Microbial decontamination of black pepper by ozone and the effect of the treatment on volatile oil constituents of the spice

Abstract

The use of ozone as a substitute for ethylene oxide to decontaminate whole black peppercorn and ground black pepper and the effects of ozone on the volatile oil constituents of the spice were studied. Black peppercorns were immersed in water and sparged with ozonised air (ozone concentration, 6·7 mg litre⁻¹) for 10 min at an air flow rate of 6 litre min⁻¹. This treatment reduced the microbial population of peppercorn by 3–4 log numbers. Ground black pepper with various moisture levels was sparged with ozonised air for up to 6 h. This treatment reduced the microbial population by 3–6 log numbers, depending on the moisture content of the spice. Higher moisture content led to a greater reduction in microbial load. The volatile oil constituents of the spice with and without ozone treatment were extracted with isopropyl ether and analysed by gas chromatography and gas chromatography-mass spectrometry. Ozone treatment of ground black pepper resulted in the oxidation of certain volatile oil constituents while the treatment had no significant effect on the volatile oil constituents of whole peppercorn.