Heat treatments delay ripening and postharvest decay of strawberry fruit

CIVELLO P.M; MARTINEZ G.A; CHAVES, A.R; AÑÓN, MARÍA CRISTINA

JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY

AMER CHEMICAL SOC

Lugar: Washington; Año: 1997 vol. 45 p. 4589 - 4594

0021-8561

Fully red strawberries (Fragaria ananassa Duch. cv. Selva) were treated for 1-5 h at temperaturesranging from 39 to 50 °C. After treatments, fruits were placed at 0 °C overnight and then held at20 °C for 3 days. Most of the heat treatments improved strawberry shelf life, with best resultsobtained for fruit heated at 42 °C and 48 °C for 3 h. Heat treatments prevented fungal developmentand decreased the number of damaged fruits. These treatments were then used to treat strawberriesat 50-75% red to analyze effects on firmness, surface color, anthocyanin content, PAL activity,polypeptide composition, and protein synthesis. Softening rate and external color development wasless in fruit heated at 48 °C compared to the control, while treatment at 42 °C did not significantlyaffect these parameters. However, both treatments reduced anthocyanin accumulation and PALactivity relative to the controls. In addition, treatment at 48 °C for 3 h reduced protein synthesis,but this effect was partially reversed after holding fruits at 20 °C for 48 h. Heat treatments (42and 48 °C) led to the accumulation of five heat shock proteins of 88, 76.5, 69, 19, and 17 kDa. Inaddition, treatment at 42 °C induced the synthesis of a 22 kDa polypeptide that was not observedin the 48 °C treatment. Fruits treated at 48 °C continued the synthesis of 69, 19, and 17 kDapolypeptides even after 48 h at 20 °C. According to these results, the lower fungal developmentand the slower ripening rate shown by heat-treated fruits suggest that this physical method couldbe useful to extend the postharvest shelf life of strawberry.