• Food Science and Biotechnology
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• v.17 no.1
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• pp.118-122
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• 2008

The use of tartary buckwheat flour as a source of dietary rutin has been limited because of the enzymatic degradation of rutin during the dough-making process, which results in a bitter taste. A variety of pretreatment regimes, including heating, steaming, boiling, and extruding, were evaluated in relation to the inactivation of the rutin-degrading enzyme responsible for rutin loss and color change during dough-making. Steaming (120 see), boiling (90 see) buckwheat grains, or extruding (180 rpm/min at $140^{\circ}C$) the flour resulted in the retention of >85% of the original rutin and eliminated the bitter taste in the hydrated flours. In contrast, dry heating at $140^{\circ}C$ for 9 min or microwaving at 2,450 MHz for 3 min did not reduce the rutin loss, and the bitter taste remained. Unlike in the flour, the rutin degradation in water-soaked grains was insignificant at room temperature. Moreover, the samples treated by steaming, boiling, or extrusion were darker and more reddish in color.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.360-367
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• 1990

The several glycoside hydrolysing enzymes related to rutin degradation are found to be rhamnosidase, glucosidase and rutinosidase. Rutinosidase was purified to electrophoretic homogeneity from cell extracts of rutin-degrading strain, MT-57, which was identified as a Arthrobacter sp. Its molecular weight was estimated to be 42, 000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 40, 000 by gel filtration. The optimum pH for enzyme was found to be 7.5, and relatively stable in alkaline solution. The optimum temperature for enzyme was $45^{\circ}C$, being stable up to $50^{\circ}C$ for 20 min. The Bm value of enzyme for rutin was 0.5 $\mu \textrm m$. The enzyme activity was increased by the chelating agent such as EDTA, $NaN_3$, and 8-hydroxyquinoline, was strongly inhibited by $CO_{2+}, Ni^{2+}$, and $Cu^{2+}$. The enzyme had high substrate specificity in the rutinoside.

• Journal of Microbiology and Biotechnology
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• v.29 no.6
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• pp.877-886
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• 2019

Brewing with buckwheat as an ingredient has been proven to be successful in several previous studies. However, few studies have focused on the effects of buckwheat on the rutin content and antioxidant activity of beer. In order to develop a lager beer with high rutin content and desirable sensory characteristics, tartary buckwheat malt was used as a brewing adjunct. The results showed that the rutin-degrading enzyme was the key factor affecting the rutin content in the wort and beer. Compared to beer made using the common mashing method, the rutin content in the buckwheat beers produced using an improved mashing method was approximately 60 times higher. The total flavonoid contents in buckwheat beers also depended strongly on the mashing methods, ranging from 530.75 to 1,704.68 mg QE/l. The rutin-rich beers also showed better oxidative stability during forced-aging. Meanwhile, the buckwheat beers were found to be acceptable in terms of the main quality attributes, flavor, and taste.