Yanli You

Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity

The effects of short-term anoxia pre-treatment on browning of fresh-cut Chinese water chestnut (CWC), stored at 4°C, in relation to antioxidant activity were investigated. CWC slices were exposed to pure N2 for 4h and then stored at 4°C for 18d. Anoxia significantly inhibited browning of CWC slices during storage, accompanied by lower contents of malondialdehyde, H2O2, and lipoxygenase activity. Furthermore, anoxia induced the activities of superoxide dismutase and ascorbate peroxidase, which could benefit scavenging reactive oxygen species and alleviating lipid peroxidation. In addition, better maintenance of reducing power and free-radical-scavenging activities against α,α-diphenyl-β-picrylhydrazy (DPPH), superoxide anions and hydroxyl was observed in N2-treated CWC slices, with higher phenolic compounds and ascorbic acid contents. Collectively, these finds suggest that N2 pre-treatment enhanced enzymatic and non-enzymatic antioxidant activity in CWC slices, and thereby contributed to alleviating lipid peroxidation and maintenance of storage quality.

Identification of Major Phenolic Compounds of Chinese Water Chestnut and their Antioxidant Activity

Chinese water chestnut (CWC) is one of the most popular foods among Asian people due to its special taste and medical function. Experiments were conducted to test the antioxidant activity and then determine the major phenolic compound components present in CWC. CWC phenolic extract strongly inhibited linoleic acid oxidation and exhibited a dose-dependent free-radical scavenging activity against alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals, superoxide anions and hydroxyl radicals, which was superior to ascorbic acid and butylated hydroxytoluene (BHT), two commercial used antioxidants. Furthermore, the CWC extract was found to have a relatively higher reducing power, compared with BHT. The major phenolic compounds present in CWC tissues were extracted, purified and identified by high-performance liquid chromatograph (HPLC) as (-)-gallocatechin gallate, (-)-epicatechin gallate and (+)-catechin gallate. This study suggests that CWC tissues exhibit great potential for antioxidant activity and may be useful for their nutritional and medicinal functions.

Influence of the nitric oxide donor, sodium nitroprusside, on lipid peroxidation and anti-oxidant activity in pericarp tissue of longan fruit

Summary The effects of nitric oxide (NO) on lipid peroxidation and anti-oxidant activity in longan fruit were investigated during storage. Fruits were dipped for 5 min in a solution containing 1 mM sodium nitroprusside (SNP), an NO donor. They were then packed into polyethylene bags and stored for 6 d at 28°C. Changes in pericarp browning index, membrane permeability, malondialdehyde (MDA) content, the rate of superoxide production, the activities of lipoxygenase (LOX), superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT), α,αdiphenyl-βpicrylhydrazy (DPPH) radical scavenging activity, and reducing power were measured. Treatment with SNP inhibited pericarp browning and suppressed increases in membrane permeability and lipid peroxidation. These effects were associated with lower LOX activity, higher APX and CAT activities, better maintenance of DPPH radical scavenging activity and reducing power, and lower superoxide production rate. However, SOD activity was higher in control (non-SNP-treated) fruit than in SNP-treated fruit over the first 4 d of storage. Overall, these findings suggest that treatment with NO enhanced the anti-oxidant activity in pericarp tissue of longan fruit during storage, and contributed to reduced lipid peroxidation. Reduced lipid damage apparently maintained the compartmentation of enzymes and substrates and, thereby, lessened enzymatic browning.

Effects of adenosine triphosphate on the vase life of cut carnation flowers

The addition of adenosine triphosphate (ATP) to vase solutions at a concentration of 0.01−0.50 mmol/L markedly extended the vase life of cut carnation flowers at 25°C and 80−90% relative humidity. The most beneficial effect on vase life was observed at 0.1 mmol/L ATP, with a 28% extension over non-ATP-treated flowers. Furthermore, the addition of ATP at 0.1 mmol/L increased flower size by 12% by the end of the vase-holding period and significantly extended the time to maximum flower expansion by 1.7 days, compared with non-ATP-treated flowers held in distilled water. Our data suggest that exogenous ATP supply is an effective method to extend the vase life of cut carnation flowers.