Crambe (Crambe abyssinica) and sunflower (Helianthus annuus) protein concentrates: production methods and nutritional properties for use in fish feed

ABSTRACT The purpose of this study was to develop and improve protein concentration techniques for two industrial by-products with the potential for use in fish feed. In particular, we chemically characterized crambe meal and sunflower meal and their protein concentrates. Three different protein concentration methods were tested: isoelectric pH (pHi), acid pH and alkaline pH. For crambe and sunflower meals extraction using the pHi method was most efficient in terms of protein yield and crude protein content in the concentrates; this method also increased lysine and methionine content in the concentrates. The water holding capacity of the sunflower protein concentrate was greater than that of the crambe protein concentrate. The crambe protein concentrate had a foam-formation capacity of 15%, which stabilized at 6% after 90 minutes. The protein concentration method also reduced total phenolic content by approximately 50% in the concentrates compared with the meals. Therefore, we conclude that protein concentration using the pHi method is the most efficient technique for crambe and sunflower meals, and the use of this technique can decrease total phenolic compounds while improving meal quality for fish feeding.

摘要 本研究旨在开发并优化两种可用于鱼用饲料的工业副产物的蛋白质浓缩技术。具体而言，本研究对海甘蓝粕（crambe meal）与向日葵粕（sunflower meal）及其对应的蛋白质浓缩物开展了化学表征。本研究共测试了三种蛋白质浓缩方法：等电点pH法（isoelectric pH，pHi）、酸性pH法与碱性pH法。针对海甘蓝粕与向日葵粕，采用等电点pH法进行提取时，所得浓缩物的蛋白质得率与粗蛋白含量均为最优；该方法还可提升浓缩物中赖氨酸与蛋氨酸的含量。向日葵蛋白浓缩物的持水力高于海甘蓝蛋白浓缩物。海甘蓝蛋白浓缩物的泡沫形成能力为15%，并在90分钟后稳定维持在6%。相较于原粕，经蛋白质浓缩工艺处理后的浓缩物总酚类物质含量可降低约50%。综上，本研究认为，采用等电点pH法进行蛋白质浓缩是处理海甘蓝粕与向日葵粕的高效工艺，该工艺可降低总酚类化合物含量，同时提升适用于鱼用饲料的粕类原料品质。