Effect of high hydrostatic pressure and activated film packaging on bacterial diversity of fruit puree

Abstract

The aim of the present study was to determine the effect of high hydrostatic pressure (HP) and films activated with a combination of enterocin AS-48 and thymol (AF) on the microbial load and bacterial diversity of fruit puree (banana, apple, pear). HP and AF were applied singly, or in combination (AFHP). Samples were chillstored. HP and AFHP treatments reduced viable counts significantly (P≤0.05). The predominant bacterial groups in the puree were fam. Comamonadaceae (23.17%) and genera Methylobacterium (21.46%), Acidovorax (8.70%) and Sphingomonas (6.63%). Pseudomonas became relevant by the end of storage (10.50%). Most of the AF samples had higher relative abundances of Comamonadaceae, Methylobacterium, Acidovorax and Sphingomonas and lower relative abundance of Pseudomonas. Application of HP treatment markedly reduced the relative abundances of Comamonadaceae, Methylobacterium, Acidovorax and Sphingomonas. Lactobacillales increased in relative abundance upon application of HP treatment but not during storage, while Pseudomonas increased towards the end of storage. The combined treatment (AFHP) achieved greatest reduction in the relative abundances of Comamonadaceae and Methylobacterium. Results indicate that AFHP treatment had greatest effects on the bacterial diversity of the fruit puree and was also the most effective in keeping total aerobic mesophiles and Enterobacteriaceae below detectable levels.