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Sweet cherries (Prunus avium L.), members of the Rosaceae family, are a rich source of sugar, proteins, and phenolic compounds, such as anthocyanins and quercetin. Their highly seasonal character and high moisture content make them perishable, necessitating preservation methods to extend shelf life and minimize losses while preserving nutritional and organoleptic quality. Drying is a common preservation method for many fruits and vegetables, including sweet cherries. It involves removing moisture from the product to reduce microbial growth and enzymatic activity. The drying temperature is a critical factor affecting the quality of the dried product, as it can influence the retention of nutrients, color, and flavor. To investigate the effect of drying temperature on the primary and secondary metabolites of two varieties (Van and Burlat) of Moroccan sweet cherries, we conducted a study using an indirect solar dryer at 50, 60, 70, and 80°C. The cherries were harvested in Marrakech in June 2019 at the mature stage, cleaned, and dried in forced convective mode. After drying, the sugar, protein, and polyphenol content were measured using spectrophotometric methods [1-4]. The rehydration capacity [5] and the color parameters were determined using a Konika Minolta CR400 colorimeter. Our results showed that the drying temperature had a significant effect on the primary and secondary metabolites of both varieties of sweet cherries. For sugars, the highest content was observed at 70°C (253.61±7.36 and 263.75±22.30 mg/g DM). For proteins, the highest content was observed at 50°C (38.78±4.71 and 30.83±4.64 mg/g DM for the two varieties, respectively), followed by 60°C, 70°C, and 80°C. For polyphenols, the highest content was also observed at 70°C (26.50±1.25 and 29.28±1.39 mg/g DM for the two varieties, respectively), followed by 60°C, 50°C, and 80°C. The drying temperature also affected the color and rehydration capacity of the dried cherries. The color difference ΔE increased with drying temperature, while the browning index BI decreased with drying temperature. The rehydration capacity decreased with increasing drying temperature. Overall, our findings suggest that 70°C is the optimal drying temperature for preserving the nutritional and organoleptic quality of Moroccan sweet cherries, while still maintaining high sugar and polyphenol content. However, further studies are needed to optimize other drying parameters, such as drying time and airflow rate, to further improve the quality of the dried product.
