Effect of drying parameters on the physicochemical, microbiological, and sensory properties of lemon balm (Melissa officinalis L.)

Abstract

Lemon balm (Melissa officinalis L.) has been recognized for multiple health benefits due to bioactive compounds. Dehydration is usually the most widely used method to preserve and concentrate these elements. However, it can also affect and totally or partially degrade the quality of the product under incorrect processing conditions. This research aimed to evaluate the effect of drying parameters on Melissa’s physicochemical, microbiological, and sensory properties. In total, four treatments were analyzed according to the experimental design (T1: 25 °C and 1.5 m s-1, T2: 25 °C and 3.0 m s-1, T3: 45 °C and 1.5 m s-1, and T4: 45 °C and 3.0 m s-1). Drying kinetics were determined using a vertical airflow dryer and a continuous weighing system. The results were compared with fresh leaves. The findings obtained show that increasing temperature and varying drying speed reduces moisture content and aw but increases enzymatic activity and essential oil content. In the drying process, temperature has a greater effect in the initial stages of the process, while drying speed on the internal structure of the raw material. By optimizing the drying conditions, it is possible to reduce the drying time by 44%. Page’s model showed excellent ability to predict drying kinetics under various drying conditions (RMSE <0.04 and R2>0.98). In terms of color, lightness decreased because of temperature, while a* and b* values were affected by non-enzymatic browning. Treatment T4 was the product with the highest acceptability. The findings obtained provide a theoretical basis to optimize the lemon balm drying process. Drying Melissa at 45 °C and 3.0 m s-1 can improve the quality and composition of the final product.