Irradiation has beneficial, detrimental effects on product quality.

Contaminated raw vegetables, fruits and fruit juices, at one time or another, have been vehicles for the transmission of pathogens. These foods are often eaten raw without the benefit of any pathogen-killing treatment.

Various data indicate that the viability of pathogenic organisms on the surface of fresh fruits and vegetables can be significantly reduced by treating them with electron beam irradiation at dose levels of 1.0 kGy and greater. However, irradiation may induce undesirable changes in the quality of a product, such as softening, browning and loss of nutritional factors.

The purpose of current research is to optimize electron beam irradiation as a technology suitable for treating agricultural commodities to make them safe and long-lasting fresh or processed products. The evaluation of the potential effect of this technology on the quality of produce will lead to recommendations for an appropriate treatment that would optimize quality, extend shelf life and eventually maintain product safety. In addition, the maturity of produce and the type of packaging system used are additional factors to consider in keeping products safe and microbial counts low.

Studies have been undertaken to determine the effect of electron beam irradiation, with dosages ranging from 1.0 kGy to 3.1 kGy, on a variety of several types of produce: whole and fresh-cut packaged cantaloupes, romaine lettuce hearts, blueberries and mangoes. The studies indicate that irradiation has both beneficial and detrimental effects on the physical, nutritional and organoleptic qualities of these foods.

In general, sensory attributes, such as overall quality, color, sogginess and off-flavor, were less acceptable at the higher dose level. However, all products maintained their overall quality when they were irradiated at low dose levels--1.0 kGy and 1.5 kGy.

Yet there still are many uncertainties regarding the potential effects of irradiation on food quality. For example, the mechanisms responsible for an increase in the phenolics content of berries must be identified and understood. The next step is to accurately predict the chemical changes responsible for changes in produce quality.

Further information. Rosana Moreira, Department of Biological and Agricultural Engineering, Texas A&M University, 306-C Scoates Hall, 2117 TAMU, College Station, TX 77843; phone: [phone]; fax: [phone]; email: [e-mail].