Buffalo milk: influence of the first stage of lactation on plasmin system and free fatty acid of buffalo milk

Sammanfattning: Buffalo milk is the second most produced milk after conductive bovine and mozza-rella is one of the most important products of buffalo milk. The milk contains high-er levels of nutrients, mainly protein and fat, which gives buffalo milk good physi-cal and chemical properties. Milk from early lactation however, is difficult to use in mozzarella manufacturing. This study analyse the impact of plasmin (PL), plasmin-ogen (PG) and free fatty acids (FFA) in buffalo milk from the first weeks of early lactation, since they are important factors in milk and can influence the quality in cheese. The aim was to investigate if these factors can be involved in the problem-atic of mozzarella manufacturing. Both individual buffalo milk and bulk milk were analysed. The milk samples, collected from six buffalos twice a week during the first 6-7 weeks of lactation, were analysed in duplicates. PL and PG activity were deter-mined by measuring the cleavage of chromogenic substrate and the formation of paranitroanilide (pNA) at 405 nm. The present results in the study should only be taken as an indication, since no statistical analyse has been performed. The average PL activity from individual buffalos indicates an increase in the second week of lactation. This activity dropped after four weeks. The average PG activity from the individual buffalos showed a decrease from week one to week three. After this period was the activity stabilized. Bulk milk showed similar results, where the ac-tivity decrease between week one and week eleven for PL and PG. FFA were de-termined through an extraction-titration method. The average FFA levels from the individuals increased from 0.12 mmol/100 g fat to 0.23 mmol/100 g fat between first to the sixth week of lactation. The bulk milk showed similar results. The fat concentration was around 7% in both the individual and bulk milk samples. The quality of the first milk unsuitable for the mozzarella production is probably not influence by FFA and protolytic enzymes such as PL and PG.