Traditional Legume Seed Fermentation Processes: What is the Individual Impact of the Cooking and Fermentation Stages on the Degradation of Anti-Nutritional Factors?

Legume seeds account for one-fifth of the plant proteins consumed worldwide, and are divided into 3 groups: pulses, oilseeds and pulses with pods. Traditional fermented products based on legume seeds are an integral part of the diet of many populations, and are generally obtained from oilseeds, such as Glycine max. Fermented seeds are known to have better digestibility, lower amounts of anti-nutritional factors and isoflavones, courtesy of the numerous steps involved in their traditional processing. The present review was therefore undertaken to provide a comprehensive assessment of the contribution of each of the main processing steps, i.e. cooking and fermentation, on the degradation of compounds with anti-nutritional activities. The data presented in this review show that the cooking operation degrades almost all thermolabile anti-nutritional factors (ANFs). Some thermostable ANFs are also eliminated by hydrolysis and diffusion into the cooking water or in the soaking water (in case soaking is performed), especially when the seed/water ratio is sufficient for the cooking or soaking water to be subsequently discarded. Fermentation dominated by Bacillus subtilis or Rhizopus oligosporus is an interesting option when the aim is to further reduce thermostable antinutritional factors that were only partially reduced during cooking.