1-Methylcyclopropene application, storage temperature and atmosphere modulate sensory quality changes in shelf-life of ‘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 is 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, specially after long storage. The aim of this research was to study the sensory profiles of 1-MCP treated (SmartFresh™, 300nLL−1) and untreated ‘Abbé Fétel’ pears after 20 and 28 weeks of storage at −0.5°C and 1°C in normal air (NA), controlled atmosphere (CA) and DCA and up to 7 days of post-storage shelf-life at 20°C, and their relationships with mechanical characteristics of the pulp (firmness, stiffness and energy-to-rupture) and sugar (SSC) and acids (TA) content. During storage and shelf-life, untreated fruit softened, more at 1°C than at −0.5°C, and to a greater extent after 28 weeks of storage, while 1-MCP treated pears on average showed higher values of firmness, stiffness and energy-to-rupture than untreated fruit, independently of storage time and days of shelf-life. Mechanical properties of the pulp were positively correlated with sensory firmness and negatively with juiciness, sweetness and aroma, the three descriptors positively correlated with overall acceptability. Cluster analysis carried out on sensory scores separately for 20 and 28 weeks samples underlined that, within either untreated or 1-MCP treated samples, similar sensory profiles could be obtained in response to the diverse combinations of storage atmosphere, storage temperature and day of shelf-life. The most preferred sensory profile (juicy, not grainy, sweet, aromatic, quite sour and less astringent) was obtained for untreated pears after 20 weeks storage at −0.5°C in CA, independently of time of shelf-life and in NA and DCA after 4 and 7 days of shelf-life, as well as in DCA pears stored at 1°C after 4 and 7 days of shelf-life. In contrast, the worst sensory characteristics (grainy, not firm, not juicy, not sweet, not sour, very astringent and not aromatic) distinguished untreated pears after 28 weeks storage at 1°C in NA. After 20 weeks storage, the two sensory profiles of 1-MCP treated fruit were both characterized by firm texture associated with graininess but differing for the flavor description, and were less preferred by the assessors. After 28 weeks storage it was possible to distinguish the sensory profile of 1-MCP treated pears stored at −0.5°C after 4 and 7 days of shelf-life, from that of 1-MCP treated pears stored at 1°C after 3 days of shelf-life. Both profiles were characterized by a firm/quite grainy texture but differed for flavor, the former being less sweet, less sour, less astringent and less aromatic than the latter.