MICROBIAL CONTROL IN WHITE CACTUS PEAR WITH BIOPOLYMERIC COATING OF CHITOSAN, CANDELILLA WAX AND THYME ESSENTIAL OIL

Abstract

White cactus pear (Opuntia albicarpa L.) undergoes decay by pathogens in postharvest, which limits its shelf life. The objective of this study was to evaluate coatings based on chitosan (Q), candelilla (Euphorbia antisyphilitica Zucc.) wax (Cw) and thyme (Thymus vulgaris L.) essential oil (Eo) to reduce microbial development on the cactus pear and increase shelf life. Emulsions based on Q, Eo, and Q+Eo were applied on freshly harvested cactus pear fruits, which were stored for 18 days at 22 ºC. Treatments with Q also incorporated Cw. Controls were uncoated fruits (Ct). Microbial inhibition was assessed through bacterial counting in culture plate, in addition to the appearance of the fruit on a visual scale 1 to 5, where 1 corresponded to appalling and 5 to excellent. Fruits with the Q+Eo treatment had an appearance close to 4 at the end of the storage, followed by those with Q, Eo, and T, which obtained a score of 1. The lowest weight loss occurred when Cw was used. With a coating of Q (2 %), Eo (2000 ppm) and Cw (5 %) microbial growth was reduced by 98.4 %, allowing a shelf life of at least 18 days at 22 ºC, with good appearance and low weight loss in fruits.