辐照可可粉的杀菌效果及对可可粉主要营养成分的影响

Decontaminative Effects of Irradiation on Microorganism and Nutritional Components of Cocoa Powder

为减少有害微生物对可可粉的污染，探讨了^60Co-γ射线辐照可可粉的杀菌效果及对可可粉蛋白质、可可脂、总糖、粗纤维、氨基酸含量、可可碱、咖啡因等营养活性成分和感官品质的影响。结果表明：剂量为3kGy时可可粉中微生物指标基本符合国标要求，剂量为5kGy时微生物指标均达到食品卫生国家标准；剂量为3—9kGy辐照时对可可粉中蛋白质、可可脂、总糖及粗纤维含量影响不明显；与对照相比，3—7kGy辐照时可可粉中的氨基酸总量虽然较低，但差异不显著；可可碱的含量有所增加，但差异也不显著；咖啡因含量随辐照剂量的增加有明显的上升趋势，两者呈显著正相关关系（r=0．9578）；与对照相比，3～5kGy辐照后，可可粉粉色、汤色、气味无明显改变。综合试验结果，确定可可粉辐照杀菌的适宜剂量为3～5kGy。

To reduce the contamination of cocoa powder by microbes the decontaminative effects of ^60Co-γ ray irradiation on cocoa powder and its main nutritional components, such as protein, cocoa butter, total sugar, crude fiber, amino acid, theobromine, caffeine as well as sensory qualities were investigated. The irradiation treatment was very effective on eliminating microorganism in cocoa powder, and the components of microorganisms varied with irradiation dose. The number of microorganisms in cocoa powder met the basic requirements of national standard when irradiation dose was 3 kGy and was full controlled within the national food standard when irradiation dose was 5 kGy. As dose ranged from 3 kGy to 9 kGy, the contents of main nutritional components changed little, and that of most amino acids were influenced but not obviously. The contents of theobromine and caffeine in irradiated cocoa powder was increased significantly （ r = 0. 957 8 ） as irradiation doses were raised. The powder color, liquor color, flavor and aroma of the cocoa powder decoction changed little after being irradiated at the dosage lower than 5 kGy. The results indicated that the optimal doses for cocoa powder irradiation was in the range of 3 - 5 kGy for the sake of various quality factors.