Joan-Hwa Yang

Antioxidant properties of several commercial mushrooms

Abstract Winter (strains white and yellow), shiitake (strains 271 and Tainung 1) and oyster mushrooms (abalone and tree oyster mushrooms) were obtained commercially and methanolic extracts were prepared from these mushrooms and their antioxidant properties were studied. The antioxidant activities by the 1,3-diethyl-2-thiobarbituric acid method were moderate to high at 1.2 mg ml−1. Reducing powers were excellent (and higher than 1.28 absorbance) at 40 mg ml−1. Scavenging effects on 1,1-diphenyl-2-picrylhydrazyl radicals were moderate to high (42.9–81.8%) at 6.4 mg ml−1. With regards to the scavenging effect on hydroxyl free radicals, tree oyster mushrooms were the highest (54.3%) at 40 mg ml−1 whereas other commercial mushrooms were low. Chelating effects on ferrous ions were 45.6–81.6% at 1.6 mg ml−1. Total phenols were the major naturally occurring antioxidant components found. Overall, tree oyster mushrooms were better in antioxidant activity, reducing power and scavenging abilities and higher in total phenol content.

Non-volatile taste components of several commercial mushrooms

Abstract Winter (strains white and yellow), shiitake (strains 271 and Taichung 1) and oyster mushrooms (abalone and tree oyster mushrooms) were collected from commercial sources. Strain yellow contained 26.7% of proteins (higher than other mushrooms). Shiitake and the two oyster mushrooms contained more than 60% of carbohydrates. Arabitol was found in the highest amounts only in winter mushrooms. Glucose, mannitol and trehalose were found in varied amounts. Total soluble sugar contents were in the order: winter mushrooms>shiitake>abalone and tree oyster mushrooms. Total contents of free amino acids also varied and ranged from 4.08 to 31.5 mg g−1 dry weight. Contents of total 5′-nucleotides were similar in the two winter mushrooms, whereas the content of flavour 5′-nucleotides was higher in strain white. Contents of total and flavour 5′-nucleotides were higher in strain 271 than in strain Tainung 1. The two oyster mushrooms were comparable in contents of flavour 5′-nucleotides. The umami taste was in the order: strain 271>winter mushrooms>two oyster mushrooms and strain Tainung 1.

Antioxidant properties of fermented soybean broth

Abstract Soybean broth (SB) and fermented soybean broth (FSB), at 100% exhibited good antioxidant activities of 0.85 and 0.80, respectively. Only FSB exhibited an excellent reducing power of 0.76–0.86 at 5–100%. FSB showed an excellent scavenging activity on 1,1-diphenyl-2-picrylhydrazyl radicals (100%) at 20–100%, while SB only at 100%. FSB at 20–100% inhibited the production of superoxide anion radicals by 81–93% but SB showed no inhibition. As its concentrations increased from 2–100%, the scavenging effect of FSB on hydroxyl radicals increased from 30–96%, whereas that of SB increased from 5–76%. Both FSB and SB were good chelators for ferrous ions. For cupric ions, SB showed significantly higher chelating effect than did FSB. These results showed that FSB was superior to SB in most antioxidant properties and that SB and FSB, more specifically FSB, might be potential antioxidants for application in food products.

Improving the antioxidant activity of buckwheat (Fagopyrum tataricm Gaertn) sprout with trace element water

Trace element water (TEW) (100, 200, 300, 400 and 500ppm) was used to grow buckwheat (Fagopyrum tataricm Gaertn) to evaluate whether the beneficial effects of trace elements on the antioxidant activity could be accomplished with the supplement of TEW. At 300ppm, TEW significantly increased the Cu, Zn and Fe contents in buckwheat sprout, but not the Se and Mn contents. The levels of rutin, quercitrin and quercetin did not differ between buckwheat sprouts grown in TEW and de-ionized water (DIW). The ethanolic extract from buckwheat sprout grown in 300ppm TEW showed higher DPPH radical scavenging activity, ferrous ion chelating activity, superoxide anion scavenging activity and inhibitory activity toward lipid peroxidation than that grown in DIW. The extract of the TEW group also enhanced intracellular superoxide dismutase activity and resulted in lower level of reactive oxygen species in human Hep G2 cells.

Physicochemical Changes of Shiitake Stipe Bread and Silver Ear Bread during Storage

Shiitake [Lentinula edodes (Berk.) Pegler] stipe and silver ear (Tremella fuciformis Berkeley) were used to substitute 5% of wheat flour to make bread. No difference among fresh white, shiitake stipe and silver ear breads was found in moisture contents. Total plate counts of breads were as high as 2.92 log CFU/g dry weight at day 0 and 3.69 log CFU/g after 12 days of storage at 4°C. The melting endothermic peaks of breads reached 105.2°C to 111.7°C. The range of thermal decomposition enthalpies were between 116.6 J/g and 158.4 J/g. Three wide-angle X-ray diffraction (WAXD) patterns were similar. An electron microscopic examination revealed that the morphology of the bread products was aggregated flakes with a few porosities. In the presence of shiitake stipe flour or silver ear flour, the natural crystallinity and morphology of bread did not obviously change after 12 days of storage. Overall, shiitake stipe and silver ear could be incorporated into bread to provide its beneficial health effects.