Harvest Discrimination of Pomegranate Fruit: Postharvest Quality Changes and Relationships between Instrumental and Sensory Attributes during Shelf Life

Abstract

Harvest maturity discrimination was carried out for "Ruby" pomegranate cultivar in simulated handling conditions for long distant supply chains. Fruit were harvested at 3 different maturities along days after full bloom (DAFB); Harvest 1 (H1) at 133 DAFB, H2 at 143 DAFB, and H3 at 157 DAFB. The effects of harvest maturity and storage duration on fruit quality attributes during a 6-wk period of cold storage (5°C, 95% RH) and subsequent 5 d of shelf life (20°C, 75% RH) were investigated. Instrumental evaluation of aril color, juice content, juice absorbance (520 nm), total soluble solids (TSS), pH, titratable acids (TA), and phytochemical components including total phenolics, flavonoids, and anthocyanins were carried out. Textural properties of arils which included hardness, toughness, bioyield point, and Young's modulus were also investigated. During the shelf life period, arils from individual fruit were rated by a trained sensory panel based on appearance, taste, and texture. Relationships between the instrumental and descriptive sensory data were explored and fruit harvest maturities were discriminated using discriminant analysis. Among the attributes evaluated, TSS:TA, sweet taste, and the CIE hue angle (h°) were the most decisive attributes distinguishing the harvest maturities. The optimum time for harvesting was at 143 DAFB (H2) when fruit TSS:TA ratio was > 55, which coincided with significantly higher rating for sweet taste in fruit at H2 than at H1 and H3 during shelf life. The harvest index proposed in the current study could be used as a guide to establish a reliable harvest maturity index to assist in assuring fruit quality in consideration of long supply chains for the investigated cultivar.