• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.801-807
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• 1988

Antithiamine activity of raw and processed brackens (Pteridium aquilinum) was evaluated by means of the thiochrome fluorescence and Lactobacillus viridescens bioassay methods and inter-related with the phenolic content and degree of browning. As blanching time of bracken elapsed, its antithiamine activity was enhanced whereas the phenolic content and brewing declined. Increased salt concnetrations in boiling water also raised the antithiamine activity, phenolic content and browning of raw bracken. When dried bracken was treated with sodium bicarbonate solution or soaked in running water, its antithiamine activity greatly decreased along with the increased phenolic content and browning. Heat cooking of bracken brought about a slight decrease in the antithiamine activity, phenolic content and browning. It was concluded that antithiamine activity existing in raw bracken Is reduced by various treatments, particularly by soaking in running water and that phenolics in bracken may play an important role in thiamine decomposition.

• Korean Journal of Food Science and Technology
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• v.20 no.6
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• pp.808-811
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• 1988

Antithiamine activities of dried wild vegetables consumed in Korea were evaluated by means of the thiochrome fluorescence and Lactobacillus viridescens bioassay methods and compared with the phenolic content and the degree of browning of the samples. Eggplant, sweet Potato stalk, bracken, red pepper leaf, Aster scaber and mugwort had higher antithiamine activities than Codonopsis lanceolata, doraji, taro stalk, pumpkin, oak mushroom and acorn starch. Wild vegetables with high antithiamine activity tended to have a high phenolic content and degree of browning. It is recommended that wild vegetables should not be cooked with thiamine-rich foods and be eaten immediately after cooking in order to minimize the thiamine decomposition.

• Korean Journal of Food Science and Technology
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• v.20 no.4
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• pp.600-605
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• 1988

Antithiamine activity of raw and cooked brackens(Pteridium aquilinum) was evaluated under various reaction conditions by means of the thiochrome fluorescence method. The effects of caffeic acid and cysteine on the thiamine decomposition were also determined by thiochrome fluorescence and Lactobacillus viridescens bioassay methods. A water extract of raw bracken exhibited a high antithiamine activity which was increased with higher pH, temperature, incubation time and concentration of bracken. The influence of reaction conditions was less apparent in cooked bracken than in raw bracken. Caffeic acid stimulated the thiamine decomposition whereas cysteine showed a suppressive effect. The effect of cysteine was lower in the decomposition of thiamine by bracken extract.