Anàlisi de l'efectivitat de l'homogeneïtzació per pressió ultra alta, radiació ultraviolada d'ona curta i la seva combinació en la higienització del suc de poma i els seus efectes sobre la qualitat i els aspectes nutricionals
- Autores: Jezer Noe Sauceda Gálvez
- Directores de la Tesis: Ramón Gervilla Fernández (dir. tes.), Artur Xavier Roig Sagués (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
- Idioma: catalán
- ISBN: 9788449097126
- Tribunal Calificador de la Tesis: Antonio José Trujillo Mesa (presid.), Sílvia de Lamo Castellví (secret.), José Salas Vicente (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencia de los Alimentos por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
This work comprises the use of two different technologies for the hygienization of apple juices. Those technologies were the ultra-high pressure homogenisation (UHPH) and short-wave ultraviolet radiation (UV-C).
UHPH was applied with pressures of 100, 200 and 300 MPa, and UV-C treatments were performed at different doses between 1.8 – 200 J/mL, sometimes in more than one pass through the system (only UV-C) or combined with different inlet temperatures (InT). The two technologies were tested in order to elucidate their microbicidal capacities in different types of apple juices (clear and cloudy, with or without the addition of ascorbic acid or chia seed extract) and in other matrices adjusted to simulate some of the interferences that apple juice can oppose to UV-C like the absorption coefficient at 254 nm (α254) and turbidity. In order to validate those treatments, spores of different species of bacteria (Bacillus subtilis, Alicyclobacillus acidoterrestris, Geobacillus stearothermophilus) and moulds (Aspergillus niger, Talaromyces macrosporus and Neosartorya spinosa) were inoculated into the matrices. Shelf-life studies over the microbial stability of the juice were also performed, and for those the endemic microbiota of the product was also taken into consideration.
UHPH was effective in inactivating the endemic microbiota of the product and A. niger spores with pressures of 200 and 300 MPa at 20 ºC InT with inactivation rates of 4 - 5 Log respectively, while the bacterial spores of B. subtilis and A. acidoterrestris could be inactivated in more than 4 Log only after 300-MPa UHPH and at least 70 ºC of InT.
UV-C treatments were effective in the inactivation of bacterial spores inoculated in matrices where turbidity and α254 values were closer to 0, and when the doses and number of passes increased, lethality rates also became higher, but it varied according to the type of microorganism, being the spores of A. niger who showed the highest resistance against those treatments.
A combination of UHPH and UV-C had an additive effect in the inactivation of microorganisms in most of the assayed combinations, except for the fungal spores of T. macrosporus and N. spinosa where a synergic effect between those technologies was observed.
The effect of these technologies in the physicochemical and quality aspects of cloudy apple juice were analysed as well. It was observed significant changes by the effect of the UHPH at 200 and 300 MPa in the parameters of ºBrix, colour, particle size, turbidity and in α254 of the product. The activity of the enzyme polyphenol oxidase was not detected after the treatment of 300 MPa, and the residual activity of pectin methylesterase was reduced in more than 70%. The antioxidant capacities of cloudy apple juice and clarified apple juice with chia extract processed by UHPH and UV-C were measured, as well as a quantitative analysis of the antioxidants profile in juice with chia extract.
A sensory analysis test was performed in order to know the preferences between juices treated by UHPH, UV-C and without treatment. Changes in their sensory attributes were detected mainly in odour and flavour of the treated juices.
