ensure that you have the recommended daily intake of Calcium. Calcium supplements can also be taken to make sure that individuals get enough calcium every day.
How Much Should I Have?
For adults, the recommended daily allowance of calcium is 1200 milligrams. For children, 1300 milligrams is recommended. Just remember, one glass of milk has about 300 milligrams of Calcium.
Ways to Reach Your 1200 or 1300 a day!
Let’s look at a day’s food intake to see how we could get enough calcium in a day. Let’s say for breakfast you have one pancake (100 milligrams), you have 1 glass of milk with it (300 milligrams). You have already had 400 milligrams. If you have a sandwich with cheese for lunch (200 milligrams) and a glass of milk, (300 milligrams) you have had 900 milligrams already. If you then have 1 cup of ice cream (200 milligrams) when you get home from school, and then later 1 string cheese for snack, you have had a Total of 1300 milligrams a day. And that is listing only the
What are the Best Sources of Calcium?
Dairy products have many nutrients including calcium, protein, and other minerals.
Dairy products are the best sources of calcium.
If you are lactose intolerant, you can still consume dairy products, and there are vegetable sources that are high in calcium.
We should consume about 1300 mg of calcium/day.
What is Milk Microbiology?
Basically it’s the study of Milk and its microorganism.
Is the study of Microorganisms; under this are bacteria, virus, protozoal parasites, and fungi.
What is Milk?
It is a white liquid produced by mammary gland of animals. It is the primary nutrition of the young before they are able to digest more complex food. Throughout the world there are 6 millions consumers in the world.
Milk is sterile at secretion in the udder but is contaminated by bacteria even before it leaves the udder. Further infection of the milk by microorganisms can take place during milking, handling, storage, and other pre-processing activities.
Raw milk – The lacteal secretion, practically free from colostrums obtained by the complete milking of one or more healthy cows (PMO).
“Consumer Milk” products:
– Homogenized milk: ³3.25% fat
– Reduced fat milk: 2% fat
– Low fat milk: 1% fat
– Fat-free milk: skim milk, <0.5% fat
(all with 8.25% solids-non-fat)
Fermented milk or dairy products have been part of human diet since ancient times. Various fermented products are made by different strains. Lactic acid fermentation is performed most often by lactic acid bacteria. Due to their abundance in nature, including mucosal surfaces of the human body, and their use in fermented foods they are labeled as GRAS (generally recognized as safe). The main genera that belong to the lactic acid bacteria group are: Lactobacillus, Leuconostoc, Lactococcus, Pediococcus and Streptococcus.
These bacteria ferment the carbohydrates in milk, the major one being lactose, to lactic acid and some other products. The acid precipitates the proteins in the milk and that is why fermented products are usually of thicker consistency than milk. The high acidity and low pH hinders the growth of other bacteria, including pathogens. Some lactic acid bacteria can produce agents with antimicrobial properties. Since milk is rich in many nutrients such as protein, calcium, phosphorus, and B vitamins dairy products are an excellent food.
Physical and Chemical Properties of MILK
It is a white emulsion or colloid of butter fat globules
Has yellow-orange carotene imparts the creamy yellow color to the glass.
Contains 30-35% grams of protein per liter of which about 80% is arrange in casein micelles
Different carbohydrates such as: lactose, glucose, galactose, and other oligosaccharides
Vitamins A, B6, B12, C, D, K, E, thiamine, niacin, biotin, riboflavin, folates, and pantothenic acid are present
Origin of microorganism in milk
Commensal micro flora- teat skin, epithelial lining of the teat canal, duct that conveys the milk from the mammary gland to the teat orifice.
Environmental contamination- soil, water equipment, dairy farm area are reservoir for many food borne pathogens
a semisolid sourish food prepared from milk fermented by added bacteria, often sweetened and flavored.
Mixed starter culture – S. Thermophilus and lactobacillus delbrueckii or lactobacillus bulgaricus.
Fermentation: lactose content of milk to yield lactic acid, CO2, acetic acid, diacetyl and acetaldehyde
Ph reduce: around 6.5 to 4.5 due to the production of organic acids
Initially streptococcus thermophilus ferments the lactose
Lactobacillus bulgaricus, which is more acid tolerant, continues to ferment the remaining lactose.
BENEFITS of Yogurt
– Easier digestibility,
– The ingested organisms enhance bioavailability of nutrients
– Ensure gastrointestinal balance,
– Promoting colon health
– Accelerates the healing of gastrointestinal tract disorder
– Reduction in cholesterol level.
Changes in milk by microorganism
Gas production: Fermentation occurs at faster rate, then raw milk present a foamy layer on the upper surface Air bubbles becomes entrapped and gas becomes saturated throughout the body of the milk. Colliforms, clostridium and bacillus species.
Roppiness or sliminess: Milk viscosity is increased, rope like structure is formed
Change in the color of milk
Blue color – pseudomonas synciani
Red color – brubibacterium erythrogenes, sarcinia marcense
Yellow color – pseudomonas synxantha
Brown color – pseudomonas putrificians
Green color – pseudomonas aurogenosa
Change in the Flavor of Milk
It is due to acidic changes in the milks:
– Clean: Low contents of acids, Streptococcus lactis
– Aromatic: streptococci and aroma- forming Leuconostoc sp. , moderated type of acidic components.
– Sharp: coliform bacteria, clostridium species, volatile fatty acids, high acidic contents
It is due to alkaline changes in the milk.Potato-like Flavour:
Acromian hydrophila, It is due to formation of tri-methyl amine
IMPORTANCE OF BACTERIA IN MILK
Bacteria – Are microscopic, unicellular, occurs in the form of spherical, cylindrical or spiral cells; Size 1-5m. Sore forming bacteria produce trouble in dairy industry because of their resistance to pasteurization & sanitization produces. Greater the bacteriological count in milk, the lower is its bacteriological quality. Pasteurized milk should have a SPC (Standard Plate Count)/ml (org) not exceeding 30,000.
Moulds/ Molds – Multi-Cellular; in maturity are as Mycelium. Used in cheese making which is responsible for defect in butter and other milk products. Spores are destroyed by pasteurization. It should also be noted that moulds, mainly of species of Aspergillus , Fusarium , and Penicillium can grow in milk and dairy products.
Yeast – Unicellular; Larger than Bacteria. Destroyed during pasteurization.
Viruses – Are ultra-microscopic forms of like can be destroyed by pasteurization or higher heat treatment.
GROWTH OF MICROORGANISM
Bacteria multiply during production and holding of milk, depending on storage time and conditions. The changes take place in the physico-chemical properties of milk are result of the activities of the individual microbial cells during their period of growth and reproduction or of substances produced during such activity.
Stages of growth :
i. Initial stationary phase
Lag phase (Phase of adjustment)
iii. Accelerated growth phase (log phase)
Maximum stationary phase
v. Phase of accelerated death.
Products of Microbial Growth :
i. Enzymesii. Decomposition products (fats, proteins, sugars).
v. Miscellaneous changes.
Destruction of Micro-organisms : May be done by following means.
i. Heat – Most widely used. Pasteurization & sterilization.
Ionizing radiation – Such as ultraviolet rays etc.
iii. High frequency sound waves – Supersonic and ultrasonic.
Electricity – Microbes are destroyed actually by heat generated.
v. Pressure – Should be about 600 times greater than atmospheric pressure.
Chemicals – Includes acids, alkalis, hydrogen peroxide, halogens etc.
Factors Influencing Growth :
i. Food supply – Milk and its products are good food source, provides all food requirements.
Moisture – Milk contains adequate moisture to development.
iii. Air – Supplies O2 to aerobic bacteria and moulds.
Acidity or pH – Preferably range 5.6 to 7.5.
v. Preservatives – Check growth depending upon concentration.
Light – More or less harmful.
vii. Concentration – High sucrose or salt content check growth.
viii. Temperature – Important means for controlling growth. According to their optimum growth temperature, bacteria can be classified into :
Psychotropic – can grow at refrigeration temp. 5-70C.
x. Mesophilic – can grow at temp. 20-400
Thermophilic – can grow at temp. above 500C.
Results of Microbial Growth in Milk :
i. Souring:- Most common, due to transformation of lactose into lactic acid & other volatile acids & compounds, principally by lactic acid bacteria.
Souring & gassiness:- Caused by coil group, indicates contamination of milk and its products.
iii. Aroma production:- Due to production of desirable flavour compounds s.a. diacetly.
Proteoloysis:- Protein decomposition leading to unpleasent odour.
v. Ropiness:- Long threads of milk are formed while pouring. Mainly Alkaligenous viscus.
Sweet curdling:- Due to production of a remain like enzyme curdles milk without souring.
DISEASES Outbreaks ASSOCIATED with MILK PRODUCTS
Standard Plate Count (SPC):
Aerobic plate count of total colony forming units of bacteria per milliliter or gram of raw, processed liquid and dry dairy products utilizing “SMEDP” 17th edition.
an NCIMS approved alternate test for SPC ( Standard Plate Count) on Raw Milk. Bacterial cells in a sample are lysed, liberated DNA is stained, and passed through light. The signal from the DNA is converted to an estimate of Bacteria and CFU’s in the original
Coliform Colony Forming Unit (CFU) Test:
Agar plate method employing a media (VRB) optimizing the growth of coliform organisms
Yeast and Mold Plate Analysis:
Determination of yeast and mold cell forming colonies in a dairy sample under specified conditions utilizing “SMEDP” 17th edition.
Direct Micro Count (DMC):
Direct microscopic count examination of stained preparation of milk, or certain other dairy products, to identify and enumerate the number of bacterial clumps present
Lab Pasteurized Count (LPC):
Raw milk in test tubes heated to 62.8C +/- 0.5C, survivors counted by standard plate count method utilizing “SMEDP” 17th edition.
Pre-Inc Plate Loop Count (PI):
Raw milk sample undergoes preliminary incubation at 13 degrees Celsius for 16-18 hours before analysis to stimulate the growth of psychrotrophic organisms and subsequently a Plate Loop Count (PLC). Is performed utilizing “SMEDP” 17th edition.
Antibiotic Sensitivity Test:
Test for sensitivity/resistance to antibiotics used in treatment of mastitis infections using the Kirby Bauer (agar diffusion) method.
VRB-MUG Agar plate test
(AOAC Official Method) for identification and presumptive identification of E Coli H157:H7
PRESERVATION of MILK
is a process of heating a food, which is usually a liquid(milk), to a specific temperature for a predefined length of time and then immediately cooling it after it is removed from the heat. This process slows spoilage caused by microbial growth in the food.
– Inactivation of bacterial pathogens (target organisms Coxiella burnettii)
– Assurance of longer shelf life (inactivation of most spoilage organisms and of many enzymes)
– Does not kill all vegetative bacterial cells or spores (Bacillus spp. and Clostridium spp.)
– Pasteurization temperature is continuously recorded
HISTORY OF PASTEURIZATION
The French scientist Louis Pasteur invented pasteurization.
To remedy the frequent acidity of the local wines he found out experimentally that it is sufficient to heat a young wine to only about 50–60 °C (122–140 °F) for a brief time to kill the microbes.
Pasteurization was originally used as a way of preventing wine and beer from souring, and it would be many years before milk was pasteurized.
Pasteurization of milk was suggested by Franz von Soxhlet in 1886.
is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents (such as fungi, bacteria, viruses, spore forms, etc.) present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media.
Dehydrated milk is manufactured dairy product made by evaporating milk to dryness.
Purpose: to preserve it; milk powder has a far longer shelf life than liquid milk and does not need to be refrigerated, due to its low moisture content.
– First invented by Russian physician Osip Krichevsky in 1802.
– Commercially available in 1832 by Russian chemist M. Dirchoff.
Milk drying methods
Spray Drying – Pasteurized milk is first concentrated in an evaporator to approximately 50% milk solids. The resulting concentrated milk is then sprayed into a heated chamber where the water almost instantly evaporates, leaving fine particles of powdered milk solids.
Drum Drying – Milk is applied as a thin film to the surface of a heated drum, and the dried milk solids are then scraped off. However, powdered milk made this way tends to have a cooked flavor, due to caramelization caused by greater heat exposure.
Freeze Drying – Same as drum drying but involves freezing which retains more amount of nutrition.
New bacteria discovered in raw milk
Chryseobacterium oranimense, which can grow at cold temperatures(7°C) and secretes enzymes that have the potential to spoil milk.“
haifense and C. bovis
By : Gladys Jane Aguhayon
BsBiology – Microbiology
In this experiment we examined with milk. We used different types of milk such as light UHT, raw milk, UHT (half-fat), UHT (full-fat), pasteurized and baby milk. We researched amount of protein, total acidity, total solid, ash, specific gravity and turbidity.
Turbidity test indicates that pasteurization process is done or not. In the raw milk tubes, turbidity was observed as the white precipitation and the result is suitable for the TSE becouse of the raw milk is not applied to heat. In the UHT tubes, faint turbidity was observed which means that the milk is not include microorganisms any more after heat treatment.
Specific gravity is made in detecting adulterations of milk. The aim of examining specific gravity, to look for the components of milk, to determine any fat is hired or not, to observe any water is added into. Adding water lowers the specific gravity, since it reduces the percentage of solids which are dissolved in the liquid part of milk. If the specific gravity of a sample of milk is below 1.030 or above 1.034, the milk may be considered to be adulterated. We observed different results in the two raw milk that are one of 1.03( was examined by the group 2) and the other( was examined by the group 8) is 1.026. Therefore we can say water may be added into the milk of group 8.