Factors Responsible for Milk Losses

There are number of factors that contribute to losses. Knowledge of these minor or major factors would be of help to dairy professionals in exercising effective controls. Most prominent factors are discussed below:

i) Capacity Utilization: Volume of milk and milk products handling in milk plants has impact over losses. It is observed that some of the losses are more or less constant. For example, losses in the milk pasteurizer are dependent on the number of times it is put On and Off and cleaned by CIP. Therefore, irrespective of quantity of milk pasteurized, the losses ought to be there depending upon scheduled number of batches and un-expected power failures. Similarly, number of milk types in the dairy plant will decide use and cleaning of milk tanks or silos.Depending on the number of cleanings, the losses in the form of sticking and flushing will result. Here again the important factor is number of tank or silo depending on the milk types and not truly the quantity of milk. If you know this fact, then, to bring down the losses, one need to plan pasteurizer operation to reduce number of batches and increase plant throughput.

ii) Product Mix: The quantum of milk solids loss in a dairy plant is associated with number of products and nature of products. More the number, higher will be the milk solids losses. Products with rich in milk solid content are normally have higher losses, whereas lower milk solids content product result in lesser losses.It is observed that dairies with only liquid milk handling is having less than 0.5 % handling losses, whereas product manufacturing dairies has as large as 2.5% milk solids loss. To have a greater feel, a product-wise milk solids loss is presented in Table

Product-wise Milk Solids Losses in Dairy Plant

iii) Pack Size: You will be surprised to know that pack size also affects the milk solids loss. Usually volume or quantity of milk and milk products packed is with a tolerance / margin as safety measure with respect to Weights and Measures Act. In such cases loss will comprise of product of the safety margin per pack and number of packs. Some times over filling of packs do occur due to improper machine adjustment. In this way, we can understand that extent of milk solids losses will be inversely proportion to the size of packs and directly proportional to the number of packs. In the bulk milk supplies by Road /Rail milk tanker, the losses are further lower. The bulk supplies are tested and measured in composite manner, which result in less chances of deviation from the real quantity /volume.

iv) Accuracy of Testing and Measurement: The testing of milk is normally done on samples. Test results would be wrong due to improper sampling /sampling method, poor quality of test apparatus, improper quality of reagents used and improper calibration of test equipments and apparatus. Some times cheaper glassware do have poor sensitivity or least count which gives inaccurate results.Wrong sampling of liquid milk is generally observed due to improper mixing before sampling, sampling from wrong point or sampling without proper mixing and ageing time. Milk made by powder reconstitution needs ageing time of atleast four hours to get proper hydration of powder particles. Testing before proper hydration gives inaccurate test result. This can be visualized by balancing milk solids of powder used and milk obtained.It has been noticed that repeated test by same technician with same apparatus and chemical may show variations on account of technician skill, other external factors and sensitivity of apparatus or combination of all these. Therefore, in general 1% variation in testing is accepted in the industry. However, in-fact accepting this norm of 1% can itself give huge variation.

v) Inefficiency of Processes: Inefficient processing may lead to heavy losses.For example: Inefficiency in temperature control or over ageing, the cream will get over ripened with high acidity. Churning of high acidity cream will result in high fat loss through buttermilk, whereas buttermilk of sweet scream has normal acidity and can be utilized by mixing in the raw milk. There are several examples of process inefficiency that has adverse bearing on milk solids losses. For operational awareness some of the inefficiency losses are listed in Table

Operational and Inefficiency Losses in Market Milk

vi) Preventive Maintenance: Some times milk or milk products line develops leakage. Leakage would be at process equipment (from chiller or pasteurizer plate), pipe lines (pipe are damaged union/valve or joints) not properly tightened or gasket is damaged or vessel /tank is damaged. This all happens due to lack of attention in preventive maintenance. In such situation, attempting leakage control at first notice itself would minimize losses. Such instances would be minimized by timely preventive maintenance of process lines and equipment.

vii) Pilferage and Spillage: Pilferage is due to poor integrity of personnel, whereas spillage is entirely the outcome of negligence. There are critical factors that are related to human instinct and can alone be a major factor, if not dealt in time.

viii) Packing Losses: Some losses are linked with packing quality, whereas others relate to inefficiency of operations. In the former type, milk solids losses occurs due to damage of packs. Prominent responsible factors in this form are: (a) Use of packing materials of less thickness or weight, (b) decrease in the pack size for the same volume or quantity, (c) increase of packing speed. The major factors in the form of operations inefficiencies to result increase in the leakage are due to poor power supply, machine maintenance,frequent break downs, too many packing breaks and improper setting /adjustment for filling quantity.

ix) Flushing Losses: Flushing is done at the end of operations of equipment and at every emptying of Storage tanks / vessels. Flushing contains residual /sticking portion of milk. Inadequate emptying or early flushing may lead to excessive quantity of milk going to waste.

x) Marketing Policies: In order to cover up internal plant inefficiencies or to provide higher advantage to retail network /consumers as a pro-marketing policies, unsold or damaged milk packs are taken back and /or replaced with good one. In this case, there is physical loss of milk solids because the returned milk /product is of rejected quality and unsuitable for reprocessing.Also liquid milk packs if allowed by transporter crew to check before loading,then due to exercise of over pressure, higher cold store leakage may cause increased milk losses.

xi) Loss due to non-utilization of by-products: During manufacture of various products like paneer, channa, rasogolla and cheese, the whey is generated,which contains significant amount of milk solids. Non-utilization of the byproduct leads to direct loss of milk solids. You will be surprised to know from the following table that a significant quantum of milk solids are present in byproducts, which may be lost, in the event of their non-utilization.

Composition of By-products of Milk