Physicochemical quality maintenance and bioactive compounds enhancement of Thai guava fruit cv. ‘Kim Ju’ by using combinative hot water and methyl jasmonate immersion

Abstract

Postharvest life of Thai guava fruits is limited due to skin damage and physicochemical changes during cold storage. Both methyl jasmonate (MeJA) and heat treatments are potential approaches maintaining postharvest quality of fruits. Thus, the aim of this work was to investigate the effects of hot water and MeJA immersion on physicochemical quality of ‘Kim Ju’ guava fruit during storage at 12 ± 1 °C for 18 d. The fruit were immersed in hot water at 40 °C for 30 min (H), 0.1 mM MeJA for 10 min (0.1 mM MeJA) or H followed by 0.1 mM MeJA (H + 0.1 mM MeJA) and untreated fruit were used as control. The determined parameters were visual appearance, colour, texture, pectin substances, antioxidant activities, bioactive compounds and antioxidant enzymes activities. The results showed that H + 0.1 mM MeJA treatment maintained visual appearance and colour as compared to 0.1 mM MeJA, H or control treatment, consequently. The treatment of H + 0.1 mM MeJA retarded softening according to the inhibition of soluble pectin increase and insoluble pectin decrease. The treatment enhanced the both antioxidant and free radical scavenging activities as compared to control. These were accompanied with the increments of bioactive compounds such as ascorbic acid, total phenols, flavonoids and peroxidase activity and the retardation of catalase activity decrease. In conclusion, the H + 0.1 mM MeJA treatment could maintain postharvest qualities involving visual appearance and texture and enhanced nutritional value of guava fruit during cold storage.

The Influence of Physical Treatments on Phytochemical Changes in Fresh Produce after Storage and Marketing

“…These changes were accompanied by changes in the levels of bioactive compounds such as ascorbic acid, total phenols and flavonoids, and changes in peroxidase activity. There was also a partial suppression of the expected decrease in the catalase activity [59].…”

“…Heat treatments were also reported to produce signals that induce the synthesis of specific proteins, some of which are enzymes metabolism of some phytochemicals. The increased activity of these enzymes leads to the accumulation of bioactive compounds in the fruit or vegetable after harvest [29,32,43,49,59,66].…”