Comparison of in vitro digestibility and DIAAR between vegan and meat burgers before and after grilling

Plant-based meat alternatives of high quality and digestibility could be a way to reduce meat consumption and, consequently, the environmental impact. However, little is known about their nutritional characteristics and digestion behaviour. Therefore, in the present study, the protein quality of beef burgers, known as excellent source of protein, was compared with the protein quality of two highly transformed veggie burgers, based on soy or pea-faba proteins, respectively. The different burgers were digested according to the INFOGEST in vitro digestion protocol. After digestion, total protein digestibility was determined, either based on total nitrogen (Kjeldahl) analysis, or after acid hydrolysis based on total amino groups (o-phthalaldehyde method) or total amino acids (TAA; by HPLC). The digestibility of individual amino acids was also determined, and the digestible indispensable amino acid score (DIAAS) was calculated based on in vitro digestibility. The impact of texturising and grilling on in vitro protein digestibility and the digestible indispensable amino acid ratio (DIAAR) was evaluated at the level of the ingredients and the finished products. As expected, the grilled beef burger had the highest in vitro DIAAS values (Leu 124 %), and grilled soy protein-based burger reached in vitro DIAAS values that could be rated as good (soy burger, SAA 94 %) protein source, according to the Food and Agriculture Or-ganization. The texturing process did not significantly affect the total protein digestibility of the ingredients. However, grilling led to a decrease in digestibility and DIAAR of the pea-faba burger (P < 0.05), which was not observed in the soy burger, but led to an increase in DIAAR in the beef burger (P < 0.005).

Automated summary

High quality and digestible plant-based meat alternatives have the potential to reduce meat consumption and the associated environmental impact. This study compared the protein quality and digestion behavior of beef burgers with two highly processed veggie burgers made from soy or pea-faba proteins. In vitro digestion was used to determine total protein digestibility, amino acid digestibility, and the digestible indispensable amino acid score (DIAAS). Grilling had varying effects on the digestibility and DIAAR of the different burgers. The findings demonstrate the nutritional characteristics of these alternative meat products and their potential as protein sources.