Enzymatic Browning in Artocarpus odoratissimus (Terap) fruits

Abstract

Enzymatic browning, which intensifies in response to tissue stress, remains a major limitation in the food industry as it adversely affects the visual quality and consumer acceptance of products. Artocarpus odoratissimus, a climacteric fruit rich in polyphenols, possesses a shorter shelf-life and is highly perishable, undergoing significant changes in tissue softening and browning. The objective of the present study is to determine the degree of browning and the browning-related enzymes in A. odoratissimus fruit during storage. The mature fruits were harvested and stored at ambient temperature (25°C) before analyses. Based on observations, terap fruits stored at 25°C exhibited surface browning by day 4, progressing to dark browning and deterioration by day 8. The higher colour changes (∆E) were obtained in fruit peel stored under 25°C, on day 4 at 23.70±1.39 and were twice as high on day 8 at 44.12±1.95. Meanwhile, the flesh colour transitions from slightly yellow on Day 4 (28.26±2.81) to entirely yellowish on Day 8 at 35.78±0.36 due to oxidation. The degree of browning for the ripened fruit peel was 0.37±0.01 and increased slightly from day 4 (0.41±0.02) to day 8 (0.47±0.01). Similarly, the flesh increased from 0.14±0.01 to day 4 at 0.21±0.01 and day 8 0.24±0.01. For the browning enzymes, the phenylalanine ammonia-lyase (PAL) and polyphenoloxidase (PPO) significantly increased in response to the storage period for peel and flesh. The browning enzyme in the peel was highly correlated with the degree of browning and PAL (R²=0.859) and PPO (R²=0.858). As for the flesh, the degree of browning was highly correlated with PAL (R²=0.766), respectively. This browning quantification can be used as a comprehensive insight to prevent browning in terap by treating them with anti-browning solutions, to enhance the fruits' quality, shelf life, and marketability.