Electronic nose pattern, sensory profile and flavor components of cold stored 'Spring Belle' peaches: Influence of storage temperatures and fruit maturity assessed at harvest by time-resolved reflectance spectroscopy

This work aimed at studying the influence of non-destructively grading fruit at harvest by time-resolved reflectance spectroscopy (TRS) on E-nose pattern, sensory attributes and flavor components of peaches stored for 1 month at different temperatures. At harvest, 240 'Spring Belle' peaches were measured by TRS, ranked according to decreasing ?<inf>a</inf>670 (increasing maturity) in three maturity classes (less, medium, more mature) and stored at 0°C and 4°C. After 2 and 4 weeks of storage, peaches were put at 20°C and less (LeM) and more (MoM) fruit were analyzed after 2 and 3 days of shelf life for firmness, expressible juice, E-nose pattern, sugar and organic acid composition and were submitted to sensory analyses. Data were analyzed by PCA and four functions were extracted explaining 75% of total variance. PC1 grouped total acids, citric acid, malic acid, sourness, mechanical and sensory firmness against Su/Ac ratio, expressible juice, juiciness and sweetness and discriminated fruit according maturity marking the highest scores for LeM fruit stored for 2 weeks at 0°C at d2 of shelf life. PC2 was mainly related to E-nose sensors, opposing W1C, W3C and W5C sensors to W2S, W1S, W5S, W2W, W1W, W3S and W6S ones and its scores decreased with increasing storage time and decreasing temperature. PC3 was positively related to glucose, fructose and sorbitol and negatively to W5S, sourness and W1Wand decreased with storage time but only at 0°C. PC4 was strongly linked to sucrose and total sugars. These results showed that sorting peaches at harvest in different maturity classes by using TRS resulted in fruit developing different mechanical, chemical and sensory characteristics after storage. Peaches classified as less mature at harvest showed higher firmness and acids content and lower sugars and were consequently judged more firm, sour, less sweet, juicy and aromatic than more mature ones. E-nose discriminated fruit mainly according to storage conditions rather than to maturity degree, even if W5S, W1W and W2W showed the highest responses in the most mature fruit, that is in fruit belonging to the more mature class stored at 4°C.