Effective valorization of agro‐waste of castor oil extraction industry as feedstock for sustainable fish production

Abstract

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, PI75, 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.

Effect of mercerization on the properties and biodegradation behavior of LDPE and LDPE/PHB hybrid composites filled with castor bean cake

“…The main use of the co-product generated after the oil extraction is as a fertiliser [7]. There are some published studies on the addition of value to the castor cake resulting from the production of biodiesel [2-5, 7-11].…”

Insect rearing on biowaste represents a competitive advantage for fish farming

“…However, the increasing cost of growing soybeans (agrochemicals and fuel in particular); soaring energy prices (even more than quadruple in some EU Member states); absence of taurine; low levels of methionine and lysine; the presence of anti‐nutritional factors (such as trypsin inhibitor) are the main drivers of searching for alternative protein sources. Numerous efforts have been made to reduce forage fishery by producing artificial fish feed from terrestrial plants 16 . With regard to the long‐separated evolution of terrestrial plants and fish, feed made from terrestrial plants typically shows questionable availability of nutrients, unbalanced amino acid profiles, antinutritional side effects (mycotoxins, polyphenols, etc.)…”

“…Numerous efforts have been made to reduce forage fishery by producing artificial fish feed from terrestrial plants. 16 With regard to the long-separated evolution of terrestrial plants and fish, feed made from terrestrial plants typically shows questionable availability of nutrients, unbalanced amino acid profiles, antinutritional side effects (mycotoxins, polyphenols, etc.) and low levels of essential fatty acids (docosahexaenoic and eicosapentaenoic acids in particular).…”