Hydrothermal and UV-C radiation treatments for postharvest control of bull's-eye rot of apples in a commercial packing line/Tratamentos hidrotermico e com radiacao UV-C no controle pos-colheita da podridao olho-de-boi em uma linha comercial de selecao de macas

This research was carried out to evaluate the effects of hydrothermal and UV-C radiation treatments for postharvest control of bull's-eye rot (BER) on 'Fuji' apples, after one and eight months storage under controlled atmosphere (CA) and 'Gala' apples, after five months storage under CA. These fruits were inoculated or naturally infected with Cryptosporiopsis perennans (causal agent of BER). 'Fuji' apples were submitted to the following treatments implemented in a commercial packing line: 1) Control; 2) Hydrothermal treatment (water at 50[degrees]C, sprayed for 12 seconds); 3) UV-C radiation (0.0069 kJ [m.sup.-2]); and 4) Hydrothermal treatment + UV-C radiation. 'Gala' apples were submitted to the same treatments described for 'Fuji', except the hydrothermal treatment water + UV-C radiation. After the treatment, the apples were incubated at 22[degrees]C for 15 days and assessed for incidence. On 'Fuji' apples, the hydrothermal treatment and/or UV-C radiation was efficient, providing more than 56% and 54% reduction of BER compared to the control, in fruit inoculated and with natural infection of C. perennans, respectively. On 'Gala' apples inoculated with C. perennans, the ermal treatment and UV-C radiation were equally effective to reduce the number of colony formation units (CFU) recovered from treated fruits (more than 70% reduction in comparison to the control) and BER incidence (more than 69% reduction in comparison to the control). On 'Gala' apples with natural infection, these treatments provided more than 85% reduction of BER compared to the control. The results show that hydrothermal treatment (water at 50[degrees]C, sprayed for 12 seconds) and UV-C radiation (0.0069 kJ [m.sup.-2]) are equally effective to control BER on 'Gala' e 'Fuji' apples when implemented in a commercial packing line. However, UV-C radiation was the most effective treatment and had the best economical return in both cultivars.