ISSN: 2577-4182

Madridge
Journal of Food Technology
Review Article Open Access

Significance of Hygienic processing of Milk

and Dairy products
Mahendra Pal1*, Mridula Devrani1 and Suneeta Pinto2
1Narayan Consultancy on Veterinary Public Health and Microbiology, 4 Aangan, Jagnath Ganesh Dairy Road, Anand, India
2Department of Dairy Technology, SMS College of Dairy Science, Anand Agricultural University, Anand-388110, India

Article Info Abstract

*Corresponding author: The food production chain has become more complex, providing a greater opportunity
Mahendra Pal for the contamination and growth of microbes. Milk is an important component of a
Founder Director of Narayan
Consultancy of Veterinary Public
healthy and well balanced diet due to its nutritional richness. Currently, around 800 to 1000
Health and Microbiology milk products of different types are prepared worldwide. A wide variety of dairy foods, such
4, Aangan, Ganesh Dairy as cheese, butter, ice cream, yoghurt, and dry milk powder, are consumed worldwide
Road Anand-38001, India
including India. Approximately, 50 to 55% of milk in India is used to manufacture a large
E-mail: palmahendra2@gmail.com
range of traditional dairy products. India is the largest producers as well as consumers of
Received: August 24, 2018 dairy products. The microbial contamination of milk and milk products can occur through
Accepted: August 28, 2018 various routes, such as environment, handlers, equipments, and packaging materials. The
Published: September 3, 2018 milk and milk products intended for human must be free from pathogens, such as
Campylobacter jejuni, Escherichia coli O157H:7, Listeria monocyogenes, Salmonella,
Citation: Pal M, Devrani M, Pinto S.
Significance of Hygienic processing of
Stahylococcus aureus, and Yersinia enterocolitica, which produce serious disease especially
Milk and Dairy products. Madridge J among children, elderly, pregnant women, and immunocompromised individuals. It is
Food Technol. 2018; 3(2): 132-136. pertinent to mention that no dairy products should be made from raw milk that serves as
doi: 10.18689/mjft-1000120
source of microbial contamination. The improper cleaning and poor sanitation of dairy
equipments may lead to food poisoning due to contamination by pathogens. Since food
Copyright: © 2018 The Author(s). This work
is licensed under a Creative Commons safety is an increasing global public health issue, it is emphasized to implement the good
Attribution 4.0 International License, which hygienic practice (GHP), good manufacturing practice (GMP), and hazards analysis and
permits unrestricted use, distribution, and critical control point (HACCP) in dairy industries to reduce the level of microbial
reproduction in any medium, provided the
contamination. It is imperative that strict hygienic measures must be adopted during the
original work is properly cited.
preparation, storage, and delivery of a variety of milk products. In addition, the education
Published by Madridge Publishers
of food handlers on the principles of milk hygiene should be imparted for the production
of superior quality of dairy products, which can be safely consumed by people.

Keywords: Dairy industry; Food handler; Hygienic production; Milk; Milk products;
Public Health.

Introduction
It is believed that consumption of milk and dairy foods started around 6000 BC. The milk
and milk products had been the choicest item of food in the dietary of Indian people from the
time immemorial. There has been a phenomenon growth of dairy industries throughout the
world including India. Dairying has become an important secondary source of income for
millions of rural households engaged in agriculture [1]. With 191 million cattle and 109 million
buffaloes, India accounts for 30.3 per cent of the global bovine population. The country also tops
in world milk output, with an estimated 155.5 million tonnes output in 2015-16 [2]. The present
per capita availability of milk is around 337 grams per day. Presently, India ranks first in global
milk production accounting for over 13% of the world ’s
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total milk production. It is estimated that about 40% of total world milk After reception of raw milk, rapid chilling should be
production is converted into cheese. Though milk and milk products are carried out immediately to temperature of 5°C.
important source of energy for our body function, sometimes, it may Clean strainer should be used for removal of extraneous
get contaminated either by spoilage producing microbes (
matters, such as dirt, hair, dust, dung, plastics, broken glass
Achromobacter, Acinetobacter, Alcaligenes, Bacillus, Clostridium,
pieces, nails, wire, pant leaves, fly etc. Proper maintenance of
Enterobacter, Flavobacterium, Micrococcus, Pseudomonas, Serratia,
pasteurization temperature is required. No milk residues should
Alternaria, Aspergillus, Candida, Cladosporium, Geotrichum, Mucor,
be left after cleaning- in- place is done. Proper sanitization of
Penicillium, Rhizopus, Rhodotorula, Saccahromyces) or disease causing
crates is very essential. It is imperative to avoid rupturing of milk
pathogens (Staphylococcus aureus, Escherichia coli 0157: H7, Salmonella,
pouches during handling. Control of air temperature in the
Campylobacter jejuni, Yersinia enterocolitica, Listeria monocytogeneses)
coolers should be maintained. It is suggested that hot water
[3]. The contamination of milk and dairy products by microbial agents is
must be used for proper flushing of vending machine [1]. Many
a worldwide problem, and can occur at any stage of food chain from
pathogens survive in environment for long periods of time, and
farm to fork. The presence of microbes in daily products are
can enter in milk from various sources. It is important to
undesirable, at these render the milk products of inferior quality. It is
mention that about 4 to 13% raw milk samples from grade A
well recognized that hygiene plays a pivotal role in the safety of foods
and hence, protects the health of the consumer. Therefore, hygienic
dairies contained bacterial pathogens.
practices should be meticulously followed to ensure that food is safe, Hygienic aspects of cream
wholesome, and will not cause any harm to the consumer, and also will Cream is milk product, which is prepared from the milk of
not allow the growth or survival of spoilage microorganisms as well cow or buffalo. It is good source of milk fat, and also fat soluble
disease causing pathogens during production, processing, handling, vitamins such as A, D, E and K [1]. Cream consists of a
packaging, storage, and distribution [1]. It is mentioned that cleaning concentration of the fat in milk, with the fat existing mainly as
and sanitation of milk and milk products contact surfaces contribute globules protected by a membrane. As such, cream can have a
around 60 variety of compositions and is normally defined according to fat
content or function. Fat content may range from 10 per cent
% of the total contamination in a dairy plant [4]. At room (half-cream) to 80 per cent plus (plastic cream) [6].
temperature, milk can be stored only for 3 hours immediately after It is incredibly important to make use of high-quality
milking. The shelf life of milk can be extended to 24 hours by
of milk to manufacture cream. Therefore, sufficient heat
cooling to 5°C. Its shelf life is further extended to 4 to 7 days by
treatment of milk should be done. Final cooling of cream
pasteurization, which was invented by French Scientist Louis Pasture
in tank to 5°C is required. Proper storage of cream at 5°C
in 1864 [1]. By UHT treatment, the shelf-life of milk is extended to
or less is very essential [1].
few months. Yoghurt has keeping quality of 1-2 days at ambient
Hygienic aspects of butter
temperature, and 1 week under refrigerated condition. It is
important to mention that standard pasteurization helps the Butter is acknowledged as one of the oldest dairy products
microbial spoilage of dairy products. Many types of products, such made from milk. It is mentioned that Egyptians used the butter
as cream, butter, ice cream, cheese, milk powder, yoghurt, and approximately 3000 B.C. [7]. In India, butter is used as food
others are prepared from the milk of dairy animals, predominantly commodity and also in connection with religious ceremonies.
from cow’s milk [3]. However, in Asian countries like India, buffalo Butter was one of the first dairy products manufactured by
milk is also frequently employed for manufacturing a variety of humans, and has been traded internationally since the 14 th
products. The maintenance of high standard of sanitation during century. Butter can be defined as a fat concentrate, which is
the processing, packaging, and distribution of milk products; and obtained by churning cream, gathering the fat into a compact
strict hygienic practices by food handlers are main actions, which
mass and then working it [5]. According to the Prevention of
are required to produce a good quality of dairy products, which are
Food Adulteration Rules 1976, the table /creamery butter
should contain not less than 80 % fat, 3 % common salt, and 1.5
safe to human health. The present communication is aimed to
% curd. Diacetyl, which is added as a flavouring agent, should
describe the processing of various dairy products in hygienic
not exceed 4 ppm [5]. Salt enhances the flavour and improves
manner in order to obtain good quality with long shelf life and
the keeping quality of butter. The butter is very rich in fat and
excellent consumer safety.
fat soluble vitamins such as A, D, E, and K. The butter is a water-
Hygienic aspects of milk
in-oil emulsion, and essentially the fat of the milk. It is usually
Milk may be defined as the whole, fresh, clean, lacteal prepared from sweet cream and it is salted. However, it can also
secretion obtained by the complete milking of one or be made from acidulated or bacteriologically soured cream, and
more healthy milch animals, excluding that obtained salt less butter is also available. The principal constituents of
within 15 days before or 5 days after calving or such normal salted butter are fat, water, salt as well as protein,
periods as may be necessary to render the milk practically calcium and phosphorus [8]. Butter can be used in several ways.
colostrum free, and containing the minimum prescribed Maximum consumption of butter is observed in the baking and
percentages of milk-fat and milk solids-not-fat. In India, confectionary industries worldwide. Many baking products such
the term “milk” when unqualified, refers to cow or buffalo as cakes, cookies, pastries, biscuits, breads, pies, crumbles,
milk, or combination of two [5]. tartlets etc. are manufactured with

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butter. In many countries of the world, butter is applied on the Hygienic aspects of cheese
slices of bread for direct consumption during breakfast. The Cheese is a highly nutritious milk product of good
preparation of sauces also requires butter. Butter is used as a keeping quality, and contains protein, fat, calcium,
cooking medium. In addition, butter is also employed to phosphorus, riboflavin, and other vitamins. Presently, over
manufacture ice cream, butter oil, and ghee (India) [5]. Buffalo 200 types of cheese are available in the world. It a fermented
milk containing about 7 to 8% fat gives more butter as dairy product, and traditionally forms part of the
compared to cow milk, which has approximately 3.5 to 4.5% fat Mediterranean diet [11]. Cheese means the ripened or un-
[9]. In Canada and USA, salted butter is relished by people ripened soft or semi-hard, hard, and extra hard product,
whereas Europeans prefer unsalted (fresh) butter. However, which may be coated with food grade waxes or poly film,
in rural areas of India, Desi butter, which does not contain and in which the whey protein / casein ratio does not exceed
any flavouring, colouring agents, and added salt, is generally that of milk. Cheese is obtained by coagulating wholly or
liked by people particularly the children [9]. partly milk and/or products obtained from milk through the
Proper pasteurization of cream is fundamental to destroy action of non-animal rennet or other suitable coagulating
the microbes. Multiplication of psychrotrops can be prevented agents and by partially draining the whey resulting from
by efficient cooling at low temperature (3-5°C). Just prior to use, such coagulation and/or processing techniques involving
churn should be sanitized with 200 mg/liter chlorine solution. coagulation of milk and/or products obtained from milk
Most of the organisms in cream are drained in buttermilk but which give a final product with similar physical, chemical and
molds are retained in the butter. In order to control the moulds, organoleptic characteristics. The product may contain starter
regular cleaning of butter churn is crucial. Blending should be cultures of harmless lactic acid and/or flavour producing
avoided as it increases the microbial count in butter [9]. In bacteria and cultures of other harmless microorganisms, safe
addition, use of clean and sanitized packing material, proper and suitable enzymes and sodium chloride. It may be in the
cleaning of surface of packing room, storage of cream at low form of blocks, slices, cut, shredded or grated cheese [12].
temperature, good ventilation in storage room, prevention of High quality of raw milk should be used. Bactofugation
aerial contamination, maintenance of high standard of hygiene of raw milk at 10,000 to 20,000 rpm can reduce bacterial
in butter packing, and hygienic practices by food handler are count by 99.98 per cent. Good, active starter cultures should
key measures, which are required to produce a good quality of be added @1 per cent to milk and care must be taken to
butter, which is safe to human health [9]. Further, it is vital to avoid microbial contamination. Pressing of cheese is to be
point out that the hygienic storage of butter at -25 to -29°C can supervised by experienced personnel. Pipelines and other
maintain the keeping quality of the product for at least one year utensils should be thoroughly cleaned and sanitized every
[10]. day. These measures are proved very effective to produce
Hygienic aspects of ice cream good quality of cheese [10].
Among the several dairy products, ice cream is most widely Hygienic aspects of milk powder
consumed frozen desert both in developed and developing Milk powder means the product obtained by partial
countries of the world. It is a rich source of fat, protein, calcium, removal of water from milk of cow and/or buffalo. The fat and/
phosphorus, and vitamins, such as A, E, riboflavin, and niacin [1]. or protein content of the milk may be adjusted by addition
According to the FSSAI (2006), ice cream, kulfi, chocolate ice and/or withdrawal of milk constituents in such a way as not to
cream or softy ice cream means the product obtained by alter the whey protein to casein ratio of the milk being adjusted.
freezing a pasteurized mix prepared from milk and/or other It shall be of uniform colour, and shall have pleasant taste and
products derived from milk with or without the addition of flavor. It should be free from off flavour and rancidity and also
nutritive sweetening agents, fruit and fruit products, eggs and be free from vegetable oil/ fat, mineral oil, thickening agents,
egg products, coffee, cocoa, chocolate, condiments, spices, added flavor, and sweetening agent [12].
ginger and nuts, and it may also contain bakery products, such It is important to state that high microbial quality of raw
as cake or cookies as a separate layer and/or coating. These milk must be used for the manufacturing of dried milk powder.
products may be frozen hard or frozen to a soft consistency so
Evaporators should be properly cleaned and sanitized as they
that they shall have pleasant taste, and smell free from off
may act as potential source of microbial contamination. Roller
flavour and rancidity.
drying is found effective as it kills most of the microbes. It is
Sugar can be a major source of moulds, yeasts, and
compulsory to maintain sanitary conditions in drying room to
bacterial spores. It is prudent to use the sugar having prevent the contamination of milk powder. Filtered air should
mesophillic count of less than 20 and yeasts and molds count be supplied for the driers, conveyers, cooling, and air sweeping
should be less than 1.0 per gram. Fresh and frozen fruits should processes. Therefore, filter pads need periodical cleaning to
be examined for yeasts. Nuts may contain moulds and remove the accumulated dust. All vacuum pans, pipelines,
therefore, nuts should be sterilized with ethylene oxide and CO 2 concentration tank, packaging room, and storage container
at the ratio of 1:9. Air can be potential source of organisms and must be thoroughly cleaned and sanitized These steps are
hence, only filtered air should be incorporated in ice cream. necessary for the production of high quality of milk powder,
Packaging materials should be effectively sanitized before use, which has long shelf life [13,14].
since they are good source of fungi.
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Hygienic aspects of yoghurt hazards identified and specifications established. The food-
Yoghurt, a fermented milk product, is an important borne pathogens found in milk may cause various symptoms,
source of protein, calcium, phosphorus, potassium, such as nausea, vomiting, fever, loose stools, and in severe
magnesium, potassium, riboflavin, vitamin A, and folic acid; cases, death [15]. Various outbreaks of food-borne illness
associated with the consumption of dairy products have been
and helps to maintain a healthy gut and immune system.
documented in literature [9,13,16,17]. Diseases caused by
Several types of stirred yoghurt are available in the market,
consumption of contaminated milk and milk products pose a
which vary in fat, sugar, texture, flavor, and type of fruits.
serious threat particularly to the infants, pregnant women,
Yeasts and moulds are mainly responsible for the spoilage of
elderly people, and immunocompromised persons [1].
yoghurt, as they are not affected by low pH. It is essential
Standards for specific pathogens have been proposed either by
that microbiological specifications should be applied to
fixing maximum permissible limits per unit (gram, ml or cm2) or
some additive used in the manufacture of yoghurt.
by testing presence or absence of the organism in a given unit
Yoghurt means a coagulated product obtained from
of food e.g. Staphylococcus aureus or Salmomella spp.,
toned milk, pasteurized or boiled milk by lactic acid
respectively. Generally, the decisions on the acceptability of
fermentation through Lactobacillus bulgaricus delbruckii var.
food lots are based on the examination of one or few samples
bulgaricus and Streptococcus thermophillus. It may also
taken from the batch. PFA specifies the maximum upper limit of
contain cultures of Bifidobacterium bifidus and Lactobacillus microflora in pasteurized milk as 30, 000 cfu/g
acidophilus and if added, the declaration to this effect shall
[18]. Further, PFA specifies the limits for coliform as absent
be made on the label. The product shall have smooth
per 0.1g, for Escherichia coli, Staphylococcus aureus, yeast
surface and custard like consistency with no whey separation
and moulds, anaerobic spore former, Listeria monocytogenes
[12]. Yoghurt should contain fat (0.0 to 3.5%), solids not fat
as absent per gram for each,and for Shigella and Salmonella
(8.25-14%), sugar (0-10%), and stabilizer (0.0 to 2%). It
as absent per 25 g of pasteurized milk. Pathogens, such as
should be free from any substance foreign to milk, such as
Listeria monocytogense, Salmonella, Shigella, and Escherichia
animal body fat, vegetable fat, and mineral oil.
coli must be absent in dry milk powder [19].
It is advised that pasteurized milk should be employed in
The dairy animals, milking machines, containers, utensils,
the preparation of yoghurt. Use of raw milk with high microbial
water, air, soil, flies, rodents, packaging material etc. are the
load causes a reduction in the quality of yoghurt. As sugar can
major sources of microorganisms that degrade the quality of
be the major source of yeasts, moulds and bacterial spores, it is
milk [20,21]. The higher percentage of microflora in raw milk
advisable to use the sugar having mesophilic count of less than
may be due to contamination from the animal and unhygienic
20, and yeasts and moulds count less than 1.0 per gram. It is
milking procedures or equipment leading to entry of pathogens
emphasized that fresh and frozen fruits should not contain
from dairy utensils and milk contact surfaces (exterior of the
yeasts. The skim milk powder and chocolate should be of high
infected udder and adjacent areas) [22,23]. Moreover, storage
microbiological quality. The utensils used in the manufacturer of
conditions of raw milk, the health status of dairy animals, and
yoghurt should be properly cleaned and washed, as unclean or
nature of their feed are also crucial in determining the
inadequately washed utensils are responsible for the high total
composition of their microflora [24]. It is pertinent to reveal that
bacterial count. Tables, floors and other sites in the dairy plant
pasteurization, which was invented by Lois Pasteur at a time
should be kept in good sanitary condition, as they are a
when millions of people became ill and died following the
potential source of yeasts and moulds. Flavouring agents should
ingestion of raw milk, is a very important practical preventive
be handled, and stored in cool and dry condition to avoid
approach from a public health point of view to guarantee safety
contamination. Potable soft water should be used in dairy plant
of milk to consumers [1]. It is imperative to monitor the
as contaminated water can serve as vehicle for spoilage
microbiological quality of raw milk and milk products from food
organisms. It is emphasized that dairy plant should be inspected
safety point of view.
daily, and microbial tests should be carried out periodically by
using swab and rinse methods. Aqueous solution of colour
made in boiled water is safe to add in the final product. The
Conclusion
packaging materials must be effectively sanitized before use, Milk has become an increasingly important source of
since they act as good source of fungi. Proper packaging under protein, and other elements necessary for the maintenance of
hygienic conditions can enhance the shelf life of the product. healthy body, and constitutes an important food component
Good hygienic practice and good manufacturing practice can for a large section of the world population. It can also serve as
reduce the level of microbial contamination. It is imperative that vehicle for many types of microbes, which can either cause
strict hygienic measures must be adopted during the spoilage or produce disease. The quality of milk is of major
preparation, storage, and distribution of milk products including concern to the food processors, consumers, and public health
yoghurt [4]. authorities. Proper packaging and storage under strict hygienic
Microbiological quality of milk and milk products conditions can undoubtedly enhance the shelf life of dairy
Microbiological standards have been proposed from products. It is recommended that properly pasteurized milk
time-to-time to ensure food safety [1]. When a food poses a should be employed in the preparation of various milk
health hazard, microbiological examination should be made, products intended for human consumption. Provision of safe,
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wholesome and acceptable milk and milk products, 9. Pal M, Awel H. Public health significance of Listeria monocytogenese in milk

through control of contamination is essential from food and milk products. Journal of Veterinary Public Health. 2014a; 12: 1-5.

safety point of view. It is pertinent to frame strategies to 10. Pal M, Feleke A, Geloye M, Waktole H, Deressa A. Microbial quality
and safety of cheese. Beverage and Food World. 2014b; 41: 32-33.
prevent the microbial contamination of dairy products at
11. Hinrichs J. Mediterranean milk and milk products. European Journal of
all stages of the food supply chain.
Nutrition. 2014; 43(Suppl. 1): i12-i17. doi: 10.1007/s00394-004-1104-8
12. Food Safety and Standard Regulations, 2010.
Acknowledgements
13. Pal M, Mahendra R. Escherichia coli 0157:H7: An emerging bacterial
The authors wish to thanks Prof. Dr. R. K. Narayan for zoonotic food borne pathogen of global significance. International
critical editing of the manuscript and Anubha for Journal of Interdisciplinary and Multidisciplinary Studies. 2016; 4: 1-4.
rendering computer help. This paper is dedicated in the 14. Pal M, Tesfaye S, Wedegebril S. Hygienic and microbiological
memory of Shri Atal Bihari Yajpayee the former Prime aspects of ice cream. Beverage and World Food. 2012b; 39: 42-43.
Minister of India who was a recipient of Bharat Ratan, the 15. Agarwal A, Awasthi V, Dua A, Ganguly S, Garg V, Marwaha SS.
Microbiological profile of milk: Impact of household practices. Indian Journal
highest civilian award. He was a great philosopher,
of Public Health. 2012; 56(1): 88-94. doi: 10.4103/0019-557X.96984
thinker, statement, politician, and administrator besides
16. Silva R, Cruz AG, Faria JA, et al. Pasteurized milk: Efficiency of
an honest, generous, kind and noble man.
pasteurization and its microbiological conditions in Brazil. Foodborne
Pathog Dis. 2010; 7: 217-219. doi: 10.1089/fpd.2009.0332
Conflict of interest 17. Pal M. Campylobacter jejuni: An emerging foodborne pathogen of global
significance. Journal of Experimental Chemistry. 2017; 4: 1-4.
Author declares that there is no conflicts of interest.
18. The Prevention of Food Adulteration Act, Microbiological
parameters for milk products. The prevention of food adulteration
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