JUDGING OF DAIRY PRODUCTS

Module 6. Fermented milk and milk products

Lesson 16

DESIRABLE AND UNDESIRABLE CHARACTERISTICS OF FERMENTED MILKS, SENSORY EVALUATION OF CHAKKA, SHRIKHAND, LASSI AND OTHER FERMENTED DRINKS

16.1 Introduction

Shrikhand is a semi-solid, sweetish-sour, wholesome, indigenous fermented milk product of western India. It is prepared by : (a) curdling of milk and/or skim milk using lactic starter culture to obtain dahi, (b) draining most of the whey from dahi to get chakka; either by suspending it in muslin cloth bag or by mechanical means such as basket centrifuge or continuous curd separator, (c) addition of sugar flavouring and/or cream (80% fat) in case of skim milk chhaka, (d) kneading together manually or in a planetary mixer to obtain homogeneous consistency, (e) mixing of other additives such as fruits, nuts, colour etc. if desired and (f) cooling it to a low temperature before (less than 10 C) it is ready for consumption.

On the basis of organoleptic evaluation,most desirable Shrikhand should have 5-6% milk fat, 38-40% moisture, 40-45% sugar and 1.0-1.1% lactic acidity. The flavour of Shrikhand is greatly influenced by the level of the developed acidity at which curd is converted to chhaka and chhaka in its turn to shrikhand. The typical consistency of shrikhand is influenced to a great extent by the moisture, fat and sugar levels in the product. The last two factors also have an influence on flavour.

16.2 Desirable Sensory Quality of Shrikhand

16.2.1 Appearance of the container

Desirably in good condition i. e. it should be properly sealed with surface showing no soiling.

16.2.2 Product appearance & colour

It shall be free from signs of free fat or syrup separation or both and uneven colour distribution.

16.2.3 Flavour

It shall have a clean, pleasant,sweetish-sour flavour, representing blend of added sugar and of fermented milk solids. It should be free from objectionable flavours and odours.

16.2.4 Texture and consistency

It shall have a typical semi-solid,uniform consistency showing a characteristic firmness and pliability and shall show smooth texture without any sign of graininess.

16.2.5 Temperature and acidity of the product

Desirably the product may be consumed or evaluated at a low temperature of about 10 C. It shall have optimum acidity around 1.0 -1.1% expressed as lactic acid.

16.3 Sensory requirements for Chakka

16.3.1 Appearance and Colour

Chakka when properly made should be free from any signs of fat or water seepage or both and moldiness. It shall be white to pale yellow and no extraneous colour shall be added.

16.3.2 Odour and flavour

Chakka shall have pleasant yoghurt (dahi) like flavour. I shall be free from objectionable flavours and odours.

16.3.3 Texture and consistency

Chakka shall be of good texture and consistency. It shall be free from coarseness. It should be manufactured and packed in equipment and premises maintained under hygienic conditions. It shall also be stored and distributed under hygienic conditions.

16.4 How to evaluate the product?

Preferably in a well-furnished sensory laboratory trained judges judge shrikhand for its quality. Usually panel of 6-8 persons is selected on the basis of duo-trio test. For preference testing (involving actual consumers) the panelists may be asked to judge the intensities or to specify in some way their preferences using the nine-point hedonic scale.

For discriminating testing, highly trained evaluators are provided with score card indicting the maximum and minimum score for each of the sensory attributes of the product, along with the suggested score deductions for defective samples is expected to help the judge in proper organoleptic evaluation. As far as possible not more than six samples should be served at a time for the evaluation.

16.4.1 Procedure

Place the shrikhand container on a table or a platform and examine it for the appearance.

Cut open and inhale its aroma, note the surface of the content and the temperature and also evaluate its colour and appearance.

Pick-up a spoonful of the product and allow it to drop back noting its consistency, body, firmness and falling behavior of the product.

Take the product into the mouth and noteit's tactual and taste sensation. Judge the product for its smoothness and uniformity by swallowing the secondary taste reaction, the taste beyond sweetand sour, will have been experienced, expectorate the sample and register if an after taste persists.

In order that the sensory panelists are made aware of the desirable and undesirable characteristics of shrikhand, they heed to be exposed to various types of shrikhand and trained to identity good quality product.

Training is very vital in the successful adoption of sensory evaluation as an instrument of quality control. For accurate judging and grading it is necessary that the judge has the awareness of different defects and their intensities. This would enable him to identify and discriminate against a defective product.

Some of the common defects observed in shrikhand can be simulated as given below:

Table 16.1 Common defects observed in shrikhand

Table 16.2 Sensory evaluation card for shrikhand

Table 16.3 Suggested score deductions for shrikhand

For computing the final score - total for all attributes, the products may be assigned a suitable grade as shown below:

Table 16.4 Score card for shrikhand