Abstract
Avocado production worldwide relies on several varieties, with “Hass” being the most commercialized; however, the available genotypes include a number of green-skin varieties with important roles in several countries. Because many technologies have already been developed in “Hass” avocado, the main objective of this study was to evaluate the effects of controlled atmosphere (CA) storage and 1-methylcyclopropene (1-MCP) application during long-term storage of “Edranol” and “Fuerte” avocados. Fruits of both varieties were harvested at two maturity stages: an early harvest close to 20–23% dry matter (DM) content and another after two months, with 22% and 32% DM content for Edranol and Fuerte, respectively. After harvest, the fruit was stored under the following conditions: (i) regular air storage (RA), (ii) CA with 4% O2and 6% CO2, and (iii) 1-MCP applied at 300 ppm. Avocados were stored at 5°C and 85% relative humidity. Physiological and quality evaluations were performed immediately after 30 and 50 days; afterwards, the avocados were maintained at 20°C (shelf life) until they reached the ready-to-eat stage. Ethylene synthesis was assessed by measuring the transcript accumulation of the ACO and ACS genes. The two varieties showed distinct respiration and ethylene production rates during ripening, and fruit stored under CA or after application of 1-MCP showed lower respiration rates than fruit stored under RA, with the lowest rate in 1-MCP-treated avocados. ACS and ACO transcript levels were also lower under both conditions. CA and 1-MCP were very effective tools for extending storage life mainly by reducing the fruit softening rate and the incidence of pulp disorders in both varieties, and interestingly, these techniques did not severely affect the days to reach the ready-to-eat stage. Therefore, the use of CA and 1-MCP technologies in “Fuerte” and “Edranol” seems to be suitable for maintaining quality through 50 days of storage.
Highlights
Avocado production worldwide relies on several varieties originating from the West Indian, Guatemalan, and Mexican races [1]
Ethylene Production and Respiration Rates. e ethylene production rates in “Fuerte” and “Edranol” stored under regular air storage (RA) were higher than those in fruit stored under controlled atmosphere (CA) and treated with 1-MCP. is difference was observed at both maturity stages (Tables 2 and 3, for “Fuerte” and “Edranol,” respectively)
Expression patterns of Genes Involved in Ethylene Biosynthesis. e ethylene synthesis pathway is well established in higher plants [22], and regulatory control is achieved at two steps: the formation of 1-aminocyclopropane-1-carboxylic acid (ACC) from S-adenosyl-lMet and the conversion of this intermediate to ethylene [23]
Summary
Avocado production worldwide relies on several varieties originating from the West Indian, Guatemalan, and Mexican races [1]. Green-skin varieties are the important varieties when “Hass” is not available in the market. Both black- and green-skin varieties need to maintain quality attributes, including appearance (size, color, and absence of damage), texture (mainly firmness), internal quality (color, absence of physiological disorders, and decay), and flavor after harvest. Among these quality attributes, Journal of Food Quality the changes during ripening are modulated by ethylene, with pulp softening and skin color being the most studied due to their importance in limiting storage potential and commercialization. Changes in quality attributes are affected by growing conditions during fruit development on the tree, i.e., cultural management and climatic conditions, and especially by factors during harvest and storage, such as maturity stage, temperature, relative humidity, length of storage, or postharvest technologies used during this period, among others [3]
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