Spouted Bed Drying of White Pepper (Piper nigrum L.) with Microwave Preheating Treatment

Abstract

Abstract Drying is an important process in the production of high quality of white pepper commodities that have a high economic value. The objective of this study was to investigate the drying process and the quality of white pepper after spouted bed drying with microwave preheating treatment based on quality parameters of total oil content and microbial contamination. The results of the study indicated that the drying process of spouted bed was able to reduce the moisture content of pepper on average by 59.94% d.b. for 31 minutes on treatment of non-preheating, 60.38% d.b. for 37 minutes on treatment of preheating of 320 watts, and 59.35% d.b. for 32 minutes at treatment of preheating of 640 watts. The initial white pepper seeds that was boiling and soaking for 3 days had a total microbial contents of 2.5 × 107 CFU/g. Total microbial of white pepper after spouted bed drying process without preheating was 1.54 × 105 CFU/g, while the total microbes of white pepper with preheating treatment of 320 and 640 watts were 3.0 × 104 and 6.0 × 103 CFU/g, respectively. Oil content in all treatments was not significantly different. Oil content obtained in the treatment of non-preheating, preheating of 320 watts and preheating of 640 watts were 2.88%, 3.21% and 2.86%, respectively. It can be concluded that, in all treatments, the amount of moisture reduction and the drying time were relatively similar. However, preheating treatment can reduce microbial content to the IPC quality standard.