Shih-Chuan Liu

Kinetics of color development, pH decreasing, and anti-oxidative activity reduction of Maillard reaction in galactose/glycine model systems.

Galactose/glycine model systems of sugar concentration 0.035, 0.069, 0.139, and 0.278M were incubated at 60, 75, and 90°C separately for studying the reaction kinetics of color development, pH change, and system anti-oxidative activity change in Maillard reaction. The results indicated that system color development followed first-ordered kinetics on galactose concentration; system pH went linearly down with a logarithm-ordered kinetics on galactose concentration; and anti-oxidative activity reduced linearly with a first-ordered kinetics on galactose concentration. The values of Q10 and activation energy ranged from 1.98 to 2.00 and from 68.8 to 69.5kJ/mol, respectively, for these three properties.

Composition of flavonoids and phenolic acids in lychee (Litchi Chinensis Sonn.) Flower extracts and their antioxidant capacities estimated with human LDL, erythrocyte, and blood models.

Lychee (Litchi chinensis Sonn.) flower is a major nectar source in Taiwan. Antioxidant activities of acetone, ethanol, and hot-water extracts of the flower were estimated through three biochemical models: inhibition of Cu(2+) -induced oxidation of human low-density lipoprotein, scavenging ability of oxygen radicals in human blood, and inhibition of human erythrocyte hemolysis induced by peroxyl radicals. Composition and content of flavonoids and phenolic acids in these extracts were also determined by high-performance liquid chromatography. Results showed that antioxidant effects of all test models as well as contents of flavonoids and phenolic acids for the lychee flower extracts were in the order: acetone extract > ethanol extract > hot-water extract. Gentistic acid and epicatechin were the major phenolic acid and flavonoid in the extracts, respectively.

Antioxidant effect and active components of litchi (Litchi chinensis Sonn.) flower.

The effects of scavenging 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radicals and inhibiting low-density lipoprotein (LDL) oxidation, and phenolic quantities were used for the activity-guided separation to identify the effective components of litchi flower. The acetone extract of the flower with notable antioxidant capacities was suspended in water and sequentially partitioned with n-hexane, ethyl acetate (EA) and n-butanol. The EA partition with the highest phenolic levels and antioxidant capacities was subjected to silica gel column chromatography. Thirteen fractions (Fr. 1-13) were collected; Fr. 10-12 with higher phenolic levels and antioxidant effects were applied to Sephadex LH-20 column chromatography. Each fraction was further separated into three sub-fractions and the second ones (Fr. 10-II, 11-II, and 12-II) were the best, which two major compounds could be isolated by semi-preparative high performance liquid chromatography (HPLC). Through Mass (MS) and Nuclear Magnetic Resonance (NMR) measurements, they could be identified as (-)-epicatechin and proanthocyanidin A2. Their contents in the litchi flower were 5.52 and 11.12 mg/g of dry weight, respectively. The study was the first time to reveal the effective antioxidant components of litchi flower.

Phenolic compositions and antioxidant attributes of leaves and stems from three inbred varieties of Lycium chinense Miller harvested at various times

Antioxidant components and properties (assayed by scavenging DPPH radicals, TEAC, reducing power, and inhibiting Cu(2+)-induced human LDL oxidation) of leaves and stems from three inbred varieties of Lycium chinense Miller, namely ML01, ML02 and ML02-TY, harvested from January to April were studied. Their flavonoid and phenolic acid compositions were also analyzed by HPLC. For each variety, the leaves and stems collected in higher temperature month had higher contents of total phenol, total flavonoid and condensed tannin. Contents of these components in the samples collected in different months were in the order: April (22.3°C)>March (18.0°C)>January (15.6°C)>February (15.4°C). Antioxidant activities of the leaves and stems for all assays also showed similar trends. The samples from different varieties collected in the same month also possessed different phenolic compositions and contents and antioxidant activities. Their antioxidant activities were significantly correlated with flavonoid and phenolic contents.

Effects of Temperature and Sugar Concentration on the Colour Development, 5-hydroxymethoxylfurfural Production, and Antioxidative Activity Development in the Caramelisation of Acidic Glucose Solution

Model acidic glucose solution systems (pH 3.0) incubated at 75 - 95°C were utilized for investigating the reaction kinetics of the brown colour development, DPPH radical scavenging activity (SDPPH) and 5-hydroxymethoxylfurfural (HMF) production of caramelisation. The result showed the reaction model of glucose on the caramel brown colour development followed first-order kinetics at 75 and 85˚C, and logarithm-order at 95˚C. The reaction models of glucose on SDPPH development and HMF production followed first-order kinetics through the experimental temperature ranges. The Ea values for glucose on caramel brown colour development, SDPPH development and HMF production were 120, 91 and 134 kJ∙mol-1; while Q10 values were 3.18, 2.34 and 3.52, respectively.

Study of the Antibacterial Efficacy of Bainiku-Ekisu against Pathogens.

The research was undertaken to determine the bacteriostatic effects of the concentrate of Japanese apricot juice (bainiku-ekisu), which is a popular health food in Taiwan and Japan, on Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922. The results show that E. faecalis, S. aureus, and E. coli could be killed or inhibited by bainiku-ekisu at concentrations between 1.0 and 10.0 mg/mL. The minimum inhibitory concentration (MIC) was 1 mg/mL for all strains, and the minimum bactericidal concentrations (MBCs) were 5, 2.5, and 2.5 mg/mL for E. faecalis, S. aureus, and E. coli, respectively. Using the growth rate to calculate the MICs and MBCs, the MICs were 1.55, 1.43, and 0.97 mg/mL, and the MBCs were 2.59, 2.63, and 2.25 mg/mL for E. faecalis, S. aureus, and E. coli, respectively. According to the D values, E. faecalis and S. aureus exhibited lower resistance than E. coli at lower bainiku-ekisu concentrations (1.0 and 2.5 mg/mL), and the resistance of these two pathogens was better than that of E. coli at higher bainiku-ekisu concentrations (5.0 and 10.0 mg/mL). The Z values of the E. faecalis, S. aureus, and E. coli strains were 3.47, 4.93, and 11.62 mg/mL, respectively.

Isolation and Identification of Steroidal Saponins in Taiwanese Rhizoma Paridis Cultivar (Paris formosana Hayata)

台灣蚤休(Paris formosana Hayata)具有九個類固醇皂苷，其化學結構是利用液－液萃取配合高效能液相層析儀進行分離純化，再經液相層析質譜儀與核磁共振儀進行結構鑑定得知。此九個類固醇皂苷包括三個furostanol glycosides: 26-O-β-D-glucopyranosyl-22α-methoxyl-(25R)-furost-5-en-3β, 26-diol 3-O-α-L-rhamnopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→4)-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside, 26-O-β-D-glucopyranosyl-22α-methoxyl-(25R)-furost-5-en-3β, 26-diol 3-O-α-L-rhamnopyranosyl-(1→2)-O-[α-L-arabinofuranosyl-(1→4)]-β-Dglucopyranoside和26-O-β-D-glucopyranosyl-22α-methoxyl-(25R)-furost-5-en-3β, 26-diol 3-O-α-L-rhamnopyranosy-(1→2)-O-[β-D-glucopyranosyl (1→3)]-β-D-glucopyranoside，二個pennogenyl glycosides (spirostanol glycosides): 25 (R)-spirost-5-en-3β, 17-diol 3-O-α-L-rhamnopyranosy-(1→4)-O-α-L-rhamnopyranosyl-(1→4)-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside和(25R)-spirost-5-en-3β, 17-diol 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→4)]-β-D-glucopyranoside以及四個diosgenyl glycosides (spirostanol glycosides): (25R)-spirost-5-en-3β-ol 3-O-α-L-rhamnopyranosyl-(1→4)-O-α-L-rhamnopyranosyl-(1→4)-O-[α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside, 3-O-α-L-rhamnopyranosyl-(1→2)-[β-D-glucopyranoside-(1→3)]-β-D-glucopyranoside, (25R)-spirost-5-en-3β-ol 3-O-α-L-rhamnopyranosyl-(1→2)-[α-L-arabinofuranosyl-(1→4)]-β-D-glucopyranoside (25R)-spirost-5-en-3β-ol和(25R)-spirost-5-en-3β-ol 3-O-α-Lrhamnopyranosyl-(1→2)-O-β-D-glucopyranoside.