γ線照射によるイチゴの貯蔵効果および<I>Botrytis cinerea</I>の致死線量

Abstract

Effectiveness of gamma irradiation as a protective means against post-harvest decay in ‘Donner’ strawberries was studied.Very fresh strawberries packed in monolayers in polyvinylchloride boxes were wrapped with ordinary cellophane or water-proof cellophane, and irradiated immediately.When strawberries were stored at 23°C, 10% infection due to mould fungi, such as Botrytis cinerea, Rhizopus and Penicillium, was found 3 days after 0 KR irradiation, 4 days after 100 KR irradiation, and 5 to 6 days after 200 KR irradiation. This means that their shelf life can be extended by 2 or 3 days by irradiation treatment. Cellophane has been found to be more favorable than waterproof one when it is used as wrap-film at room temperature.Weight of irradiated berries decreased, independently of dose, linearly with storage time.When strawberries were stored at 8°C, berries were found to be kept clean for 7 to 8 days without irradiation, for 11 to 12 days with 200 KR irradiation and for 14 to 16 days with 300 KR. In this case, water-proof cellophane is more effective.Main pathogen, strain no. TO-1 of ‘Donner’ berries produced in Gumma Pref. was isolated and identified as Bot. cinerea. From its survival (vs. dose) curve and the survival curve of B. cinerea IAN 5128 (one of the collection of the Institute of Applied Microbiology, Univ. of Tokyo) as a standard rot, their lethal doses were determined as 970 KR and 540 KR, respectively. It has been found that Botrytis are more resistant to radiation than Aspergillus and Penicillium.