Electron Beam Radiation of Dried Fruits and Nuts To Reduce Yeast and Mold Bioburden

Abstract

Dried fruits and nuts make up a significant portion of the commodities traded globally, and the presence of yeasts and molds on dried fruits and nuts can be a public health risk because of the potential for exposure to toxigenic fungi. Since current postharvest treatment technologies are rather limited for dried fruits and nuts, electron beam (E-beam) radiation experiments were performed to determine the doses required to reduce the yeast and mold bioburden of raisins, walnuts, and dates. The indigenous yeast and mold bioburden on a select number of commodities sold at retail ranged from 10(2) to 10(3) CFU/g. E-beam inactivation kinetics based on the linear model suggest that the decimal reduction dose required to eliminate 90% of the microbial population (D10-value) of these indigenous fungal populations ranges from 1.09 to 1.59 kGy. Some samples, however, exhibited inactivation kinetics that were better modeled by a quadratic model. The results indicate that different commodities can contain molds and yeasts of varying resistance to ionizing radiation. It is thus essential for the dried fruit and nut industry to determine empirically the minimum E-beam dose that is capable of reducing or eliminating the bioburden of yeasts and molds in their specific commodities.

The effect of electron beam on dates infestation

“…The reduction in YMC by EB was correlated to the doses used, with 2.0 kGy eliminating between 70 and 100% of YMC in date samples. This result is supported by Ic et al (2007), as they found 1.09e1.59 kGy was required to eliminate 90% of the YMC on dried fruits. All EB doses used in the present study reduced the YMC to below reference criteria for dried fruits which have maximum value of 3 log CFU/g (Food Administration, 1995).…”

“…Ic, Kottapalli, Maxim, and Pillai (2007) found 1.09e1.59 kGy was required to eliminate 90% of the yeast and mold on dried fruits. The effect of EB on food quality has been reported in different studies; Egea, Murcia, Sánchez-Bel, Romojaro, and Martínez-Madrid (2005) found no significant difference on physico-chemical and nutritional properties of apricots treated with 0.5 and 1 kGy.…”

Quantifying the Reduction in Potential Health Risks by Determining the Sensitivity of Poliovirus Type 1 Chat Strain and Rotavirus SA-11 to Electron Beam Irradiation of Iceberg Lettuce and Spinach

“…The surviving rotavirus (log PFU/g) and poliovirus (log PFU/g) concentrations were plotted as a function of the measured dose (kGy). The slope of the curve was determined from the regression analysis, and the negative reciprocal of the slope was calculated to be the D 10 value (dose required to reduce virus titers by 90%) (21). The data from the experimental replicates were used in plotting the virus inactivation curves (Fig.…”

Scientific Opinion on the efficacy and microbiological safety of irradiation of food

“…fresh-cut fruits and fresh fruit salads IAEA 2006;Prakash and Foley, 2004). The use of irradiation was also investigated on dried fruits and nuts (Ic et al, 2007).…”

“…For instance, D 10 values of the indigenous fungal microflora were around 1-1.6 kGy (Ic et al, 2007). Globally, bacterial, non spore forming, food-borne pathogens as Salmonella or E. coli O157, are not more resistant to irradiation than the spoilage or indigenous microflora of fruits.…”