Browsing by Author "Freitas, A."
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- Effect of UV-C radiation on bioactive compounds of pineapple (Ananas comosus L. Merr.) by-productsPublication . Freitas, A.; Moldão-Martins, M.; Costa, H.S.; Albuquerque, T.G.; Valente, A.; Sanches-Silva, A.BACKGROUND: The industrial processing of pineapple generates a high quantity of by-products. To reduce the environmental impact of these by-products and the inherent cost of their treatment, it is important to characterise and valorise these products, converting them into high added value products. Ultra-violet radiation is one of the main sustainable sanitation techniques for fruits. Since this radiation can induce plant stress which can promote the biosynthesis of bioactive compounds, it is important to evaluate its effect in fruits. RESULTS: The amounts of vitamins (C and E) and carotenoids (α-carotene, β-carotene, β-cryptoxanthin, lutein, lycopene, neoxanthin, violaxanthin and zeaxanthin) in pineapple by-products (core and rind) were analysed before and after treatment with UV radiation. All treated and untreated pineapple by-products contained β-carotene as the main carotenoid (rind, 2537-3225 µg; and core, 960-994 µg 100 g(-1) DW). Pineapple rind also contained lutein (288-297 µg 100 g(-1) DW) and α-carotene (89-126 µg 100 g(-1) DW). CONCLUSION: The results provide evidence of the potential of pineapple by-products as a source of bioactive compounds with antioxidant activity, which can be used by pharmaceutical, cosmetics and food industries. In addition, UV-C was shown to be a treatment that can add nutritional value to pineapple by-products.
- Impact of UV-C Radiation On Carotenoids Content of Pineapple by-Products (Ananas comusus) Processing IndustriesPublication . Freitas, A.; Moldão-Martins, M.; Costa, H.S.; Sanches-Silva, A.Pineapple is one of the most worldwide processed fruits, originating high amounts of by-products, namely core and rind. In the production of processed fruits there is one important step in order to comply with the food safety legal requirements, which is the fruit decontamination. In the conventional sanitation technique of fruits chlorine is utilised, but it has several disadvantages for human health and for the environment due to the production of secondary compounds. The ultraviolet radiation at a wavelength of 190-280 nm (UV-C) is a non-chemical method, alternative to the use of chlorine, which does not leave residues in the fruit and in the environment. Beyond the sanitizing effect, UV-C radiation can also induce stress in the plant which can promote the biosynthesis of bioactive compounds, namely carotenoids. The aim of the current work was to study the impact of a low dose of UV-C radiation on carotenoids content of pineapple by-products.. The study focused on the pineapple core and rind, and the following carotenoids, -carotene, β-carotene, β-cryptoxanthin, lutein, lycopene, neoxanthin, violaxanthin and zeaxanthin were evaluated. The carotenoids content was determined by ultra performance liquid chromatography (UPLC®). The calibration curve of each carotenoid was done using six concentrations of the standards. For all carotenoids, the coefficient of determination (r2) of the calibration curves was higher than 0.997. The pineapple core had fewer types of carotenoids, and less quantity of each carotenoid, than the pineapple rind. Lutein and -carotene were detected in pineapple rind but not in the core. β-cryptoxanthin, zeaxanthin, violaxanthin, neoxanthin and lycopene were not detected in any pineapple by-product. With respect to the applied UV-C treatment, it induced the production of -carotene and -carotene in pineapple rind but had no significant (P>0.05) impact on lutein, nor on the content of -carotene of pineapple core.
- Influence of Ultra-Violet Radiation on the Ascorbic Acid Content of Pineapple By-products Determined by HPLCPublication . Freitas, A.; Valente, A.; Albuquerque, T.G.; Moldão-Martins, M.; Costa, H.S.; Sanches-Silva, A.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.