Molecular composition of lipid and protein fraction of almond, beef and lesser mealworm after in vitro simulated gastrointestinal digestion and correlation with the hormone-stimulating properties of the digesta

Abstract

The current production of meat presents many disadvantages for the environment and much research focuses on alternative protein sources. Insects are novel protein sources highly valued for their nutritional and sustainable potential. However, many aspects concerning biological and nutritional properties of the insects after digestion, in comparison with other protein sources, are still overlooked. In this work, a comparative study on three different protein sources, namely almond, lean beef and insect Alphitobius diaperinus (lesser mealworm), was performed after in vitro simulated gastrointestinal digestion. An in-depth characterization of the chemical composition of the solubilized protein and lipid fractions of the digesta was performed by applying different analytical techniques, including chromatographic methods coupled to mass spectrometry and 1H NMR spectroscopy. Beef and insect were proven to be very similar in amino acid composition and protein solubilization after digestion, when considering the proper corrections for the chitin content. Lipid fraction from insects was solubilized during digestion as the one of almonds, but with a fastest kinetics. Thus, lesser mealworms are a good source of both lipids and highly nutritional proteins. Then, the amino acid composition of raw and digested protein fraction from the three sources was related to the PYY, ghrelin, GLP-1 and CCK release and rats’ food intake. The composition of amino acids in insect digesta was found to be related to specific effects on enterohormone release, and the modulation of food intake in rats.