Analysis of nutritive composition of black soldier fly larvae derived from food waste and chemical components of sandworm

To investigate the nutritive composition and chemical composition of black soldier fly larvae derived from food waste and sandworm, insect meal（crush by grinding, crush by grinding after press and degreasing） prepared by fresh larvae from 14-day-old food waste source black soldier fly was collected for safety analysis（heavy metal content and total bacteria counts）. The nutrient compositions（crude protein, crude ash and crude fat） and the contents of fatty acids and amino acids in black soldier fly larvae were determined before and after degreasing process. In addition, the contents of heavy metals（Hg, As, Cd, Pb, and Cr） and the chemical analysis（organic matter, moisture, total nutrient, organic carbon, and salt） and pH value of sandworm were examined. The results showed that the heavy metal content and total bacteria counts of black soldier fly larvae derived from food waste met the requirements of feed hygienic standard（GB 13078—2017）. The contents of crude protein, crude ash and crude fat of undegreased black soldier fly larvae were 42.05%, 6.36% and 30.34%, respectively, while the contents of crude protein, crude ash and crude fat of degreased black soldier fly larvae were 54.40%, 8.66% and 11.15%, respectively. The protein content of degreased black soldier fly larvae was higher than that of soybean meal（P＜0.05） and fish meal（P＞0.05）. Compared with soybean meal and fish meal, a higher level of saturated fatty acids（59.218%） was observed in the undegreased black soldier fly larvael. From the perspective of single fatty acid composition, it is mainly composed of lauric acid, oleic acid, palmitic acid, and linoleic acid, which is quite different from that of soybean meal and fish meal. The content of total amino acid in black soldier fly larvae was 38.25%, which was mainly glutamic acid, asparaginic acid, histidine and leucine, and the ratio of essential amino acid to non-essential amino acid was 1.0. The content of amino acid was 50.04% after degreasing treatment, and the degreasing treatment did not affect the composition and proportion of amino acid in black soldier fly larvae. The composition of amino acid in degreased black soldier fly larvae was equivalent to soybean meal and fish meal. No arsenic, mercury and cadmium were detected, and there were a low level of lead and chromium in the sandworm excreted from the black soldier fly larvae derived from food waste. The sandworm was weakly alkaline, the contents of its organic matter, moisture and total nutrient were 84.87%, 26.09%, 6.54%, respectively, which met the standards of organic fertilizer（NY 525—2012）, but the salt content was high. The results demonstrated that the black soldier fly larvae derived from food waste was a high-fat and high-protein feedstuff, which could be used as protein feed material to replace the soybean meal and fish meal after degreatement. At the same time, it could be used as organic fertilizer, but it must be desalted.