Cellular Changes in “Hass” Avocado Mesocarp During Cold-Pressed Oil Extraction

Abstract

The aim of this study was to understand factors affecting oil release from “Hass” avocado cells during the cold-pressed oil extraction process. Early-season “Hass” avocado fruit and pulp were sampled from a commercial extraction process. Light microscopy and electrical impedance spectroscopy were used to examine avocado flesh structure at defined steps during the extraction process (destoning, grinding, malaxing, and decanting). Most parenchyma cells were ruptured during destoning, grinding, and mixing before malaxing. In contrast, the other oil bearing cells, idioblast cells, appeared to remain unruptured and intact during the extraction process. The greatest reduction in electrical resistance was observed after the destoning step. There were also significant differences between the resistances of flesh after destoning, grinding, and prior to malaxing samples. Malaxing for two hours assisted the process of oil aggregation, which led to a greater oil yield. These findings will help to develop methods to enhance oil extraction from early-season “Hass” avocado fruit.