Relationship between sensory characteristics and optical properties in ‘Conference’ pears

Pears are appreciated by consumers for their juicy-buttery texture, sweet flavour and pleasant aroma. Sweetness and juiciness are the main drivers for consumer liking, while firm-grainy textures and lack of flavor are disliked. Thus, it is important that the industry can provide high quality fruit to encourage pears consumption. Nondestructive techniques, such as time-resolved reflectance spectroscopy (TRS), can help producers in discriminating pears with different sensory characteristics to satisfy consumer expectations. The aim of this work was to study the relationship between sensory characteristics, quality, and optical properties (absorption and scattering) measured by TRS, in ‘Conference’ pears. At harvest, fruit were measured by TRS for absorption coefficient at 650 nm (μa650), ranked by μa650 in three maturity classes (less, medium, more mature), and randomized in four samples according to 1-MCP treatment (treated, untreated) and storage atmosphere (air; CA: 2 kPa O2, 1 kPa CO2). After 4 months of storage at -1°C plus 7 days at 20°C, less and more mature pears were measured by TRS at 650, 780 and 940 nm, analyzed for firmness (FF), soluble solids (SS) and acidity (TA) and submitted to sensory analysis. Cluster analysis applied on sensory attributes produced three groups (W1, W2, W3), each one representing a specific sensory profile. W1 showed the lowest scores for sweetness and the highest for sourness and astringency. W2 grouped pears with the lowest scores for firmness and astringency and the highest for sweetness, aroma and acceptability together with the lowest FF, μa940 and µs780 values. W3 showed the highest scores for firmness and graininess and the lowest for juiciness and aroma, coupled with the lowest TA and the highest FF, μa650, μa940 and µs780 values. Discriminant analysis based on TRS optical properties correctly classified W1, W2 and W3 profiles in 27, 92 and 67% of the cases, respectively.