Antimicrobial Activities of Phenolic Extracts Derived from Seed Coats of Selected Soybean Varieties

Abstract

Soybean hulls or seed coats consist of complex carbohydrates, proteins, lipids, and polyphenols such as anthocyanidins, proanthocyanidins, and isoflavones. The polyphenolics in the seed coats give them various colors such as black, brown, green, yellow, or even a mottled appearance. In this study, the antimicrobial effects of phenolic extracts from the seed coats of different colored soybeans (yellow, dark brown, brown, and black) were evaluated against foodborne pathogens such as Salmonella Typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni in broth-cultures as well as on chicken skin. The highest total phenolic content was observed for the phenolic extract from soybean variety (R07-1927) with black colored seed coat (74.1 ± 2.1 mg chlorogenic acid equivalent [CAE]/g extract) and was significantly different (P <0.0001) from the extract of the conventional soybean variety (R08-4004) with yellow colored seed coat (7.4 ± 1.2 mg CAE/g extract). The extract from black colored soybean produced reductions of 2.10 ± 0.08 to 2.20 ± 0.08-log CFU/mL for both E. coli O157:H7 and C. jejuni after 3 d when incubated in broth-culture having 4-log CFU/mL of bacteria, whereas a 6 d incubation was found to reduce S. Typhimurium and E. coli O157:H7 at 2.03 ± 0.05 and 3.3 ± 0.08-log CFU/mL, respectively. The extract also reduced S. Typhimurium and E. coli O157:H7 attached to chicken skin by 1.39 ± 0.03 and 1.24 ± 0.06-log CFU/g, respectively, upon incubation for 6 d. Soybean seed coat extracts may have a potency as antimicrobial agents to reduce foodborne bacteria contaminating poultry products.

Bactericidal and Cytotoxic Activities of Polyphenol Extracts fromSolanum tuberosumspp.tuberosumand spp.andigenaCultivars onEscherichia coliand Human Neuroblastoma SH-SY5Y CellsIn Vitro

“…In a recent study, black mulberries had stronger antibacterial activity against E. coli than nonblack mulberries, which correlated with higher content of anthocyanins and flavonols [ 39 ]. Similar results were obtained with phenolic extracts from the seed coats of different colored soybean varieties against E. coli O157:H7 [ 40 ].…”

Opinion on the Hurdles and Potential Health Benefits in Value-Added Use of Plant Food Processing By-Products as Sources of Phenolic Compounds

“…The influence of the soybean seed coat was studied by Abutheraa et al [ 194 ]. The darker the color, the higher was the TPC ( Figure 4 D).…”

A Critical Review on Polyphenols and Health Benefits of Black Soybeans

“…The extract from BSB produced significant growth reductions of food borne pathogens such as Escherichia coli, Salmonella typhimurium and Campylobacter jejuni in broth-cultures as well as on chicken skin [119]. A previous study also showed an isolated monomeric protein (molecular mass of 25 kDa), containing N-terminal sequence, which resembles a segment of chitin synthase.…”