Products of Lactobacillus delbrueckii subsp. bulgaricus Strain F17 and Leuconostoc lactis Strain H52 Are Biopreservatives for Improving Postharvest Quality of 'Red Globe' Grapes.

Xiang Fang,Wencan Ke,Xusheng Guo,Fuyun Li,Diru Liu,Qinchun Duan,Ying Zhang,Jianxiong Du,Zhuo Wang,Ross C Beier

doi:10.3390/microorganisms8050656

Abstract

‘Red Globe’ table grapes are large, edible, seeded fruit with firm flesh that tastes good, but can have poor postharvest shelf-life. This study was conducted to explore the effects of products of Lactobacillus delbrueckii subsp. bulgaricus strain F17 and Leuconostoc lactis strain H52 on ‘Red Globe’ table grapes for the enhancement of shelf-life and improvement of grape quality characteristics during postharvest storage. Strains F17 and H52 were isolated from traditional fermented yak milk obtained in the Qinghai–Tibetan Plateau. Samples from untreated and treated grapes were analyzed for physicochemical, biochemical, and microbiological properties (weight loss, decay rate, pH, total soluble solids content, titratable acidity, total phenols, sensory evaluation, and microbial growth) for 20 days. The results demonstrated that supernatants from both strains significantly reduced weight loss, decay rate, aerobic mesophilic bacteria, and coliform bacteria counts; delayed maturity and senescence of table grapes; and reduced titratable acidity and total phenols. However, the supernatant of strain F17 was more effective and resulted in better sensory evaluations and had a significant inhibitory effect on yeast and molds by day 5. Meanwhile, the supernatant from strain H52 had a significant inhibitory effect on fungi over the whole storage period. In addition, the results of the Pearson correlation analysis suggested that weight loss, decay rate, total soluble solids content, and microorganisms were highly correlated with the sensory evaluation data and quality of postharvest grapes when treated with the products of strain F17. On the basis of these data and sensory organoleptic qualities, the supernatant containing products from strain F17 had the best potential as a biopreservative to improve the postharvest quality of ‘Red Globe’ table grapes.

Highlights

‘Red Globe’ table grapes are large, edible, seeded fruit with firm flesh that tastes good, but can have poor postharvest shelf-life
The results of the Pearson correlation analysis suggested that weight loss, decay rate, total soluble solids content, and microorganisms were highly correlated with the sensory evaluation data and quality of postharvest grapes when treated with the products of strain F17
Grape berry treatment by the supernatants of strains F17 and H52 significantly reduced the weight loss of table grapes, which indicates that Lactobacillus and Leuconostoc supernatant-treatment had a positive effect on maintaining the sensory quality of grapes

Summary

Introduction

‘Red Globe’ table grapes are large, edible, seeded fruit with firm flesh that tastes good, but can have poor postharvest shelf-life. Our laboratory has been studying the problem of how to extend the shelf-life and improve the quality of postharvest fruit and vegetables. Coating table grapes with ‘aloe vera gel’ could reduce the loss of phenolics and ascorbic acid, resulting in a higher retention of total antioxidant activity, which improved the overall preservation of grape berries during cold storage and extended the shelf-life of grapes [12]. Lactobacillus and their metabolites are widely used to control foodborne pathogens and spoilage organisms in meat products to ensure food quality and safety [24,25,26,27], to the best of our knowledge, the application of products of lactic acid bacteria to improve table grape quality during storage at 25 ◦C has not been reported. The overall effects of the supernatants of strains F17 and H52 were evaluated on the preservation of ‘Red Globe’ table grapes

Methods

Results

Discussion

Conclusion