[Effect of the addition of tropical fruits--pineapple (Ananas comosus) and papaya (Carica papaya)--on the production of biological silage from fish].

Microbial Fish Silage was produced from under-utilized fish mixed with juice and waste fruits (pineapple and papaya) at 35 degrees C. Six different products were elaborated as following: A: fish muscle with pineapple juice; B: fish muscle with fruit wastes; C: gutted fish with pineapple juice; D: gutted fish with fruit wastes; E: whole fish with pineapple juice; F: whole fish with fruit wastes. Process development was evaluated by measuring: pH, acidity, non-protein nitrogen, consistency and exudate liquid. Results indicated a slow decrease in pH value and production of acidity during 20 storage days. The addition of fruits to silage did not have any effect on these values. Silage liquefaction or hydrolysis was related to the following parameters: consistency, non-protein nitrogen and exudate liquid. The addition of fruits was related to silage liquefaction or hydrolysis, and it was measured by the consistency. Exudate liquid and non-protein nitrogen increased during storage time. However silage made from whole fish showed highest values in those parameters than other processing conditions. This results suggested that hydrolysis involve first enzymes from guts and second enzymes from muscle and head. Pineapple juice did not contribute to hydrolysis process. Mainly sensory changes in the silage occurs during first 24 hours and they were related to chemical changes. Proximal analysis did not change during silage process and microbial counts indicated the freshness of raw material used i this study.