Changes in Microbial Load of Black Pepper (Piper nigrum L.) During Processing

Abstract

The qualitative and quantitative changes in microbial flora in 2 varieties of black pepper, (‘KS 27’ and ‘P 24’) during processing by traditional method (sun-drying), blanching followed by sun-drying and mechanical drying and during storage were studies. The moisture content of berries after 3 days of traditional method of drying was 15% whereas in blanching followed by drying and mechanical drying, the moisture contents were 8.5% and 7.5%, respectively. The microbes were enumerated on nutrient agar (NA), Luria Bertani’s (LBA, for coliforms), Rose Bengal (RBA) and Aspergillus flavus agar medium (AFM). In traditional method of drying, there was no significant reduction in bacterial population after 4 days of drying in both the varieties. Blanching followed by drying showed no reduction in coliform, but there was significantly reduction in bacterial population. Fungi were completely eliminated after blanching but reappeared during drying probably as contaminants from the atmosphere. In the mechanically dried samples, bacterial population was high in fully dried samples of ‘P 24’ and ‘KS 27’. The ‘P 24’ berries harbored more fungi in partly dried sample (6 h), while ‘KS 27’ contained more fungi in the fully dried sample (12 h). The results indicated the effectiveness of mechanical dryer for producing black pepper free from bacteria and fungi for export.