Dominic Soloman, George (2016) Proteomic and quality analysis of uv-c and thermal treated cut chokanan mango (mangifera indica l.) and josephine pineapple (ananas comosus l. merr.) / Dominic Soloman George. PhD thesis, University of Malaya.
Abstract
The increasing demand for high quality fruit products, fresh-cut and the likes that meet safety standards has spurred the development of treatments such as ultraviolet-C (UVC) light and thermal treatment. In this study, fresh cut Chokanan mangoes and Josephine pineapples were subjected to UV-C treatment (for 15, 30 and 60 minutes at 25 ± 1 °C) and thermal treatment (at 70 ± 1 °C for 5, 10 and 20 minutes). The proteomic changes in the fruits following UV-C and thermal treatments as well as the effects of the treatments on the quality characteristics (physicochemical, nutritional, microbial, sensorial and shelf-life) were evaluated and compared with untreated fruits (control). UV-C and thermal treatments resulted in significant changes in the expression of several proteins that are known to play important roles in various metabolic processes. Spots that were differentially expressed following UV-C and thermal treatment were identified through LCMS-MS and classified according to functional groups. They were, in the order, stress and defence, energy and metabolism, cell structure and finally ripening and senescence. Several allergenic proteins were found to be reduced in expression following UV-C and thermal treatment which could prove to be invaluable in reducing allergic reactions in patients. As for the quality attributes, no significant changes were observed in pH, total soluble solids and titratable acidity after UV-C and thermal treatment. UV-C treated fruits showed significant improvement in selected quality parameters, which included a significant enhancement in polyphenols (up to 7%), DPPH scavenging activity (up to 4 %) and total antioxidant capacity (up to 17%) when compared to the control. Thermal treatment on the other hand resulted in a decrease in these quality parameters. In iii addition, significant reduction in microbial load was observed in both UV-C and thermally treated fruits with UV-C achieving higher microbial inactivation. Both UV-C and thermal treatment successfully extended shelf-life of fresh cut fruits to a maximum of 15 days. Sensory attributes (appearance, aroma, texture, and taste) were evaluated by 90 panellists using a hedonic scale, and results showed that UV-C treated fruit samples were preferred more than thermally treated fruit samples. The sensory evaluation verified that UV-C treatment for 30 minutes was the most promising treatment compared to the other treatments.
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