Analysis of the effectiveness of ultra-high pressure homogenisation, short-wave ultraviolet radiation and their combination on the hygenization of apple juice and their effect on the quality and nutritional aspects

This PhD thesis project involves hygienizing apple juices using two separate processes. The two technologies utilized were short-wave ultraviolet radiation and ultra-high pressure homogenization (UHPH) (UV-C). The two technologies were put to the test in various apple juices, including clear and cloudy juices with or without the addition of ascorbic acid or chia seed extract, as well as in other matrices modified to simulate some of the UV-C interferences that apple juice can cause, such as the absorption coefficient at 254 nm (254) and turbidity. Spores of various bacteria (Bacillus subtilis, Alicyclobacillus acidoterrestris, Geobacillus stearothermophilus) and mold (Aspergillus niger, Talaromyces macrosporus, and Neosartorya spinosa) species were introduced into the matrices in order to validate those treatments. Studies on the juice's microbiological stability during storage were also carried out, and for them, the product's endemic microbiota was also taken into account.