Comparison of protein quality and digestibility between plant-based and meat-based burgers

Nowadays, consumers are increasingly inclined toward plant-based meat analogues for sake of food security, safety, and sustainability. This growing interest, not only from consumers but also from food companies, brought the offer on the market to be wide and vast. From our previous study it emerged that the market supply, especially the Italian one, is diversified both in terms of protein sources and nutrient content. Although these products are increasingly consumed, for most of the meat analogues today on the market, little is still known about their actual protein quality and digestibility. To fill this gap, in this study different commercial plant-based burgers (2 soy-based and 2 pea-based) were selected and compared to two beef burgers, as controls, in terms of protein quality and digestibility. The findings of this study demonstrated the essential amino acidic profile lacks lysine for almost all burgers (including the meat-based ones) compared to the amino acid scoring pattern set by FAO/WHO (for older children and adults), even if the sum of essential amino acids was within the range of sufficiency. All samples showed good initial protein integrity with low hydrolysis (above 6%) and percentage of D-enantiomers (above 15%). The study of the digestibility, performed by the validated INFOGEST in vitro model, showed better protein solubilisation in the case of meat burgers (63 ± 3% and 61 ± 8%), but a good digestibility also in the case of plant-based ones (from 55% to 40%). The degree of hydrolysis of the solubilised proteins was very high in all samples (from 65% to 40%) indicating a very good protein accessibility to digestive enzymes. The analysis of the peptide fraction of digestates indicated a high prevalence of collagen proteins in beef burgers and of reserve proteins in plant-based burgers. This study showed that the differences between these products are mostly dependent on the quality of the raw materials used, rather than on the vegetal or animal protein source. Therefore, to have a product with a good protein quality and digestibility, independently from the protein origin, the consumer needs to make an accurate choice, carefully reading the ingredient list.