Bioprocessing of jojoba oil refinery waste into a valuable protein isolate: a protein source for sustainable aquafeed development

Abstract The amounts of protein in the produced jojoba protein isolates (JPI) from defatted jojoba meal (DJM) varied from 489.06 to 741.79 g kg −1 , with dry matter and protein recoveries ranging from 88.04 to 296.62 and from 132.97 to 677.52 g kg −1 , respectively, across 16 pH conditions. The pH level of 12.0/5.0 showed significantly higher protein content and recoveries ( P < 0.001) and was selected for mass‐scale production. The amino acid composition and nutritional indices of JPI were superior to those of DJM and comparable with the values for soy protein isolate and whole egg protein. Additionally, JPI contained 56.50% less simmondsin content compared with DJM and exhibited notably low anti‐nutritional factors, including tannins, phytates, and hydrogen cyanide. A 60 day feeding experiment was conducted to assess the nutritional quality of JPI in the diet of rohu, Labeo rohita fingerlings, where JPI was substituted for soy protein isolate at 0, 25, 50, 75, and 100% on a protein equivalency basis, denoted as control, JPI25, JPI50, JPI75, and JPI100, respectively. Results indicated that JPI inclusion significantly affected growth performance and nutrient utilization ( P < 0.05), with the JPI50 group exhibiting the best growth performance. Growth performance in the JPI25 and JPI50 groups did not differ significantly from the control ( P > 0.05). Furthermore, JPI‐fed groups demonstrated significantly higher digestive enzyme activities compared with the control ( P < 0.05). Overall, this study established that JPI is a valuable protein‐rich alternative in fish feed, with a recommended replacement of 75% soybean protein isolate with jojoba protein isolate yielding optimal growth performance and digestive efficiency in rohu fingerlings.