EFFECTS OF PECTIN-BASED EDIBLE COATINGS CONTAINING A BACTERIOCIN OF BACILLUS METHYLOTROPHICUS BM47 ON THE QUALITY AND STORAGE LIFE OF FRESH BLACKBERRIES

Abstract

The aim of the current research is to investigate the effects of edible coatings based on celery pectin singly and in combination with a bacteriocin of Bacillus methylotrophicus BM47 on the quality and storage life of fresh blackberries under refrigeration conditions. In this study three experimental groups were prepared: uncoated blackberries as a control, blackberries with 1% pectin coatings and blackberries with 1% pectin coatings+bacteriocin of B. methylotrophicus BM47. During the storage at 4°C and 75% RH for 16 days, the weight loss, decay percentage, total soluble solids (TSS), titratable acidity (TA), pH, organic acids, sugars, total phenolic content, total anthocyanins and antioxidant activity were analyzed. The results showed that the application of pectin and pectin+bacteriocin coatings led to a reduction in weight loss with 6.3% and 6.7% compared to the control fruit on the 16-th day of storage. A decrease in decay percentage was also noticed, which was most pronounced in the pectin+bacteriocin coated fruit compared to the pectin coatings and control. The pectin and pectin+bacteriocin coatings reduced TSS levels with 0.4% and 0.6%, respectively compared to the control on the 16-th day of the storage, but did not affect TA and pH values. The pectin and pectin+bacteriocin coatings had no effect on decreasing total phenolic and anthocyanin contents or the concentration of sugars (glucose and fructose) in both treatments and the control fruit. The pectin and pectin+bacteriocin edible coatings exhibited a protective effect on the ascorbic acid content, maintaining concentrations of 57.5 mg/100 g of fw and 58.8 mg/100 g of fw (day 16), which were close to the initial values. The pectin and pectin+bacteriocin treatments had also a positive impact on antioxidant activity in the coated blackberries. Both edible coatings effectively inhibited its decrease with the prolongation of the storage time and kept antioxidant levels of 231.8 TE/100 g of fw and 232.4 TE/100 g of fw (day 16) that were close to the initial values.