Presented To: Dr. Nitika

Presented By: Venus Bansal Anurag Singla Arpan Pahwa

The common characteristics of various types of concentrated milk products is the reduced water content. The product in this category vary with respect to:The degree of concentration Percentage of milk fat Whether preserved or perishable The method of preservation The milk fraction utilized

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Some forms of concentrated milk products are intended for beverage consumption, while others are primarily used as ingredients in the formulation of various food products. It mainly include condensed milk and evaporated milk. Some traditional milk products like basundi and rabri also categorized as concentrated milk products.

Acc. to PFA, it is the product obtained from cow or buffalo milk or a combination thereof, or from standardized milk, by the partial removal of water, it may contain added calcium chloride, citric acid and sodium citrate, sodium salts of orthophosphoric acid and polyphosphoric acid not exceeding by 0.3% by weight of the finished product. It should not contain not less than 8.0% milk fat, and not less than 26.0% milk solids Contd

Sensory considerations: - In addition to meeting the legal composition and chemical requirements, high-quality evaporated milk should be: Creamy-white in color Have a relatively viscous body Smooth in texture and possess a relatively mild pleasant flavor Containers properties Should present an attractive appearance Neat well-applied label The ends of the can should be polished No evidence of bulges or dents

Coffee whitening properties Color Container integrity Curd tension Fat separation Fill of container Film formation Flavor

Gelation Lactose crystallization Sedimentation Serum separation Viscosity Whipping quality

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Undue agitation should be avoided during transportation of cans to the laboratory. It should be carried in an upright position. Examination of the can appearance should be done without lifting the can. It should be noted for the degree of polish and seam integrity. The container should be cut around the periphery of the upper end of the can. After cutting it should be examined carefully.

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Recommended examination specifications are: Color: - Evaporated milk should display a light, uniform cream color. Uniformity: - Evaporated milk should be uniform or homogeneous as evidence by the complete absence of a cream layer, curd formation, destabilized milk fat. Body and Texture:- The contents of the can should be poured slowly into a clean glass beaker and note the flow properties of the product. It should pour in a similar manner to a thin cream without any apparent ropiness Contd

Observe the condition of the container:- the observer should look for either spangling, blackening of the seams or container corrosion. Spangling refers to the appearance of alternate clean, bright and dark, overlapping blotches on the surface. Determine the product reaction in coffee:- evaporated milk should impart a rich, golden-brown color to coffee. Determine the flavor:- high-quality evaporated milk should have a specific milk/cream flavor.

The principal defects occurring in freshly processed and stored evaporated milk are:

Flavor Sediment Discoloration Feathering Lack of sterility Grainy

Mineral fat separation Low viscosity Fat separation Curdy Gassy

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1. 2.

3.4.

Flavor:- The most common flavor defect in evaporated milk associated with age-darkening and browning of the product. The cooked flavor in evaporated is because of the liberation of sulfhydryl groups. Fat separation:- The buttery defect appears as a 0.641.27cm layer of heavy cream at the top of the can. The causes of this defects are:Inadequate homogenization High storage temperature Extended storage period Improper handling while in storage Contd

Prevention:- Homogenization at 1000-1500 pounds and incorporation of stabilizing agents has been helped to control this defect. Low temperature storage and correct handling of the product will eliminate this defect. Curdy:- It may be noted by the presence of coagulated protein particles interspersed throughout the milk or by a continuous mass of coagulum or PREVENTIONS soft gel. CAUSESHigh sterilizing temperature Shaking the evaporated milk after causing precipitation of proteins sterilization causing curdling Poor quality of milk Take milk from healthy cows w/o colostrum or stripper milk and non acidic

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Shorter preheating period at lower Lengthened preheating periods temperature (98C) Excessive homogenizing pressure Homogenizing 1500 pounds pressure 1000-

Other preventive measures: Addition of extraneous water to evaporated milk lessens intensity of curdling during sterilization. Degree of concentration should be proper. Adding bicarbonate of soda reduces excess of calcium and magnesium and diminishes tendency of evaporated milk to curdle. Contd

Feathering:- The feathering of evaporated milk in hot coffee is difficult to predict by macroscopic examination, it is more routinely ascertained by actually testing the sample in hot coffee. The reason for this defect is excessive viscosity of milk. It is also affected by the salt balance of milk.

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Gassy:- This defect is uncommon. It is manifested by bulged cans and sometimes by a hissing sound of escaping gas when the can is punctured upon opening. It is occasionally due to certain physical-chemical causes and microbial fermentation is most typical cause. Organisms responsible for this defect are B. putrificus, Plectridium novum, Plectridium foetidum. It is also caused by exposing evaporated milk to storage temperature below freezing point of water. Prevention:- Proper sterilization with highest sterilizing temperature. Storage at optimum storage temperature

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Grainy:- A grainy evaporated milk is the one which lacks smoothness and uniformity throughout. It appears coarse. It is often associated with an excessively heavy, viscous body. In sandy or gritty condensed milk the crystals are very numerous and large enough to grind between the teeth. This defect is found in hermetically sealed cans after the sterilizing process. Prevention:- Use of lower sterilizing temperatures and shorter sterilizing periods. Low viscosity:- Low viscosity evaporated milk may be noted by its more water-like consistency. It lacks creaminess and pours from the container as readily as fresh milk. Low viscosity is due to high heat stability.

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Color:- The principal color defect is browning. This results from Maillard reaction. The dark (brown) color is due to oxidizing action of excessive heat on milk sugar causing milk to caramelize. Storage at high temperature also tends to darken the color with age. Prevention:- Reducing the sterilization temperature or shortening the sterilizing period or both. Storage of evaporated milk at low temperature.

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Sediment:- Sedimentation in evaporated milk may be of two distinct kinds. The sedimentation occurring from settling of somatic cell, denatured protein and/or foreign material is usually darker in color than the product itself. The second type of sedimentation results from the crystallization of specific calcium and magnesium salts such as tricalcium phosphate, magnesium phosphate and tricalcium citrate. The rapidity with which the sediments are formed is influenced by the nature of the milk, conditions of manufacture and temperature of storage. Preventions: Selection of good quality milk, correct processing conditions and low temperature storage. Higher viscosity of product.

a) b)

Description:- Sweetened condensed milk is the food obtained by partial removal of water only from a mixture of milk and safe and suitable nutritive carbohydrate sweeteners. The finished food contains not less than 8% by wt. of milkfat, and not less than 28% by wt. of total milk solids. The product is pasteurized and may not be homogenized. Optional ingredients:- The following safe and suitable characterizing flavoring ingredients, with or w/o coloring and nutritive carbohydrate sweeteners, may be used:Fruit and fruit juice, concentrated Natural and artificial food flavoring Contd

Sensory considerations:- Sweetened condensed milk contains a sufficiently high percentage of sugar for preservation, thus flavor is predominantly intense sweet. a) Clean and pleasant flavor b) Smooth and uniform body c) Light, translucent-yellow color Sweetened condensed milk is primarily used as an ingredient in candy, cookies, pies and ice-cream.

The evaluator should place a representative container on a table for examination. The can should be exactly in upright position. Next, the evaluator should cut and turn back the container lid so that the milk surface may be closely examined and contents easily decanted from container. The recommended order of visual examination is:Appearance of the container:- The container of product should appear to be in good condition. The can ends should be as bright as new tin. Contd

Appearance of product surface:- The product surface should have color intensity same as under layers of condensed milk. The product should be uniform in consistency with no lumps, free fat or film formation. Color:- The color should be uniform throughout. The evaluator should determine whether the SCM has a creamy or less desirable brownish color. Viscosity:- The observed flow of product should resemble that of a medium-heavy molasses. There should be no indication of gel or custard-like formation. Contd

Sediment:- After the can has been emptied, the evaluator should scrap the bottom and note the presence or absence of a thickened layer. Flavor:- A small teaspoonful of the SCM should be placed into the mouth and mouth feel, taste and aroma sensations should be observed.

The principal defects occurring in freshly processed and stored sweetened condensed milk are:1. Flavor:- SCM tends to have none of the volatile flavors that occur in fresh milk. When properly manufactured its free of flavor defects. However following off-flavors develop with increased storage time:a) Metallic:- The metallic off-flavor of SCM is distinctly chemically induced by copper contamination. The sugar and acid in boiling milk in the pan tend to cause the formation of copper oxide and copper salts in the dome of the pan. These salts fall into condensed milk in the consecutive operations. Contd

Prevention:- Proper cleaning of the dome and its surface daily b) Rancid:- This occurs infrequently in SCM. Rancidity results from milkfat hydrolysis by enzymes secreted by spoilage bacteria or indigenous milk lipase. It is caused by use of polluted or filthy water which is contaminated with bacteria and fungi. Prevention:- Avoid using this water for washing cans, pipes and other equipments.

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Strong:- The strong or strong-caramel is often used to describe the off-flavor that accompanies the progressive thickening and browning of condensed milk. SCM not held at low temperature grows darker (brown) in color with age. If exposed to high temperature during storage and transportation the SCM turns brown in color. This brown color is due to the oxidizing action of heat on lactose and sucrose. Prevention:- Cold storage and maintaining low temperature during transportation.c)

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Tallowy:- On opening a tin the sample may appear paler than normal and aroma may be reminiscent of beef tallow and remains even after exposure to the air for several days. This defect is now rare in SCM. Tallowy condensed milk is produced through the action of the oxygen of the air in the container on the butter fat of the milk, the reaction being catalyzed ordinarily by small amounts of copper. It develops below 0C. Prevention:- Use of stainless steel equipments.d)

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Off-flavors caused by MO:- Certain osmophilic and osmoduric MO, including yeast, molds and bacteria, under certain conditions can grow and cause spoilage in SCM. This is accompanied by characteristic physical and appearance changes, gas production, off-flavors and odors. The resultant odor may be acidic, stale, cheesy, unclean, or yeasty.

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Body and texture:- The following body and texture defects may be encountered:a) Buttons:- Formed buttons are visually observed as round, firm, cheesy curds at the product surface. They result from the proteolytic activity of certain molds. These can be eliminated by preventing contamination by osmophilic molds and other MO. Main organism is Aspergillus repens. Prevention: Maintaining proper sanitary conditions. Sterilizing cans before filling. Contd2.

b)

Holding evaporated milk at a temperature of 10C or below. Sealing cans under a vacuum of 20 inches or more, or by charging the cans with an inert gas. Lumpy:- The product may exhibit lumpiness within portions of the container contents. Portions of the product may be actually gelled.CAUSES PREVENTION

Poor quality of fresh milkUnclean factory conditions

Rigid inspection of fresh milk as it arrivesThorough scouring of milk tanks, pipes and pumps

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Milk from freshened containing colostrum

cows Avoid colostrum milk Keep separate the last cans drawn from pan and recondense

Presence of organic and mineral acid

Fat separation:- This occurs seldom in SCM. This defect may be noted by either an off-flavor, fatty film at the surface and/or floating droplets of free fat. This occurs if fat globules are too big, especially if viscosity is low. Prevention:- Proper homogenization.c)

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Gassy:- This may be recognized by a bloated or huffed can. Causative agent is yeast Torula lactis condensi. Formation of gas takes place in cans and barrels of condensed milk causing bulging or bursting of containers. The source of contamination may be the raw milk, or inferior quality sugar or unhygienic factory conditions especially not properly washed and sanitized equipments and filling machine. Preventions: To avoid this defect good quality raw milk and properly preheating temperature should be used.d)

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e)

Only good quality sugar without any yeast contamination should be selected. Proper sanitary conditions should be maintained during manufacture and packaging of condensed milk. The containers should be filled fully with little space for air or oxygen. Sandy (rough, grainy, granular):- This defect is associated with SCM that contains detectable or oversized lactose crystals. The solid lactose particles impart a distinct grittiness and lack of smoothness to the product. This may also be due to sucrose crystals, when concentration of this sugar exceeds saturation Contd

level. The chief factor which prevents this defect is great viscosity of condensed milkCAUSES Un-dissolved sugar crystals PREVENTIONS Thoroughly dissolve the sucrose to be added and Heat the milk or water in which sucrose is to be dissolved to boiling point sugar Raising temperature of water that goes into condenser Closing the holes in the pipe which are nearest to the pan cold Warm SCM by allowing to stand in warm room

Excessive chilling crystals in the pan

of

Warming up condensed milk

of

too

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Superheating at the end of batch

Removal of any conditions that tend to expose finished/nearly finished milk to excessive heat Temperature of water in cooling vat should be about 32C and should flow slowly and be evenly distributed About 5 rpm is satisfactory

Improper, rapid cooling

Excessive stirring

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f)

Settled:- This defect is associated with SCM in which a distinct settling of sugar crystals has occurred. The syrup that settles out forms a thick sugary layer on the container bottom. Key measures for prevention of this defect include efforts to ensure small crystals and development of an adequate product viscosity to retard sedimentation.CAUSES PREVENTIONS

Effect of sediment

density

on

sugar Proper evaporation condensing

and

Effect of fat content on sugar It has effect to a lesser degree sediment

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Effect of cane sugar content on Milk should contain optimum to sugar sediment high % of sugar crystalsg)

Thickened:- This defect is manifested by an extensive gel formation, which makes the product appear mare solid than liquid. Excessively thickened condensed milk is usually associated with browning. Physical and chemical factors, and certain MO are commonly responsible for thickening of SCMCAUSES PREVENTIONS There is no significant evidence of this

Effect of cows feed

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Effect of bacteria:- Fermentation Maintaining proper caused by bacteria associated with sanitary conditions filth and dirt

and

strict

Finishing in pan with high steam Finishing the batch with low steam pressure, overheating pressure in the jacket and coils

Exposure to high temperature, ageing

storage Storage below 15C