Acceleration of Domiati Cheese ripening by new and promising proteolytic enzymes

ABSTRACT

Domiati cheese were traditionally manufactured with addition of ripening enzymes [Milezyme Apl 440; HT-proteolytic L.175; Brome lain or Papa-in] before rennetting at 0.4 unit/kg milk, then they were pickled in their own whey until full ripening was attained. Utilization of these enzymes caused a marked reduction of ripening period from 90 to 30 days, on the other hand they induced slight reductions in cheese yield. Better organoleptic properties were obtained with all utilized enzymes. The best results were obtained with HT-proteolytic. The lowest score were obtained with Milezyme Apl and Bromelain. Total solids and total nitrogen were lower in all treated cheese correspond to their controls, while cheese acidity, total volatile fatty acids and all ripening indices were higher. This trend was mush more pronounced in cheese treated with HT-proteolytic or Bromelain enzymes. Changes in soluble protein compounds during pickling were followed by using gel filtration applied on Sephadex G-50. The absorbance patterns of all cheese extracts revealed the presence of two peaks. When the ripening period was extended to 30 days, the absorbance patterns did not change for all treatments, but for Bromelain treatment cheese had higher peaks. The electrophoretic patterns of fresh cheese and cheese after ripening showed slight changes in alpha s-and beta-caseins regions. There wer considerable differences with respect to number and area of peaks. The peaks number and shapes were completely different from each other, indicating that these enzymes have different proteolytic actions. Papian seemed to be the strongest proteolytic agent and Milezyme Apl was the second strongest