Replacement of soybean oil by Hermetia illucens larvae fat in broiler diets alters the breast muscle lipidome and reduces lipid oxidation of the breast muscle during heat-processing.

Replacement of soybean oil by insect fat from Hermetia illucens (HI) has been reported to increase the proportions of saturated fatty acids (SFA) and decrease those of polyunsaturated fatty acids (PUFA) in total lipids of breast and thigh meat in broilers. Since the susceptibility of meat to oxidation is strongly dependent on its PUFA content, the present study hypothesised that replacement of soybean oil by HI larvae fat in broiler diets reduces the formation of lipid oxidation products, including oxidation products of cholesterol and phytosterols, in heat-processed breast muscle of broilers. To test this hypothesis, 100 male, 1-day-old Cobb 500 broilers were assigned to three groups and fed three different nutrient adequate diets, which varied only in the fat source (group HI-0: 0% HI larvae fat and 5% soybean oil; group HI-2.5: 2.5% HI larvae fat and 2.5% soybean oil; group HI-5.0: 5.0% HI larvae fat and 0% soybean oil), in a three-phase feeding system for 35 days. While the growth performance of the broilers was not different, the absolute and relative breast muscle weights were higher in group HI-5.0 than in group HI-0 (p < 0.05). The proportions of C12:0, C14:0, C14:1, C16:0, C16:1 and total SFA were higher and those of C18:1, C18:2 n-6, C18:3 n-3 and total PUFA were lower in breast muscle total lipids of group HI-5.0 than in groups HI-2.5 and HI-0 (p < 0.05). Lipidomic analysis of breast muscle revealed that the concentration of triacylglycerols was 46% and 53% lower in groups HI-2.5 and HI-5.0, respectively, than in group HI-0 (p < 0.05), whereas all other lipid classes detected did not differ among groups. Concentrations of thiobarbituric acid-reactive substances, 7α-hydroxycholesterol, 7ß-hydroxycholesterol and total cholesterol oxidation products in heat-processed breast muscle were lower in group HI-5.0 than in group HI-0 (p < 0.05). Concentrations of oxidation products of phytosterols in heat-processed breast muscle were generally much lower than those of cholesterol oxidation products and did not differ between the three groups of broilers. In conclusion, complete replacement of soybean oil with HI larvae fat in broiler diets strongly alters the fatty acid composition of breast muscle total lipids and reduce lipid oxidation of the breast muscle during heat-processing.

Supplementation of Sulfur-Containing Amino Acids or Essential Amino Acids Does Not Reverse the Hepatic Lipid-Lowering Effect of a Protein-Rich Insect Meal in Obese Zucker Rats.

The present study tested the hypothesis that the liver lipid-lowering effect of insect meal (IM) is caused by its low methionine concentration. A total of fifty, male obese Zucker rats were randomly assigned to five groups of 10 rats each (casein (C), IM, IM + Met, IM + Cys, and IM + EAA). While group C received a diet with casein, the IM-fed groups received a diet with IM as the protein source. In groups IM + Met, IM + Cys and IM + EAA, the diets were additionally supplemented with methionine, cysteine and essential amino acids (EAA), respectively. Hepatic concentrations of triacylglycerols and cholesterol, and hepatic mRNA levels and activities of lipogenic and cholesterogenic enzymes were markedly lower in the IM-fed groups than in group C (p < 0.05). All of these parameters either did not differ across the IM-fed groups or were only slightly higher in groups IM + Met, IM + Cys and IM+EAA than in the group IM. In conclusion, the results indicate that a difference in the amino acid composition between IM and casein, a low concentration of methionine in IM and a reduced cysteine synthesis secondary to a decreased methionine availability resulting from feeding IM are not causative for the lipid-lowering effect of IM.