Intermittent high-power short-time microwave-vacuum treatment combined with steam impingement for effective microbial decontamination of black pepper (Piper nigrum)

Black Pepper (Piper nigrum) also known as black gold is one of the most traded spices in the world. Recent in-stances 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. 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. 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.

Automated summary

Black Pepper, also known as black gold, is a highly traded spice, but recently, export rejections have increased due to the presence of bacteria like Escherichia coli, Salmonella, and high microbial load. In this study, a novel combination of microwave-vacuum-steam treatment was developed to reduce the microbial load in black pepper at low temperatures. The treatment resulted in significant reductions in E. coli, Salmonella, and total mesophilic plate count. The optimized condition for the treatment was determined. This study provides a potential industrial method for bulk decontamination of spices.