Evaluation of peanut skin and grape seed extracts to inhibit growth of foodborne pathogens

Abstract

Peanut skin extract (PSE) and grape seed extract (GSE) are derived from waste products in the wine and peanut industries, respectively. Both have high concentrations of polyphenols, known to possess antioxidant and antimicrobial properties. PSE primarily contains “A‐type” procyanidins, while GSE primarily contains “B‐type” procyanidins. These differ structurally, but are both isomers of epicatechin dimers. The objective of this study was to evaluate the antimicrobial effects of PSE containing A‐type procyanidins and GSE containing B‐type procyanidins against select foodborne pathogens (Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium). The minimum inhibitory concentration (MIC) of the two extracts on L. monocytogenes, E. coli O157:H7, and S. Typhimurium was determined using the pour plate method. GSE had a significantly lower MIC (p ≤ .05) than PSE for L. monocytogenes (GSE = 60.6 ppm, PSE > 68.2 ppm) and S. Typhimurium (GSE = 45.7 ppm, PSE = 60.6 ppm), but no difference in inhibition of E. coli O157:H7. Since GSE contributed to greater inhibition, GSE extract was fractionated into monomer‐rich (consisting primarily of catechins, epicatechins, and epicatechin gallates) and oligomer‐rich (consisting of dimers, trimers, tetramers, up to decamers) components. Growth curves of all three pathogens in the presence of full extract, monomer and oligomer fractions were compared separately. None of the extracts inhibited S. Typhimurium growth. Generally, the extract containing greater oligomer components inhibited growth of L. monocytogenes and E. coli O157:H7 when compared to the control. Results indicate that an extract with type B procyanidins higher in oligomers may have greater antimicrobial properties.

Antioxidant Activity of Flavonoids in LPS-Treated IPEC-J2 Porcine Intestinal Epithelial Cells and Their Antibacterial Effect against Bacteria of Swine Origin

“…Against the same bacteria, A-type oligomeric procyanidins (source: litchi pericarp) were only bacteriostatic at 2500 and 3500 µg/mL, while bactericidal at 3000 and 4500 µg/mL concentrations [54]. In the work of Levy et al [55], grape seed extract (containing B-type procyanidins) had significantly lower MIC values against Listeria monocytogenes and S. Typhimurium, but showed similar inhibitory effect against E. coli than peanut skin extract (rich in A-type procyanidins). Alshaibani et al [56] investigated the effect of cranberry PAs against seven enteropathogenic E. coli (EPEC) and six ETEC strains, and reported 18,000 µg/mL as the MIC, and a minimum bactericidal concentration (MBC) of 36,000 µg/mL of the extract.…”

“…Against the same bacteria, A-type oligomeric procyanidins (source: litchi pericarp) were only bacteriostatic at 2500 and 3500 µg/mL, while bactericidal at 3000 and 4500 µg/mL concentrations [ 54 ]. In the work of Levy et al [ 55 ], grape seed extract (containing B-type procyanidins) had significantly lower MIC values against Listeria monocytogenes and S . Typhimurium, but showed similar inhibitory effect against E. coli than peanut skin extract (rich in A-type procyanidins).…”

Plant Phenolics and Phenolic-Enriched Extracts as Antimicrobial Agents against Food-Contaminating Microorganisms

“…Grape seed extracts were also proved to be effective growth suppressors of other food-related bacteria such as S. Typhimurium, Listeria monocytogenes, Bacillus spp., Pseudomonas aeruginosa and Campylobacter spp. [32][33][34]. Among exotic fruits, extracts and betacyanin fractions of red pitahaya exhibited a good antimicrobial spectrum against Gram-positive and Gram-negative bacteria, yeasts and molds at concentrations from 7.8 µg/mL to 50 mg/mL [35,36].…”

Procyanidin-Rich Extract from Grape Seeds as a Putative Tool against Helicobacter pylori

“…In particular, procyanidins are considered to have a relevant role in antimicrobial activity, mainly associated with their structure, facilitating the interaction between hydroxyl groups and bacterial membrane. This may be because they allow formation of more branches able to disrupt the bacterial cell membrane [ 18 ]. It is important to highlight that the number of hydroxyl groups of the procyanidins increase proportionally with the increase of the degree of polymerization of the procyanidin chains, allowing us to relate, at least partially, the high antibacterial activity of the extract with the high content of procyanidin oligomers (trimers to pentamers).…”

“…Among others bioactive properties attributed to catechins and procyanidins, they have been associated to antibacterial properties against several pathogenic bacteria [ 14 , 15 ]. They can inhibit the growth of a broad spectrum of Gram-negative [ 16 , 17 , 18 ] and Gram-positive [ 19 , 20 , 21 ] bacteria, depending on its concentration, type of phenolic compounds presents in the extract, bacterial species, and tested strains.…”