Antimicrobial screening of pecan shell extract and efficacy of pecan shell extract-pullulan coating against and on blueberries.

Pecan shell is considered an agricultural waste; however, it contains various bioactive compounds with potential inhibitory effect against microorganisms. This study evaluated the antimicrobial efficacy of pecan shell extract (PSE) using disc-diffusion method and on blueberries as an antimicrobial coating using pullulan. For study 5 and 10 % of aqueous (A-PSE) or ethanol pecan shell extract (E-PSE) incorporated into pullulan film were tested against different bacterial and fungal strains. Pullulan film disc was used as control. The diameter of growth inhibition (mm) around discs was measured. For study, PSE-P (5 % w/v aqueous pecan shell extract+5 % w/v pullulan), P (5 % w/v pullulan) or control (water) were spray coated on blueberries inoculated (∼5 log CFU/g) with ; and stored at 4 °C, 50 ± 10 % RH for 15 days. The effect of antimicrobial coating against pathogens and its impact on quality during storage were determined. A-PSE and E-PSE films were more effective against Gram-positive bacteria and showed no antifungal effect at tested concentrations when evaluated . Immediately after coating on blueberries, PSE-P significantly reduced by 2 log CFU/g and lowered survival until day 5 than control or P. Native aerobic microbial population was reduced ( < 0.05) by 0.7 log CFU/g immediately after coating. PSE-P coating or storage time had no significant effect > 0.05) on the survival of . . and native fungal population. PSE-P maintained the firmness of blueberry with no significant effect on its color, TSS, and pH during 15 days storage. PSE-P significantly reduced ( < 0.05) the spoilage rate by 21 % than control (28.5 %) and P (37 %); and minimized ( < 0.05) weight loss during storage. Pecan shell extracts show promise as a potential antimicrobial compound whose application on various food products or packaging material could be further explored.