*Article* **Antioxidative Responses to Pre-Storage Hot Water Treatment of Red Sweet Pepper (***Capsicum annuum* **L.) Fruit during Cold Storage**

**Jirarat Kantakhoo and Yoshihiro Imahori \***

Laboratory of Postharvest Physiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-1 Gakuen-cho, Nakaku, Sakai, Osaka 599-8531, Japan; jirarattim@gmail.com **\*** Correspondence: imahori@plant.osakafu-u.ac.jp; Tel.: +81-72-254-9418

**Abstract:** The effects of hot water treatments on antioxidant responses in red sweet pepper (*Capsicum annuum* L.) fruit during cold storage were investigated. Red sweet pepper fruits were treated with hot water at 55 ◦C for 1 (HWT-1 min), 3 (HWT-3 min), and 5 min (HWT-5 min) and stored at 10 ◦C for 4 weeks. The results indicated that HWT-1 min fruit showed less development of chilling injury (CI), electrolyte leakage, and weight loss. Excessive hot water treatment (3 and 5 min) caused cellular damage. Moreover, HWT-1 min slowed the production of hydrogen peroxide and malondialdehyde and promoted the ascorbate and glutathione contents for the duration of cold storage as compared to HWT-3 min, HWT-5 min, and control. HWT-1 min enhanced the ascorbate-glutathione cycle associated with ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, but it was less effective in simulating catalase activity. Thus, HWT-1 min could induce CI tolerance in red sweet pepper fruit by activating the ascorbate-glutathione cycle via the increased activity of related enzymes and the enhanced antioxidant level.

**Keywords:** *Capsicum annuum* L.; hot water treatment; chilling injury; ascorbate-glutathione cycle
