Non-thermal pasteurization of orange (Citrus sinensis (L.) Osbeck) juices using continuous pressure change technology (PCT): A Proof-of-Concept

Non-thermal pasteurization of orange juices using a continuous pressure change technology (PCT) device was investigated on pilot plant scale for the first time. PCT treatment was conducted by pressurizing orange juice and nitrogen at moderately high pressures (P = 25 or 50 MPa) in a tubular continuous reactor. Abrupt decompression was achieved by a relief valve at the end of the tubular system. As compared to freshly squeezed juice, PCT treatment slightly reduced levels of carotenoids, vitamin C and hesperidin by 19, 5, and 14 %, respectively. Peroxidase was completely inactivated, whereas residual pectin methylesterase activities amounted to 26-27 %. Simultaneously, total aerobic plate counts were substantially reduced by at least 3.4 log10 cfu/mL. The mean volume-weighed particle diameter d43 was drastically reduced from 652 mm in freshly squeezed juice to 6 and 31 mm at 25 and 50 MPa, respectively. Concomitantly, CIE-L*a*b* color values indicated a brighter and more intense yellow color of PCT-treated juices. While cloud separation in freshly squeezed juice was completed within 3 days, cloud stability in PCT-treated juices was retained for 5 days.