PHYSICO-CHEMICAL AND MICROBIOLOGICAL EVALUATION OF RAW MILK FOR IT’S SUITABILITY FOR FURTHER INDUSTRIAL PROCESSING

Abstract

The study was aimed to evaluate the suitability of raw milk for processing based on Physico-Chemical, indirect and direct microbiological examination. Raw milk samples (mixed) were collected from different collection centers of milk pocket zones of Bangladesh. All milk samples were subjected to perform physico-chemical, indirect and direct microbiological examination like color, flavor, taste, acidity, pH, fat%, SNF%, Total solids%, Water%, Protein%, Methylene Blue Reduction Test, Total Bacterial Count, Coliform Bacterial Count etc . The color of the test samples was found normal (whitish) and the flavor of the milk samples was also found normal. The taste of the milk samples was slightly sweet (100%) and the average specific gravity of the milk samples was found 1.03±0.001. The average fat% was found 3.98%. The highest fat% was found 4.19% in January and the lowest was 3.78% in April. The average SNF% was found 7.4%. The highest SNF% was 7.48% in November and the lowest was 7.32% in April. The average total solids and water contents were found 11.38% and 88.62%. The highest total solid was found 11.62% in the month of December and the lowest was 11.14% in April. The highest water content was found 88.86% in April and the lowest was 88.38% in December. The average Protein% was found 3.39%. The highest protein was found 3.49% in December and the lowest protein was found 3.31 in April. Considering seasons, the highest fat% was found 4.07% in Autumn and the lowest was found 3.85% in Summer. The highest SNF% was found 7.43% in Rainy Season and the lowest was found 7.37% in Winter season. The highest total solid was found 11.48% in Autumn and the lowest was found 11.23% in Summer. The highest protein was found 4.06% in Autumn and the lowest was found 3.33% in Summer. The highest Water% was found 88.77% in Summer and the lowest was found 88.53% in the Autumn. The average acidity and pH were found 0.137% (0.137 ± .004) and 6.85 (6.85 ± .004) which are within the acceptable range. On the other hand, the average total viable bacteria and coliform count were found 4.37 × 106 (Cfu/ml) (4.37 × 106 ± 1015744) and 3.88 ×105 (3.88 ×105 ± 209820) (Cfu/ml). However, the highest acidity and lowest pH were found 0.143% (0.143 ± .005) and 6.83 (6.83 ± .019) in the month of May and the lowest acidity and highest pH were found 0.135% (0.135± .012) and 6.85(6.85± .005) in December. While the total viable count and coliform count were 3.99 × 106 (3.99 × 106 ± 429885) (Cfu/ml), 5.7 ×105 (5.7 ×105 ± 312029) (Cfu/ml) respectively. In December the total viable count and coliform count were 4.8 × 106 (4.8 × 106 ± 1529546) (Cfu/ml), 2.72 ×105 (2.72 ×105 ± 103252) (Cfu/ml) respectively. Considering the season, the highest acidity and the lowest pH were found 0.139% and 6.83 in the Summer. And in the Summer the total viable count was found 3.78 × 106 (3.78 × 106 ± 8355483) (Cfu/ml) and the coliform count was found 4.1 ×105 (4.1 ×105 ± 256969) (Cfu/ml). And the lowest acidity and the highest pH were found 0.136% and 6.84 in Autumn. Accordingly, the total viable count was found 5.64 × 106 (5.64 × 106 ± 2004106) (Cfu/ml) and the coliform count was found (3.88 ×105 ± 209820) (Cfu/ml). The average reduction time of MBR test, total viable count and total coliform count were found 56.75 ± 3.52 (Minutes), 4.37 × 106 ± 1015744 (Cfu/ml) and 3.88 ×105 ± 209820 (Cfu/ml), respectively. The highest reduction time of MBR test was found 67.25 ± 6.23 minutes in July in comparison with the total bacterial count was found 4.57×106± 759909(Cfu/ml) along with the coliform count was found 4.88 ×105 ± 481759 (Cfu/ml) and the lowest reduction time was found 49 ± 2.28 minutes in October in comparison with the total viable count of 6.7×106±1925381 (Cfu/ml) and the coliform count was found 3.1×105 ± 189675 (Cfu/ml). Considering the season the highest reduction time of MBR test was found 57.644 ± 3.516 minutes, the total bacterial count was found 3.88×106 ± 1336450 (Cfu/ml) and the coliform bacterial count was found 2.75×105±191612 (Cfu/ml) in the Winter season. The lowest reduction time was found 55.77±2.701 minutes, the total bacterial count was found 3.78×106± 8355483 (Cfu/ml) and the coliform bacterial count was found 4.11×105± 256969 (Cfu/ml) in the Summer season.