Influence of storage (time, temperature, atmosphere) on ripening, ethylene production and texture of 1-MCP treated ‘Abbé Fétel’ pears

Abstract

‘Abbé Fétel’ is the most important pear cultivar in Italy but is susceptible to superficial scald and soft scald during storage, the former effectively prevented by 1-methylcyclopropene (1-MCP) treatment at harvest and by dynamic controlled atmosphere (DCA). However, 1-MCP at −0.5°C prevents pear ripening, and DCA can favor the appearance of soft scald, especially after long storage. The aim of this research was to study how postharvest treatments (storage atmosphere, temperature and time) can modulate the ripening ability in storage of 1-MCP treated ‘Abbé Fétel’ pears. To this aim, control and 1-MCP treated (SmartFresh™, 300nLL−1) pears stored in air (NA), controlled atmosphere (CA) and DCA at either −0.5°C or 1°C for 20 and 28 weeks were evaluated for ripening in storage by relating the spectral maturity indices IAD (index of absorbance difference), bound to chlorophyll, and Icarot (carotenoids index), bound to carotenoids, to ethylene production, background skin color, mechanical properties of the pulp (firmness, stiffness and energy-to-rupture) and sugar (soluble solid content) and organic acid (titratable acidity) contents. The 1-MCP treatment drastically reduced ethylene production, impaired skin yellowing and fruit softening during storage of fruit kept at −0.5°C, regardless of storage atmosphere and length of storage. The 1-MCP treatment coupled to 1°C storage in NA succeeded in maintaining firmness and green color in storage but without blocking them, as indicated by the significant decrease in texture parameters and background skin hue achieved already in storage. 1-MCP treated samples which did not ripen in storage (DCA@−0.5°C, DCA@1°C, CA@−0.5°C of both storage times and CA@1°C at 20 weeks) were distinguished from the 1-MCP treated pears which began to ripen at different times in storage, i.e. NA@−0.5°C, showing the least marked changes, and NA@1°C after 28 weeks, having the highest changes in ripeness in storage. In control fruit, IAD index better correlated to TA and ethylene production, while Icarot index better correlated to pulp mechanical properties and allowed the differentiation of control samples according to the ripeness degree reached already in storage, with NA@1°C fruit after 28 weeks being the ripest and DCA@−0.5°C pears after 20 weeks, the least ripe.