The antioxidant activity of crude green tea polyphenol (GTP) on the lipid oxidation of carp (Cyprinus carpio L.) and catfish (Clarias gariepinus Burchell) was investigated. Each fish was trimmed to remove scales, head, fins, tail, viscera, bones, visible fat and skin, and treated with different concentrations of GTP 0.01, 0.03, 0.05 and 0.01% of vitamin C (VC). Control muscle sample (CK) contained no antioxidant. Lipid oxidation was evaluated over a course of 9 days and using a 3-day periodical interval analysis for peroxide value, thiobarbituric acid-reactive substances and free fatty acid. Carp minced fillet containing 0.03% GTP showed the best characteristics (P < 0.05) in relation to oxidative stability. For catfish, 0.05% GTP concentration was more effective in delaying lipid oxidation, when compared with the control sample and VC. However, 0.01%-treated minced fillet with VC was less effective than 0.01% GTP in reducing lipid oxidation. These results demonstrate that tea polyphenols inhibited lipid oxidation, and are effective alternatives to VC in food industry. PRACTICAL APPLICATIONSGreen tea polyphenol (GTP) is a natural antioxidant. It can improve the quality of food products during refrigerated storage because of the presence of 3 Corresponding 738 catechin in its composition. GTP promotes health by preventing lipid oxidation, and has been shown to possess antibacterial and antiviral characteristics. In food industry, it can be used as alternatives to the synthetic antioxidants because the use of these types of antioxidants is controlled nonetheless because of their carcinogenic potential. Extraction of GTPGTP was extracted according to the method of Agarwal et al. (1992) and Chen and Chan (1996) with modification. Then, 20 g of dried green tea sample was twice extracted with 100 mL of ethanol with shaking at 40C water bath for 740 S. DEMBELE ET AL.
The comparative antioxidant effect of adding different crude green tea polyphenols (GTP) and vitamin C (VC) on the susceptibility of dried catfish (Clarias gariepinus) quality changes during ambient storage was investigated. Catfish fillet was treated with different concentrations of GTP: 1% NaCl plus 0.01% GTP, 1% NaCl plus 0.03% GTP and 1% NaCl plus 0.01% of VC before drying process. Control muscle sample (CK) was treated only with 1% of NaCl solution (without GTP extract) contained only 1% NaCl, but not GTP. Samples were oven‐dried for 5 days at 45C. The quality change was evaluated over a course of 4 weeks for pH, volatile basis nitrogen, peroxide value, thiobarbituric acid reactive substances and free fatty acid. The results indicated that the most effective antioxidant was GTP and there was no significant differences (P < 0.01) between laboratory‐extracted crude green tea polyphenol and commercial crude green tea polyphenol. This study pointed out that GTP is a good natural antioxidant in comparison with VC and CK, so, it could be easily used in food industry to improve quality and shelf life of food products. PRACTICAL APPLICATIONS Fish is a very important foodstuff because of its high protein content and nutritional value. It is also a greatly perishable product, especially in hot climates and tropical areas where cold preservation techniques are often missing and quality losses can occur very rapidly after catch. Addition of antioxidants during drying process can be used to inhibit lipid oxidation and microbial and insect infestation. However, questions regarding the safety of synthetic antioxidants together with consumer's preference have led to increased interest and research on natural antioxidants. Consumers favor natural antioxidants, which may have a positive effect on human health. Green tea polyphenol (GTP) as a natural antioxidant has lower toxicity than synthetic antioxidants like butylated hydroxyanisole and butylated hydroxytoluene, and more effectiveness than VC. It can be used as an alternative to VC to extend the quality of fish and fish products during storage.
A study was conducted in southern Mali to characterized Parkia biglobosa populations in the aim to contribute to the domestication of the species. Fields and fallows in the north sudanian, south sudanian and north guinean zones were concerned. Adult trees were marked in plots of 0.25 ha each and leaves and fruits were harvested from each tree for characterization. Petiole and laminar length, number of pairs of pinnae and leaflets, pedicel and pod length, pod wide, pod and seed weight, number of seed per pod were measured. The north guinean zone showed the highest number of pairs of pinnae and leaflets, the longest pods (23.06±9.91 cm in the fields), the highest mean seed weight (3.74±0.96 g in the fields) and the highest mean number of seeds per pod (17 ± 3 seeds in the fields). The South Sudanian zone showed the longest pedicels (3.85±1.08 cm in the fallows), the highest mean laminar length (18.02 cm) and mean petiole length (6.45 cm) in the fields but the same mean number of seeds per pod as for the north Guinean. The north Sudanian zone showed the widest (17.88±7.98 cm in the fields and 18.24±2.11 cm in the fallows) and heaviest (14.87±3.95 g in the fallows) pods. Leaf variables like the number of pairs of pinnae and leaflets seem to be influenced by the climatic gradient. The others leaf, pod and seed variables seem not to be influenced by the climatic gradient. These findings suggest that many leaf and fruit variables are controlled by endogenous factor that could be genetic. However, the manifestation of the endogenous factor seems to be influenced by factors such as environment and management practices.
Parkia biglobosa offers food, medicine and income to rural populations. A study, was undertaken in three agro-climatic zones in southern Mali, to characterise P. biglobosa populations. Plots of 0.25 ha each were established in fields and fallows and adult trees in the plots were monitored. Natural regeneration was monitored in five subplots of 12.5 m x 12.5 m = 156.25 m2 each within each plot and data were collected from 2019 to 2021. Natural regeneration of P. biglobosa was found to be very weak in all sites. The mean density of seedlings varied from 11 to 24 seedlings ha-1 with a decreasing trend from 2019 to 2021. In Zanzoni, where the weakest regeneration was observed, the density varied from 0 to 8 seedlings ha-1. The highest density of seedlings was observed in Somasso in 2019 (42 seedlings ha-1) and 2020 (30 seedlings ha-1). In 2021, the highest density was observed in Diou (25 seedlings ha-1). The weakness of natural regeneration is very alarming for this tree species facing several other threats (ageing and decreasing adult tree populations, sanitary constraints, several pressures, etc.). It is therefore very important and imperative to investigate ways for regenerating the species for its sustainability and for maintaining the parklands biodiversity. Artificial regeneration (planting), could be the one and ultimate way to ensure the sustainability of P. biglobosa.
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