The effect of intermittent cooling during drying on phytochemical retention of misai kucing (Orthosiphon stamines)

This paper discusses the possibility to adopt intermittent cooling during drying of misai kucing. Intermittent cooling was done for 30, 60, 90 and 120 min at 25 °C (ambient condition) during drying process. The effect of intermittent cooling time during drying on phytochemical retention in misai kucing was investigated using cabinet dryer. Intermittent cooling had shown better retention of rosmarinic acid in misai kucing as compared with continuous drying. The level of rosmarinic acid, the marker compound in misai kucing was higher in samples subjected to intermittent cooling treatment as compared to continuous drying. Intermittent cooling from 60 – 120 min reduced drying time from 25 h to 23 h. Colour of dried misai kucing was retained better when the plant subjected to intermittent cooling for 60 min and above. However, antioxidant activity, total phenolics and flavonoids content were not affected by intermittent cooling treatment.