Soaking and cooking modify the alpha-galacto-oligosaccharide and dietary fibre content in five Mediterranean legumes

Abstract

The effects of soaking and cooking on soluble sugars, alpha-galacto-oligosaccharides (a-GOS) and soluble dietary fibres (SDF) and insoluble dietary fibres (IDF) were assessed in five legumes (lentil, chickpea, fenugreek, faba bean and Egyptian faba bean). In raw seeds, total a-GOS content ranged from 2500 mg/100 g (chickpea) to over 4000 mg/100 g (fenugreek). Stachyose was predominant in fenugreek, lentil and chickpea, whereas verbascose was the main a-GOS in faba bean and Egyptian faba bean. IDF represented 69-87% of the total dietary fibres in all studied legumes, while SDF content varied noticeably. During soaking, total a-GOS content decreased between 10% (lentil and faba bean) and 40% (chickpea). In fenugreek, soaking reduced IDF and increased SDF concentration, possibly due to partial IDF solubilisation from the cell wall. Cooking further decreased a-GOS and increased total dietary fibre content. The different behaviours of these five legumes during processing illustrate the high biodiversity within legume species. ARTICLE HISTORY

Comparison of Faba Bean Protein Ingredients Produced Using Dry Fractionation and Isoelectric Precipitation: Techno-Functional, Nutritional and Environmental Performance

“…Faba beans, and other pulses, are known to be high in FODMAPs, particularly GOS, for example Njoumi et al [67] reported 3.5% (DM) GOS in raw faba beans. As the cutoff level of GOS that can trigger gastrointestinal symptoms in IBS patients is estimated to be 0.3 g per serving of food [68], consumption of pulses such as faba beans may cause gastrointestinal discomfort.…”

Chemical composition and in vitro fermentation characteristics of legumes using canine fecal inoculum

“…It has been widely reported that legumes contain high proportions of sucrose and related oligosaccharides such as raffinose, stachyose, and verbascose ( Sosulski et al, 1982 ; Saini and Gladstones, 1986 ; Saini, 1989 ; Apata, 2001 ; Njoumi et al, 2019 ). However, actual concentrations of these oligosaccharides may vary depending on multiple factors including growing conditions/stress ( Jones et al, 1999 ), seed maturation ( Saini, 1989 ), and cultivar ( Martinez-Villaluenga et al, 2005 ).…”

Bioactive Compounds of Legume Seeds

“…The total levels of αgalactooligosaccharides averaged around 25 mg g À1 in raw legume seeds. Stachyose was present in significant levels for lentils and chickpeas, while verbascose was the major oligosaccharide in fava beans [53]. In another study, Fan et al [61] reported that raffinose, stachyose, and verbascose were primarily concentrated in the seed cotyledons as compared to seed coat.…”

“…However, grass pea has dietary fiber content around 8 g 100 g À1 , while hyacinth bean has even more of around 10 g 100 g À1 . Insoluble dietary fiber represents most part of the total (around 70 to 87%), and soluble dietary fiber varies from one legume to another [53]. Interestingly, dietary fiber has been known to interact with other bioactive compounds such as phenolic compounds which, in turn, impact the health advantages of these compounds.…”