Volatile profiles of ripening West Indian and Guatemalan-West Indian avocado cultivars as affected by aqueous 1-methylcyclopropene

• Published in: Postharvest biology and technology 2013-06, Vol.80, p.37-46
• Main Authors: Pereira, Marcio Eduardo Canto, Tieman, Denise M., Sargent, Steven A., Klee, Harry J., Huber, Donald J.
• Format: Article
• Language: English
• Subjects: 1-MCP; Biological and medical sciences; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; Persea americana; Sesquiterpenes; Volatile compounds
• ISSN: 0925-5214; 1873-2356
• DOI: 10.1016/j.postharvbio.2013.01.011

► The volatile profile of avocados changed during ripening and among cultivars. ► 1-MCP treatments delayed ripening and increased emissions of alkanes during ripening of ‘Booth 7’ and ‘Monroe’. ► Several compounds were detected in only one cultivar and could be useful for classification purposes. ► Sesquiterpenes were the main group of volatiles in all cultivars, with β-caryophyllene as the major compound, but were fairly detected in ripe fruit. ► Results suggest that ethylene participates in the regulation of the sesquiterpene α-copaene. Separate experiments were conducted with three major commercial avocado (Persea americana Mill.) cultivars grown in Florida: ‘Simmonds’ (early-season, West Indian race); ‘Booth 7’ (mid-season, Guatemalan-West Indian hybrid); and ‘Monroe’ (late-season, Guatemalan-West Indian hybrid). Fruit were harvested at preclimacteric stage and left untreated (Control) or treated 24h after harvest with aqueous 1-methylcyclopropene (1-MCP) at 1.39 (treatment M1) or 2.77μmolL−1 a.i. (treatment M2) (75 or 150μgL−1) for 1min at 20°C. Whole fruit ripening was monitored at 20°C/92%±3% R.H. and based on whole fruit firmness, respiration and ethylene evolution. Fruit volatiles were assessed at preclimacteric (24h after harvest), mid-ripe (half of initial fruit firmness) and ripe maturity stages, from 100g of chopped pulp using a purge and trap system. Untreated, firmer fruit ‘Monroe’ (268N at harvest) ripened within 12 d of harvest while softer fruit ‘Simmonds’ (118N) ripened within only 6 d. 1-MCP treatment extended ripening time from 33% (M1) to 83% (M2). All fruit softened normally, indicating the potential benefits of aqueous 1-MCP as a postharvest treatment for avocado when applied at these concentrations. Volatile profiles differed among the three cultivars with several compounds detected in only one cultivar, results that may contribute to a potential identification of the origin of the cultivar based on fruit volatile composition. The West Indian cultivar ‘Simmonds’ had much higher emission of hexanal (preclimacteric fruit) and cis-3-hexenal and cis-3-hexen-1-ol (ripe fruit) than the Guatemalan-West Indian hybrids ‘Booth 7’ and ‘Monroe’. On the other hand, these latter hybrids had much higher levels of alkanes than ‘Simmonds’. Treatment with 1-MCP increased emissions of alkanes during ripening of ‘Booth 7’ and ‘Monroe’. Total volatiles of avocado decreased during ripening mainly due to the significant reduction of sesquiterpenes, the m