In this article we will discuss about the methods adopted for buying, collection, cooling and transportation of milk.
Buying of Milk:
Various methods for buying milk are employed, singly or in combination, as given below:
(a) Payment According to Weight or Volume (also known as a Flat Rate):
Advantages- (i) saves time; (ii) simple to calculate.
Disadvantage- Encourages watering or skimming. Payment by weight is preferred to payment by volume as the former is not affected by either foam or specific gravity. (It is popular in the unorganized sector.)
(b) Payment According to the Fat Content of Milk (includes, among Others, The Straight Fat Method of Payment):
Advantages-
(i) practical;
(ii) discourages adulteration with water.
Disadvantages-
(i) does not prevent removal of skim milk;
(ii) does not take into account the solids-not-fat content of milk. (Practised by most dairies.)
(c) Payment According to the Use Made of Milk:
This practice is followed mainly for milk products.
(d) Payment of Premiums:
Usually confined to market milk, Based on quality of milk as measured by- (i) sediment test; (ii) flavour score; (iii) bacterial count or Methylene Blue Reduction Time. (Encourages the production of high-grade milk.)
(e) Payment According to the Cost of Production:
Complicated, although rational.
Note:
The urgent need for a sound pricing policy for milk and milk products in this country is being increasingly realized by dairy planners today. The problem, no doubt, is complicated, as the price has to be acceptable to the producers, processors and manufacturers, distributors and finally consumers. Further, the approach must be of long-range significance to dairy development.
A rational milk pricing policy should ensure- a guaranteed price and market to the producers throughout the year, which will be an incentive to them to produce more milk; a regular supply of wholesome milk at reasonable rates to the consumers; and an attractive margin of profit to the milk processors and product manufacturers.
In fixing the producers price for fluid milk, the following basic considerations have to be kept in view:
i. The price should be related to the cost of milk production and ensure a fair margin of profit to the producers;
ii. It should take into account the seasonal variation in production (supply) and demand; and,
iii. It should be linked with the consumers’ price index, taking into account general market trends.
From the point of view of the milk processor/milk-product manufacturer, the price of milk should take into account the following:
i. The stage of operation of the plant;
ii. The costs of transportation, processing/manufacturing and distribution;
iii. Plant capacity so as to utilize ail surplus milk in the milk-shed area; and
iv. The market objective of the plant, including its programme of product diversification.
The consumers’ price has to be fixed after consideration of the size of the population that is to be covered by the milk scheme- the distribution of people in different occupational and income groups (viz., lower, middle and higher) that are to be served; and the total cost of transportation, processing/manufacturing and distribution (which should be adequately covered, besides leaving a reasonable margin of profit to the milk plant).
It is, therefore, necessary to strike a balance between the producers’ price which is to serve as a production incentive and the consumers’ price which should be within the purchasing power of the average consumer throughout the year.
At present each milk plant or dairy product factory has evolved an arbitrary system of milk pricing, which seems to have no relation to the actual cost of milk production. Liquid milk plants have a differential pricing system for flush and lean months based on the fat and SNF contents of milk, with provision for the payment of a premium for a higher fat and SNF content than the specified standard. Dairy product factories purchase milk by and large on a per kilo fat basis at different prices for different seasons.
The minimum standards prescribed by the PFA (1976) rules for cow milk are 3.0 to 4.0 per cent fat and 8.5 to 9.0 per cent solids- not-fat, while those for buffalo milk are 5.0 to 6.0 per cent fat and 9.0 per cent solids-not-fat throughout the country. With a view to encouraging milk production through high yielding indigenous and cross-bred cows, it is necessary to adopt a pricing policy which would provide an adequate incentive for production of cow milk.
The National Dairy Development Board has suggested the two-axis milk pricing policy. Such a policy ensures payment for milk on its compositional quality evaluated rationally on its fat and solids-not-fat components. This would discourage adulteration of buffalo milk and at the same time ensure a common pricing approach to cow and buffalo milks.
However, one difficulty that can be foreseen in this system is the accurate testing of milk at source for its solids-not-fat content. Since the estimation of solids-not-fat in milk is a time-consuming process, research would have to be undertaken to develop a rapid test which could be carried out under field conditions.
The overall pricing policy for milk products should encourage efficiency of production, minimization of costs, quality of the product, etc. Dairy factories should try to create the feeling that the price of producers’ milk is not predetermined unilaterally at a fixed rate but varies, rather, with season and quality.
Collection of Milk:
In almost all developed dairying countries, production of milk is confined to rural areas, while demand is mostly urban in nature. Hence milk has to be collected and transported from production points in the milk-shed areas to processing and distribution points in cities.
(a) The common systems for collection (assembling) of milk are as follows:
(i) By Co-Operative Organizations:
It is formed by individual or collective milking societies. Suits producers best as no profit-making middlemen are involved.
(ii) By Contractors:
Less return to producers.
(iii) By Individual Producers:
Practical for those situated near processing dairies.
Note:
A ‘milk-shed’ is the geographical area from which a city dairy receives its fluid milk supply. The allocation of definite milk-sheds to individual dairies for the purpose of developing the same is now being considered in India.
(b) Milk Collection-Cum-Chilling Centres/Depots:
Normally attached to city dairies.
Objects:
These are:
(i) To preserve the quality of raw milk supplies, and
(ii) To provide easy transport to the processing dairy.
Location:
This is guided by:
(i) Adequate milk production;
(ii) Adequate (potable) water supply;
(iii) Proximity to a good road or railway station;
(iv) Electric supply, and
(v) Sewage disposal facilities.
Major Items of Equipment:
(i) Milk weigh tank/pan and weighing scale
(ii) Drop (dump) tank with cover;
(iii) Can washer;
(iv) Milk pump (sanitary type);
(v) Surface/plate cooler;
(vi) Refrigeration unit (of suitable capacity);
(vii) Cold room (of suitable capacity);
(viii) Milk testing unit, etc.
Operational Procedure:
Essentially this is the same as in a small dairy. On arrival, the milk is graded for acceptance/rejection, weighed, sampled for testing, cooled and stored at a low temperature until despatch to the processing dairy.
Cooling and Transportation of Milk:
Cooling (On the Farm or at the Chilling Centre):
Importance:
Milk contains some micro-organisms when drawn from the udder; their numbers increase during subsequent handling. The common milk micro-organisms grow best between 20 and 40°C. Bacterial growth is invariably accompanied by deterioration in market, quality due to development of off-flavours, acidity, etc. One method of preserving milk is by prompt cooling to a low temperature.
Effect of Temperature:
Table 1.17 shows the bacterial growth factor in milk at different storage temperatures:
It will be seen from Table 1.17 that 10°C is a critical temperature for milk. Freshly drawn (raw) milk should, therefore, be promptly cooled to 5°C or below and also held at that temperature till processed.
Principle:
The principle of heat-exchange, i.e. heating and cooling.
Methods:
I. In-Can or Can-Immersion Method:
From carrying-pails, the milk is poured directly into cans through a strainer. When the can is full, it is gently lowered into a tank/trough of cooling water. (Note- The water level in the tank should be lower than the level of milk-in-cans, to prevent water entering into the milk).
Advantages:
(i) Not only is the milk cooled, but it also stays cool, and
(ii) A much smaller mechanical refrigeration unit is required.
Disadvantages:
(i) It cools the milk very slowly, and
(ii) There is danger of milk contamination in case tank-water enters milk- in-can.
II. Surface Cooler:
This may be plain-conical, spiral or horizontal-tubular in shape, although the last-named is now commonly used. The milk is distributed over the outer surfaces of the cooling tubes from the top by means of a distributor pipe or trough and flows down in a continuous thin stream.
The cooling medium, mostly chilled water is circulated in the opposite direction through the inside of the tubes. The cooled milk is received below in a receiving trough, from which it is discharged by gravity or a pump.
Advantages:
(i) Transfers heat rapidly and efficiently;
(ii) Is relatively inexpensive;
(iii) Also aerates the milk, thus improving its flavour.
Disadvantages:
(i) Requires constant attention for rate of flow (which must neither be too slow nor too fast);
(ii) Greater chances of air-borne contamination;
(iii) Cleaning and sanitization not very efficient, and
(iv) Slight evaporation losses.
III. In-Tank or Bulk-Tank Cooler:
Used extensively in developed dairying countries like the U.S.A. Properly designed bulk milk tank coolers, which are normally run by a mechanical refrigeration system, will cool the milk rapidly to a low temperature (5°C or below) and automatically maintain this temperature during the storage period.
Milk can be poured directly from the milking pail (under Indian conditions) into the tank. Subsequently milk can be drawn into cans or pumped into a tanker, for despatch to the city dairy.
Advantage:
Permits collection of producers’ milk on alternate days.
Disadvantage:
Relatively expensive in initial equipment.
IV. Milk Chilling Centres:
Now that electricity is available even in most Indian villages, these have great scope in this country, largely because of predominantly small and scattered milk production. The number of organized dairy farms in India is rather small. Consequently, the centres can provide the only alternative solution to the collection and chilling of village milk. They can profitably be run by the producers themselves through their co-operative organizations.
Transportation:
Importance:
Under Indian conditions, milk has to be regularly collected and transported twice a day (morning and evening).
Modes of Transport:
These depend upon the carrying load, the distance of collection and local conditions. Their particulars have been given in Table 1.18.
Road vs. Rail Transport:
The individual advantages of each have been stated in Table 1.19.
Can vs. Tanker Transport:
The individual advantages of each have been given in Table 1.20.
Types of Containers Used:
These are made of:
(i) Baked earth
(ii) Wood or bamboo
(iii) Metal (generally brass)
(iv) Galvanized-iron (GI)
(v) Second-hand tins (mainly vegetable oil/ghee)
(vi) Tinned-iron or aluminium-alloy (used by organized dairies).
Problems:
The problems in relation to collection and transportation of milk are:
(i) Milk is liquid, perishable and balky;
(ii) Small and scattered production of milk;
(iii) Tropical climate;
(iv) Lack of transport facilities;
(v) Lack of countrywide organizations for milk collection and transport;
(vi) Vested interests among local milk merchants.