Optimizing 60Co-γ irradiation for effective decontamination of strawberries: Harmonizing safety and quality

This study evaluated the effects of gamma irradiation on the microbial decontamination and quality parameters of strawberries. Strawberry fruits were exposed to gamma rays from a 60 Co source at doses of 0, 750, 1000, 1250, 1500, and 2000 Gy. Instrumental color measurements (L*, a*, b*, chroma) and phytochemical analyses, including anthocyanin content, were conducted to assess color changes. The microbial load, firmness, pH, acidity, reduced sugar concentration, antioxidant activity, total phenolic content, and total soluble solids were also evaluated to determine overall fruit quality. Additionally, microstructural changes and tissue firmness were evaluated by scanning electron microscopy (SEM) and a texture analyser, respectively. The results revealed that gamma irradiation significantly reduced fungal contamination and increased redness and anthocyanin content at moderate doses (up to 1250 Gy), enhancing fruit appearance. However, increasing the radiation dose adversely affected the contents of reduced sugars, total phenolic compounds (notably catechin, epicatechin, and ellagic acid), soluble protein, Brix, and firmness. Although gamma irradiation did not significantly alter acidity, a slight decrease in pH was noted. Notably, at 1250 Gy, increases in anthocyanin levels and antioxidant activity were observed, alongside increased redness and chroma indices, rendering the strawberries darker. Texture analysis and scanning electron microscopy (SEM) images revealed no visible damage to the strawberry tissue after irradiation, confirming the potential of this treatment to maintain structural integrity. These results suggest that a gamma irradiation dose of 1250 Gy effectively achieves microbial decontamination while minimizing undesirable changes in fruit quality. These findings suggest that an optimal irradiation dose balances microbial safety and quality preservation.