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- Food preservative potential of lemongrass (Cymbopogon citratus) essential oilPublication . Soares, Marta De Oliveira; Ferreira da Vinha, Ana; Silva, Carla Sousa e; Castro, Ana; De Pina Catarino Pires, PedroThe economic charges and health implications of food spoilage and food waste handling are increasing. Contamination of food sources by different sources of contaminants remains a major public health concern. In the last decades, researches have focused on developing safer natural products and innovations to meet consumers' acceptance as alternatives to synthetic food preservatives. Many recent novel preservative techniques and applications of both natural and synthetic origin continue to proliferate in food and chemical industries. In particular, some essential oils of plant origin are potent food preservatives and are thus attractive alternatives to synthetic preservatives. For the reasons mentioned above, this studied aimed evaluate the chemical composition, antioxidant, antibacterial and antifungal properties of the essential oil obtained from the Cymbopogon citratus of Angolan origin. Its major constituents analyzed by GC-MS were α-citral (40.55%), β-citral (28.26%), myrcene (10.50%) and geraniol (3.37%). The essential oil antioxidant capacity antioxidants (DPPH IC50 of 41.7 μg/ml) and superior to that of extracts obtained from fresh leaves of the plant (DPPH IC50 of 55.7 μg/ml). The oil also demonstrated high antibacterial activity even Aureus, Klebsiella pneumoniae and antifungal activity against Candida albicans and Non-Candida albicans, Candida parapsilosis and Candida tropicalis.
- Variation in chemical composition and antioxidant activity of fresh tomato fruit: combined effect of cultivar and storagePublication . Ferreira da Vinha, Ana; Silva, Carla Sousa e; Castro, Ana; Soares, Marta De Oliveira; Oliveira, M. Beatriz P.P.; Costa, A.S.G.Tomato (Lycopersicon esculentum Mill.) is one of the most consumed vegetables in the world and probably the most preferred garden crop. It is a key component of the Mediterranean diet, commonly associated with a reduced risk of chronic degenerative diseases. Currently there are a large number of tomato cultivars with different morphological and sensorial characteristics. Its consumption brings health benefits, linked with its high levels of bioactive ingredients, including carotenoids such as β-carotene, a precursor of vitamin A, and mostly lycopene, which is responsible for the red colour, vitamins in particular ascorbic acid and tocopherols, phenolic compounds including hydroxycinnamic acid derivatives and flavonoids, and lectins. The content of these compounds is variety dependent. Besides, unlike unripe tomatoes, which contain a high content of tomatine (glycoalkaloid) but no lycopene, ripe red tomatoes contain high amounts of lycopene and a lower quantity of glycoalkaloids. Current studies demonstrate the several benefits of these bioactive compounds, either isolated or in combined extracts, namely anticarcinogenic, cardioprotective and hepatoprotective effects among other health benefits, mainly due to its antioxidant and anti-inflammatory properties. This study intended to evaluate the influence of different postharvest cooling conditions in the chemical composition, antioxidant activity and microbiological contamination of tomato cultivars namely: Cereja, Chucha, Rama and Redondo. Pink fruits were kept for 15 days under three different storage temperatures (6ºC, 12ºC and 25ºC) during which their lycopene, ascorbic acid contents, total phenolics and antioxidant activity were evaluated every three days. Counts of colony forming units of coliform bacteria, yeasts and molds and the presence of Escherichia coli, were determined before and after 15 days of storage. All studied parameters revealed that temperature and storage duration caused statistically significant differences in nutritional values of every cultivar. It was observed an increase in the lycopene concentration and antioxidant activity with temperature and storage duration. The phenolic and ascorbic acid contents showed a slight increase during storage at every temperature. Microbial contamination was only found in cultivars that grew in direct contact with the soil (Chucha and Redondo) and bacterial population increased exponentially with storage temperature. Our results indicate that the ideal temperature to maintain optimal physiological, biochemical and microbiological profiles of the cultivars studied is 12ºC and that the cv. Rama fruit is the most suited for consumption in natura.