Effects of 1-MCP and ULO on quality parameters, bioactive compounds, volatiles and sensory quality of Williams pears (Pyrus communis L.) during long-term storage

The aim of this study was to evaluate the quality parameters of Williams pears, including skin color, firmness, soluble solids content and titratable acidity, as well as the levels of vitamin C, polyphenols, and volatiles in fruits treated with 1-MCP and stored in normal atmosphere or in untreated fruits stored in ultra-low oxygen atmosphere (ULO, 1 kPa O2 / 1 kPa CO2). Analyses were performed after 5, 7, and 9 months of cold storage (-1 degrees C) followed by an additional shelf-life period of 5 days of storage at 20 degrees C. Fruits were also subjected to a descriptive sensory analysis by a trained panel and superficial scald was also evaluated. Our results confirmed that one of the main problems with 1-MCP pears is their "evergreen" behavior. They also showed that the efficacy of 1-MCP against superficial scald decreases significantly over long-term storage. In contrast, fruits stored under ULO conditions exhibited a very low incidence of scald (3 %) even after 9 months of storage. While ULO pears contained 30 % fewer polyphenols and half the vitamin C levels of 1-MCP pears, they were 10-13 times richer in volatile esters, the key aroma compounds of Williams pears. ULO pears were also found significantly juicier, sweeter and more aromatic than 1-MCP pears, which were perceived much firmer. Our results clearly demonstrate that ULO storage is the most relevant strategy for professionals to offer consumers Williams pears with a good eating quality throughout winter without using chemical treatments.