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Item Open Access Thermal inactivation of Alicyclobacillus acidoterrestris spores isolated from a fruit processing plant and grape juice concentrate in South Africa(Academic Journals, 2013) Groenewald, Willem H.; Gouws, Pieter A.; Witthuhn, R. CorliThermal inactivation at 95°C for two strains of Alicyclobacillus acidoterrestris isolated from contaminated fruit juice concentrates were investigated in a 0.1% (m/v) peptone buffer solution (pH 7.04) and grape juice (pH 4.02, 15.5 °Brix). The thermal inactivation of A. acidoterrestris spores followed first-order kinetics, suggesting that as the microbial population is exposed to a specific high temperature, the spores were inactivated at a constant rate. D-values determined in the buffer solution were calculated to be 1.92 ± 0.39 and 2.29 ± 0.50 min, while in grape juice D-values were found to be 2.25 ± 0.53 and 2.58 ± 0.32 min for the two strains tested.Item Open Access The use of ultraviolet radiation as a non-thermal treatment for the inactivation of alicyclobacillus spores in water, wash water from a fruit processing plant and grape juice concentrate(CUT Free State, 2013) Groenewald, W. H.; Gouws, P. A.; Cilliers, F. P.; Witthuhn, R. C.Alicyclobacillus acidoterrestris is a non-pathogenic, spore-forming bacterium that can survive the commercial pasteurisation processes commonly used during fruit juice production. Surviving bacterial endospores germinate, grow and cause spoilage of high acid food products. Fruit juices can be treated using ultraviolet light (UV-C) with a wavelength of 254 nm, which has a germicidal effect against micro-organisms. In this study, A. acidoterrestris was inoculated into water, used wash water from a fruit processing plant and grape juice concentrate. Ultraviolet dosage levels (J L−1) of 0, 61, 122, 183, 244, 305 and 367 J L−1 were applied using a novel UV-C turbulent flow system. The UV treatment method was shown to reliably achieve in excess of a 4 log10 reduction (99.99%) per 0.5 kJ L-1 of UV-C dosage in all the liquids inoculated with A. acidoterrestris. The applied novel UV technology could serve as an alternative to thermal treatments of fruit juices for the inactivation of Alicyclobacillus spores as well as in the treatment of contaminated wash water used in fruit processing.