PRELIMINARY SIGNS OF PHYSIOLOGICAL MATURITY AND POSTHARVEST PERFORMANCE OF MENDEZ AVOCADO FRUIT

Mendez avocado has great economic importance in Mexico, because a significant proportion of its annual harvest coincides with limited availability of Hass avocado, from June to September. Although production and export of Mendez avocado has increased in recent years, its minimum quality requirements are not established, unlike Hass avocado. This research compared quality parameters at harvest and post-harvest of Mendez and Hass avocados produced by the Summer-Fall bloom in Michoacan. Physiological maturity was determined by evaluating the postharvest performance of fruit harvested in biweekly sampling from May to August. At physiological maturity, respiration rate and ethylene production were quantified in refrigerated fruit (5.5 +/- 2 degrees C and 90 +/- 5 % RH) for 0, 7, 14 and 28 d. Physiological maturity was different (P <= 0.05) between both cultivars, and it was reached 10 months after blooming. Hass avocados contained 21.1 % of pulp dry matter, while Mendez avocado had 22.7 %. Although average fruit length for both cultivars was similar, average equatorial diameter was greater in Mendez avocado (6.72 cm) than in Hass avocado (6.42 cm). Post-harvest performance of Mendez avocado, as measured by skin color change, ethylene production, respiration rate, days to maturity of consumption, weight loss of fruit, and pulp characteristics (color, odor, flavor and texture), was similar to Hass avocado performance when the fruit was harvested at physiological maturity..