Evaluation of Quality and Sensory Attributes of Purple Passion Fruit (Passiflora edulis Sims) Harvested at Different Stages of Maturity

Maturity at harvest significantly affects the eating and keeping quality of climacteric fruits such as purple passion fruit. This study's objective was to determine the effect of harvest maturity of purple passion fruits on selected quality and sensory attributes. Fruits were harvested from a commercial orchard in the Moiben district of Uasin Gishu County in Kenya at three stages of maturity based on intensity of the purple peel color as; ≤25% (S1), 50% to 75% (S2), and 100% (S3). After initial measurements, the fruits were left to ripen at ambient room conditions (25±1 °C and RH 60±5%). During the storage period, six fruits from each maturity stage were sampled regularly and evaluated for cumulative weight loss, peel color change, total soluble solids (TSS), total titratable acidity (TTA), sugars, ascorbic acid, and beta carotenes. At the end of the storage period, untrained panelists evaluated the sensory attributes of the extracted juices including color, acidity, sweetness, aroma and overall preference. The data shows that S1 fruits failed to attain the full purple color, retaining a lower (greener) hue of 296°±3 at the end of storage compared to 310°±4 of S3 fruits. Similarly, other quality attributes of S1 fruits were inferior to those of S2 and S3 fruits. Juice from S1 fruits had high initial TTA, which remained relatively higher compared to that of S2 and S3 fruits throughout the storage period. The TSS content of the juices increased gradually from the initial 8.9±0.7, 12.5±0.9 and 13.7±1 to peaks of 12.6±0.8, 14.2±0.9 and 14.8±1 (°Brix) in S1, S2, and S3 respectively. Consequently, at the end of storage, S1 fruits’ juice had the lowest TSS : TTA ratio. Ascorbic acid content decreased gradually from the initial 46.2±4, 43±3 and 40±3.8 to 27.1±2, 26.1± 4 and 25.4±3 (mg/100ml) in S1, S2, and S3 fruits’ juice, respectively, at the end of storage period. Beta carotene and sugar levels increased gradually during storage, with S1 fruits having the lowest levels. Cumulative weight loss was most rapid in S1 fruits, which lost 37.4±2.5% of the initial weight at the end of storage compared to 29.6±1.8% in S3 fruits. The untrained sensory panelists showed preference for S3 fruits’ juice as evidenced by high scores on the hedonic scale. This evaluation by untrained panelists’ positively correlated with instrumental evaluation of the quality attributes. Results affirm the importance of harvest maturity on passion fruit quality attributes and overall consumer acceptance.