Quality of Electron Beam Irradiated Strawberries

Abstract

MATERIALS & METHODSFresh 'Tristar' strawberries were treated by electron beam irradiation to determine the effects on postharvest quality attributes and shelf life. The intensity of red color rated by sensory panelists decreased as irradiation dosage increased from 0 to 2 kGy. Hunter 'L' values were higher for fruit treated with 2 kGy than for 0 and 0.5 kGy. In&on firmness values were lower for all irradiated fruit than for control fiuit. Panelists rated irradiated fruit less firm than nonirradiated fruit stored 1, 2 and 4 days. An increase in off-flavor was noted among all treatments stored 6 and 8 days. Irradiation suppressed fungi on stored berries. Irradiation doses of 1 and 2 kGy extended shelf life 2 and 4 days, respectively. Electron beam irradiation technology has excellent potential for extension of shelf life of fresh strawberry fruits.'TRISTAR' STRAWBERRIES (Frugaria X ananassa Duch.) were harvested at the Iowa State University Horticulture Research Farm, Ames, IA, transported to a laboratory within 1 hr after harvest, and :sorted for size (2.0 to 2.5 cm diam) and degree of ripeness (tilly red ripe, with no blemishes) into plastic containers (20.6 X 15.0 X 4.0 cm) with airexchange holes. About 35 berries were placed one layer deep in each container. Three containers/treatment were prepared. Fruit were not washed before irradiation. All treatments were stored at 2°C = 3 hr before irradiation.

Strawberry Texture and Pectin Content as Affected by Electron Beam Irradiation

“…Firmness data were reported by Yu et al (1995) and were compared with our data on pectin content changes. Instron firmness decreased with an increase in irradiation dose.…”

“…The effects of electron beam irradiation on texture and pectin changes of strawberries are unknown. We used both Instron and sensory methods to evaluate the firmness of irradiated strawberries and found similar results with electron beam and gamma irradiation, i.e., strawberries lost firmness after electron beam irradiation (0.5, 1, and 2 kGy doses) (Yu et al, 1995). Our current objective was to determine underlying changes in pectic substances as influenced by lowdose irradiation and any relationship between fruit texture and such changes.…”

Quality of electron beam irradiation of blueberries (Vaccinium corymbosum L.) at medium dose levels (1.0–3.2 kGy)

“…Miller and McDonald (1996) observed that blueberries irradiated with gamma rays at 0.5 and 1.0 kGy were softer by 33% and 38%, respectively. Yu et al (1995) showed that strawberries were significantly less firm after electron beam irradiation at doses of 0.5, 1.0 and 2.0 kGy.…”

Effect of High Electric Field on Shelf Life of Strawberries.

“…Recently, Yu et al ( 1995) found that electron beam irradiation suppressed fungi growih on fresh strawberries with the extension of their shelf life. There is no report on HEF application for the extension of the shelf life of strawberries.…”