Rhizopus oligosporus and Lactobacillus plantarum Co-Fermentation as a Tool for Increasing the Antioxidant Potential of Grass Pea and Flaxseed Oil-Cake Tempe.

Bożena Stodolak,Anna Starzyńska-Janiszewska,Magdalena Mika,Agnieszka Wikiera

doi:10.3390/molecules25204759

Bożena Stodolak, Anna Starzyńska-Janiszewska + Show 2 more

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https://doi.org/10.3390/molecules25204759

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Abstract

Tempe-type fermentation originating from Indonesia can enhance the antioxidant activity of plant material. However, this biological potential depends on substrates and applied microorganisms. This study aimed to determine whether co-fermentation with Rhizopus oligosporus and Lactobacillus plantarum improved antioxidant activity of tempe obtained from grass pea seeds with flaxseed oil-cake addition (up to 30%). For this purpose, substances reacting with Folin–Ciocalteu reagent and free radicals scavenging potential were measured in water-soluble fractions and dialysates from simulated in vitro digestion. Additionally, the water-soluble phenolic profile was estimated. The higher level of water-extractable compounds with antioxidant activity was determined in co-fermentation products than in fungal fermentation products. Moreover, the fermentation process with the use of L. plantarum contributed to a greater accumulation of some phenolic acids (gallic acid, protocatechuic acid) in tempe without having a negative effect on the levels of other phenolic compounds determined in fungal fermented tempe. During in vitro digestion simulating the human digestive tract, more antioxidant compounds were released from products obtained after co-fermentation than fungal fermentation. An addition of 20% flaxseed oil-cake and the application of bacterial–fungal co-fermentation, can be considered as an alternative tool to enhance the antioxidant parameters of grass pea tempe.

Highlights

Tempe is a food product of Indonesian origin obtained from legumes, cereals or agricultural waste via solid state fermentation
Grass pea seeds from European countries are considered a good source of phenols in a vegetarian diet, with dominant p-coumaric acid derivatives in the phenolic profile [2]
The level of compounds reacting with Folin–Ciocalteu reagent (FCRS) depended on the substrate kind—the addition of 10% (FOC10) and 20% (FOC20) flaxseed oil-cake to grass pea seeds resulted in an increase in FCRS by 67% and 87%, respectively, whereas the highest dose (30%) of oil-cake (FOC30) did not further enrich the tempe in the said compounds (Table 1)

Summary

Introduction

Tempe is a food product of Indonesian origin obtained from legumes (mainly soy), cereals or agricultural waste via solid state fermentation. The indispensable microorganism in tempe-type fermentation is Rhizopus sp., usually R. oligosporus [1]. Tempe production can be regarded as an alternative way of processing legume seeds to obtain convenient foods of diversified nutritional, organoleptic and bioactive properties. An interesting example is grass pea (Lathyrus sativus L.) seeds, which contain valuable proteins and a relatively high level of mineral compounds. Grass pea seeds from European countries are considered a good source of phenols in a vegetarian diet, with dominant p-coumaric acid derivatives in the phenolic profile [2].

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