The comprehensive studies of Hermetia illucens larvae protein’s biological value

A high protein content in the insect biomass allows to classify this product as a very promising source of protein, comparable in nutritional and biological value with proteins of animal origin. Despite a long history of safe use, in some countries insects are considered a new type of food which safety must be proven before entering the food market. The long-term Russian experience in novel food's research allows to identify the crucial stages, among which, along with toxicological and allergological tests, the protein's biological value determination takes an important place. The conclusion about the biological value of protein is formed on the basis of integrated use of chemical and biological methods, which gist comes down to the study of the nitrogen balance in the growing organism (biological method) and the calculation of the amino acid score (chemical method). The aim of the research was the comprehensive assessment of Black soldier fly (Hermetia illucens) larvae protein's biological value using chemical and biological methods. Material and methods. Biological studies based on measuring of net protein ratio/net protein utilization were performed on 28 growing (between 25-50 days of life) male Wistar rats, with an initial body weight of ~65.5±1.2 g. Rats in the control group (n=14) received a semi-synthetic casein diet with a protein content of ~12% in calories, the test group (n=14) received a diet including an equivalent amount of H. illucens protein. The diet's ingredients were replaced with the consideration of the proteins, fats, and carbohydrates content in the included product following the principle of isocaloricity and isonitrogenicity (by mass fraction of total nitrogen). H. illucens biomass and casein in the test and control groups, respectively, were the main significant sources of nitrogen in the diet. Body weight, feed intake, and fecal and urine nitrogen losses were measured during the experiment. The biological value and digestibility of protein were judged by coefficients of protein efficiency ratio, net protein ratio, true protein digestibility, true protein biological value, true net protein utilization. Chemical studies included studies of the amino acid composition of H. illucens biomass protein and calculation of the digestible indispensable amino acid score (DIAAS). Results. The general condition of animals of the both groups during the whole experiment was satisfactory, the weekly body weight increase corresponded to the level of growth typical for Wistar rats, intergroup differences were not detected. Despite the fact that in a number of indicators the test group animals differed from the control [there were noted a decrease of the net protein ratio (by 5%, p>0.05), true protein digestibility (by 11%, p<0.05), net protein utilization (by 13%, p<0.05), caused by increased excretion of nitrogen with urine (by 8%, p>0.05) and feces (by 186%, p<0.05), with the same amount of nitrogen intake], the test rats' growth rate and the nitrogen's retention degree indicate a relatively high biological value of insect protein. According to the DIAAS, H. illucens protein is characterized by high content of histidine, threonine, valine, isoleucine and leucine (DIAAS=100 and more), and is also a source of sulfur-containing amino acids - methionine and cysteine (DIAAS=86) and lysine (DIAAS=97). Conclusion. The comprehensive studies of Hermetia illucens larvae protein's biological value demonstrated a high protein content, its balanced amino acid composition and high biological value, which allows to consider Hermetia illucens as a potential source of complete dietary protein.