Combined Microwave-Vacuum Decontamination and Drying of Black Pepper (Piper Nigrum) Pretreated with Steam

Abstract

Objective: • To develop and optimize a combined MW-Vacuum-Steam process for decontamination and drying of black pepper • Mathematical modelling and study of the qualitative changes in black pepper Methodology: Black Pepper (Piper nigrum) also known as black gold is one of the most traded spices in the world. Recent instances have reflected increased numbers of export rejections due to the presence of Escherichia coli, Salmonella and a high load of microbes. This study presents the potential of a novel combination of microwave-vacuum–steam treatment that is capable of bringing down the high microbial load in the product at relatively low temperatures. Different mathematical models like Newton, Henderson & Pabis, Page and Wang & Singh models were applied to study the drying kinetics. Results and Conclusions: The treatment has resulted in 7.59 log reduction for E. coli, 9.25 log reduction in Salmonella and around 3.28 log reduction in total mesophilic plate count. The optimized condition was found to be 4.19 W/g MW power density, 3 s steam time and 134 s process time. Page model and Wang & Singh model was found to be most significant. The process optimized and developed in this study with low microwave power density has the potential to be used industrially for bulk decontamination of spices