Effect of Fresh and Dried Blueberry (Vaccinium myrtillus) Fruit and Leaf Extracts on Probiotics and Pathogens

Abstract

Blueberry (Vaccinium myrtillus) has a significant place among berry fruits, and is a rich source of phenolic compounds with antioxidant, antimicrobial, anti-diabetic and anti-inflammatory properties. Recently, studies on plant-derived antimicrobial agents against pathogens have increased. In this study, the antibacterial activity of fresh and dried blueberry fruit and leaf extracts grown in three different locations of Erdek and Kapıdağ, Turkey and phenolic standards were determined. The extracts and phenolic standards were tested against Salmonella Enteritidis (ATCC 13076), Escherichia coli (ATCC 25922), Staphylococcus aureus spp. aureus (ATCC 29213), Enterobacter aerogenes (ATCC 13048), Listeria monocytogenes serotype 1/2b, Salmonella Typhimurium, Lactobacillus delbrueckii NRRL B 548, Lactobacillus casei NRRL B 1922, and Lactobacillus acidophilus NRRL B 4495 by the disc diffusion method. Fresh and dried blueberry fruit and leaf extracts exhibited phenolic composition with a dose-dependent inhibitory effect against the growth of pathogens and probiotics. The dried leaf extracts were the most effective (20-25 mm) against all bacteria (except L. acidophilus NRRL B 4495) in comparison to positive control (24-26 mm) while syringic acid (16-26 mm), trans ferulic acid (14-26 mm), and naringin (14-26 mm) were the most effective and caffeic acid (16-18 mm), resveratrol (16-19 mm) and (+)-catechin (16-18 mm) were the least effective phenolics on all pathogens. S. Enteritidis (ATCC 13076) was the most resistant to phenolics, followed by L. monocytogenes serotype 1/2b and S. Typhimurium. Syringic acid, hesperidin, 3-hydroxyl-4-methoxy-cinnamic acid, and rutin hydrate were the effective phenolics on LAB. Results indicated that blueberry extracts are effective against pathogens and LABs (except L.acidophilus), and they may have an important potential as a natural preservative while phenolic standards may exhibit variations in their effects. © 2019 Authors. All rights reserved.