Effect of Fruit Maturity on Microstructural Changes and Oil Yield during Cold‐Pressed Oil Extraction of ‘Hass’ Avocado

Abstract

The aim of this study was to determine the effect of avocado fruit maturity (as estimated by time of harvest during the season) on cold‐pressed oil yield. ‘Hass’ avocado fruit at six different stages of on‐tree maturity (harvested between September and April 2016/2017) were processed in a commercial cold‐pressed oil extraction plant. After destoning and grinding, the fruit pulp was malaxed for 120 min. Avocado pulp samples were examined by light microscopy, electrical conductivity, and electrical impedance spectroscopy. More intact parenchyma cells were observed by microscopy in early‐season fruit. The greatest cell disruption occurred after the grinding step as shown by electrical resistance values. The late‐season fruit were found to have higher conductivity and lower electrical resistance values which indicated more cell disruption occurred during extraction. Cell walls extracted from fruit harvested later in the season showed a higher yield of the water‐soluble polysaccharides and a lower yield of the trans‐1,2‐diaminocyclohexane‐N,N,N′,N′‐tetraacetic acid (CDTA)‐soluble polysaccharides. The cold‐pressed oil extraction yield (g oil/100 g fresh flesh) was found to increase with fruit maturity from 10.4 in the early season to 22.5 (g oil/100 g fresh flesh) in the late season. The extraction efficiency (cold‐pressed extraction yield/total oil content) also increased from early season (77.2%) to late season (96.6%). In conclusion, the avocado flesh cellular structure ruptured more easily in late‐season fruit suggesting of a contribution to more oil release and improved extraction yields.

Avocado oil: Production and market demand, bioactive components, implications in health, and tendencies and potential uses

“…Avocado oil is mainly obtained by mechanical (cold pressing) and chemical (use of organic solvents) methods from the flesh of avocado fruit, although occasionally it is also extracted from the skin and the seed. Fruit cultivar, maturity stage, extraction method (Costagli & Betti, 2015; Wong et al., 2011), fruit tissue type, and different extraction conditions such as pH, temperature, or added enzymes (Werman & Neeman, 1987) are factors determining the avocado oil yield and quality (Permal et al., 2020; Woolf et al., 2009; Yang et al., 2020). The commonly produced oil has the quality grade for culinary uses, but it is usually further refined for the cosmetic industry (Costagli & Betti, 2015; Tan, 2019).…”

Óleo da polpa de quatro variedades de abacate: extração, rendimento, caracterização e avaliação da atividade antioxidante

“…Avocado is an important source of fatty acids and the factors that can interfere with nutrient content are the variety, climate and region of cultivation of the avocado, time of the harvest year, maturation stages, among others (Shezi et al, 2020;Yang et al, 2020;Acosta-Díaz et al, 2019;Ferreyra et al 2016).…”

“…The difference in pulp oil yield can be explained according to research by Yang et al (2020) and Ferreyra et al (2016), due to the effects caused by harvest season, choice of cultivar, altitude, location and climatic conditions of the place of cultivation, and influence the oil extraction yield. The changes suffered by the fruit during the ripening process can also influence the oil yield, as little oil is found in the avocado pulp, which is still green, showing higher oil concentrations when the fruit is ripe (Shezi et al, 2020).…”

Effect of malaxing time and temperature on rheological properties of 'Hass' avocado pulp and oil yield during oil extraction

“…Avocados are predominately grown in NZ for fresh fruit export, after second grade fruit is sold locally, any reject or unsaleable fruit is generally processed to extract the avocado oil to produce a highquality culinary oil. To achieve maximum oil yield, a number of preharvest and postharvest factors for avocados need to be considered because they influence the release of oil from the parenchyma cells as reported in Yang et al (2019bYang et al ( , 2020. The recovery of oil from the avocado flesh is dependent on the fruit maturity, the time of harvest during the fruit season and the ripeness of the fruit (Woolf et al, 2009;Yang et al, 2019bYang et al, , 2020.…”

“…To achieve maximum oil yield, a number of preharvest and postharvest factors for avocados need to be considered because they influence the release of oil from the parenchyma cells as reported in Yang et al (2019bYang et al ( , 2020. The recovery of oil from the avocado flesh is dependent on the fruit maturity, the time of harvest during the fruit season and the ripeness of the fruit (Woolf et al, 2009;Yang et al, 2019bYang et al, , 2020.…”