UV-C-inactivation of microorganisms in naturally cloudy apple juice using novel inactivation equipment based on Dean vortex technology

• Published in: Food control Vol. 20; no. 12; pp. 1103 - 1107
• Main Authors: Franz, Charles M.A.P., Specht, Ingrid, Cho, Gyu-Sung, Graef, Volker, Stahl, Mario R.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2009
• Subjects: antibacterial properties; Apple juice; Bacteria and yeasts; bacterial contamination; clarity; Dean vortex; Escherichia coli; food contamination; Food irradiation; food processing; food processing quality; inactivation; Lactobacillus brevis; Malus; naturally cloudy apple juice; Saccharomyces cerevisiae; ultraviolet radiation; UV-C; UV-C; Bacteria and yeasts; Apple juice; Lactobacillus brevis; Escherichia coli; Saccharomyces cerevisiae; Dean vortex; Food irradiation
• ISSN: 0956-7135; 1873-7129
• DOI: 10.1016/j.foodcont.2009.02.010

A novel UV-C irradiation device in laboratory scale was tested for its potential to inactivate bacteria in naturally cloudy apple juice. In this device, liquid flows through a helically wound tubing wrapped around a quartz glass tube containing a 9 W UV lamp with an irradiation intensity of 60 W/m 2 at 254 nm. The equipment was capable of reducing numbers of inoculated Escherichia coli and Lactobacillus brevis from an initial concentration of approximately 10 6 CFU/ml or 10 4 CFU/ml to below detectable limits in commercial naturally cloudy apple juice at a flow rate of 2 l/h, and to well below 1 × 10 2 also at higher flow rates of 4 and 8 l/h. Numbers of Saccharomyces cerevisiae could be reduced from an initial level of ca. 1 × 10 4–1 × 10 2 CFU/ml or less at flow rates of 2 and 4 l/h. Although E. coli could be effectively inactivated also in self-extracted, as well as industrially processed apple juice, contaminating yeast and lactic acid bacteria were not completely eliminated.