Comparison of guava (Psidium guajava) qualities between naturally ripened fruit and artificial temperature treated fruit after harvest

To reuse abandoned farmland of former tea and citrus farms in Shizuoka, Japan, guava (Psidium guajava L.) cultivation was initiated, although producers encountered problems such as drop of matured fruit and non-uniform maturation period. In the present study, we attempted to reveal the effectiveness of simultaneously harvesting the immature fruit. The immature fruit planted on the southern slope of the former tea farm were harvested and separated into three groups based on skin color: green (control), yellow-green, or yellow. Artificial yellow-green, yellow, and orange skin color fruits were also obtained through temperature treatment (25°C) for 3- and 9-days. Analyses were performed to determine fruit quality, including soluble solid content (SSC), titratable acidity (TA), ascorbic acid content, flesh color, and antioxidant activity. Since all of the naturally ripened orange fruits dropped, we could not analyze the fruit quality of that group. The artificial orange fruit after 9-days of 25°C treatment showed higher antioxidant activity than the yellow fruit ripened naturally, although the SSC was slightly lower. Moreover, developmental changes in the fruit skin color after temperature treatment showed a positive correlation with red flesh pigmentation contents, demonstrating that fruit qualities of the orange fruit after 9-days of 25°C treatment were comparable to those of the naturally ripened fruit. Therefore, the simultaneous harvest technique at the immature stage can overcome the quality and harvest-loss problems, when it was combined with the postharvest temperature treatment, generating new opportunities for guava cultivation in Japan’s temperate regions.