Evaluation of Semi-Solid-State Fermentation of Elaeocarpus serratus L. Leaves and Black Soymilk by Lactobacillus plantarum on Bioactive Compounds and Antioxidant Capacity.

Chia-Yu Tsui,Chun-Yao Yang

doi:10.3390/foods10040704

Abstract

Elaeocarpus serratus L. leaves (EL) containing phenolic compounds and flavonoids, including myricitrin with pharmacological properties, could be valorized as nutritional additive in foods. In this study, the semi-solid-state fermentation of EL and black soymilk (BS) by Lactobacillus plantarum BCRC 10357 was investigated. Without adding EL in MRS medium, the β-glucosidase activity of L. plantarum quickly reduced to 2.33 ± 0.15 U/mL in 36 h of fermentation; by using 3% EL, the stability period of β-glucosidase activity was prolonged as 12.94 ± 0.69 U/mL in 12 h to 13.71 ± 0.94 in 36 h, showing positive response of the bacteria encountering EL. Using L. plantarum to ferment BS with 3% EL, the β-glucosidase activity increased to 23.78 ± 1.34 U/mL in 24 h, and in the fermented product extract (FPE), the content of myricitrin (2297.06 μg/g-FPE) and isoflavone aglycones (daidzein and genistein, 474.47 μg/g-FPE) at 48 h of fermentation were 1.61-fold and 1.95-fold of that before fermentation (at 0 h), respectively. Total flavonoid content, myricitrin, and ferric reducing antioxidant power in FPE using BS and EL were higher than that using EL alone. This study developed the potential fermented product of black soymilk using EL as a nutritional supplement with probiotics.

Highlights

Phenolic compounds found in plant materials are known to have many biological benefits for human health
This study developed the potential fermented product of black soymilk using E. serratus leaves as a nutritional supplement with L. plantarum
The Elaeocarpus serratus L. leaves were collected in January 2019 from the orchard (23◦29 18.1” N 120◦28 15.7” E) in Chiayi City, Taiwan, and were thoroughly rinsed with distilled water to remove the dust on the surface [5]

Summary

Introduction

Phenolic compounds found in plant materials are known to have many biological benefits for human health. The leaves of E. serratus are the by-product after harvest of fruit, and have significant quantities of polyphenols and flavonoids, including myricitrin with antioxidant activity and pharmacological properties [5,6,7,8]. Geetha et al (2018) reported that the ethanolic extracts of leaf and seeds from E. serratus had anti-arthritic activity in Wistar rats using oral administration. They performed the acute toxicity studies of the extracts to Wistar male rats and indicated that the extracts were quite safe with no acute toxicity, even at a high dose of 5000 mg/kg b.w. orally administered [9]. For the preparation of nutraceuticals, the extracts and fermented product of E. serratus leaves have the potential to be used as a nutritional supplement in foods, such as in black soymilk product

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