Study of Quality Control of Milk and Milk Products in Bangladesh
Milk vita co-operative company
The dairy sector of the country is one of the principle agricultural industries. Since the basic national objective is to provide of inputs to farmers at low cast and to reduce the income gap between rich and the poor. The presents government is keen to undertake programs in the light of the objectives out lined. It has been recognized that some rural benefits are already flowing to a group of co-operatively organized small farmers through the Bangladesh milk producer co-operative union limited.
Milk and Milk products are nutritionally enriched, food since it harbor many potent pathogen. Its microbial quality has always been crucial important to public health. The experiments were subjected to measure the physical, chemical and microbiological qualities of milk vita brands milk and milk products in the market of Bangladesh. After observing the quality control system the results show that there was regarding physical parameters (specific gravity, colour, appearance) is quit standard of their standard range they fallow. Such as CLR is about or near to 28 ± 0.5 in every sample. Regarding chemical test fat, total solid, acidity, SNR maintain their standard range. That are within acceptable range. Regarding total bacterial count is < 10, 000 in every milk and milk products. So that is in acceptable range. The coli form count varied from 0+0 10 with an average 5 cfu/ml. Maximally it was found 0 count. Fecal coli form were not tested. The observation results. Showed that the milk and ice-cream samples from milk-vita maintained recommended standard obliged by Bangladesh Standard Testing institute (BSTI). The study demonstrated that post-process contamination and ineffective pasteurization compromised the quality and shelf life of pasteurized milk and milk product. However to reduce contamination with microorganism to a minimum and obtain good keeping quality of the product, the raw material are to be examined, the equipment containing the food is to be adequately cleaned, sanitized and tested. The preserving process is to be checked, packaging and storage are to be supervised. Personal hygiene and cleanliness is also to be strictly maintained.
Milk is considered as one of the most nutritionally complete natural liquid food. It is rich in high quality protein, essential minerals and vitamins that are beneficial for human health. The composition of milk is protein 3.5%, Fat 4%, mineral matter 0.75%, water 87.25% and Lactose 4.75%.
The difference in quality of milk depends chiefly on the quantity of fat there in casein, lactose and mineral matter being nearly constant water varying but little unless milk is adulterated.
Along with all of the essential nutrients milk also contains a number of micro-organisms. Most of these bacteria, present in milk are generally harmless. In fact some of them are beneficial for us in some way or the other. But several factors such as the health of the animal, improper handling, pollutants from air and water etc. can contaminate raw mil and make it potentially dangerous. Several pathogens grow well in milk. This brings us to the technique of pasteurization which is used to kill all these pathogens.
Pasteurized milk is the milk that has been heated to high temperatures to kill all the harmful bacteria, and virus pasteurized milk can not be said to be 100% sterile. It can reduces the rish of a number of diseases caused by pathogens. Pasteurization does not after the taste of milk and retains all the milk health benefits.
Though pasteurization kill most of the pathogens it is necessary to control the quality of raw and pasteurized milk. The quality of milk is tested by physical, chemical and microbiological analysis. Microbiological test play crucial role in case of milk quality control.
Sanitation and Hygiene condition also play important role in milk quality. All equipments and personal hygiene is essential.
Therefore, by observing all of the above condition, for good quality of milk it is important to maintain strictly the standard rules.
Ice-cream has a long history as a population dairy food item. Ice cream is a nutritionally enriched dairy product produced by freezing pasteurized minture of milk. Solid other than fat, sugar, emulsifier and stabilizer. Dairy ice cream is a complex matrix consisting of ice, air, fat and the concentrated unfrozen serum.
The major steps in the manufacture of ice-cream include preparation of the ice cream mix, homogenization, pasteurization, cooling ageing, freezing and churning. The formulation and stability of the ice-cream manufacture.
Quality of ice-cream depends on both intrinsic factors that include manufacture procedure and intrinsic factors that include proportion of the ingredients used.
Ice-cream a milk based product is good media for microbial growth. Primary sources of microbial to ice-cream include water and raw milk whereas secondary sources include flavoring agents, utensils and handling.
Due to no enforcement of inspection act and lack of maintenance of standard relation to hygienic quality of ice-cream, the consumer of this country are deprived of getting quality ice cream.
Other Dairy food such as Roshmalai and curd also a nutritious and delicious food which quality depends mainly on milk quality and processing system. Sometimes post processing contamination also cause health hazard.
Therefore the present research program has been undertaken the following objectives:
To evaluate the physical, chemical and microbiological quality of milk and milk products produced in milk-vita dairy plant in Dhaka.
To ascertain the sanitary status of Milk-vita company produced pasteurized milk and milk derivatives in Dhaka and to made awareness among consumer regarding quality of milk and ice-cream and other milk foods.
In 1946, late M. Mukhlesur Rahman pioneer of dairying in Bangladesh a Dairy plant with a capacity of 2,000 liters. Per day was established at Lahirimohonpur. Pabna (Presently Shirajgong) with the target to send milk products to Calcutta (India) market that any within the easy rail communication system. After the partition, Eastern milk products limited, a private company purchased this dairy in 1952 from the original owner. In 1965, the first milk producer’s co-operastive was formed under the name Eastern milk producer’s co-operative union limited through government pasteurization over the plant at lahirimohonpur.
The dairy plants were owned and operated by the Eastern milk producer’s co-operative union Ltd. along with the other two existing dairies. The nomenclature of the organization was changed to Bangladesh milk producers co-operative union Ltd. In 1977 keeping its brands name of products the same, milk vita.
Bangladesh milk producers’ co-operative union ltd. popularly known by its brand name milk vita, was established by the Bangladesh government in 1973, immediately after liberation war, based upon the recommended by UNDP / PAO and DANIDA in the pattern of Amul, India. It was initiated as a development project of the government titled, co-operative dairy complex, to provide the city dewellery with a regular supply of fresh and hygienic milk and milk products at a reasonable price.
Milk vita Dhaka dairy plants products are :
· Pasteurized milk
· Milk vita ice-cream
· Milk vita rush malai
· Milk vita sweet curd
Another products of Milk vita company are:
· Fresh milk
· Flavored milk
· Full cream milk powder
· Milk vita chocolate
· Condense milk
· Milk vita cream
· Milk vita lollys
· VHT milk
Milk vita Dhaka dairy products type:
· Pasteurized liquid milk
Pasteurized flavored milk:
· Chocolate flavor
· Mango flavor
Milk vita ice-cream:
· Milk vita curd :
· Sugar free curd
· Sweet curd
In Milk vita Dhaka Dairy plant pasteurized milk is the main product. For production of pasteurized milk m any materials and machines are used. Such as:
· Milk earning taken: Capacity 5000 l – 10,000 L
· Standardization unit
· Milk storage vat : Capacity 10,000 L
· Pasteurizer : Two part :
· Heat chamber
· Chilling chamber
· Milk storage vat
· Filling machine
· Packaging machine
· Milk carrying container etc.
For ice cream production:
· Chocobar ice-cream production machine
· Cup ice-cream production machine
Pasteurized milk production flow chart: 1
Dairy collection point
20 different place ® sampling
Dhaka dairy plant
Milk carrying tanker
¯ ® Sampling & quality test
Milk storage vat
Milk storage vat
Milk packaging machine
sampling & quality test
Rejected packet milk recycled
Pasteurized milk production system :
Dairy collection point :
It is a former level collection point. Where cows milk are collected from some selected farmer.
Milk Vita Company has their own dairy farm such as Baghabari dairy farm. Farmer level collected milk also store here and then transferred to Dhaka dairy plant another district dairy plant of milk Vita Company.
Dhaka Dairy Plant:
Milk is collected here from 20 different places such as Baghabari, Shibpur, Laherimohonpur, Tangail etc. Two type milk are collected here that is pasteurized and chilled milk.
Milk earning tanker:
Capacity of milk earning tanker is 5000 L to 10,000 L temperature of the tanker is 0-50C. Two type milk contained here are a) Pasteurized milk and b) chilled milk.
From milk earning taker milk sample send to laboratory for its quality test. If test result satisfactory then the milk is accepted. If adulterate the it was rejected and drained out.
Standardization occurs by mining full cream milk powder and skim milk powder to maintain the fat percentage about 3.5%.
Milk storage vat:
Capacity of milk storage vat is 10,000L standardize milk stared in thing vat.
Numerous time and temperature combination are recommended but the most usual for milk vita is 75-800C for 15 seconds followed by rapid cooling to below 50C. This is normally referred to as high temperature short time (HTST) treatment. It is carried out as a continuous process using a plate heat exchanger to heat the milk and a holding section to ensure that the milk is completely pasteurized. Pasteurization is used to reduce the microbial counts in milk.
Homogenization of milk occur by pressure. It is used to distribute all the contents of milk in same volume. So that the layer of milk is thin.
Milk storage vat:
After homogenization milk is transferred to a milk storage vat. The temperature of the vat is maintained 0-50C.
Filling machine used to fill the main in packet for marketing.
The milk vita packet contain 1 letter, ½ letter and ¼ letter. The packet is properly labeled. Such as name of the company7, BSTI recommendation, pasteurized mfg date, price, expired date etc.
After packaging milk packet stored in a storage room at temperature 100C for 1 day for long time storage the milk stored at < – 200C temperature. Pasteurized packet milk transferred to the laboratory for sampling.
After all processing and sampling done then it is given for marketing and transfer to all retailer shop.
Chocobar production machine
Ice-cream production system :
Ingredient mix contain : For 1 day
|Contents||Vanilla / Chocolate|
Condensed milk kg
SMP (own) kg
FCMP (own) kg
Production system are described in flow chart.
Ice-cream production flow chart : 2
Ice-cream mining vat
Pasteurize and homogenize
Again vat (6-8 h)
Ice-cream containing freezer (air inoculation at -200C)
¯ ¯ ¯
Liter box Vanila cup Chocobar
¯ ¯ ¯
½ L, 1 L Hardening Hardening
¯ ¯ ¯
Hardening Hardening Hardening
¯ ¯ ¯
Cartooned Cartooned Filling
¯ ¯ ¯
Freezing Room Rapping
(Cold storage- 20 to -250C)
Rosomalai production system :
Ingredients amount :
Baking powder – 0.023kg
A laboratory i essential to enable the management of the plant to guarantee products of approved quality. These must at all times and in all conditions satisfy the standards prescribed laboratory control should therefore be planned accordingly. It must be pointed out that any system of control and tests must be built up as the result of experience and taking into account the stage of development of the production area and the availability of trained personnel. It should ensure a product satisfactory for the consumer.
As a minimum the following operating must be under full laboratory control and for this purpose the necessary apparatus must be provided:
· Milk reception
· Processing and manufacture of the milk
· Cleaning and sanitizing in the plant
The finished products, possibly until they reach the consumer. The mot suitable test must be selected taking into account the local conditions and requirements.
Simple platform tests are essential to enable the plant to identify milk of poor quality quickly and to prevent it from being processed before it is submitted to more complete testing. Field test will b e based upon the laboratory recommendation and the results obtained will be periodically cheeked by the laboratory.
It is also very important that raw milk be tested for both hygienic quality and composition so that a suitable system of payment can be established as soon as practicable. While in the initial stages laboratory control might firstly aim to prevent adulteration, essential to establish any realistic development of the quality control system.
In the laboratory there are two parts:
· One for initial sampling and adulteration test.
· Other for microbiological test.
Physical and chemical testing lab:
Milk sample and ice cream sample firstly taken in this lab and initial test such as lactometer test, fat test, alcohol test and adulterate test performed to identify the quality of the sample initially for excerpt it or reject it. This lab contains many chemical solution for the test and centrifuge machine and essential apparatus for different test.
To detect the microbiological quality of the milk (Pasteurized) and ice cream this libratory is used. The libratory contain different media for bacterial counting, laminar flow, incubator.
· Quality control is a process employed to ensure a certain level of quality in a product or service the basic goal of quality control is to meet specific requirements and are dependable, satisfactory and fiscally sound.
· Essentially, quality control involves the examination of a product, service or process for certain minimum levels of quality. That is to identify products or services that do not meet a company’s specified standards of quality. It a problem is identified then stopping the production temporarily.
· Quality control can cover not just products, services and processes but also people. Employees are an important part of any company. If a company has employee that don’t have adequate skills or training have trouble understanding directions or misinformed, quality may be severely diminished.
· Quality control of food is the identification of quality characteristics of food that is acceptable to consumers. This includes internal factor as appearance (size Shape, color, gloss and consistency) tenure and flavor, and internal (Chemical, physical, microbial).
· Food quality is an important food manufacturing requirement, because food consumers are susceptible to any form of contamination that may occur during the manufacturing process.
· Besides ingredient quality, there are also sanitation requirements. It is important environment is as clean as possible in order to produce the safest possible food for the consumer.
· Food quality also deals with product traceability, e.g. of ingredient and packaging suppliers, should a recall of the product be required.
Quality control for milk and milk products:
Milk testing and quality control is an essential component of any mil processing industry. Milk being made up of 87% water is prove to adulteration by middlemen and unfaithful from workers. More over, its high nutritive value makes it an ideal medium for the rapid multiplication of bacteria, particularly under unhygienic production and storage at ambient temperatures. To make good dairy products, good quality raw materials are essential.
Milk quality control is by of approve tests to ensure the application of approved practices, standards and regulations concerning the milk and milk products. The tests are designed to ensure that milk products meet accepted standards for chemical composition and purity as well as levels of different micro-organisms. These have to ensue that the health and nutritional status of the people is protected from consumption of contaminated and sub-standard food staffs and that prices paid are fair to the milk producers, the milk processor and the final consumer.
Steps involved in quality control are-
· At the form
· At milk collection centers
· At the dairy factories
· Within the dairy factory
· During marketing of processing products.
For quality of raw milk the basic quality tests are carried out of various stages of transportation of milk from the producer to the processor and finally to the consumer. Raw milk quality depends on its internal factor such as color, flavor, texture, taste and internal factors such as physical test, chemical test and microbiological test good quality raw milk is essential for good quality milk and milk products.
Pasteurized milk :
Pasteurized milk is which has been heat treated to will pathogens which case disease. Not all pathogens are removed during the pasteurization process. So pasteurized milk is not 100% sterile. Quality control is also essential for pasteurized milk. Otherwise it cause human health hazard. For the quality control physical test, chemical test, microbiological test and adulteration test is done for pasteurized milk.
Many factors including the flavor, body and texture, melting quality, color, package, appearance are influence the quality of ice-cream. Milk fat accounts for most of the rich. Sensations of ice-cream. Milk fat contributes a mellowness and flavor as no other constituent can other factor such as milk solids-non fat (SNF) contribute to flavor. So that it is important to control the quality of milk before ice-cream production. For quality control of ice-cream appearance, small, physical test, chemical test and microbiological test are performed.
The study was carried out at the quality control laboratory, milk vita, Dhaka dairy plant.
The following test should be envisaged by the plant laboratory to exercise continuous and accurate control over all the plants operations. The selection of the tests will depend upon local conditions and requirements. How ever, some of them must be considered essential from the very beginning, particularly those on raw milk to detect adulteration. If any and on manufactured products to guarantee their hygienic condition. Recommended tests and priorities for their introduction are given below.
Organoleptic characteristics: The plant shall provide one or more graders to examine milk and milk products for odor and appearance.
· Rapid test for acidity: Such as alcohol, clot on boiling etc.
· Fat determination: Using simple established methods such as butyrometric test for milk and each milk product.
Total solids (Water content): Determination of the water content is necessary to control milk and milk products and may be obtained by simple methods, for instance, from density and fat content of liquid milk and simple drying tests for milk products.
· Adulteration with water: Gross adulteration of liquid milk with water can be shown by density tests, but for more accurate control by a freezing point test. Other tests for adulteration should be introduced when thought to be necessary.
· Irritable acidity.
· Milk solids non fat (SMF) in milk products
· Suitable tests for oxidation
· Solubility of milk powder.
General tests: For checking of chemicals, reagents, glass ware, apparatus, strength of detergents, chlorine solution etc.
Coli form test: To detect contamination of milk and milk products. Provision should be made for confirmatory test when necessary.
· Suitable dye reduction tests: Such as methylene blue.
· Total colony count.
· Microbiological tests : For the determination of yeast and moulds.
· General tests : For estimation of plant cleaning efficiency, cans, equipment, water examination etc.
It is essential to examine the raw milk quality. To prevent human health hazard and spoilage of the product which cause the economic loss of the industry quality control is important.
Firstly sample is collected from the milk carrying tanker which comes from different dairy farms. The it is send to the laboratory for testing its quality is good or poor. If it is good quality then it is accepted and if poor quality then it is rejected and drained out.
Analysis of the sample: Such basic types of tests containing different methods were performed with collected raw milk samples.
· Specific gravity
· Organoleptic test
· Clot-on-boiling test (COB)
· Chemical analysis :
· Determination of fat percentage
· Determination of solid non fat percentage
· Determination of total salid percentage
· Determination of acidity.
· Alcohol test
No microbiological test was performed for raw milk in Dhaka Dairy Plant of milk vita.
· Soda test
· Salt test
· Sugar test
· Formalin test
· H2O2 test
Immediately after collection raw milk samples subjected to determine specific gravity way determined by lactometer method. This test is called CLR test that means correct lactose reading.
· Firstly lactometer drawn into the milk sample in a container.
· Then set the temperature at 200C.
· After that the milk temperature rises.
· The standard temperature of good quality raw milk is 27. Less than 25 is poor quality milk and this is not accepts for then usage such as pasteurization. But in milk vita company CLP reading 22 or 23 they accepted because of prevent their economic loss.
· If the temperature do not set at 200C such as 170C or 220C. Then add 0.2 of CLR if >200C. OR many 0.2 of CLR if temp is >200C for proper reading or measurement.
· This lactometer test is an initial test for milk quality.
Organoleptic test is done by the senses test is done for small, the appearance, the taste. It is a cheap and quick test. The organoleptic test is performed of the reception plat form and it makes possible to separate milk with defects.
If the milk smalls sour or unpleasant odor or has changed colors or appearance. It should be placed separately and submitted to further laboratory test.
To check the taste of taste of raw milk by testing is not recommended as there is always the danger of infection of a person who is doing the control by pathogenic bacteria in milk.
The characteristics foreign tastes of milk should not be done.
Organoleptic test on appearance can defect different defects of milk.
a) Color defects:
· Transparent milk, due to addition of water.
· Bluish milk, due to action of bacteria
· Red milk, due to presence of blood in milk
· Yellow milk, due to action of microfilms in the milk.
b) Consistency defects:
Coagulated milk, due to action of microorganisms which cause sweet or sour curdling.
Dirty milk, with particles of mud, grass, hair due to unhygienic production
Viscous, ropy milk, due to action of microorganism in milk which cause soppiness
Although the organoleptic is quick enough and very helpful as plat from rejection test, it is not always reliable. This is a subjective test and depends on skill and senses of taster.
Clot-on-boiling (COB) test:
COB test is important for observing raw milk quality. But this test not done in this Dhaka dairy plant. But this test performed in Baghabari dairy plant of milk vita.
Chemical analysis is performed by using chemical reagent mix with milk sample and the result of reaction examined to measure weather the milk quality is good or bad. This chemical analysis is more reliable than physical analysis for quality control. Different types of chemical test that is done in the milk vita Dhaka dairy plant are given below:
Rapid alcohol test:
The alcohol test is used to detect the presence of developed acidity or abnormality in the milk. It is a rapid and simple plat form rejecting test.
· 2 ml 68% alcohol taken into the test tube
· Then 1 ml raw milk also taken in this test tube
· After then mixing them well
· If clotting or precipitation occurs, it indicates milk with developed acidity. If milk remains unchanged it is suitable for further processing.
· Clotting of milk is caused not only by acid and rennet but also by increased albumen (Colostrum), and salt concentration (Mastitis) in milk.
· Developed acidity which of bacterial origin
· If precipitation occur in 2:1 ratio of alcohol and milk sample then 1:1 ratio is used for proper identification
· After that milk again precipitate then it was rejected.
Determination of fat percentage:
The percentage of fat in raw milk samples were determined by Gerber fat test method.
The membrane of fat globules and proteins are destroyed by sulfuric acid and single fat layer separated. To improve the separation amyl alcohol is added. The mixture is centrifuged in a special Gerber tube, called butyrometer and the volumetric percentage of fat can be read on the scale of the butyrometer at the temperature of 650C.
Standard pipettes for milk (7.5 ml)
Automatic filler for sulphuric acid, 10ml
Automatic filler for amyl alcohol, 1ml
Thermometer, range 0-1000C
Surphuric acid, amyl alcohol.
· Pipette 7.5 ml of milk. Then pouring the milk in butyrometer.
· 10 ml sulphuric acid taken into a butyrometer
· Mix them well
· Adding 1ml of amyl alcohol
· Close the neck of the butyrometer with a stopper
· The milk and the acid is mixed correctly and no white particles can be seen
· The color should be dark red. It the color is different, adulteration can be suspected.
· Centrifuge the butyrometer immediately after mining. Centrifuge for 5 minutes, after the centrifuge has reached 1100 rpm.
· Then read the fat percentage on the scale by adjusting the color with the stopper at the bottom level
· The standard fat reading is 3.5% in milk vita company.
Determination of acidity:
Acidity is tested by titrimetric method : Immediately after milling the milk has a slightly acid reaction. But the acidity will increase through action of lactic acid bacteria which will ferment lactose into lactic acid. It is the developed acidity of milk. It is important to check the acidity of raw milk, because increased acidity can cause coagulation of milk during pasteurization or coagulation by itself.
But in Dhaka dairy pant of milk vita they do not done it. This is one of the lacking of this industry.
Determination of solids non-fat of milk:
Solids non-fat milk includes the constituents of milk inclusive fat, free water and gases. SNF is more constant and is normally between 8.5-9%. Therefore, the determination of SNF is used to check the quality of the milk. Milk with less than 8.5 percent of SNF is regarded as adulterated. In here determination of SNF is performed by indirect method.
This is a rapid method, not as accurate as direct method. The determination of solids in milk is based on gravity and fat percent in milk.
Richmond method formula :
SNF = Solid non-fat %
F = Fat %
G = Lactometer degrees
* Determination of Total solid percentage :
Total solid (TS) of milk is variable and range at cow’s milk between 11-14 percent. It is necessary to check the TS of milk. Determination of TS is performed by indirect method.
To calculate the total solids of milk different formally are used. But here Richmond method formula is used that is given below:
TS = SNF + F Where,
TS = Total solid
SNF = Solid non-fat
F = Fat %
Milk is sterile at secretion in the udder but is contaminated by bacteria even before it leaves the udder. Expect in the case of mastitis, the bacteria at this point are harmless and few in number. Further infection of the milk by microorganism can take place during milking handling, storage and other processing activity.
Types of microorganism found in raw milk are given below:
1) Latic acid bacteria :
· Lactococcus delbrueckii
· Lactococcus lactis
2) Coliforms :
· Escherichia coli
3) Spoilage microorganisms in milk :
· Corne bacterium
4) Pathogenic microorganism in milk :
· Bacillus cereus
· Listeria monocytogeness
· Yersinic enterocolitica
· Salmonella spp
· Escherichia Coli 0157 : H7
· Campylobacter jejuni
All of these kinds of microorganism present in raw milk. Sometimes it can cause sincere health hazard. So it is necessary to control all of this bacteriological condition especially pathogenic organism.
In the mil vita company of Dhaka dairy plant no microbiological analysis performed in case of raw milk. Bacterial count is an also important thing. But they do not done it. Microbiological test do not done for raw milk but this is important for raw milk quali9ty control.
Raw milk can be contaminated by a number of pathogens. Pasteurization is a technique of heat treating milk to destroy all the pathogens present in it. This process was named after its creator, Louis Pasteur, a French chemist and microbiologist. Pasteurization process also increases the milk shelf life. It reduce the number of risk of discuses. Pasteurization does not alter the taste of milk and rating the all milk health benefits.
Milk is heated at 800C and above for 15 sec, to kill the rapidly growing microorganisms. It is necessary to control the quality of pasteurized milk. So that some physical test, chemical test and microbiological test are done for pasteurized milk for its quality control.
Test results can be no better than the sample on which the tests are made. This procedure has been drawn up to ensure that when a sample is taken it is representative of the quality of pasteurized milk being examined. It is essential to protect the sample against change during the period between the time of collection and the time of analysis.
* Retail packs of pasteurized milk:
· Labeling retail pack with marker pen with number corresponding to laboratory records.
· Recording date, time of sampling and production date code.
· Then remove retail pack to laboratory for testing.
· Thoroughly mix contents of retail pack.
· After that open retail pack and draw sample off.
· Then recording temperature of sample.
· Retail packs which can not be tested immediately should be kept cool in the refrigerator.
· Recording test results on relevant laboratory report record book.
· Organoleptic test
· Specific gravity test
· Alcohol test
· Fat content Gerber method
· SNF test
· TS test
· Acidity test
· Total colony count
· Coli form count
· Physical test procedure of pasteurized milk is same as raw milk test, that are previously described.
Chemical test procedure of pasteurized milk sample are same as raw milk sample test, that’s are previously described.
i) Total colony count:
The total bacteria count is the number of bacteria in a sample that can grow and form countable colonies on standard methods agar after being held at 320C for 48 h.
To get on overall assessment of milk quality it is important of knew the number of microorganisms. For particular dairy products the standards prescribe the highest allowed number of microorganism.
· Bunsen burner
· Glass pipettes, 1.0 and 100 ml capacity
· Dilution tubes
· Petri dishes
· Laminar flow
All equipment should be thoroughly cleaned and sterilized before use. Petri dishes and pipettes plugged with cotton wool are sterilized.
Dilution fluid that is normal saline solution is used.
Plate count agar (PCA) :
PCA is a microbiological growth medium commonly used to assess or to monitor total bacterial growth of a sample. PCA is not a selective medium.
The composition of plate count agar may very, but typically it contains (W/V).
0.25% yeast extract
PH adjusted to neutral of 250C.
· Mix the milk sample thoroughly
· With a sterile pipette transferring 1 ml milk in a test tube which contain 9 ml saline water.
· Further dilution are made by same way at 10 fold dilution.
· Dilution bottles mix by skiing up and down.
· Then transfer the 2 dilution samples in a two petridishes.
· 1 Plating done from original samples that contain 1 ml.
· To each dish 10 ml of melted medium kept in the water bath at 450C are powering.
· Allow the dishes to stand until medium has set. Invert the dishes transfer to incubator.
· Incubate overnight such as 22-24 h at 37-400C.
· The range of total colony count in 25,000 to 30,000 for milk vita standard. Above this range the milk is poor quality.
Ice-cream is most of the popular and favorite food for children. So it is essential to control the quality of ice-cream. For quality control of ice-cream physical, chemical and microbiological test should be done.
· Physical test done in the laboratory of Dhaka dairy plant of milk vita.
· Fat content test
· Total plate count
· Coli form count
Different types of microbes are present in ice-cream. Some are less harmful and some are pathogenic which occur health hazard. Microbes present in ice-cream are coli forms, staphylococcus, aureus, face cal coli form, yeast mald etc.
For quality test of ice-cream only ice-cream of chocobar and vanila are used for plating.
i) Total plate count :
Same as for milk sample method
ii) Coli form count :
Same as for milk sample method.
Adulteration of milk
There are many methods known for detection of adulteration in milk but here only 5 adulteration test are performed. These are simple but rapid and sensitive methods to detect adulteration.
i) Soda test :
Taking 2ml milk sample in a test tube
Add 2ml 100% alcohol and 2 drop Rosalie acid.
Shaking the mix well
If the color of milk changes to pinkish red, then it is adulterated with sodium carbonate / Sodium bicarbonate and hence unfit for human consumption.
If the color not changes or brown live color it is good quality.
ii) Sugar test:
Generally sugar is mixed in the milk to increase the solids non fat content of milk to increase the lactometer reading of milk, which was already diluted with water.
Taking 1ml milk in test tube
Add 5 ml sugar solution
Then heating at boiling temperature
Appearance of red color indicates the presence of added sugar in milk
Addition of salt in milk is mainly resorted to with the aim of increasing the corrected lactometer reading.
1ml milk taken in a test tube
Add 5 ml salt solution
4 /5 drop potassium cremate added
If the contents of the test tube towns yellow in color, then milk contains salt in it.
If it is chocolate colored, then the milk is free from salt.
In milk vita company adulteration test do not perform routinely.
Fig: Adulterate milk Fig: Adulterate milk
GMP and HACCP
Hazard analysis critical control point (HACCP):
Raw and end-products may be tested for the presence, level or absence of microorganisms. Traditionally these practices were used to reduce the manufacturing defects in dairy products and ensure compliance with specifications and regulations HACCP involves a critical examination of the entire food manufacturing process to determine every step where there is a possibility of physical, chemical or microbiological contamination of food which would render it unsafe or unacceptable for human consumption these identified points are the critical control points (CCP). There are seven prevail to HACCP:
· Analyze hazards
· Determine CCPS
· Establish critical limits
· Establish monitoring procedure
· Establish deviation procedure
· Establish verification procedure
· Establish record keeping procedures.
Before these principles can be put into place, a prerequisite program and preliminary set up necessary.
· Premise control
· Receiving and storage control
· Equipment performance and maintenance control
· Personnel training
Preliminary set up:
· Assemble team
· Describe the product
· Identify intended use
· Construct flow diagram and plant schematic
· Varity the diagram on site.
Good hygienic and manufacturing practice:
It is obvious to follows the good hygienic and manufacturing practice. But it is very weakly followed in milk-vita Company.
The workers do not were any a prove and gloves. It is very unhygienic condition. Their storage rooms are very dirty. Rejected mil packet recycled but it was in very wealth condition. Laboratory staff do not were any musk, gloves, aprone that is not allowed for any laboratory test.
Finally the production of milk and milk product are unhygienic and they do not follow any HACCP and GMP method.
C.I.P. (Cleaning-in-place) of Daily Equipment
The sanitary condition of product contact on equipment and pipolins is dependent primarily on the effectiveness of cleaning and sanitizing procedures. Only when these procedures are effective and conducted properly will the contamination potential of those contact surfaces be eliminated.
The term cleaning as related to the care and maintenance of equipment in dairy plants refers to the treatment given to all product contact surfaces following each period of use to first remove all physical evidence of soil and to apply a bactericidal treatment to sanitize all surfaces.
Two solutions are normally utilized to clean the dairy equipment and pipelines : Sodium hydroxide and nitric acid solution. For economical reasons they can be utilized a number of times but they must be adjusted to their initial strength every day before carrying out a new cleaning operation.
2 types CIP system followed
a) 5 step CIP (Mainly used)
b) 7 step CIP
· Normal water
· Hot water
· Caustic soda (1% solution)
Firstly washing by normal water about 5-10 min.
The using hot water for cleaning the temp. of the water is 850C and above for 10 min.
Then wash with caustic soda. This time termp. is 80-850C
After that rinse with chot water to free from caustic soda. Temp is 70-800C
Lastly cold water rising for 5 to 10 min
In case of step procedure after 5 step nitric acid is used and then rinse with hot water then normal water.
The results of various physical properties chemical composition and microbiological sanitation are described.
Physical parameters :
After 10 days observation the results of physical test for quality control of raw milk are given below:
|Sample||Temperature||CLR||Color||Appearance of milk|
|1||70C||27.6||Yellowish Brown||No coagulation|
|2||70C||27.8||Yellowish Brown||No coagulation|
|3||70C||26.5||Yellowish Brown||No coagulation|
|4||70C||28.4||Yellowish Brown||No coagulation|
|5||70C||27.0||Yellowish Brown||No coagulation|
|6||70C||26.9||Yellowish Brown||No coagulation|
|7||70C||28.6||Yellowish Brown||No coagulation|
|8||70C||27.8||Yellowish Brown||No coagulation|
|9||70C||28.0||Yellowish Brown||No coagulation|
|10||70C||28.4||Yellowish Brown||No coagulation|
The standard lactometer reading (CLP) is 27 the normal color of milk is red brown appearance of milk must be non coagulated.
After 10 days observation the result of chemical test for quality control of raw milk are given below: