SHARMA, R. S.LAL, PEETAM2018-05-172018-05-171995http://krishikosh.egranth.ac.in/handle/1/5810046481The survey on status of aflatoxin M1 in milk of individual animals and market milk was carried out in and around Arsaiid town. Out of 223 milk samples analysed, 210 (94.17%) samples were found contaminated with aflatoxin Mi. The aflatoxin Ml content in positive samples ranged from 0.006 to 0.763 jig per 1 with an average of 0.097 ± 0.001 \ig per 1. All the bulk milk sanpies contained aflatoxin Mi bslcw the action level of Food and Drug Administration (0.50 µg/l). Only a few samples of milk from the individual cows exceeded the said limit. The carry-over study of aflatoxin Bi from naturally contaminated rations to milk as aflatoxin M1 was studied, in 10 Indian cows divided into five groups of two cows under each, at aflatoxin Bi intake levels of 12.50 (Control), 25.00 (T1), 52.53 (T2), 77.90 (T3) and 108.45 (T4) µg per kg of ration. The experiment was conducted in three phases, each phase comprised of seven days feeding. Feeding of aflatoxin B1 contaminated rations to the cows reduced feed intake and nilk yield. However, such effects were non significant. The effects were more pronounced at higher levels and long term feeding. The aflatoxin M1 content in milk increased significantly (P < 0.05) as the level of aflatoxin Bi increased in the diet. The average values for aflatoxin M1 content in milk of the cows during the feeding period was 0.04, 0.08, 0.14, 0.36 and 0.65 µg per 1 for Control,, T1, T2, T3 and T4 respectively. Carry-over rate of aflatoxin Bi from feed to milk as aflatoxin Mi increased significantly (P < 0.05) with increased ingestion of aflatoxin Bi by the cows. The per cent conversion of aflatoxin Bi to aflatoxin M1 was 0.32, 0.48, 0.52, 0.60 and 1.03 for Control T1, T2, T3 and T4 respectively. The carry-over rate was high in high yielders and low in the low yielders. Feeding of the rations containing more that 77.90 y.g aflatoxin Bi per kg ration led to secretion of milk containing more than 0.50 ug aflatoxin M1 per 1, thus exceeding the present Food and Drug Administration limit. Chemical composition of milk viz. fat, protein, lactose and SNF was not affected significantly at any level of aflatoxin Bi intake during the experiment. However, some what reduction in fat and protein content was observed. No appreciable reduction in aflatoxin M1 content of naturally contaminated milk was observed during chilling and cold storage (5°C, 24h), batch pasteurization, HTST pasteurization and pre-heating, whereas, 14.5 and 12.21 per cent reduction was observed during boiling and eterilisation respectively. Similarly, 19.38 per cent reduction in the toxin content was observed during khoa making, while fermentation of milk using L. acidophilus, S. thermophilus and S.. laotis plus S. cremoris. during preparation of dahi from the aflatoxin Mi contaminated milk, a reduction of 29.33 to 57.66 per cent toxin was observed and the mixed strain starter culture gave maximum reduction in the toxin content. Evaluation of partitioning behaviour of aflatoxin Mi during preparation of milk products like chakka, paneer, casein, Cheddar cheese and Swiss cheese from the naturally contaminated milk indicated that maximum amount of toxin goes with these products. The enrichment factors for these products were 3.30, 2.57, 4.22, 3.15 and 4.98 times, respectively. On separation of aflatoxin M1 contaminated whole milk into skim milk and cream, the distribution, of the toxin was 69.13 and 30.87 per cent in skim milk and cream respectively.enDAIRY CHEMISTRYA STUDYThesis