Sensory Evaluation of Milk Powder

The sensory evaluation of milk powders assumes great significance in our country. Milk powders, particularly skim milk powder (SMP) is manufactured in large quantities at feeder balancing plants in the flush season and subsequently used in lean period in reconstituted form to maintain milk supply. Also it has become an important export commodity. In this chapter we shall discuss the sensory evaluation of both, whole milk powder (WMP) and Skim Milk Powder SMP.

i. Desirable Attributes and Defects in Milk Powders

i) WMP: The flavour of dry whole milk should be clean, rich, sweet and pleasant.Frequently, dry milk may be unduly criticized as having a heated ‘or a ‘cooked’ taste. This may be expected or even desired. The common flavour defects of WMP are oxidized/tallowy, chalky, scorched, rancid and stale. The product should be free flowing to some extent with absence of lumps. Presence of hard lumps is a serious defect in WMP. The colour of WMP depending on the source of fat varies from white to deep yellow. The defects such as scorched particles, browning or lack of uniformity should be absent.

ii) SMP: The flavour of good quality SMP, when reconstituted should be similar to that of fresh skim milk, that is, normally a flat taste because of practically no fat in it. Otherwise, the flavour is clean, sweet and pleasant and may have a slightly cooked or heated perception. The chief flavour defects of SMP are stale/storage, neutralizer and scorched. SMP prepared by spray process is very fine in particle size and free flowing. The product pours readily somewhat like that of corn meal. Cake formation is the most frequently occurring defect related to texture of SMP. Sometime the defect is so serious that the product looks as hard as a rock. The colour of SMP should be uniform and showing complete absence of scorched particles and browning. The product should have a creamy white or light yellow colour.

iii. Score Card of Milk Powders

The weightage given to different attributes of milk powders is shown in table .

Score card for milk powders

iii. Scoring Technique of Milk Powders

i) Method of Reconstitution: Generally the dry milks are reconstituted to the composition of their native liquid form for examining odour, taste and presence of undissolved particles (sediments). The required quantities of WMP (13 g) and SMP (10g) are dissolved in warm water (40-45oC) to make the final volume to 100 ml and left for about 30 min before judging.

ii) Sequence of Observations

a) First of all observe the external condition of the package for cleanliness, neatness etc.

b) Open the package and immediately inhale the aroma. Take a small amount of powder in to mouth for taste and tactual perceptions.

c) Simultaneously observe the appearance of powder for colour, lack of lumps/ cakes and free flowing properties.

d) Then start judging the reconstituted milk adopting the same technique as discussed easier for fluid milk.

e) Try to correlate the flavour perceived in dry form with that noted in reconstituted form.

f) Record all observations along with intensity of defect, if any, in the score sheet.

Sensory Evaluation of Dahi

i. Desirable Characteristics and Defects of Dahi

i) Colour and appearance: The colour of dahi ranges from creamy yellow for cow to creamy white for buffalo dahi. It should be pleasing, attractive and uniform without showing any sign of browning and visible foreign matter. Dahi should have smooth and glossy surface without appearance of any free whey on sides or top. A cream or malai layer on the top is indication of wholesomeness and purity, hence desirable.

ii) Flavour: A pleasant, sweetish aroma and a mild clean acid taste are looked for in dahi. It should be free from any off flavour. A good diacetyl flavour is always desired in dahi. Skim milk dahi lacks the natural rich flavour and considered as flat. Dahi shall not show any sign of bitterness, raw, yeasty, cheesy, sharp, and unclean off flavours.

iii) Body and texture: Good dahi is a weak gel like junket when made from whole milk. The body should be firm, homogenous and free from gas holes/ bubbles. On cutting it should appear clean/sharp. The surface should be smooth, preferably with a creamy layer. Defects like grainy/lumpiness, ropy, shrunken, thin and wheying off should be absent in dahi.

iv) Acidity: Generally acidity in the range of 0.75 to 0.85%, as lactic acid is appropriate for good quality dahi. Excessive acidity imparts too much sourness/ sharp/ astringent taste to the product, whereas low acidity in dahi is considered as raw/bland.

ii. Score Card of Dahi

The following score card is suggested for sensory evaluation of dahi (Table)

Score Card for dahi

iii. Scoring Technique of Dahi

i) Temper dahi to about 10-15oC for proper judging.

ii) Note the condition of container/package for fullness, cleanliness and general appearance.

iii) Remove the closure lid of the package and immediately observe the aroma by inhaling the product. Simultaneously, examine the appearance of dahi for uniformity of colour and presence of visible extraneous/foreign matter.

iv) Cut the curd by using a knife or spoon and observe for the firmness and evenness of cut. Also observe the interior of dahi mass for smoothness, presence of air/gas holes and free whey.

v) Place a spoonful of dahi in the mouth. Ascertain the taste and aroma of product. While manipulating in mouth also note the tactual properties on the tongue and between teeth for grittiness/graininess..

vi) Note whether the acidity level is pleasant and typical to the product.

vi) Finally rinse your mouth with water.

Sensory Evaluation of Paneer

i. Desirable Attributes of Paneer

i) Colour and Appearance: Paneer should have uniform white colour with greenish tinge if made from buffalo milk and slightly yellow colour if prepared from cow milk.

ii) Body and texture: The body of paneer should neither be too firm no too soft.It should retain its shape. The texture of good quality paneer should be compact, smooth, slight spongy and velvety. While masticating it should impart feeling of fibrous texture with modest chewiness.

iii) Flavour: Paneer has a characteristic blend of the flavours of heated milk, curd and acid. It shall be pleasant, mildly acidic, slight sweet and nutty.

ii. Score Card of Paneer

The 100 points score card for paneer is exactly same as for khoa, presented in table  (Flavour 45; body and texture 35; colour and appearance 15 and package 5)

iii. Scoring Technique of Paneer

i) The optimum temperature of judging the paneer is about 15oC. It is highly essential that temperature of all the samples should be same for uniformity in evaluation of body and texture.

ii) Like all other dairy products, start with the visual observation of the package for cleanliness, proper protection and absence of soiling material/whey etc. on the surface.

iii) Remove the package/wrapper and immediately inhale the smell and observe the surface. The spoilage of paneer during storage starts from surface due to formation of bacterial slime (greenish/ yellowish coloration) and production of putrid or acid smell. Also note the colour of product, presence of burnt particles or foreign particles in the paneer samples.

iv) Then with the help of a knife or a trier, collect a slice/plug of paneer from the larger block. This should also be brought under nose to inhale the smell of interior portion. While cutting the sample particularly note the resistance offered, and whether the plug is intact or broken into pieces.Apply some pressure on the paneer block with the thumb and note whether the compressed area returns back to its original form after removing pressure.

v) Take a sufficient piece of paneer in the mouth and while masticating note the ease of biting by teeth and the taste quality and overall flavour. Then expectorate the sample

iv. Defects in Paneer

i) Colour: Dull, uneven colour due to surface evaporation, presence of burnt particles, mould growth, greasy surface due to bacterial slime.

ii) Body and texture: Dry/hard, rubbery, brittle, weak, sticky/ pasty, grainy/ mealy, too open (lack compactness).

iii) Flavour: Sour, putrid, burnt, smoky, rancid, whey-like, musty, yeasty, bitter, feed/weed and foreign.

Sensory Evaluation of Khoa

i. Desirable Attributes of Khoa

a) Colour and Appearance: A good quality khoa, in general, should have uniform whitish colour with perhaps a tinge of brown colour. Khoa made from cow milk, however, has light yellow to deep yellow colour. The surface should be slightly oily/greasy i.e., showing the signs of little free fat. It should not have any foreign matter.

b) Flavour: A typical mildly cooked flavour, similar to that perceived from boiled milk, is most acceptable. The taste should be pleasantly sweet. Good quality product shall not have any abnormal or objectionable flavour.

c) Body and Texture: The texture of khoa depends on its variety. In general a uniform and slightly granular (equal to pinhead size) texture is most desirable. Pindi khoa is required for making burfi and peda in which homogenous texture with very fine grains is required. Pindi khoa has smooth, compact and homogenous texture. Dhap khoa has slightly loose texture with grains of bigger size than that of Pindi khoa. Danedar khoa is used for making kalakand and milk cake in which presence of big grains with brown colour are considered desirable attributes.

ii. Score Card of Khoa

A 100-point score card is more purposeful and objective, hence it is recommended for judging of khoa (Table )

Score card for khoa

iii. Scoring Technique of Khoa

i) Tempering: Khoa should be kept at room temperature for judging purpose. It is, however, desirable to have a constant temperature of about 30oC for consistency in judging throughout the year.

ii) Sampling: A uniform sample weighing about 50 g for each judge is collected from the bulk khoa. Alternatively, the judges may also use a cheese trier to withdraw the khoa sample.

iii) Sequence of observations:

a) The first step in judging khoa is the examination of packaging material, which should be neat and clean. The product should be properly protected.

b) Immediately after collecting a representative sample of khoa either by a knife or cheese trier, bring it under the nose and inhale the odour of khoa and make a mental memory of the same. Then observe the colour and appearance.Special attention should be paid to the detection of burnt particles, if any.

c) The texture of khoa is evaluated by observing the nature of plug for smoothness, cohesiveness and whether it sticks to the trier. Pressing and rolling a small piece of khoa in between the fore fingers and the thumb, note the hardness, presence of free fat, etc. Spread a small mass of khoa on the palm of your hand with the thumb and examine the uniformity, size and toughness of the grains.

d) Take a sufficient quantity of khoa in the mouth. While rolling it about in the mouth and chewing it in between the teeth, note the tactual and taste sensations.Expectorate the sample and note if any after-taste persists.

iv. Undesirable Attributes of Khoa

a) Colour and appearance defects: Too brown/dark, lack of uniformity, moist/ dry/ mouldy, surface, visible burnt/foreign particles.

b) Body and texture defects: Hard/dry, weak/loose, lack cohesiveness, grainy/ gritty and sandy texture.

c) Flavour defects: Flat, smoky, burnt, sour/acidic, metallic, rancid, oxidized, stale, salty and neutralizer.

Sensory Evaluation of Cheddar Cheese

i. Desirable Attributes of Cheddar Cheese

i) Colour: The colour of Cheddar cheese should be uniform throughout. The most desired colour is very light straw for the natural colour cheese or deep straw or yellow orange for the medium coloured cheese. The cheese should be translucent, that is, it should appear as if one could actually see into the cheese for a short distance.

ii) Finish and Appearance: Cheese with a desirable finish should show flat, parallel ends; square, even edges; an evenly-folded, neat, close fitting bandage or wrapper free from wrinkles; a clean, thin, uniform, close-adhering coating of paraffin, showing no blisters or scales; and freedom from cracks, mold, rot spots, or soiled areas.

iii) Body and Texture: The desired body and texture of cheddar cheese is that which yields a full, solid, close-knit plug possessing smoothness, meatiness, waxiness and silkiness and which is entirely free from gas holes. Such cheese slices well.

iv) Flavour: High quality American Cheddar Cheese has a characteristic cheddar flavour, described as clean, fine, nutty and pleasantly sweet.

ii. Score Card of Cheddar Cheese

The weightage given to different attributes is given in the score card (Table )

Score card for Cheddar Cheese

iii. Scoring Technique of Cheddar Cheese

i) Tempering Cheese: Cheese should be kept in a room at 10-15.5oC for a sufficient of time to secure a uniform temperature throughout all parts of the cheese. A plug taken from warm cheese appears weak bodied while a plug from cold one will appear brittle or corky. Hence, to know the true characteristics of cheese, tempering is must before scoring.

ii) Sampling: It is done with a cheese trier. The edges of a cheese trier are sharper than a butter trier. A trier that cuts a larger plug has an advantage over one of small diameter because it is much easier to detect the degree of openness and the colour defects on the larger plug. Cheese trier is inserted in the middle of the cheese block, rotated at 180o and withdrawn. After drawing a plug of cheese, break the upper 2 cms and put in the hole again from where the plug was drawn.

iii) Sequence of observations

a) Aroma: Immediately after withdrawing the plug of cheese from the block pass it slowly under the nose and inhale strongly to ascertain the aroma. Then examine the remaining plug carefully. Make mental record of all these observations.

b) Colour: Note whether the colour is bright, clear or dull; whether it is uniform, free from mottles or light and dark portions, or it has seams or faded areas surrounding the mechanical holes.

c) Openness: Observe the nature and extent of openness in the cheese. Note whether the holes are regular, angular, rounded, large, or small. Observe also the luster or shine of their inner surfaces and note if they are dry or wet.

d) Body and texture: Hold the ends of the plug by the fore-fingers and the thumbs of the two hands and bend the plug slowly into a semi-circle, observing when it breaks and the nature of the break. Observe carefully whether the plug shows a resistance towards bending and finally breaks suddenly, or bends one half of one third and eventually tears apart slowly.Take one of the broken pieces between the thumb and the fingers and work it up into a uniform mass, observing its resistance to the pressure of the thumb and the fingers. Spread the mass thinly over the palm of the hand with the thumb and observe whether the mass feels smooth, silky, waxy and fine or whether it is sticky, pasty, mealy or crumbly. Reassemble the particles, compress them into a ball, noting meanwhile the response of the cheese to its manipulation. Also note the behaviour of cheese while biting, chewing, mastication and swallowing.

v) Flavour: Place the worked mass (ball) under the nose and observe the aroma.Compare this aroma with that noted when the sample was first removed from the cheese block. Place a small portion of the unworked plug into the mouth, chew it up to the semi-solid state, roll into the mouth, expectorate and note the flavour. Rinse the mouth occasionally with lukewarm saline water (1%), which cleans the mouth satisfactorily to the previous cheese flavours.

iv. Undesirable Attributes of Cheddar Cheese

a) Colour: Some of the commonly found colour defects in cheese are: acid cut (bleached/faded); atypical colour specks (white or black, rust, etc.); mottled and seamy (uneven/wavy). White specks observed in highly ripened cheese are not considered as a defect.

b) Finish and appearance: The judge may look of huffed, uneven size and edges of black, blistered/cracks, light spots, molds, rough and soiled surface defects as these may be correlated with some body and texture and flavor defects in cheese.

c) Body defects: Corky (dry/hard), crumbly, curdy (rubbery), greasy, pasty,spongy, weak (soft) and short.

d) Texture defects: Mealy/grainy (gritty), gassy, sweet curd holes and open.

e) Flavour defects: High acid/sour, bitter, flat, moldy/yeasty, rancid, fruity, whey taint, unclean, tallowy, etc.

Sensory Evaluation of Ice cream

Ice cream is a highly popular frozen dairy product and liked by persons of all age group. Hence, several varieties of ice cream are available in market. Here we are discussing the sensory evaluation of plain/vanilla ice cream.

i. Desirable Attributes of Ice Cream

a) Colour: The colour should be attractive, uniform, pleasing and typical of the flavour present in ice cream. Vanilla ice cream is invariably plain (no colour).The colour defects of ice cream are grey/dull; non-uniform, vivid and unnatural.

b) Package: The package or container should be neat, clean, attractive, full and protective. The common package defects are: soiled, rusty, damaged, shrunken ice cream, ill shaped, etc.

c) Melting quality: Good quality ice cream should show little resistance towards melting when a dish is exposed to room temperature. During melting, the mix should drain away as rapidly as it melts and form a smooth, uniform and homogenous liquid in the dish. Any variation from this behaviour is due to some defect and leads the consumers to be suspicious of its quality. Though the weightage to the melting quality is low (5 points), it is an important attribute on account of its correlation with the body and texture.

d) Body and Texture: The desired body in the ice cream is firm, has resistance, responds rapidly to dipping and melts down at ordinary temperature to a creamy consistency. The desired texture should be fine, smooth, velvety and carries the appearance of creaminess throughout.

e) Flavour: Vanilla ice cream should be pleasantly sweet, having a creamy, delicate bouquet vanilla flavour that cleans up well, leaving only a very pleasant aftertaste.

ii. Score Card of Ice cream

The following score card based on 100 points is used for judging ice cream(Table)

Score Card for Ice Cream

In general practice, the item of bacteria is not done along with judging and the perfect score of 15 is allowed.

iii. Scoring Technique of Ice Cream

i) Tempering of ice cream: Ice cream starts melting immediately after removing from hardening room. Arrangement should, therefore, be made to hold the ice cream at a uniformly low temperature so that its true body & texture characteristics can be perceived. The temperature of judging, however, should not be so low that ice cream is intensely cold and very hard. Also, its evaluation at very low temperature temporary nimbs the taste senses that take long time for recovery to normal condition. Generally, temperature in range of –15oC to –12.2oC is satisfactory for tempering the ice cream for sensory evaluation. To achieve, this ice cream should be taken out from the hardening room and placed in dispensing cabinet several hours prior to judging. In this way, ice cream tempers uniformly.

ii) Sampling: The retail package of ice cream should be served as such for judging.In case of a large lot or bulk, a regular ice cream dipper or scoop is used for drawing the sample. The sample for melt down need not be large but must be uniform in size among the various lots of ice cream being judged. For this, a certain quantity of ice cream is kept in a clean petri-dish and melting qualities should be observed from time to time during scoring. The samples from large lots can be placed in separate plates or all in one large service plate. For taking a sample into the mouth a metal spoon is better than a wooden spoon.

iii) The condition of ice cream starts changing immediately after taking it out of the cold store. Therefore, the judging and scoring of ice cream should be very fast. The judges should record their observations as quickly as possible, particularly about the body and texture characteristics. The observations should be made in the following sequence:

a) Examine the container for cleanliness, fullness, printing defects, etc.

b) Note the colour of ice cream for its intensity and uniformity.

c) While sampling with a dipper/scoop or spoon, note the way the product cuts and the feel of the dipper as its cutting edges pass through the frozen mass. Note particularly whether the ice cream tends to curl up or roll in serrated layers behind the dipper thus indicating excessive gumminess or stickiness. The feel of “dipping”, that is, the resistance offered, the evenness of cutting, the presence of spiny particles and whether the ice cream is heavy and soggy, or light and fluffy, should be carefully observed.

d) Unless the ice cream has been melted and mix warmed, it is so cold that for all practical purposes any odoriferous substances present are practically non-volatile and, therefore, little or no aroma may be detected. During the judging of ice cream, taste reactions (such as sweet, salty, sour or bitter) are perceived earlier than odour. Therefore, place a little sample directly into the mouth for warming and liquefying it. While manipulating the sample between the teeth and the palate, note the taste and odour sensations.The texture characteristics, such as gumminess, grittiness, coarseness, sandiness, etc. should also be felt simultaneously.

e) Note the melting qualities of ice cream. The judges should observe whether the ice cream has retained its form and appropriate size, even though some free liquid may have oozed out, whether the melted liquid is creamy curdled, foamy, watery, and whether the tiny channels are formed as the melt drain flow down the sides of mass.

iv. Undesirable Attributes of Ice Cream

The defects related to colour and package have been given earlier and those of melting behaviour, body & texture and flavour are mentioned as below:

Melting quality: Does not melt or delayed melting, flaky or scummy, foamy or frothy, wheying off or curdled and watery.

Body and texture: Crumbly (brittle/flaky/snowy), gummy (pasty/sticky), shrunken, soggy (heavy/doughy), weak, buttery/greasy, coarse (grainy/ icy/spiny), fluffy and sandy.

Off flavours: Cooked, sour, old ingredients, rancid, salty, inadequate or excessive flavour, oxidized/tallowy, neutralizer, etc.

Sensory Evaluation of Table Butter

i. Desirable Attributes of Table Butter

Butter package should be neat, clean and tidy in appearance and showing good finish. Salt must be uniformly distributed and properly dissolved. A uniform light straw colour throughout is most attractive and liked by the consumers. The body of good quality butter should be firm and showing a waxy, close knit texture. It should have smooth spreadability. A desirable flavour of butter is mild, sweet, clean and pleasant. It is so delicate that consumers always like to eat more.

ii Score Card of Butter

100 points score cards recommended by ADSA and BIS are given in table.

Table  Score card for table butter

 iii. Scoring Technique for Butter

i) Tempering of butter: Butter should be tempered at 10oC for proper evaluation of its flavour and body and texture.

ii) Sampling: The sample of butter should be drawn with the help of a butter trier from a larger block/lot. The trier should not be washed in warm water but should be wiped with a soft tissue or absorbent paper. Washing the trier in warm water results in a melted, greasy surface on the plug of butter taken.This obscures the true condition of the body and texture of butter and makes observation of the colour difficult.

While taking the sample from a large lot, stand squarely in front of the sample and observe the cleanliness and neatness of the package. Notice if this appearance is carried throughout. Remove the wrapper and observe the surface of butter. Get a mental picture of your observations. Then hold the butter trier firmly in the hand, insert it diagonally near the centre of the butter turn it at 180o and withdraw the plug. In case of retail pack (100 g or less), a spatula may be used in place of a trier.

iii) Immediately after withdrawing the plug and before making any colour observations, pass the butter plug slowly under the nose, inhale through the nose very slowly and notice the aroma present. Make a mental record of this aroma.

iv) After observing the aroma, examine the colour for uniformity throughout.

v) Then examine the body and texture by pressing the ball of the thumb against the sides of the plug until it shows a break. Notice the presence or absence of free moisture or beads of water and their clearness and also the nature of  break, that is, whether it is smooth or judged.

vi Break a piece, about three cms, from the plug of butter and put it into the mouth. Chew it until it melts. Then roll the melted butter in the mouth until it comes to body temperature. Meanwhile, feel the presence of “grit” which is un-dissolved salt between the teeth. Also critically feel the manner in which the butter melts. Notice the various sensations of taste and smell. Just before expectorating the melted butter, roll it to the back roof of the mouth to detect the palate flavours.

vii) Expectorate the sample, observe the aftertaste and notice whether or not the flavour persists. All the observations should be recorded in the score card.

iv. Undesirable Attributes

Colour: The main defects of table butter are: lack of uniformity, mottled, streaks,mold discolouration and bleached. Colour problem with butter are not very common and serious.

Body and Texture: This attribute is of paramount importance from consumers’ point of view particularly when butter is applied to bread, hence discussed in more details here.

i) Crumbly or brittle: Such butter lacks cohesiveness and do not stick together but falls apart when broken or some pressure is applied. Crumbly butter has poor spreadability.

ii) Gummy: Such butter sticks to the roof of the mouth and gives a gum like impression.

iii) Leaky: Butter that shows beads or droplets of moisture on the plug and on the back of trier is termed as leaky.

iv) Mealy or grainy: This defect can be detected by pressing the partly melted butter between the tongue and palate. Mealy butter lacks smoothness, hence it is a serious defect.

v) Sticky: Butter sticks on the trier or spoon.

vi) Weak: Melt quickly when exposed to room temperature.

vii) Greasy: Extremely smooth and quick melting when butter is taken into mouth are indication of greasy butter.

viii) Gritty: This defect is related to un-dissolved salt content in butter.

Flavour: The common flavour defect defects of table butter are: high acid,neutralizer, rancid, oxidized, fishy, yeasty, flat, fruity, briny and aged. The methods of simulating these defects have been discussed earlier in Unit 2.

Sensory Evaluation of Ghee

The judging of ghee is probably most ambiguous because of regional preference involved in it. Consumers in different regions of the country prefer different type of flavour in ghee. In north India acidic and mild curdy ghee is preferred, in west definite curdy ghee, in south slightly to moderately cooked ghee and in eastern regions slight curdy ghee is preferred. Therefore, the ghee evaluators should consider these quality aspects and the area for which ghee is marketed. Despite this regional preference, the most desirable attributes of ghee must be remembered and judging should be done accordingly.

i. Desirable Characteristics

A good ghee sample is desired to have a pleasant, nutty and slightly cooked flavour. Ghee flavour is best described as a lack of oiliness or of blandness, sweetly rather than sharply acid. Any suggestion of rancidity is considered objectionable.

The body and texture of ghee plays an important role in its organoleptic evaluation.A good ghee sample should have well-developed granules dispersed fairly, thickly  and uniformly over the entire mass. Breakdown of granulation may result in the greasy body, which lowers the ghee score.A bright yellow colour caused by the presence of carotenoid pigments, is associated with cow ghee and constitutes a desirable criterion in areas where it is preferred.Buffalo ghee is white in colour. Sometimes, it may also have greenish tinge depending on the region and feeding schedule. Ghee from mixed milk has invariably straw yellow colour. The colour of fats always appears deeper to the eyes when melted than when in solid form.

ii. Score Card for Ghee

The main attributes and weightage given to each are shown in table .

Score Card for Ghee (BIS)

iii. Technique of Sensory Evaluation of Ghee

i) Sampling: A representative sample should be drawn from the bulk or large lot in a clean and dry glass bottle. The bottle should have a cap/lid to close.

ii) Tempering of ghee: Whenever possible, the samples should be presented at room temperature. However, the temperature of ghee can be varied depending on the method of evaluation. Many panelists feel that odour, taste and residue can be better detected when ghee is tempered to about 40oC.For texture evaluation ghee should be properly crystallized. The crystallization temperature for cow ghee ranges between 25-30oC and for buffalo ghee between 30-35oC.

iii) Rinsing medium: One per cent luke warm (40oC) saline water (NaCl) for oral rinsing the mouth in between the samples is very effective for fatty foods like ghee.

iv) Procedure: Sensory evaluation should always start with the visual observations of the ghee sample. The colour of the melted samples should be judged first, followed by observation on suspended impurities (residue). Odour is perceived immediately after removing the lid and inhaling the smell. Subsequently a spoonful of ghee is taken in mouth for taste and aroma. The body and texture should be evaluated at the end with the help of a spatula or glass rod.

iv Undesirable Attributes of Ghee

Colour defects: Two possible defects can be observed in ghee. i) too dark/ brown due to high heating temperature during ghee making and ii) bleaching, which is due to excessive oxidation of ghee during storage.

Flavour defects: The common flavour defects in ghee are: acidic, oxidized, rancid, curdy, smoky, burnt and bland or flat (lacking). The off flavours are simulated in small lots of ghee as described below for familiarizing the judges.

i) Acidic ghee: Ripen cream to lactic acidity levels of 0.5, 1.0 and 1.5% and convert directly into ghee or first convert into butter and then ghee.

ii) Curdy ghee: (a) Melt 500 g cooked butter at 80oC and leave it for 30 minutes for pre-stratification and remove about 80% of the serum. Heat remaining part upto 100oC, store at room temperature, or (b) add about 5 g of curd (dahi) into 100 g ghee and leave for 10-12 hrs at 40oC before evaluation.

iii) Smoky ghee: Put an empty glass beaker/container in inverted position on a smoke fire for sometime. Pour about 100 g normal melted ghee into the bottle. Close the bottle and turn it upside and down side three to five time.

iv) Burnt ghee: Raise the temperature of butter/ghee at last stage of ghee making to about 130oC.v) Flat/lacking defects: Either take butter oil for evaluation or prepare ghee from butter under vacuum.

vi) Rancid and oxidized ghee: Methods of developing these defects are given earlier in Unit 2.

Texture Defects: Greasy texture is a common defect in ghee and can be developed by overnight freezing (storage in refrigerator) of freshly prepared ghee followed by thawing. This practice may be repeated several times.