Thumbnail Image

Theses

Browse

19991
Reset filters
Subject: Veterinary Public Health × Author: KAU × Author: Reenu, John × End date: 1999 × Start date: 1996 ×
Reset filters

Search Results

Now showing 1 - 1 of 1
  • Thumbnail Image
    ThesisItemOpen Access
    Bacterial profile of pasteurized milk and its public health significance
    (Department of Veterinary Public Health,College of Veterinary and Animal Sciences, Mannuthy, 1999) Reenu, John; KAU; Nanu, E
    A total of 100 pasteurized milk samples consisting of 20 each from five different brands namely A, B, C, D and E were subjected to different bacterial counts to evaluate the bacterial quality of milk samples available in and around Trichur. An attempt was also made to isolate and identify E. coli and to test the sensitivity of these isolates to six antibacterial agents. Brand D had the lowest total viable count (4.47 ± 4.23 10glO cfu/ml) and the highest was in C (7.65 ± 7.22 10glO cfu/ml)., Analysis of the data revealed a highly significant (p<0.01) difference in the count of the samples between brands except between A and E and B and C. The psychrotrophic count was lowest in samples belonging to brand D (3.57±3.23 10glO cfulml and highest in C (6.95± 6.73 10glO cfulml). Highly significant (p<0.01) difference in the count was noticed between samples belonging to all brands, except Band C. (. The lowest coliform count was observed in brand D (1.24 ± 1.0410glO cfulml) and highest in C (5.38 ± 5.13 10glO cfulml). Highly significant (p<0.01) difference was observed between the counts of samples belonging to different brands except between A and E and B and C. Samples of brand D were found to be free from E. coli. The highest E. coli count was found in brand B (3.39 ± 2.74 10glO cfu/ml) and lowest in C (0.87 ± 0.87 10glO cfulml). Highly significant (p observed between brands except between D and C, e and E and E and A. Of the hundred pasteurized milk samples examined, 82% did not meet the total viable count criteria prescribed by BIS (1992). Only 75% samples from brand D and 15% from E met the criteria. Eighty five per cent samples from brand D met the coliform count limit prescribed for pasteurized milk by BIS (1992). The per cent of samples belonging to brands E and A that met the above criteria was 35 and 25, respectively. Only five per cent samples from brands Band e met this en teria. Sixty four isolates were identified as E. coli . Antibiogram of these isolates . showed that 96.9% were sensitive to gentamicin and norfloxacin. The per cent of isolates that showed sensitivity to tetracycline, cotrimazine, cephotaxime and nitrofurantoin were 92.2, 67.2, 56.3 and 54.7 respectively. To study the effect of pasteurization on the bacterial quality of raw milk and to find out the shelf life under refrigerated conditions, one raw milk sample and 12 sachets of pasteurized milk were collected from a batch on each day from the dairy plant. This was repeated at varied interval for ten days. The total viable, psychrotrophic, coliform and E. coli counts of raw milk samples were 6.74 ± 6.17, 6.67 ± 6.13, 3.41 ± 2.93 and 2.42 ± 2.27 10glO cfu/ml. No E. coli was found in freshly pasteurized milk samples. Total viable count of these samples was 5.05 ± 4.38 10glO cfu/rnl. The psychrotrophic and coliform counts were 4.85 ± 4.26 10glO cfu/ml and 2.36 ± 2.01 10glO cfu/ml respectively. Pasteurization reduced total viable and psychrotrophic count by 2 log and the coliform count by one. In the refrigerated sample the initial bacterial growth rate was very slow, and there was no significant increase in total viable and psychrotrophic counts for up to seven days of storage. Thereafter the increase in these counts were significantly different from that of initial count. An increase in coliform count was observed but it did not differ significantly from that of freshly pasteurized milk. Off odour was detected for the first time on the io" day and it was noticed in 30% of the samples and by 11 th day 100% samples showed off odour. Only on 1 ih ( days clot on boiling was noticed for the first time, that too only in one sample from a '. batch. As far as pasteurized milk is concerned, clot on boiling is not a suitable test for assessing the quality of pasteurized milk. The storage life was found to be at least . nine days for pasteurized milk kept in a refrigerator. Inspite of the fact that bacterial counts were well above the suggested norms by BIS, the milk had a keeping quality of nine days. Hence there is an indication for modification of the existing norms.