Impact of Germination on the Protein Solubility and Antinutritive Compounds of Lupinus angustifolius and Vicia faba in the Production of Protein-Rich Legume-Based Beverages

Lupines and faba beans are protein-rich legumes, whichcan be utilizedas a plant-based substitute for animal proteins in human nutritionin general and in the beverage industry in particular. However, theirapplication is hampered by low protein solubility in the acidic pHrange and by antinutrients such as flatulence-causing raffinosefamily oligosaccharides (RFOs). Germination is known in thebrewing industry for increasing enzymatic activities and mobilizingstorage compounds. Therefore, germinations of lupines and faba beanswere performed at different temperatures, and their impact on proteinsolubility, the concentration of free amino acids, and degradationof RFOs, alkaloids, and phytic acid was evaluated. In general, changeswere comparable for both legumes but less pronounced in faba beans.Germination depleted the RFOs entirely in both legumes. The proteinsize distribution was found to be shifted toward smaller fractions,the concentrations of free amino acids multiplied, and protein solubilityincreased. No substantial reductions in the binding capacity of phyticacid toward iron ions were observed, but a release of free phosphatein lupines was detected. The results prove that germination is anapplicable process for refining lupines and faba beans for use notonly in refreshing beverages or milk alternatives but also in otherfood applications.

Automated summary

Lupines and faba beans, protein-rich legumes, can be used as a plant-based alternative to animal proteins in the beverage industry. However, their usability is hindered by low protein solubility and the presence of antinutrients. This study found that germination can enhance protein solubility, increase levels of free amino acids, and decrease the concentration of antinutrients in lupines and faba beans. These findings demonstrate the potential of germination as a process for refining these legumes for various food applications.