Combined effect of calcium chloride and peroxyacetic acid on quality and shelf life of minimally processed longan fruit

Abstract

Efficacies of calcium chloride solution (CaCl2, 0.25-1.0%), a textureimproving agent, and peroxyacetic acid (PAA) solution, a microbial population reducing sanitizer, on the peel and aril of two whole longan fruit cultivars, "Daw" and "Beawkeaw," were investigated. A solution of 0.5% CaCl2 increased aril firmness by 29.4 and 18.2% for cv. Daw and Beawkeaw, respectively, and did not cause any undesirable bitter taste. A dip of whole longan or peeled aril in 100 or 50mg/L PAA solution for 3min, respectively, efficiently reduced microbial load (total bacteria, yeast and mold) in comparison to unwashed controls. Longan aril were processed and stored in clear clamshell containers at 4±1oC for 8 days. The aril firmness, L* value and TA content decreased but weight loss, pH level, reducing sugar, total bacteria and yeast-mold count increased while the TSS and total sugar content only slightly changed throughout the storage period. The immersion of longan aril in PAA and CaCl2 solutions resulted in the decrease in pH, TSS, total sugar and reducing sugar contents while firmness, weight loss and L* value increased. The treatment had no effect on TA content but could delay microbial growth when compared with the control. The shelf lives of longan aril at 4±1oC of the control and the treatments were 3 and 5 days for cv. Daw and 3 and 4 days for cv. Beawkeaw, respectively.