# Heat shock and glycine betaine treatments partially alleviate chilling injury in banana by enhancing phenolic and sugar metabolism

## TL;DR

Applying glycine betaine and hot water reduces banana chilling injury by boosting phenolic and sugar metabolism, improving fruit quality and shelf life.

## Contribution

The study shows that combining glycine betaine with hot water treatment effectively reduces chilling injury in bananas.

## Key findings

- GB + HWT reduced chilling injury in bananas by 48% and maintained fruit firmness.
- Treatments increased phenolic metabolism enzymes (PAL, C4H, 4CL) and soluble sugar levels.
- GB + HWT improved postharvest fruit quality by regulating sugar metabolism and phenolic accumulation.

## Abstract

Bananas are a widely consumed fruit in the world, but are highly susceptible to chilling injury below 13 °C, which reduces their quality. This study investigates the impact of hot water treatment (HWT), combined hot water and glycine betaine (HWT + GB), and hot air treatment (HAT) affects banana sugar and phenylpropanoid metabolism under cold stress, and the role of phenolics and soluble sugars in the alleviation of chilling injury (CI). The research findings showed GB + HWT treatment reduced the chilling CI index of bananas by 48 % and maintained fruit firmness. This treatment also showed increased TPC (25 %), TFC (47 %), PAL (29 %), 4CL (51 %), and C4H (50 %) activities and promoted phenolic compounds accumulation. GB + HWT treatment regulates sugar-metabolizing enzymes and balances sucrose, fructose, and glucose levels. The findings indicate that GB + HWT treatments alleviate chilling injury in bananas by stimulating phenolic and sugar metabolism, thereby enhancing fruit quality and extending shelf life.

•Glycine betaine plus hot water reduced banana chilling injury by 48 %.•Treatments enhanced phenolic metabolism through increased PAL, C4H, and 4CL activities.•Sugar metabolism enzymes (AI, SPS, SS) were positively regulated by treatments.•Soluble sugars (sucrose, fructose, glucose) accumulated more in treated bananas.•Combined GB + HWT treatment maintained firmness and improved postharvest fruit quality.

Glycine betaine plus hot water reduced banana chilling injury by 48 %.

Treatments enhanced phenolic metabolism through increased PAL, C4H, and 4CL activities.

Sugar metabolism enzymes (AI, SPS, SS) were positively regulated by treatments.

Soluble sugars (sucrose, fructose, glucose) accumulated more in treated bananas.

Combined GB + HWT treatment maintained firmness and improved postharvest fruit quality.