Phytochemical and Prebiotic Properties of Functional Mulberry Products Produced by Membrane-based Process

Abstract

Mulberry (Morus alba L.) fruits are beneficial for human health. They provided many benefits such as lower cholesterol, cancer risk and blood sugar. In this study, functional mulberry juices (MBI) were produced by adding isomaltooligosaccharide (IMO) and mineral supplements and pasteurizing by microfiltration (MF). MF system used was 0.2 µm polysulfone hollow fiber and operated at constant crossflow velocity (CFV) of 1.0 m/s, temperature of 20±2°C and transmembrane pressure (TMP) of 0.8 bar. The mulberry juice was pre-treated by commercial pectinase 0.1% (V/V) before MF. The result showed that phytochemicals such as L-ascorbic acid and anthocyanin no significant difference (p<0.05) after microfiltration. The highest values of L-ascorbic acid and anthocyanin content were 14.19±0.06 mg/ml and 127.07±2.28 mg/g, respectively. In addition, the effect of antioxidant capacity (DPPH and FRAP) and total phenolic content of functional mulberry juice showed no significant difference (p<0.05) under the condition of 20±2°C. The final product after microfiltration step produced clarified juice and concentrated juice. Batch culture of MBI on short-chain fatty acids (SCFAs) by GC-FID, enumeration of fecal bacteria by NGS method and phenolic metabolites by LC-MS/MS were studied. The effect of IMO on beneficial bacteria (bifidobacterial) increased significantly (P<0.05) after 24h fermentation in MBI2 (5.03%) and MBI8 (17.53%), meanwhile the percentage of bacteroides after 24h decreased significantly. Moreover, studied on SCFAs analysis results showed that IMO can increase the production of propionic acid and butyric acid in the colon. The highest concentrations of propionic and butyric acid on MBI2 and MBI8 were increased by 11.66 ± 1.69, 13.68 ± 0.50 mM and 9.55 ± 1.01, 10.79 ± 0.33 mM, respectively at 48 h fermentation. LC-MS/MS method for the quantification of phenolic metabolites in human feces. The most abundant phenolic compounds were 3-(2-hydroxyphenyl) propionic acid, 3,4-dihydroxybenzaldehyde, L-phenylalanine, aminocaproic acid, 3,4-dihydroxybenzaldehyde and cholic acid in functional mulberry juices. Thus, IMO can support the growth of bifidobacterial such as Bifidobacterium scardovii, Bifidobacterium stercoris.