Influence of Ultra-Violet Radiation on the Ascorbic Acid Content of Pineapple By-products Determined by HPLC

Freitas, A.; Valente, A.; Albuquerque, T.G.; Moldão-Martins, M.; Costa, H.S.; Sanches-Silva, A.

http://hdl.handle.net/10400.18/576

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Abstract(s)

The ultraviolet radiation at a wavelength of 190-280 nm (UV-C) is a non-chemical method, alternative to the use of the conventional sanitation technique of minimally processed fruits and vegetables (chlorinated-water). This technique has several advantages such as low cost, easy use, elimination of most types of microorganisms and no production of secondary compounds which could have a negative impact on Human Health. UV-C radiation can also induce stress in the plant which can promote the biosynthesis of nutraceuticals, namely carotenoids and vitamin C. The aim of the current work was to quantify L-ascorbic acid of pineapple by-products (core and rind) and to study the effect of UV-C radiation. The content in L-ascorbic acid was determined by high performance liquid chromatography (HPLC). The calibration curve of L-ascorbic acid was done using six concentrations of the standard (1, 20, 40, 60, 80 and 100 µg/ml), the equation of the calibration curve obtained was y = 88300x + 3930 and the coefficient of determination (r2) was 0.9998. The pineapple core not submitted to UV-C radiation presented significant higher (P<0.05) L-ascorbic acid content (487.7 mg/100 g dry matter) than the rind not submitted to UV-C radiation (252.2 mg/100 g dry matter). The UV-C treatment applied led to an increase of the L-ascorbic acid content in the rind (14%) and a decrease of this acid in the core (12%). The different content in L-ascorbic acid of the pineapple rind when compared with the core could be due to differences between the tissues composition and structure, as well as to a better response of pineapple rind to abiotic stress than the core. UV-C treatment has short penetration depth and its penetration capacity depends upon the composition and structure of the product, hence the different response of the pineapple by-products under analysis to the UV-C radiation might have been a consequence of differences inherent to the pineapple by-products tissue composition and structure. UV-C radiation contributes to the safety and nutritional quality of fruits and is currently seen as a promising sanitising treatment of fruits and vegetables surface.