硫代葡萄糖苷检测技术及其在花椰菜硫苷研究中的应用

文章综述了硫代葡萄糖苷类化合物检测技术研究进展以及近10年在花椰菜硫苷研究中的应用,并展望其未来的发展方向.     

Effect of domestic cooking on the red cabbage hydrophilic antioxidants

The contents of vitamin C, total phenolics, anthocyanins, hydroxybenzoic and hydroxycinnamic acids as well as 2,2′‐azinobis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid) monocation radical scavenging activity were evaluated in two varieties of red cabbage before and after conventional and steam‐cooking. During the conventional cooking 32.7–64.5% of vitamin C and 45.7–66.9% of total phenolics were retained in cooked tissue. Decreasing cooking water volume by half led to better retention of both phenolics (by 2.7–14.5%) and vitamin C (by 14.2–18.4%). However, shortening the cooking time by half affected the retention of phenolics and vitamin C only by 3.8–6.7% and 0–2.2%, respectively. Steam‐cooking is recommended to prevent the major loss of scavenging activity, because under these conditions, the corresponding TEAC (Trolox Equivalent Antioxidant Capacity) values were reduced only by 5–20%. Moreover, the content of vitamin C was decreased by 2.1–22.7% while losses of total phenolics were up to 10%. The phenolics are the major source of free radical scavenging activity of red cabbage, since the contribution of vitamin C to TEAC for fresh and cooked red cabbage was from 18.2 to 28.5%.     

Ascorbic acid improves the antioxidant activity of European grape juices by improving the juices' ability to inhibit lipid peroxidation of human LDL in vitro

Antioxidant activities of red and white European grape juices towards copper induced lipid oxidation of human low-density lipoproteins (LDL) were examined in vitro . LDL lipid peroxidation was assessed spectrophotometrically by monitoring the development of conjugated lipid hydroperoxides at 234 nm. Red grape juice concentrate inhibited lipid peroxidation of LDL by prolonging the lag phase by 2.7 times relative to a control when evaluated at a total phenolic concentration of 10 μM gallic acid equivalents (GAE). Both red grape juices tested blocked lipid peroxidation of LDL at 20 μM GAE. White grape juice exerted prooxidant activity at 5–20 μM GAE. The antioxidant activity, inhibition of lipid peroxidation of LDL in vitro , was correlated with the juices' levels of total phenols ( r  > 0.98, P  < 0.01), anthocyanins ( r  > 0.99, P  < 0.01), flavan-3-ols ( r  > 0.97, P  < 0.05), and hydroxybenzoates ( r  > 0.96, P  < 0.05) when the phenolic composition of each grape juices was analysed by HPLC. 5 μM ascorbic acid alone did not exert antioxidant activity towards LDL, but combinations of 5 μM ascorbic acid with 5 μM GAE juice phenols eliminated the prooxidant activity of white grape juice, and significantly improved the antioxidant activities of red grape juices.     

Effect of germination on vitamin C,phenolic compounds and antioxidant activity in flaxseed (Linum usitatissimum L.)

Flaxseed (Linum usitatissimum L.) is well known for its health benefits and chemical composition. This study aimed to evaluate the dynamic changes caused by germination in vitamin C, phenolic compounds and antioxidant activities of flaxseed. It was observed that eight‐day germination of flaxseed sprouts caused increases in phytochemical contents, that is 22.1‐fold increase in vitamin C, 2.67‐fold increase in phenolics and 5.48‐fold increase in flavonoid contents as compare to initial concentration in flaxseeds on dry weight basis. The stimulation was also noted in the three identified phenolic acid ingredients including caffeic acid, p‐coumaric acid and ferulic acid. Similarly, the total PSC and ORAC values of flax sprouts at day 8 increased by 3‐ to 4‐folds compared to nongerminated flaxseeds. It is revealed that comparatively, 8‐day germination of flax sprouts leads to a significant increase in vitamin C, phenolic constituents and total antioxidant activities than those of flaxseeds.