TITLE

Comparison of β-carotene, total phenolic, and antioxidant activity of jute mellow (Corchorius olitorius L.) leaf tea with green teas

AUTHOR(S)
Moong-Ngarm, A.; Bootprom, N.; Khunarak, J.
PUB. DATE
June 2004
SOURCE
Asia Pacific Journal of Clinical Nutrition;2004 Supplement, Vol. 13, pS163
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
In recent years, the health benefits of foods have gained much attention. Natural antioxidants in foods, such as b-carotene and phenolic compounds, are among the most interesting bioactive compounds. The protective influence of diets rich in fruits and vegetables against certain diseases have been attributed partly to their antioxidant content. Jute mellow or moroheiya leaves are extensively consumed as a nutritive and health vegetable in several countries because of their abundant content of carotenoids, vitamins and minerals. The fresh leaves of jute mellow were found to exhibit high antioxidant activity. However, the antioxidants b-carotene and total phenolics are greatly influenced by processing, yet no investigation on the impact of processing conditions on b-carotene, total phenolic, and antioxidant activity of the jute mellow leaves has been conducted. Production of dried leaves and consumption as tea is a popular process. The purpose of this study was to investigate whether the three different processing conditions (toasted at 55°C for 2 hours, blanched and then roasted at 70°C 45 min, and roasted at 70°C 45 min) of making teas affects the amount of b-carotene, total phenolic, and antioxidant activity. The study also compared the amount of these compounds with those of Japanese and Chinese green teas. The antioxidant activities of the tea extracts were evaluated using α-α-diphenyl-l-picrylhydrazil (DPPH) radical scavenging activity and the b-carotene bleaching methods. The total phenolic compounds and b-carotene levels were determined using the Folin-Ciocateu and spectroscopic methods, respectively. The results indicated that tea processing conditions significantly reduced the antioxidant capacity of jute mellow leaf tea extracts and b-carotene content of jute mellow leaf tea compared with fresh jute mellow leaves, whereas no effect on the level of phenolics. The b-carotene and total phenolic content of all jute mellow leaf tea were between 4200 ± 492 to 5200 ± 212 µ g/100g and 396.70 ± 2.05 to 475 ± 4.81mg/100g, respectively. All jute mellow leaf tea extracts exhibited 74.89 ± 1.20 to 80 ± 1.23% inhibition on b-carotene bleaching and 69.73 ± 2.16 to 75.38 ± 0.06% on DPPH radical scavenging activity, significantly lower than those of Japanese and Chinese green tea extracts (92.43 ± 0.13 and 88.79 ± 0.43%, respectively).
ACCESSION #
34013683

 

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