Novel studies on membrane extraction of bioactive components of green tea in organic solvents: part I

Nwuha, Victor

doi:10.1016/s0260-8774(00)00031-5

Cited by 37 publications

(16 citation statements)

References 7 publications

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“…Nwuha [89] employed G-10 and G-20 membranes for isolation of catechins with a low caffeine content from a crude tea extract (Polyphenon-60). The tea extract was dissolved in 80% v/v ethanol and then filtered though a G-10 or G-20 membrane, which was held by a porous Teflon layer in the form of an O-ring.…”

Section: Membrane Separationmentioning

confidence: 99%

Extraction and isolation of catechins from tea

Vuong

Golding

Nguyen

et al. 2010

J of Separation Science

154

106

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Tea is a major source of catechins, which have become well known for their antioxidant potential. Numerous human, animal, and in vitro studies have linked tea catechins with prevention of certain types of cancers, reduction of the risks for obesity, diabetes, and cardiovascular disease, and improvement of the immune system. Tea catechins are widely used in various neutraceuticals, pharmaceuticals, and cosmetics for either enhancing product shelf-life or for enhancing human health. Thus, the demand for catechins has increased considerably. Catechins have been extracted and isolated from tea leaves by numerous methods through several steps including: treatment of the tea leaves, extraction of catechins from teas into solvents, isolation of catechins from other extracted components, and drying the preparations to obtain catechin extracts in a powder form. This paper outlines the physical and chemical properties of the tea catechins and reviews the extraction steps of the various extraction methods, as a basis to improve and further develop the extraction and isolation of the tea catechins.

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Section: Membrane Separationmentioning

confidence: 99%

Extraction and isolation of catechins from tea

Vuong

Golding

Nguyen

et al. 2010

J of Separation Science

154

106

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“…Ethanol, mixed with water, was selected as the best organic solvent used to improve the solubility of the bioactive components [17]. The maximum extraction yield was obtained when using a mixture of 50% of ethanol and 50% of water (v/v).…”

Section: Polyphenols Extractionmentioning

confidence: 99%

“…Likewise, the coefficient of multiple determination of the polynomial model termed R 2 , indicates that more than 98% of the variability in the response could be explained by the second-order polynomial predicted equation given above. In this respect, the validity of the model has been established by comparing the obtained results at the four check points (experiments [17][18][19][20] with the predicted values (Table 2). These results seem to confirm the validity of the model.…”

Section: Model Equationmentioning

confidence: 99%

Enzymatic propyl gallate synthesis in solvent-free system: Optimization by response surface methodology

Bouaziz¹,

Horchani²,

Salem³

et al. 2010

Journal of Molecular Catalysis B: Enzymatic

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a b s t r a c tThe ability of a non-commercial immobilized Staphylococcus xylosus lipase to catalyze the esterification of propanol with gallic acid was investigated and the antioxidant as well as the antimicrobial activities of the ester formed were evaluated. The response surface methodology, based on a three variables Box-Behnken design (reaction temperature, enzyme amount and 1-propanol/gallic acid molar ratio), was used to optimize the experimental conditions of propylgallate synthesis. The maximum conversion yield (90% ±3.5) was obtained by using 400 IU of immobilized lipase and a propanol/gallic acid at a molar ratio of 160 at 52 • C. The obtained ester was characterized by spectroscopic methods, NMR and FTIR. The antioxidant activity of propyl gallate was evaluated and compared to the synthetic classical antioxidants, BHA and ascorbic acid, taken as references. In addition, the antimicrobial activity of the propyl gallate was tested against S. xylosus, Escherchia coli and Staphylococcus aureus using disc diffusion and macrodilution methods. Our results show that the synthesized propyl gallate ester presents a higher antioxidant and antimicrobial power than the parent gallic acid as well as the synthetic classical antioxidants.

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“…In the literature, there are other reports on the effect of membrane filtration on the chemical composition and antioxidant activity of fruit juices , extraction of polyphenols from grape seeds (Nawaz et al 2006), treatment of olive mill wastewater (Turano et al 2002), extraction of the bioactive components of green tea in ethanol solvent (Nwuha 2000), extraction of carnosine from chicken muscle extracts (Maikhunthod & Intarapichet 2005), recovery of isoflavones from a waste water (Xu et al 2004) and clarification of vinegar (Lopez et al 2005). …”

Section: Membrane Filtrationmentioning

confidence: 99%