Milk testing for quality assurance is an essential component of any milk processing industry. Pricing of milk is mainly based on the percentage level of fat and solids-not-fat (SNF) contents. Different types of lactometers and different formulae are in use for estimating SNF and TS percentage. Gravimetric method is the standard and accurate method for estimation of SNF. However, this method is time consuming and demands a better analytical skill. Therefore, this study was undertaken to develop a suitable formulae and validation of the same. In this study total 339 milk samples (154 individual and pooled milk samples from Deoni and HF cow from Institute Livestock Research Centre, 135 individual and pooled buffalo milk samples from Yelahanka and Chikkaballapura, 25 commercial samples from Experimental dairy Plant and 25 Market samples) were collected and analyzed. Twenty-two lactometers (ISI and Zeal), 25 milk butyrometer, 8 milk pipettes and 9 thermometers were calibrated and used in the study. Correlation between fat and SNF for cow and buffalo milk was established by using SPSS-16.0 version statistical tool. Regression equation for prediction of coefficient (Fat and CLR in the formula) and constant was used. In, ISI, S1, New 27°C, S2 S3 and New 29°C formula 74.07, 75.77, 80.24, 9.33, 0 and 77.33 total percentage of samples are within 0.2% error in SNF for buffalo milk and in case of cow milk 88.98, 73.72, 91.52, 35.48, 5.64 and 91.93 total percentage of samples were within 0.2% error in SNF. Based on these observations 4 formulae were developed, for buffalo milk F1=0.25CLR+0.25Fat+0.38 at 27°C and F2= 0.25CLR+0.25Fat+0.57 at 29°C. For cow milk, F3=0.25CLR+0.25Fat+0.39 at 27°C and F4=0.25CLR+0.25Fat+0.56 at 29°C. Validation result for these formulae shows that 80.24, 77.33, 91.52 and 91.93 percentage of samples were within the acceptable range. The developed formula helps in estimating the SNF and TS contents in milk nearer to the gravimetric value.

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