Yonghua Zheng

Effect of high oxygen atmosphere storage on quality, antioxidant enzymes, and DPPH-radical scavenging activity of Chinese bayberry fruit.

The influence of high O(2) atmosphere on postharvest decay, quality, total phenolic, total anthocyanin contents, antioxidant enzymes activity, and antioxidant activity of Chinese bayberry fruit was investigated. Freshly harvested Chinese bayberry fruits were placed in jars and ventilated continuously with air or with 80 and 100% O(2) for up to 12 days. Samples were randomly selected initially and at 3-days interval during storage. The fruit exposed to high O(2) was resistant to decay, had high levels of total soluble solids, titratable acidity and ascorbic acid contents, and also reduced the increment of pH value. High O(2) treatment was less stressful as reflected by having the significantly lower malonaldehyde contents and higher catalase, ascorbic acid peroxidase, and peroxidase activities during storage. Both 80% and 100% O(2) treaments had also retained the bioactive contents and 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity during storage. These results indicate that elevated O(2) levels may improve the ability of the antioxidative defense mechanism in Chinese bayberry and result in a better control of fruit decay.

Effect of Nano‐Packing on Preservation Quality of Fresh Strawberry (Fragaria ananassa Duch. cv Fengxiang) during Storage at 4 °C

UNLABELLED A novel nano-packing material with lower relative humidity, oxygen transmission rate and high longitudinal strength was synthesized by blending polyethylene with nano-powder (nano-Ag, kaolin, anatase TiO(2), rutile TiO(2)), and its effect on preservation quality of strawberry fruits (Fragaria ananassa Duch. cv Fengxiang) was investigated during storage at 4 degrees C. Results showed that nano-packaging was able to maintain the sensory, physicochemical, and physiological quality of strawberry fruits at a higher level compared with the normal packing (polyethylene bags). After a 12-d storage, decreases in the contents of total soluble solids, titratable acidity, and ascorbic acid of nano-packing were significantly inhibited. Meanwhile, decay rate, anthocyanin, and malondialdehyde contents were decreased to 16.7%, 26.3 mg/100g, 66.3 micromol/g for nano-packing and 26.8%, 31.9 mg/100g, 75.4 micromol/g for normal packing; polyphenoloxidase (PPO) and pyrogallol peroxidase (POD) activities were significantly lower in nano-packing than the control. These data indicated that the nano-packaging might provide an attractive alternative to improve preservation quality of the strawberry fruits during extended storage. PRACTICAL APPLICATION Nano-packing exhibited identified quality benefits applicable to the preservation of fresh strawberry. Furthermore, nano-packing has the advantages of simple processing and feasibility to be industrialized in contrast with other storages. Thus, the utilization of nano-packing will likely assist commercial producers and retailers in extending the shelf life of products over a broader range in the future.

Effect of exogenous γ-aminobutyric acid treatment on proline accumulation and chilling injury in peach fruit after long-term cold storage.

The effect of exogenous γ-aminobutyric acid (GABA) on chilling injury of peach fruit was investigated. Freshly harvested peaches were treated with 1, 5, or 10 mM GABA at 20 °C for 10 min and then stored at 1 °C for up to 5 weeks. The results showed that all of the GABA treatments could reduce chilling injury of peach fruit with 5 mM being the most effective concentration. GABA treatment significantly enhanced the accumulation of endogenous GABA and proline, which resulted from the increased activities of glutamate decarboxylase, Δ(1)-pyrroline-5-carboxylate synthetase, and ornithine δ-aminotransferase and decreased proline dehydrogenase activity. Our results revealed that GABA treatment may be a useful technique to alleviate chilling injury in cold-stored peach fruit, and the reduction in chilling by GABA may be due to the induction of endogenous GABA and proline accumulation. These data are the first evidence that exogenous GABA induced chilling tolerance in postharvest horticultural products.

Methyl jasmonate reduces decay and enhances antioxidant capacity in Chinese bayberries.

The effects of methyl jasmonate (MeJA) on postharvest decay and antioxidant capacity in harvested Chinese bayberry fruit were investigated. Chinese bayberries were treated with 0, 1, 10, 100, or 1000 micromol L(-1) MeJA at 20 degrees C for 6 h and then stored at 0 degrees C for 12 days. MeJA at 10 micromol L(-1) was most effective in reducing fruit decay; quality parameters including pH value, total soluble solids, and titratable acidity were not significantly affected by MeJA treatment. Fruit treated with 10 micromol L(-1) MeJA exhibited significantly higher phenylalanine ammonia-lyase activity and higher levels of total phenolics, flavonoids, and anthocyanins as well as individual phenolic compounds than control. These fruits also maintained significantly higher antioxidant activity as measured by scavenging capacity against 1,1-diphenyl-2-picrylhydrazyl, superoxide, and hydroxyl radicals and by the reducing power test compared to the control. These results indicate that MeJA can effectively reduce fruit decay and improve antioxidant capacity of Chinese bayberry fruit.

Effect of methyl jasmonate on energy metabolism in peach fruit during chilling stress

BACKGROUND Energy status is associated with ripening, senescence and physiological disorder of various types of fruit after harvest, including peaches. Methyl jasmonate (MeJA) was effective in enhancing chilling tolerance in cold-stored peach fruit. The effect of MeJA on energy metabolism in peach fruit was investigated. RESULTS MeJA treatment increased the contents of adenosine triphosphate and adenosine diphosphate, but decreased the content of adenosine monophosphate, which resulted in a higher level of energy charge in peach fruit. Enzyme activities including H+-adenosine triphosphatase, Ca2+-adenosine triphosphatase, succinic dehydrogenase and cytochrome c oxidase were also higher in MeJA-treated fruit than those in control fruit. Meanwhile, MeJA treatment markedly inhibited the increase of ion leakage and the accumulation of malondialdehyde, super-oxidant radical and hydrogen peroxide. CONCLUSION These results indicated that MeJA could enhance chilling tolerance of peach fruit by inducing enzyme activities related to energy metabolism and maintaining high levels of ATP and energy charge.

Effect of cultural system and essential oil treatment on antioxidant capacity in raspberries.

The effects of cultural system and essential oil treatment on antioxidant capacities in raspberries were evaluated. Raspberries were hand-harvested from organic and conventional farms in Maryland, USA, and were treated with essential oil including carvacrol, anethole, cinnamic acid, perillaldehyde, cinnamaldehyde, and linalool. Results from this study showed that raspberries grown from organic culture exhibited higher value of antioxidant capacities and individual flavonoids contents. Moreover, the organic culture also enhanced the activities of antioxidant enzymes. In addition, essential oil treatments promoted the antioxidant enzymes activities and antioxidant capacities of raspberries, and the most effective compound was perillaldehyde. In conclusion, raspberries produced from organic culture contained significantly higher antioxidant capacities than those produce from conventional culture. Postharvest essential oil treatments have positive effect on enhancing antioxidant capacities in raspberries from both organic and conventional cultures.

Enhancing antioxidant capacity and reducing decay of chinese bayberries by essential oils.

The effects of essential oil treatment on fruit decay and antioxidant capacities in Chinese bayberries were evaluated. Chinese bayberries were treated with essential oils, including carvacrol, cinnamaldehyde, perillaldehyde, and linalool. Results from this study indicated that all essential oils significantly reduced fruit decay of Chinese bayberries, and the most effective compound was carvacrol. Treatment with carvacrol, cinnamaldehyde, perillaldehyde, and linalool significantly increased total phenolic, anthocyanin, and individual flavonoid contents. In addition, all essential oils maintained significantly higher antioxidant capacities as measured by scavenging capacity against superoxide, hydroxyl, and 1,1-diphenyl-2-picrylhydrazyl radicals and by the reducing power test compared to the control. Moreover, the activities of antioxidant enzymes were also enhanced by all essential oils. Thus, postharvest essential oil treatment has positive effects on reducing decay and enhancing antioxidant capacities in Chinese bayberries.

Combined salicyclic acid and ultrasound treatments for reducing the chilling injury on peach fruit.

The effects of salicylic acid (SA; 1 mmol L(-1)) and ultrasound treatment (40 kHz, 10 min) either separately or combined on the chilling injury (CI) in cold-stored peach fruit ( Prunus persica Batsch cv. Baifeng) were investigated. The results showed that SA treatment alone alleviated CI during storage. Ultrasound alone had no influence, but when it was combined with SA, it resulted in greater inhibition of CI than SA alone. The activities of antioxidant enzymes, such as catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase, were induced by a combination of SA with ultrasound. In addition, the combined treatment also increased the endogenous SA concentrations in peaches. These results suggested that the induced tolerance against CI by the combination of ultrasound and SA treatment in cold-stored peach fruit was related to the induction of antioxidant enzymes and the increase in the SA concentration.

6-Benzylaminopurine delays senescence and enhances health-promoting compounds of harvested broccoli.

The effect of 6-benzylaminopurine (6-BA) on the color, antioxidant activity, and contents of total phenols, glucosinolate, and sulforaphane in broccoli florets was investigated. The results showed that 6-BA treatment markedly inhibited the increase of the L* value and malondialdehyde (MDA) content and retarded the decrease of the H value. 6-BA treatment reduced the rate of chlorophyll degradation by regulating the activities of chlorophyllase and Mg-dechelatase. When compared to control florets, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging activity and the activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) were enhanced in florets treated with 6-BA, whereas the activity of peroxidase (POD) was significantly reduced. The contents of total phenols, glucosinolate, and sulforaphane in broccoli florets were also profoundly increased after treatment with 6-BA. These results indicated that 6-BA could maintain the quality, delay senescence, and improve the nutritional value of broccoli.

Domestic cooking methods affect the nutritional quality of red cabbage

The aim of this work is to investigate the effects of domestic cooking methods, including steaming, microwave heating, boiling and stir-frying on the nutritional quality of red cabbage. Compared with fresh-cut red cabbage, all cooking methods were found to cause significant reduction in anthocyanin and total glucosinolates contents. Moreover, steaming resulted in significantly greater retention of vitamin C and DPPH radical-scavenging activity, while stir-frying and boiling, two popular Chinese cooking methods, led to significant losses of total phenolic, vitamin C, DPPH radical-scavenging activity, and total soluble sugar as well as reducing sugars. Normally, red cabbage consumed fresh in salads could maintain the highest nutrition. However, considering the habits of Asian cuisine, it is recommended to use less water and less cooking time, such as steaming based on our present results, so as to retain the optimum benefits of the health-promoting compounds.