Castor protein isolate (CPI) was prepared by aqueous solubilization of defatted castor kernel meal under alkaline conditions (pH 12.0), with precipitation at the isoelectric point (pH 5.0) followed by heat treatment. Five experimental diets were prepared by substituting soybean protein isolate (SPI) at 0%, 25%, 50%, 75%, and 100% with CPI based on protein equivalent basis. The diets were assigned as control, PI₂₅, PI₅₀, PI_75, and PI₁₀₀, respectively. A 60-day feeding trial was conducted following a completely randomized design. Results revealed significant improvement in growth rates, feed conversion, and protein retention in Labeo rohita fingerlings (P < 0.05) at 124.50 g CPI kg⁻¹ diet (PI₇₅). However, these were similar between control and PI₁₀₀ (P > 0.05). Dietary CPI did not alter the hepatosomatic index, viscerosomatic index, survival, carcass composition (except crude protein), and digestive enzymes (P > 0.05). The metabolic enzymatic profile of rohu fingerlings was significantly affected due to dietary treatments (P < 0.05) but oxidative stress enzymes were not affected by feeding of CPI. The activity of the aminotransferases, lactate dehydrogenase, and malate dehydrogenase did not differ (P > 0.05) between control and PI₁₀₀. The preparation of protein isolate is therefore a way forward for the effective valorization of toxic castor meal and could be used at 164.0 g kg⁻¹ inclusion (complete substitution of soybean protein isolate) in the diet of L. rohita. © 2021 Society of Industrial Chemistry and John Wiley & Sons Ltd.

中文翻译：

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有效利用蓖麻油提取工业的农业废弃物作为可持续鱼类生产的原料

蓖麻分离蛋白 (CPI) 是通过在碱性条件 (pH 12.0) 下将脱脂蓖麻仁粉溶于水，在等电点 (pH 5.0) 处沉淀，然后进行热处理来制备的。通过用基于蛋白质当量的 CPI 替代 0%、25%、50%、75% 和 100% 的大豆分离蛋白 (SPI) 来制备五种实验日粮。饮食被分别指定为对照、PI ₂₅、PI ₅₀、PI ₇₅和PI ₁₀₀。按照完全随机设计进行了一项为期 60 天的喂养试验。结果显示， 在 124.50 g CPI kg 下，Labeo rohita鱼种的生长速度、饲料转化率和蛋白质保留率显着提高( P < 0.05)^-1饮食（PI ₇₅）。然而，这些在对照和 PI ₁₀₀之间是相似的（P  > 0.05）。膳食CPI不改变肝体指数、内脏指数、存活率、胴体成分（粗蛋白除外）和消化酶（P  > 0.05）。由于日粮处理，罗胡鱼种的代谢酶谱受到显着影响（P  < 0.05），但氧化应激酶不受 CPI 饲喂的影响。转氨酶、乳酸脱氢酶和苹果酸脱氢酶的活性 在对照和 PI ₁₀₀之间没有差异 ( P > 0.05). 因此，分离蛋白的制备是有效利用有毒蓖麻粕的一种方法，可以在L. rohita的饮食中以 164.0 g kg ^{-1 的}含量（完全替代大豆分离蛋白）使用。© 2021 工业化学学会和 John Wiley & Sons Ltd.