Molecular hydrogen-based irrigation extends strawberry shelf life by improving the synthesis of cell wall components in fruit

Abstract

Strawberries (Fragaria × ananassa Duch.) are highly perishable due to their soft texture, and easily decay during transportation and storage. Our previous report showed that molecular hydrogen-based irrigation in the form of hydrogen nanobubble water (HNW) could obviously improve flavor and consumer preferences of strawberry fruit at the harvesting stage. This study further investigated whether this approach could influence the shelf life of strawberry. During storage for 15 d at 4 ℃, HNW delayed the degradation in the quality of strawberry fruit, evaluated by alteration in sensory attributes (including aroma, luster, color, shape, and general evaluation), weight loss, contents of vitamin C, soluble sugar, and titratable acidity, and sugar/acid ratio. The higher levels of lignin, cellulose, and hemicellulose were observed. Compared to conventional surface water (control) irrigation, the firmness of fruit was increased by HNW irrigation at the harvest stage, and progressively maintained during the storage period. Molecular evidence revealed that before the harvesting period, the transcripts of cinnamyl CoA reductase (CCR) and cinnamyl alcohol dehydrogenase (CAD), as well as cellulose synthase 1/4/6 (CesF1/4/6), the representative genes for the synthesis of lignin, cellulose, and hemicellulose, were induced by HNW irrigation. These changes were positively matched with the increased lignin, cellulose, and hemicellulose contents at the harvesting period. Overall, the extended shelf life of strawberries achieved by molecular hydrogen-based irrigation might be due to the improvement in lignin, cellulose, and hemicellulose accumulation. Therefore, this study demonstrated the effectiveness of HNW irrigation for retarding the decay of harvested strawberries.