Introduction

 Milk is a white liquid produced by the mammary glands of mammals.

 Primary source of nutrition for young mammals before they are able to digest other types of food.

 Throughout the world, there are more than 6 billion consumers of milk and milk products.

Physical & Chemical properties

 Milk is a white emulsion or colloid of butter fat globules

 Presence of fat globules and the smaller casein micelles provide the opacity to the milk.

 Yellow-orange carotene imparts the creamy yellow colour to a glass of milk.

 It contains many other nutrients.

 Milk contains 30–35 grams of protein per liter of which about 80% is arranged in casein micelles.

 Different carbohydrate including lactose, glucose, galactose, and other oligosaccharides.

 Calcium, phosphate, magnesium, sodium, potassium, citrate, and chlorine are all included.

 Vitamins A, B6, B12, C, D, K, E, thiamine, niacin, biotin, riboflavin, folates, and pantothenic acid are all present in milk.

Microorganisms in milk

 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.

Milk supports the growth of a variety of bacteria including pathogenic one.

 Acid-forming bacteria, such as Streptococcus lactis, Str. faecalis Lactobacilli. These ferment lactose, forming lactic acid, and lead to the formation of curd.

 Alkali-forming bacteria, such as Alkaligenes sp. Achromobacter. Aerobic spore-forming bacilli These render the milk alkaline.

 Gas-forming bacteria, such as Coliform bacteria Cl. peifringens Cl. Butyricum. These produce acid and gas.

 Proteolytic bacteria, such as Bacillus subtilis, B. cereus, Proteus vulgaris, Staphylococci Micrococci. These bacteria are responsible for proteolytic activity.

 Inert bacteria, such as Achromobacter do not produce any visible change.

Lactic Acid Bacteria

 lactococci

 L. delbrueckii subsp. lactis (Streptococcus lactis )

 Lactococcus lactis subsp. cremoris (Streptococcus cremoris )

 lactobacilli

 Lactobacillus casei

 L.delbrueckii subsp. lactis (L. lactis )

 L. delbrueckii subsp. bulgaricus

 (Lactobacillus bulgaricus )

Leuconostoc

 Coliforms: coliforms are facultative anaerobes with an optimum growth at 37° C.

 Coliforms are indicator organisms; they are closely associated with the presence of pathogens but not necessarily pathogenic themselves.

 They also can cause rapid spoilage of milk because they are able to ferment lactose with the production of acid and gas, and are able to degrade milk proteins.

 They are killed by HTST treatment, therefore, their presence after treatment is indicative of contamination.

 Escherichia coli is an example belonging to this group.

Pathogenic Microorganisms in Milk

 The following bacterial pathogens are still of concern today in raw milk and other dairy products:

 Bacillus cereus

 Listeria monocytogenes

 Yersinia enterocolitica

 Salmonella spp.

 Escherichia coli O157:H7

 Campylobacter jejuni

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CIP CLEANING GUIDELINES

In order to provide a high quality milk to the marketplace a pipeline milking system must clean up perfectly after each milking. The ability to clean a pipeline milking system depends on these factors:

1. Adequate hot water

2. Proper engineering & system design

3. Adequate surface contact by the chemical solution

HOT WATER NEEDS:

Due to OSHA rules a household heater may not deliver water at a temperature greater than 140°F. For this reason a dairy farm will be required to use a commercial electric, gas or oil fired water to meet its’ hot water requirements. It is recommended that electric hot water heaters be quipped with two 6000 KW heating elements if they are available. The actual amount of 165°F hot water available from any hot water heater is about 70% of its’ capacity. Thus an 80 gallon water heater will only provide 56 gallons of 165°F hot water when it is needed to clean the milk pipeline and the bulk milk tank. Each water heater has a recovery rate based on a rise in heat per hour. Michigan Dairy Laws require the hot water needs to be calculated for each dairy farm. Most modern automatic washers have three cycles. Warm rinse, hot wash, and cold or warm acid rinse. The warm rinses are usually at a temperature of 95°F to 110°F. The hot wash is normally 165°F or hotter.

HOT WATER FOR BULK TANK WASH

Water needed for a bulk milk tank will vary according to size and manufacturer. Check with the dealer or operator’s manual for actual water volumes and temperature of each cycle.

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Source: https://www.michigan.gov/documents/132-136_CIP_Cleaning_Guidelines_13202_7.pdf

PEYNİR VE YOĞURT OLUŞUM MEKANİZMASI
Prof. Dr. Erdoğan KÜÇÜKÖNER
Süleyman Demirel Üniversitesi, Mühendislik-Mimarlık Fakültesi, Gıda Mühendisliği Bölümü, Isparta
erdogankucukoner@sdu.edu.tr

Özet

Peynir ve yoğurt farklı hayvanlardan elde edilen sütlerden üretilebilmektedir. Birer protein jeli olan bu ürünlerde süt proteinleri ürünlerin oluşumunda temel önem arz etmektedirler. Peynir, sütün peynir mayası denilen uygun proteolitik enzimlerle ve/veya zararsız organik asitlerle pıhtılaştırıldıktan sonra; peynir altı suyunun ayrılması, pıhtının şekillendirilmesi ve tuzlanmasıyla elde edilen, taze veya olgunlaştırıldıktan sonra tüketilen bir süt ürünüdür. Yoğurt, fermentasyonda spesifik olarak Streptococcus salivarius subsp. thermophilus ve Lactobacillus delbruecki subsp. bulgaricus’un simbiyotik kültürleri kullanılarak elde edilen fermente bir süt ürünüdür. Yoğurt ve peynirin duyusal, kimyasal, beslenme ve sağlık açısından özelliklerini, üretimde süte uygulanacak işlemler ile depolama sırasında dikkat edilmesi gereken hususlar etkilemektedir.

Anahtar kelimeler: Süt, peynir, yoğurt.

Abstract

Cheese and yogurt are able to be produced from milks of different animals. Milk proteins in these products, being protein-gels, are important to the product formation. Cheese produced by removing whey from curds and salting and giving shape through press just after coagulation (curdling) of milk by proteolytic enzymes and/or harmless organic acids is a dairy product consumed as a fresh or a ripened. Yogurt is a fermented dairy product produced by specifically inoculation of symbiotic cultures of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbruecki subsp. Bulgaricus during fermentation. Applied processes on milk in the production and the subjects watched out during the storage affect the properties of yogurt and cheese in terms of sensory, chemical, nutrition and health.

Keywords: Milk, cheese, yogurt.

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Kaynak: http://helalvesaglikli.org/docs/kongre/1/sozlu_bildiriler/4_peynir_ve_yogurt_olusum_mekanizmasi_prof_dr_erdogan_kucukoner.pdf

PEYNİR TOZU VE PEYNİR ALTI SUYU TOZU ÜRETİMİ
Prof. Dr. Erdoğan KÜÇÜKÖNER
Süleyman Demirel Üniversitesi, Mühendislik-Mimarlık Fakültesi, Gıda Mühendisliği Bölümü, Isparta
erdogankucukoner@sdu.edu.tr

Özet
İnsan hayatındaki öneminden dolayı, sütün ürünlere işlenmesi gıda endüstrisinde önemli bir yere sahiptir. Bu süt ürünlerinden biri olan peynir; sütün ısıtılması, starter kültür ilave edilmesi, proteolitik enzimlerle pıhtılaştırılması, pıhtının süzülerek peyniraltı suyundan ayrılması, telemenin tuzlanarak ve baskılanarak şekillendirilmesi ile elde edilen, taze veya olgunlaşmış halde tüketilen besleyici bir süt ürünüdür. Peynir tozları gıda endüstrisinde çok farklı alanlarda kullanılmakla birlikte, en yaygın olarak gıdalara lezzet verme amaçlı kullanılmaktadır. Peynir tozunun bu özelliğinden çerez kaplamaları başta olmak üzere preslenmiş çerezlerde, peynir esaslı soslarda, çorbalarda, patates cipslerinde, tuzlu çeşnilerde ve tuzlu bisküvilerde yaralanılmaktadır. Sütünün peynir yapımından sonra katı kısımdan ayrılan geride kalan sıvı kısmına ise peynir altı suyu denir. Peynir altı suyu tozu gıda sanayinde; şekerlemeler, unlu mamuller, et ürünleri, çorbalar, soslar, içecekler gibi birçok üründe kullanılmaktadır. Ayrıca, hayvan beslenmesinde ucuz ve yüksek kaliteli protein kaynağı olmasıyla beraber karbonhidrat kaynağı olarak da tercih edilmektedir.

Anahtar kelimeler: Maya, peynir, süt, peynir altı suyu.

Abstract
Processing of milk has an important place in food industry due to its importance on human-life. One of the dairy product, cheese, produced by heating of milk, addition of starter culture, coagulation (curdling) by proteolytic enzymes, draining of whey, salting and giving shape by press is a nutritious product consuming as a fresh or a ripened. Cheese powder utilized in so many different areas of food industry is widely used as a flavor enhancer
for foodstuffs. This feature of cheese powder is utilized in firstly coating of snack foods, additionally cheese-based sauces, soups, potato chips, salty dressings and in salty biscuits. Remaining aqueous phase, separated from solid part in the cheese production, is named “whey”. In food industry, whey powder is used in different food products like candies, bakery products, meat products, soups, sauces, drinks etc. Furthermore it is preferred for animal-
feeding due to its high carbohydrate content besides to being a cheap and high quality protein source.

Keywords: Yeast, cheese, milk, whey.

…

Preparing Milk for Processing
Got Milk
What is Milk?
It is the normal secretion of the mammary glands of all mammals
Its primary purpose is to nourish the young of the species
The Cow
Principal source of milk for human consumption in the United States

A great deal of variety among the milk of different animals exists which affects processing
The Cow
The most important factor that determines the composition of milk is the breed of cow.
Dairies are inspected by veterinarians, they are regulated by States and Cities.

Essential to protect public health concerns
Cold temperatures and environmental conditions of cattle are important to milk quality.

Stainless steel is recommended for use in equipment because it does not react with milk to cause off-flavor
The milking operation stimulates muscles in the udder of the cow causing let-down of milk into teat canals.

The machines work like vacuums and suck the milk into receiving vessels that lead to a holding tank
Holding Tanks
Refrigerated to cool the milk to less then 8 degrees C in order to control bacterial multiplication

Milk should not stay in the holding tanks for more than 2 days before transporting.

Tank Trucks
Milk is shipped in sanitized milk cans by trucks from smaller dairies or by tank truck transportation from larger dairies.
Drivers inspect the milk to see if it is cold and has a good aroma.
They also take a sample for further processing
Inspection Standards
Samples are analyzed for fat and solid contents and microbiological data.

Tests are conducted to determine bacterial count, determination of sediment, and evaluation of milk flavor.
Grade A Pasteurized Milk Ordinance
1978 – Recommendations of the U.S. Public Health Services/ Food and Drug Administration is used as a guide to the setting of standards of milk quality
Milk Flavor
Can acquire off-flavor
Cows eating unusual feed and or by absorption of odors and chemicals.
Poor milk handling equipment
Copper causes oxidized flavors that are metallic, oily and fishy.
Health Consideration of Dairy Products
Milk and other dairy products are a significant amount of nutrients for humans.

Milk is a good source of protein, calcium, and riboflavin.
3 C’s of Milk
Always Keep Milk…..

Clean!
Cold!
Covered!
Health Consideration of Dairy Products
Cow’s milk unlike human milk must be modified to meet nutrient requirements of infants.
Milk is low in iron which babies need in order to prevent anemia.
Milk can help to prevent osteoporosis, acne problems, poor eyesight, and fragile teeth.
Trends in Consumption
Since 1975 the available milk supply has increased.
Campaign slogans…..
Got Milk?
Milk does a Body Good!
Three A Day (Milk, Yogurt, Cheese)

Review
What is the most important factor that determines the composition of milk?
Why do we want to keep milk in stainless steel containers?
How long should milk stay in holding tanks?
What can milk help prevent?

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Contents

Types of Liquid milk

Preparation of sample

Detection of Adulterants

Cane sugar

Quantitative determination of sugar

Starch

Quantitative determination of starch

Cellulose Added Urea

Quantitative determination of urea

Ammonium Sulphate

Glucose

Sodium Chloride

Saccharin

Dulcin

Foreign Fat

Neutralisers

Hypochlorites and Chloramines

Quarterly Ammonium Compounds

Detergent containing Alkyl benzene sulphonic acid

Skimmed Milk Powder

Gelatin 16

Detection of Preservatives

Formalin

Hydrogen Peroxide

Boric acid and Borates

Salicylic acid

Phosphate Test for Pasteurisation in milk

Turbidity Test for Sterilised milk

Determination of Total Solids

Determination of Fat

Cream including Sterilised Cream, Whipped Cream and Malai

Determination of Fat

Thickeners in Cream

MILK AND MILK PRODUCTS MANUAL FOR ANALYSIS OF MILK AND MILK PRODUCTS

Cream Powder

Curd

Determination of Fat

Determination of Total Solids

Channa or Paneer

Cheese (All Varieties)

Ice Cream, Kulfi and Chocolate Ice Cream,

Dried Ice Cream Mix, Dried Frozen Dessert

Condensed / Evaporated (Sweetened, unsweetened and Skimmed) Milk

Milk Powder ( Whole, Skimmed, Partially Skimmed) Infant Milk Food, Milk Cereal Weaning Food etc

Khoa

Table ( Creamery ) and Deshi Butter

Ghee /Butter Fat

Chakka and Shrikhand

Yoghurt

Whey Powder

Edible casein products

Determination of Lactose by Colorimetric method in Milk based Sweets
…

Source

What is Milk Microbiology?

Basically it’s the study of Milk and its microorganism.

Microbiology?

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)

Introduction

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

YOGURT

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.

Ratio 1:1

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

Sour Flavour:
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

Bitter Flavour:
It is due to alkaline changes in the milk.Potato-like Flavour:
Pseudomonas mucidolense

Fishiness:
Acromian hydrophila, It is due to formation of tri-methyl amine

IMPORTANCE OF BACTERIA IN MILK

1. 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.

2. 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.

3. Yeast – Unicellular; Larger than Bacteria. Destroyed during pasteurization.

4. 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 :

1. i. Initial stationary phase

2. Lag phase (Phase of adjustment)

iii. Accelerated growth phase (log phase)

1. Maximum stationary phase

2. v. Phase of accelerated death.

Products of Microbial Growth :

1. i. Enzymesii. Decomposition products (fats, proteins, sugars).

iii. Pigments

1. Toxins

2. v. Miscellaneous changes.

Destruction of Micro-organisms :  May be done by following means.

1. i. Heat – Most widely used. Pasteurization & sterilization.

2. Ionizing radiation – Such as ultraviolet rays etc.

iii. High frequency sound waves – Supersonic and ultrasonic.

1. Electricity – Microbes are destroyed actually by heat generated.

2. v. Pressure – Should be about 600 times greater than atmospheric pressure.

3. Chemicals – Includes acids, alkalis, hydrogen peroxide, halogens etc.

Factors Influencing Growth :

1. i. Food supply – Milk and its products are good food source, provides all food requirements.

2. Moisture – Milk contains adequate moisture to development.

iii.  Air – Supplies O2  to aerobic bacteria and moulds.

5. Acidity or pH – Preferably range 5.6 to 7.5.

6. v. Preservatives – Check growth depending upon concentration.

7. 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 :

1. Psychotropic – can grow at refrigeration temp. 5-70C.

2. x. Mesophilic – can grow at temp. 20-400

3. Thermophilic – can grow at temp. above 500C.

Results of Microbial Growth in Milk :

1. i. Souring:- Most common, due to transformation of lactose into lactic acid & other volatile acids & compounds, principally by lactic acid bacteria.

2. 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.

1. Proteoloysis:- Protein decomposition leading to unpleasent odour.

2. v. Ropiness:-  Long threads of milk are formed while pouring. Mainly Alkaligenous viscus.

3. Sweet curdling:- Due to production of a remain like enzyme curdles milk without souring.

DISEASES Outbreaks ASSOCIATED with MILK PRODUCTS

Microbiology Analyses

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.

Bactoscan Analysis:

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

Microbiology Analyses

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.

Microbiology Analyses

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.

Microbiology Analyses

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.

Microbiology Analyses

E-Coli:

VRB-MUG Agar plate test

E-Coli 0157:H7:

(AOAC Official Method) for identification and presumptive identification of E Coli H157:H7

PRESERVATION of MILK

METHODS

Pasteurization

Sterilization

Dehydration

1) Pasteurization

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.

Louis Pasteur

Sterilization

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.

Dehydration

Dehydrated milk is manufactured dairy product made by evaporating milk to dryness.

Dehydration

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.

Spray Drying

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.

Freeze Drying

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.“

1. haifense and C. bovis

END

By : Gladys Jane Aguhayon

BsBiology – Microbiology

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ÖZET

Bu araştırmada; içme sütü üretim aşamalarındaki trans yağ asitlerinin belirlenmesi amaçlanmıştır. Bu amaçla; örnek bir süt fabrikasına gelen ve işlenen sütlerin trans yağ asitleri cins ve % miktarları yağ asidi metil esterleri şeklinde GC ile belirlenmiştir. Sonuçlar istatistiksel olarak değerlendirilmiştir.

Sütün bileşimi üzerine; hayvanın ırkı, laktasyon periyodu, meme hastalığı, sağım aralığı, beslenmesi ve mevsimler olmak üzere çeşitli faktörler etkili olmaktadır. Süt yağı; sütün en değerli bileşenlerinden biridir ve diğer hayvansal yağlardan çok çeşitli yağ asitlerini (doymuş ve doymamış) içermiş olması özelliği ile ayrılmaktadır. Süt yağındaki yağ asitlerinin gıda değerinin yanında, aroma ve tekstür oluşumu açısından da büyük önem taşıdığı da bilinmektedir. Ülkemizde süt ve trans yağ asitleri üzerine birçok araştırmalar yapılmasına rağmen, üretim aşamalarının trans yağ asidi üzerine etkileri incelenmediği görülmüştür. Yağların fiziksel, duyusal ve fonksiyonel özellikleri, insan sağlığına etkileri ve muhafaza koşulları kimyasal yapıları ile ilgilidir. Yağlara farklı özellikler kazandıran kimyasal yapı, trigliseritler ile içerdikleri yağ asitleri çeşit ve miktarları ile ifade edilmektedir. Yağların bu değişik etkilerinde farklı yağ asidi bileşimine sahip oluşları ve herhangi bir teknolojik işleme tabi tutulmuş iseler, bu işlem sonucu uğradıkları değişim önemli rol oynamaktadır.

Yapılan çalışmada; toplam trans yağ asidi miktarları; çiğ sütlerde %2.86–6.30, pastörize sütlerde %1.85–6.55, sterilize sütlerde %2.50–9.77, 1 hafta 50C’de depolanmış sütlerde %3.28–11.67, 1 hafta 200C’de depolanmış sütlerde ise %5.32–7.12 arasında tespit edilmiştir. Elde edilen sonuçlar istatistiksel olarak değerlendirildiğinde üretim aşamalarının trans yağ asitleri oluşumu üzerine etkisi önemsiz bulunmuştur.

Anahtar Kelimeler: İçme sütü, trans yağ asidi, kalite

ABSTRACT

Determination of trans-Fatty Acids on the Milk Processing Stages

In this study, it has been aimed to determine trans fatty acids in drinking milk processes. With this aim, the trans fatty acids percent amount and type in the milk come and processed from a sample milk factory have been determined as a fatty acids methyl ester forms by GC. The results are evaluated by statically.

The composition of the milk is related with assorted factors like strain of animal, period of lactation, diseases of nipple, hiatus of milking, nutrition of animal and seasons. Milk oil is one of most valuable composition of the milk, separates from other animal fat with containing many various fatty acids (saturated and unsaturated). The fatty acids in the milk oil are also known with being an important role on the creation of texture and aroma. Physical, sensorial and functional properties of oils, their affect on human health, and their conservation conditions are related with their chemical composition. The chemical composition which gives them different properties finds voice in triglyceride and type and amount of fatty acids of it. The different composition of fatty acids and the mutation under any technological process have important role on this various influence of oils.

In this study, total trans fatty acid amounts of raw, pasteurized, sterilized, storages of 50C at one week, storages of 200C at one week were within the ranges 2.86–6.30%, 1.85–6.55%, 2.50–9.77%, 3.28–11.67%, 5.32–7.12%. The results of obtained were evaluated by statically; there were found that the effect of milk production processes is unimportant.

Key Words: Milk, trans-Fatty Acids, Quality

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