Studies on quality changes in shrimp feeds exposed to gamma, e-beam and X-ray irradiation

摘要

The objective of this study was to compare the effects of gamma, electron beam and X-ray irradiation on quality changes in shrimp feeds so that pathogen-free feeds could be produced using a safe irradiation source. Chemical quality changes to proteins in feeds exposed to three types of radiation were evaluated by determining pepsin digestibility, protein solubility in dilute alkali, and available lysine. In addition to protein quality tests, total volatile nitrogen, ammoniacal nitrogen and thiobarbituric acid reactive substances were also measured in gamma irradiated fish meal. Microbial sterility was achieved in shrimp feeds at all levels of gamma and electron beam (15, 30 and 45 kGy) and X-ray (8.5 kGy) irradiation. The gamma irradiated feeds were also used in shrimp feeding trials to assess their biological performance. Sterilization of shrimp feeds by gamma radiation at 15, 30 and 45 kGy levels did not affect percent survival, weight gain or feed conversion ratio. However sterilization by autoclaving did significantly affect all aspects of biological performance. This study leads one to interpret that sterilization of shrimp feeds by gamma irradiation induced far less chemical quality changes than sterilization by autoclaving and that the changes induced by autoclaving had a greater deleterious effect than gamma radiation on shrimp biological performance. E-beam and X-ray irradiation offer benefits similar to gamrna irradiation and are safer and their use in future studies on feeds and feedingredients deserve attention.