Fermentation of Legumes with Rhizopus Oligosporus : Effect on Physicochemical, Functional and Microstructural properties

Impact of dehulling, germination and fermentation on the bioactive and functional properties of grey pea flour

Introduction

Grey pea is a largely overlooked legume in the Nordic countries, and its potential uses in various food products remain unexplored. It is a nutrient-rich crop with low environmental impact, making it an attractive option for sustainable and nutritious plant-based alternatives.

Objectives

To investigate the impact of dehulling, germination, and fermentation on the bioactive (polyphenol content and antioxidant capacity) and functional characteristics (water absorption index, water solubility index, water and oil binding capacity, emulsifying properties and gelation concentration) of grey pea flour. Additionally, protein content and pasting properties (temperature, peak viscosity, trough viscosity, breakdown, final viscosity, and setback) were measured.

Methods

Dehulling was performed using a runner disk sheller. Germination was carried out for 24 and 48 h at ambient temperature, and fermentation was conducted for 8 h at 43°C using a starter culture.

Results

The results indicate that dehulling did not significantly affect functional properties and gelling capacity (p = 0.297 for oil absorption capacity, p = 0.5 for emulsion activity, and p = 0.607 for emulsion stability), but it resulted in a notable decrease in total polyphenol content (TPC) and antioxidant capacity (TAC). Conversely, 48 h of germination increased TAC measured by two methods: FRAP (19%) and DPPH (30%). This process increased through viscosity by 1.2-fold, while it did not significantly affect the water absorption index (WAI), water solubility index (WSI), or the emulsifying properties of grey pea flour. Fermentation significantly improved TPC (p < 0.001 for whole grey peas and p = 0.004 for dehulled grey peas), with a TPC increase of up to 67% in fermented dehulled pea flour. TAC measured by both methods, showed significant increases, ranging from 35 to 104%. However, fermentation reduced emulsifying and pasting properties, as indicated by the peak, through and final viscosity, which may be desirable only for certain food products. Further, germination and fermentation showed significant increases in protein content, by 4 and 8%, respectively.

Conclusion

Fermented grey pea flour exhibited enhanced bioactive characteristics, while 48-h germination positively impacted pasting properties. Overall, these processes led to changes in both the bioactive and functional properties of grey pea flour, creating opportunities for the use of these flours in a wide array of food products.

Exploring the Impact of Solid-State Fermentation on Fava Bean Flour: A Comparative Study of Aspergillus oryzae and Rhizopus oligosporus

Fava bean (Vicia faba L.) is a protein-rich pulse with high nutritional value, but its functional and sensory characteristics limit its application in foods. Solid-state fermentation (SSF) can modify the composition of plant proteins, modulate its functionality, and enhance the sensory aspects. In this study, fava bean flour (FB) was fermented with Aspergillus oryzae and Rhizopus oligosporus to produce FBA and FBR, respectively, ingredients with distinct nutritional, functional, and aroma characteristics. The protein content increased by 20% in FBA and 8% in FBR, while fat levels rose more significantly in FBR (+40%). The overall content of fermentable oligo-, di-, mono-saccharides, and polyols (FODMAPs) decreased by 47% (FBA) and 57% (FBR), although polyol production by A. oryzae was observed. SSF improved the nutritional profile of FBA and FBR, with a notable increase in the concentration of essential amino acids observed, and a reduction in most antinutrients, with the exception of trypsin inhibitors. SSF resulted in the formation of aggregates, which increased the particle size and reduced protein solubility. Emulsions prepared with the fermented ingredients separated faster, and the foaming capacity of both FBA and FBR was decreased, but an increase in water-holding capacity was observed. SSF resulted in the production of predominantly savoury-associated aroma compounds, with compounds characteristic of metallic and mouldy aromas reduced. These results indicate the potential of SSF to transform FB with enhanced nutritional value and improved sensory and functional properties.

Tempeh fermentation improves the nutritional and functional characteristics of Jack beans (Canavalia ensiformis (L.) DC)

The effect of two processing methods of Jack beans (i.e. cooked bean (CB) and cooked tempeh (CT)) on the in vitro digestibility of protein and starch, as well as the production of short chain fatty acids (SCFAs), γ-aminobutyric acid (GABA), and tryptophan (Trp) metabolites after in vitro colonic fermentation, was investigated. CT was obtained by fungal fermentation after cooking under acidic conditions. CT had significantly higher protein, lower digestible starch, lower total fiber, higher free phenolic compounds, and higher ash content compared to CB. CT exhibited better in vitro protein digestibility than CB and less glucose release during in vitro digestion than CB. A comparable concentration of total SCFAs and GABA was produced after in vitro fermentation of CB and CT, but CB produced more indole than CT, resulting in higher amounts of total Trp metabolites. In summary, our findings show that tempeh fermentation improves the nutritional quality of Jack beans and describe the impact of fermentation on the digestibility of nutrients and the formation of metabolites during colonic fermentation.

Mung bean protein as an emerging source of plant protein: a review on production methods, functional properties, modifications and its potential applications

Plant protein is rapidly becoming more of a prime interest to consumers for its nutritional and functional properties, as well as the potential to replace animal protein. In the frame of alternative protein new sources, mung bean is becoming another legume crop that could provide high quality plant protein after soybean and pea. In particular, the 8S globulins in mung bean protein have high structural similarity and homology with soybean β-conglycinin (7S globulin), with 68% sequence identity. Currently, mung bean protein has gained popularity in food industry because of its high nutritional value and peculiar functional properties. In that regard, various modification technologies have been applied to further broaden its application. Here, we provide a review of the composition, nutritional value, production methods, functional properties and modification technologies of mung bean protein. Furthermore, its potential applications in the new plant-based products, meat products, noodles, edible packaging films and bioactive compound carriers are highlighted to facilitate its utilization as an alternative plant protein, thus meeting consumer demands for high quality plant protein resources. © 2023 Society of Chemical Industry.