The application of pullulan coating enriched with extracts from Bergenia crassifolia to control the growth of food microorganisms and improve the quality of peppers and apples
•Flavones and phenolic acids were identified in the LBL extracts.•Pullulan films enriched with LBL extracts showed antimicrobial activity.•Pullulan coating maintains peppers and apples quality during postharvest storage.
The objective of this study was to investigate the composition of polyphenolic compounds of water and ethanol extracts from leather bergenia leaves (LBL) and to determine the antimicrobial properties of pullulan coating enriched with these extracts. The result showed that both extracts consisted mainly of flavonols and phenolic acids. The antimicrobial activity of pullulan coating solution was determined at different concentrations: 0.4, 1, 2, 5, 10, 20% (w/v) of extracts. The incorporation of LBL extracts showed antimicrobial activities of the films against both Gram-positive and Gram-negative bacteria and molds. Pullulan films incorporated with 20% of LBL extracts showed the strongest antimicrobial activity. In the next part of the study pullulan coating solution with a 20% concentration of water LBL extract was chosen and used as coating on pepper and apple surfaces. Non-coated samples of food were also used as controls. Samples coated with the antimicrobial solutions showed advantages in reducing microbial growth by 1 log CFU/g as compared to the control samples. Physico-chemical and organoleptic observations were also evaluated after storage. The application of the pullulan film enabled an extension of the storage time of the peppers and apples as a result of reduced weight losses and helped to maintain their hardness.
Journal: Food and Bioproducts Processing - Volume 94, April 2015, Pages 422–433