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The objective of this paper was to review milk processing techniques and consumption rate in West African Sub-Region. The Nigerian dairy industry represents an important component of the agribusiness sector of the economy with great economic, nutritional, and social benefits. Processing of fresh milk is achieved by local techniques into various traditional milk products. About 47kg of liquid milk per individual is consumed per year in Nigeria compared to an average of 25kg for the sub-Saharan Africa region. Consumers display strong preference for locally produced and processed products such as nono (sour milk), kindirmo (sour yoghurt), maishanu (local butter), cuku (Fulani cheese) and wara (Yoruba cheese). The choice of preference is based on flavour, perceived nutritional value and regional customs and beliefs. Similarly, the local products are believed to be cheaper than their imported counterparts. Sour milk and local butter accounted for over 30% of all dairy products consumption. Urban household consume about 20% more dairy products than rural household. Pastoralists are mostly the producers but consume less of the products. Modern milk processing techniques and higher consumption rate should be encouraged in West African Sub-Region to ensure improved human and animal productivity in the region.
Keywords: Milk processing techniques; Consumption rate; Nutritional benefits; West africa
Abbrevations: WHO: World Health Organization; FOS: Federal Office of Statistics; HTST: High Temperature Short-time Method; WAMCO: West Africa Milk Company
Major human dietary problem in Africa and Nigeria is the gross deficiency in animal protein intake, both in quantity and quality. The low protein intake has been responsible for reduced human productivity with high incidence of infant mortality, severe malnutrition and general weakening of human body which pre-dispose people to diseases, low health status, and shorter lifespan . For instance, the average consumption of animal protein per day is lower than the minimum of 35g recommended by the FAO for daily maintenance .
Dairy products especially milk is the most complete food one can take having all the nutrients necessary for growth and development of the body. They provide the most important amino acid required for body building as well as tissues repairs in human beings. Animal protein equally supplies its own level of energy required for daily activities. It is also essential for the synthesis of certain hormones, enzymes and body products in both man and animals.
According to the Federal Department of Livestock and Pest Control Services in 1990, cattle population in Nigeria is about 13.9 million . Out of this number, 13.5 million (96%) are in the
hands of the pastoralists which are managed in a traditional way. This pastoral herd is responsible for the supply of milk consumed in Nigeria. Only few imported breeds such as Friesians and Brown Swiss and their crosses are kept for experimental purposes in government owned agencies. Some few private commercial dairy farms exist in the country. These farms produce an insignificant proportion of milk in Nigeria.
In northern Nigeria, where bulk of the milk is produced, milk consumption is about 50l per capita per year compared to a national average of 20 to 25l per capita per year. This is four times below the minimum quantity recommended by the World Health Organization (WHO) and between 20 and 25 times less than the European average . Imported products represent more than 90% of the milk consumed in Nigerian cities, and this figure rarely drops below 75% . The dependence on imported milk has become a classical vicious circle and getting out of it has becomes a problem. The traditional milk production and processing industry has not been able to fulfill the aspirations of the people in terms of quantity and quality. It is that, this paper was designed to review milk processing techniques and consumption rate in West African Sub-Region (Table 1).
According to FAO  report, the dairy industry provides
a means of livelihood for a significant proportion of pastoral
families in Nigeria. For instance, about 183,000 rural households
were said to have derived some income from the dairy industry
in 1986. This ability of the dairy enterprise to generate regular
income and to contribute to the household diet on a regular basis
throughout the year is an advantage over other agribusiness
enterprises . In addition, apart from providing employment
to the processors, it also provides income to informal milk
traders, cooperatives and others who have any dealing with
the milk markets. Estimates from vaccination, cattle tax and
sample surveys put the cattle population in Nigeria at about
12 million , while the Federal Office of Statistics  put it at
16 million. About 96 percent of the total cattle population in
Nigeria is believed to be in the hands of pastoralists , who
are predominantly Fulanis, the Shuwa Arabs, and the Bororos.
Consequently, they are the most important source of domestic
milk in Nigeria . These herdsmen practice a traditional
type of management whereby cattle are held in the vicinity of
the village or urban areas during the wet season and then taken
to lower pastures during the hot months in search of greener
grazing areas .
Milk is a fluid food produced in the mammary gland of
female animals following parturition. It is an emulsion of butter
fats and water. The aqueous phase contains proteins, lactose,
minerals, enzymes and vitamins as shown in Figures 1-3 .
Dairy products consumption in Nigeria is higher than the
average consumption by the sub-Saharan African consumption.
About 47kg of liquid milk per individual is consumed per year
in Nigeria compared to an average 25kg for the sub-Saharan
Africa region. Consumers display strong preference for locally
produced and processed products such as milk, butter and
yoghurt. The choice is based on flavor, perceived nutritional value
and custom. The local products are also much cheaper than their
imported counterparts. Sour milk and local butter accounted for
over 30% of all dairy products consumption. Urban household
consume about 20% more dairy products than rural household.
Pastoralists are mostly the producers but consume less of the
products. The bulk of the milk produced by Pastoral Fulanis are
sold to urban duelers for exchange of money, grains and other
life necessities .
Since milk is 87% water, its physical properties are essentially
those of water, modified to some extend by the concentration
and state of dispersion of solid constituent. The measurements
of physical properties are useful in quality control and to detect
variation from the normal in case of deterioration. It is also useful
in the design of dairy equipment and in detecting adulteration of
Milk is heavier than water because of the dissolved
constituents. The degree of acidity or alkalinity is termed PH.
The PH of 7 neutral, less than 7 is acidity and more than 7 is
alkalinity. Therefore, milk has a PH 0f 6.5 – 6.7 and is slightly
acidic. The freezing point of milk is -0.54 to -0.59°C and the
boiling point of milk is 100.17°C. The colour of milk ranges from
white to yellow or cream color .
According to Olawoye and Kubkomawa, the average
composition of cow milk is as follows: Water (87%), Fats (2.9%),
Lactose (4.9%), Proteins (3.5%) and Ash (0.7%). The total solid
is 13% while non-fat solid is 9%. There is, however, variation in
composition of milk between animal species. Milk composition
differs between breeds and putting breeds of the cow may also
vary between one milking and the next and udder quarters, even
in the same animal. Other factors determining milk is the plane of
nutrition, temperature, availability of water, length of lactation,
health of the animal, management and age of the animal .
It is the application of some treatments to raw milk to make
it safe for human consumption or to convert to other desirable
products. Such treatment could involve heating and cooling for
separation of milk constituent or formulation .
Milk produced from udder of cow has different bacteria,
some could cause disease or they are pathogenic, this disease
could enter the milk through flies, contaminated water or
utensils. The most obvious reason for processing is to safeguard
the public health through parturition or sterilization of milk
and milk products. This ensures elimination of disease-causing
bacteria. Other reasons for processing are to get evaporated
and condensed milk, this will reduce the cost of transportation
because you have reduced the quantity of water. It also reduces
storage spaces. Processing also produces cream which is used for
ice cream. The milk protein, casein is processed into cheese of
different varieties. Another reason for processing is to conform to
industry and health regulations, for example, in countries where
dairy products are inspected before they are sold, unprocessed
dairy product will not be passed for sale if set safe standards
are not met. Such standards require some degree of processing.
Examples of dairy products are fresh milk, fermented milk,
cheese, yoghurts and whey as shown in Figures 4 & 5 .
According to Olawoye and Kubkomawa, pasteurized milk is a
process by which milk or milk products are heated to a specific
temperature and held there for a specific time to destroy all
pathogenic bacteria as shown in Figures 6.
Two methods are employed in pasturalization this includes:
The Holding, Vat or batch Method: Raw milk is heated in a
container to at least 62°C and holding at such temperature for 30
minutes. The milk is then cooled for packaging.
The High Temperature Short-time Method (HTST):
Milk is heated to at least 72°C and holding at that temperature
continuously for at least 15 seconds in an approved and properly
operated equipment, such as plate or tube-type pasteuriser. The
milk is pumped through heat exchanger where it has contact with
heat for 15 seconds and the milk is then cooled and packaged.
Pasteurization kills about 99.6% of all bacteria .
Sterilization or sterilized milk: It is a product obtained
from raw milk that is heated to a high temperature of 92.4°C
- 97.0°C for long periods of 15-30 minutes so that all microorganisms,
both pathogenic and non-pathogenic are destroyed.
Generally, the batch method or continuous flow method at ultrahigh
temperature is used. The flavor of sterilized milk is not
pleasant and heating at such a high temperature might result in
a decrease in the vitamin content .
It is made by evaporating water from whole milk at 70.4°C
- 73.2°C in a vacuum. About 50% of the water in the original
milk is boiled off. This process can be achieved in the house
by slowly evaporating water from milk in a pot, or the pot is
placed in a water bath until the milk smells like evaporated milk
popularly known as peak milk or carnation brand. Industrially,
the concentrated milk is filled into tins and sterilized under
pressure at 116°C for 15 minutes to kill all micro-organisms and
in-activated enzymes as shown in Figure 7.
The product is obtained by concentrating whole milk under
a vacuum to concentration ranging from 2.5: 1 to 4:1. The usual
ratio is 2.8:1. This means 2.8 volume of milk or its multiple is
evaporated until one volume remains. About 18% sugar in the
form of sucrose is added and the product is termed sweetened
condensed milk as shown in Figure 8.
Skimmed milk is defined as milk from which an enough
proportion of milk fat has been reduced in order to reduce
its milk fat content to less than the minimum for whole milk.
Skimmed is also designated as non-fat, fat-free or defatted milk.
It can stay for 16 months without spoilage before fat is removed
and fewer mediums for bacteria growth are removed but, whole
milk stays only 10 months as shown in Figure 9.
When cream is agitated by churning, large chumps form
to yield butter. This is because fat particles have mucin-like
materials which are sticky; agitation causes large chumps to form.
This chump of yellow fat form is called butter. A vessel in which
cream is agitated is called the churn and churning is the process
or the act of operating the churn. Cream is put into a churn where
it is subjected to mechanical agitation. In a short time, yellowish
granular appears, which is the first form of butter. The liquid is
drained off and the granules are washed several times too with
clean cold water. The granules are worked or kneaded into a solid
mass which is called butter. During the kneading process, 1 – 2%
salt is added by weight to enhance flavour of butter, the butter
is then cut into rectangular shape and wrapped in water proof
material and stored in a cool place. Butter contains about 80%
fats, 16% water, 1% curd and 2.5% salt. The first liquid drained
from butter after churning is called butter milk; in India butter
oil is called Gee as shown in Figure 10.
Cheese is the product made from the separated curd obtained
by coagulating the caesin of milk, skimmed milk or milk enriched
with cream. Curd is the coagulated part of milk or coagulum. The
coagulation is accompanied by means of rennin or other suitable
enzymes, lactic acid, fermentation or by the combination of
the two. The curd may be modified by heat, pressure, ripening
ferments, special mould or suitable seasonings. Cheese is a
complex food product consisting mainly of casein, fat and water.
The percentage of fat in cheese is influenced to the greatest
degree by the percentage of fat in milk used for its production as
shown in Figures 7-9.
There are several ways of making different kinds of cheese.
Basically, there are two (2) common procedures required for
most cheese making: Production of coagulum or curd and curing.
A pure culture of specific bacteria is added to the milk to produce
a desired acidity and flavor. A protein coagulant (rennin) is added
to precipitate the protein which forms the body of the cheese.
After precipitation of milk solids (cured formations), the liquid
which remains is called whey. This is drained off and the curd is
washed thoroughly with clean cold water. The cheese is put into
cheese cloth and the water is pressed out. About 2 – 5% salt is
added and the cheese is formed into specific shapes and stored
for several weeks to develop characteristic flavor. Coloring
agents may be added to the cheese (Figures 11-13).
Fresh milk from healthy udder contains very few bacteria.
The bacterial load is about 500 - 1000/ml. Milk will be
contaminated with bacteria after it is drawn from the udder,
the number of bacteria will increase greatly during holding and
transportation. The rate at which organisms multiply depends
on temperature of the milk and species of bacteria present.
Under normal circumstances, milk will stay for a period of 72
hours when it is kept at 4°C. The multiplication is also influenced
by the degree of bacterial contamination in the milk. Sources of
bacteria in milk are: through the hair of the animal, the dung,
air, feed-stuff, soil, milk handling equipment and the milker’s
cloth, hair of the milker and other activities. Milk is a very good
nutrient medium and once micro-organisms enter the milk, their
numbers increase rapidly.
There is a decrease in the number of bacteria in milk for a
period after it has been drawn from the udder. This is determined
by plate count. This action lasts for about 3 hours after the milk
has been drawn. High temperature of 59°C - 79°C for 30 minutes
appear to destroy the germicidal property of milk. Bacterial
action in milk is due to unfavorable conditions which kill the
bacteria. Some bacteria may be ingested by the leukocytes in
the milk. Bacterial action in raw milk has little or no effect on
streptococcus lactose bacteria and acid producing bacteria. This
situation enables the lactic acid bacteria to ferment lactose in
milk to enough acidity, which prevents growth of the bacteria
and any other pathogenic bacteria. The lactic acid prevents the
growth of most types of bacteria most likely to be present and
thus act as a preservative.
There are 2 methods by which pathogenic bacteria enter
milk and cause epidemic. It could enter through the udder of
the cow and the organisms include; Mycobacterium tuberculosis,
var-bovis, brucella; Coxiella burnettr (the rickettsiae of fever)
and streptococcus pyogenis. Through infected persons or other
vectors that may introduce the bacteria into the milk, which
are Salmonell shigella, Streptococcus pyrogen, Conynebacterium
diptheriae and Staphylococcus aureus. Others include yeast and mould that may be present in the milk. Yeast and mould are
regarded as contaminants in milk and its products, there are also
contaminants from the air and can grow on sour milk, they utilize
some of the acid and produce a decrease in the acidity and shelf
life of sour milk. This pre-dispose the milk to rapid composition
of milk proteins by growth of putrefying bacteria .
There is the need to keep good sanitary measures in any dairy
industry, therefore, the equipment is supposed to be sterilized
based on the following steps:
a. Steam sterilization of equipment; if you are using
autoclave or steamships chest, steam can induce a moist
treat high enough to kill all bacteria.
b. Hot water sterilization of equipment; this is a physical
cleaning which removes visible dirt as well as sterilizing the
equipment, the water temperature must be 92.4°C and last
for five minutes.
c. Chemical sterilization; this is bacteriological cleaning
attained by chemicals sterilization. Chemicals of the halogen
group, bromine, fluorine, iodine have been used. Chlorine
and other chemicals make the best bactericide for sterilizing
d. It is expected that, after milking, the equipment should
be cleaned thoroughly with the chemicals stated above.
Rinse and flush equipment with simple amount of cool
cleaning water. For hand cleaning, use fibre or nylon bristle
brushes, the water should be hot (43 - 48°C). Circulating method
of cleaning: Rinse or flush through system until the rinse water
shows up clear at the discharge. Add phosphoric acid and water
and heat to 70.4°C and make sure it circulates through the
equipment for 30 minutes. Flush again with clean cool water
in order to ensure that, there is no acidic taste. Add an alkaline
detergent and flake caustic soda and clean equipment again.
Flush very well with clean water until there is no “slippery” feel
to the water and it does not taste bitter. Drain equipment and let
it stand until it is sterilized prior to use .
Milk is sold in the village level in the raw form as madara or
locally processed in to kindirmo and nono and hawked around
by the Fulani women and girls. This happens, usually, at the
onset of the rains when the product is bountiful . They also
organize dealers who go around from village to village to buy the
milk and ship it to places where its lacking, e.g. the Fulani women
who use to transport the product from Maiduguri, Borno State
to places like Adamawa and even down to the far East and West.
There are also some locally installed industries, e.g. Nagge and
Adama Beverages in Yola who buy the product and process it into
yoghurt and sell to consumers. There are also some retailers,
usually at the motor parks who buy the milk from the dealers
and stock it into chill ice milk for customers and travelers. But
matured and well-established companies like West Africa Milk
Company (WAMCO) Vom, produces, processes and sells to the
consumers finished products like peak, cheese, yoghurt, butter
There are poor dairy processing technologies and
consumption rate in Nigeria and elsewhere in West African Sub-
Region. Dairy processing techniques are not well developed with
traditional methods being the common feature. This traditional
industry processes these products into ‘nono’ (fermented milk),
fura da nono, kindirmo, yoghurt, cheese and market them in
semi-urban and urban cities. Other factors responsible for low
consumption of the products include the poor socio-economic
status of the people. In order to promote the processing
techniques and consumption rate, there should be sustained
dairy technologies provided by government and the private
sectors. This will enhance productivity, raise living standard
of the populace, and reduce poverty and diseases around the