Technological Characterization of Experimental Natural Rennets Pastes
2008
Ferrandini, E. | López, M.B. | Castillo, M. | De Renobales, M. | Virto, M. | Hernández, I. | Price, A.V. | Laencina, J.
Four types of lamb rennet pastes were characterized according to the sort of abomasa and the treatment it received: full fresh abomasa (FFA), full dried abomasa (FDA), empty dried abomasa (EDA), and empty frozen abomasa (EFA). These rennet pastes were studied by means of different technological parameters (milk clotting time, chymosin content, lipase activity, and aptitude against milk coagulation).The highest level of clotting activity (391.20 IMCU/g) corresponded to the rennet EDA whereas the lowest (172.87IMCU/g) was found in EFA. The chymosin content of the pastes classified them as rennet extracts, the highest chymosin level (80.46%) being found in the paste from FDA and the lowest (71.10%) being obtained from FFA.The highest level of lipase activity (10.57 U/g) was found in EDA whereas the lowest (1.46 U/g) was in paste FDA. Milk coagulation aptitude was studied through the use of a near infra-red radiation dispersion sensor. The highest value of Rmax (0.049 min-1) found in the rennet paste made with EDA indicated a higher level of casein hydrolysis and greater aggregation speed. For the same rennet at tmax value of 6.1 min was established lower than for other rennet preparations which reflected the fact that this rennet hydrolyzed 80% of the K-casein in a shorter period of time. It is concluded that the best natural lamb rennet paste of this work was FFA due to it combines appropriate proteolytic and lipolytic activities although it does not reach the maximum values for each technological parameters analyzed.
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