Stabilization of avocado puree by using emblica fruit extract during chilling and freezing storage

Abstract

Avocados are one of the potential economic fruits, gaining huge global attention. They have high nutritional values and can provide several health benefits. However, they are easily perishable and susceptible during processing and storage. This research aimed to evaluate the effect of pretreatment methods combined with emblica fruit extract and anti-browning agents on the quality of avocado puree during chilling and freezing storage.

The ripe avocado was selected for this study. For pretreatment, the avocados were divided into two groups to be blanched in 1) tap water and 2) alkaline water (pH: 10.6) at 85 °C for 3 min. Fresh and non-blanched avocado was used as a control group. The blanched avocado was then homogenized by a blender for 2 min. During blending, anti-browning agents including ascorbic acid, citric acid, mixture of ascorbic acid and citric acid, and emblica fruit extract were separately added into the puree prior to be stored at 4 °C and -20 °C for 5 days and 7 weeks, respectively. Avocado puree samples were determined for color and pH during storage, while polyphenol-oxidase (PPO) activity and total bacterial plate counts were analyzed after storage.

The results showed that blanching avocado in alkaline water helped delay color changes and browning reaction during storage. Furthermore, PPO was completely inhibited. After storing at 4 °C for 5 days and -20 °C for 7 weeks, the color of avocado blanched in alkaline water showed the highest value of lightness and greenness. Browning reaction in avocado puree could be controlled by adding ascorbic acid combined with alkaline water. Emblica fruit extract caused the puree to become darker during storage; however, its color depended on the extract concentrations. The pH of all treatments tended to decrease, and less than 1 log CFU/g of total bacteria plate counts were detected in all samples except fresh avocado in the control group which had more than 4 log CFU/g. This study indicated that the stabilization of avocado puree by blanching in alkaline solutions combined with the addition of ascorbic acid could maintain the puree quality during storage under both chilling and freezing conditions.