Purpose: The research assessed the effect of UV-C intensity on total yeast and mold count, bacterial reduction, blueberry quality, and shelf-life.
Methods: Blueberries were exposed to three different radiation intensities of low=1.1 mW/m2; medium 4.1 mW/m2 and high=7.6 mW/m2 as treatment and those intensities were applied separately at three different doses (1, 2, and 4 kJ/m2) as an experimental block. By the time the treatments were completed, fifty blueberries were packed in groups, in plastic clamshells, and stored 4◦C. Untreated blueberries were packed and stored, as previously described, as controls. At each sampling time of 0, 1, 7, 14, 21, 28, 35, 49, and 70 days, berries were immediately analyzed or freeze dried.
Results: Gray mold (Botrytis cinerea) was the main causal agent for decaying fruit. Weight loss, titratable acidity, soluble solids, and firmness were not significantly affected by UV-C intensity. UV-C treatment reduced decay, significantly, and fruit exposed to higher intensities showed significantly lower mold deterioration (p<0.05). Mold count were not affected by increased intensity, suggesting that decrease mold decay did not result from greater germicidal effect of UV-C, but some indirect mechanism mediated improving defense response of fruit by increased intensity. Total anthocyanin content and total phenolic content values increased with treatment intensity.
Significance: UV-C treatment reduced storage loss by one third at the end of 10 weeks. For a given dose, increasing UV-C intensity increased fruit quality and reduced spoilage loss, while significantly reducing the treatments time.