Insects in Atlantic salmon (Salmo salar) diets – comparison between full-fat, defatted, and de-chitinised meals, and oil and exoskeleton fractions

The present study investigated the effect of meals and fractions of black soldier fly larvae (BSFL; Hermetia illucens) in diets for Atlantic salmon (Salmo salar) on the physical quality of feed pellets, nutrient utilisation, and growth performance. Six extruded diets were produced: control diet (CD); full-fat BSFL meal diet (IM); defatted BSFL meal diet (DFIM); de-chitinised BSFL meal diet (DCIM); BSFL oil diet (IO) and BSFL exoskeleton diet (EX). The full-fat, defatted and de-chitinised meals replaced 15% of protein in the control diet. An eight-week study was conducted using salmon with average 28 g initial weight. The full-fat and de-chitinised meals in the diets numerically reduced pellet hardness, expansion, and water stability. The full-fat and de-chitinised meals improved growth rate of salmon, whilst defatted meal, oil and exoskeleton supported similar growth performance as the control. Feed intake and growth rate of fish fed full-fat meal diet were higher than those fed the other insect diets, but defatted meal gave a better feed conversion ratio than full-fat meal. Defatted meal, de-chitinised meal and exoskeleton reduced protein digestibility in fish, however; defatted meal increased the digested protein retention. In conclusion, use of full-fat BSFL meal improved feed intake and growth rate of salmon when replacing 15% of dietary protein. The present results suggest that less processed fullfat form of BSFL is more optimal in diets for salmon and further processing to remove lipid or exoskeleton fractions would only lead to an additional cost.

Valorization of Heat-Treated Brewers' Spent Grain Through the Identification of Bioactive Phenolics by UPLC-PDA and Evaluation of Their Antioxidant Activities

Thermal processing not only disrupts cell membranes and cell walls, but also cleaves covalent bonds releasing low molecular phenolic. This study examined the impact of various heat treatments (100, 140, and 160°C) on the composition of phenolic acids and antioxidant activities in extracts obtained from defatted brewers spent grain (BSG) meal. Heating BSG at 160°C resulted in a 2-fold increase in total phenolic content [TPC, 172.98 ± 7.3 mg Gallic acid equivalent (GAE)/100 g defatted meal] and total flavonoid content [TFC, 16.15 ± 2.22 catechin equivalents (CE)/100 g defatted meal] compared to the untreated BSG extracts. The antioxidant activities of treated BSG extracts, determined by radical scavenging and ferric reducing antioxidant power (FRAP) were significantly (p < 0.5) higher than the corresponding untreated BSG extracts. Eleven phenolic acids were identified and quantified in BSG extracts by Ultra Performance Liquid Chromatography with Photodiode Array (UPLC-PDA). The amounts varied significantly (p < 0.05) depending on the degree of toasting BSG was subjected to. Chlorogenic acid, an ester of caffeic and quinic acid was the predominant phenolic acid present in all fractions. Significant (p < 0.05) increases in TPC, TFC, individual phenolic acids and antioxidant activity were observed in BSG extracts exposed to increasing oven temperatures. These results confirm the ability of heat processing to release bioactive phenolic from their bound forms thereby enhancing the phenolic acids and the digestibility of BSG meal in the intestinal tract.

Analysis of Antinutritional Components of Oil and Meal in Different Provenances of Jatropha curcas from India

The present work describes the estimation of antinutritional components such as phorbol esters in oil, trypsin inhibitors and phytates in the defatted meal of Jatropha curcas seeds collected from different geographical locations of India. The phorbol ester, trypsin inhibitor and phytate content in the defatted seed meal were extracted and estimated. Phorbol esters, the major toxic components vary from 0.9 to 3.2 mg/g in oil and 0.2 to 1.6 mg/g in the defatted meal. Similarly, a wide variation was observed for trypsin inhibitor (5.72-23.09 mg/g of defatted seed meal) and phytate (7.9-10.1 %) content in the meal of seeds collected from different geographical locations of India. The study also examined the variation of concentration of antinutritional components with the effect of meteorological parameters mainly climatological temperature and rainfall over stations. The phorbol esters content in the seed and meal are increased/decreased from region to region with the subsequent variation of temperature and rainfall. A similar trend is also observed in variation of trypsin inhibitors in seed cake whereas the variation of phytate concentration is not correlated with rainfall and temperature.