鲜切雪莲果护色效果的研究

研究不同褐变抑制剂对鲜切雪莲果护色效果,通过正交试验并运用多指标试验设计综合加权评分法对多种抑制剂护色效果的进行综合选优.试验结果表明:采用0.5％柠檬酸+0.5％抗坏血酸+0.05‰焦亚硫酸钠浸泡10min的复合处理,试验综合加权评分值为97.6414.雪莲果的PPO活性为0.007、褐变度为3.62、感官品质为7,在10d内抑制褐变效果最好.     

紫薯浊汁饮料的研究

对紫薯浊汁饮料的加工技术进行了研究。通过正交试验,确定了紫薯桨防褐变、饮料稳定性等工艺条件。     

Postharvest evaluation of soilless-grown table grape during storage in modified atmosphere

BACKGROUND: Soilless growth systems, developed mainly for vegetables and ornamental crops, have also been used recently as an alternative to soil culture for table grape in order to achieve optimal production performance. In this study, sensory, physical and chemical parameters were analysed in table grapes obtained from soil and soilless growth systems at harvest and during storage in air or modified atmosphere. RESULTS: At harvest, soilless‐grown berries were 30% firmer than those grown in soil. Moreover, they showed 60% higher antioxidant activity and total phenol content than soil‐grown fruits. Modified atmosphere storage resulted in a better quality of table grapes compared with those stored in air. Furthermore, soilless growth was more suitable than soil growth for preserving visual quality and controlling rachis browning and weight loss. CONCLUSION: Since the soilless system produces berries that are cleaner and of higher quality than those grown in soil, the implementation of soilless growth for the production of health‐promoting and convenience fruits is suggested. Copyright © 2011 Society of Chemical Industry     

Novel Browning Inhibitor Formulation for Fresh-cut Apples

ABSTRACT: Development of a browning inhibitor for fresh-cut apples that would not support human pathogen survival was investigated. Granny Smith and Fuji wedges were treated with acidic or neutral browning inhibitors with and without addition of sodium hexametaphosphate. Wedges in modified atmosphere packaging pouches were observed for browning during storage at 4 °C and 10 °C. A pH 2.9 dip containing ascorbic acid, citric acid, and sodium hexametaphosphate suppressed browning for at least 3 wk at 4 °C, whereas formulations without hexametaphosphate failed within 1 wk. These results demonstrate that browning in fresh-cut apples can be controlled with a formulation unlikely to support human pathogen survival or growth.     

Effect of red sweet pepper dehydration conditions on Maillard reaction,ascorbic acid and antioxidant activity

In this study we evaluated the application of low pressure-controlled temperature drying in the production process of dehydrated sweet red pepper and contrast the quality of this dehydrated vegetable in terms of the concentration of some heat liable components (ascorbic acid), decrease on the antioxidant activity and formation of furosine (Amadori compound of lysine formed during the Maillard reaction). Analysis of data showed that furosine is a good indicator for controlling the dehydration process of red pepper. In addition, the stability of the antioxidant activity and proteical damage (measured as furosine formation) in red pepper is a function of the dehydration conditions: Higher temperatures exert a strong influence on the kinetics of degradation, accelerating the rate of decomposition of antioxidant compounds and the loss of proteical quality.     

Light exposure inhibiting tissue browning and improving antioxidant capacity of fresh-cut celery (Apium graveolens var. dulce)

Fresh-cut celery is perishable and susceptible to tissue browning during storage. In this study, the effect of continuous light exposure (2000 lux) on browning related enzyme activity of fresh-cut celery was investigated during 8 d storage at 7 °C using darkness (0.2 lux) as control. Light exposure significantly suppressed polyphenol oxidase (PPO) and peroxidase (POD) activities, and subsequently decreased soluble quinone accumulation and browning index (BI) evolution during storage. In addition, phenylalanine ammonia lyase (PAL) activity, total phenol (TP) content, and antioxidant capacity (AC) values were all higher when the fresh-cut celery samples were exposed to light than in darkness during storage. A significant positive correlation between TP and AC was observed at both light (R = 0.884, P < 0.01) and dark (R = 0.705, P < 0.01) conditions.     

An industry trial provides further evidence for the role of corks in oxidative spoilage of bottled wines

Commercially available corks were tested for oxygen permeability and for the presence of oxidants by observing the change in concentration of antioxidants and the extent of browning in white wines stored in bottles with different closures. Bottles (375 mL) filled with a Semillon-Chardonnay blend were sealed with either a roll-on tamper-evident (ROTE) aluminium screw cap closure with a tinfoil laminate wad, or a combination of ROTE + cork, or cork alone. Both peroxide- and chlorine-washed corks, each from three different suppliers, were used in the trial. The bottles were filled, closed and stored in air under controlled conditions for 16 and 22 months. At each occasion, sample lots of 24 bottles of each closure type were analysed. Four types of corks, chlorine- and peroxide-washed corks from two of the suppliers, had greater oxidative capacity than those from the third supplier and the ROTE closure alone. The seals provided by three of the four types of closure with increased oxidative capacity were also permeable to oxygen. Only some of the seals provided by the peroxide-washed corks, and none of the seals provided by the chlorine-washed corks, from the third supplier appeared to be permeable to oxygen compared to the ROTE closure alone. In all cases where permeation was observed, the extent of oxidation caused by this characteristic was highly variable amongst corks within a given batch. In contrast, the effect of an increased oxidative capacity in cork appeared to be similar whether observed amongst corks from within and amongst batches, and irrespective of cork type and supplier origin. The results of this study shows the incidence of these defects in corks that are commercially available to winemakers in Australia.     

Temperature Sensitivity and Pressure Resistance of Mushroom Polyphenoloxidase

Measurements of residual enzyme activity and FTIR-spectroscopy revealed that mushroom polyphenoloxidase is a thermosensitive enzyme readily inactivated by temperatures exceeding 50°C. The enzyme is, however, very pressure stable. At room temperature no enzyme inactivation occurred at pressures up to 6 kbar. FTIR-spectroscopy revealed that a modification in enzyme conformation occurred below 9 kbar. Kinetic studies showed that pressure and temperature did not always act synergistically with respect to enzyme inactivation. FTIR-spectroscopy showed that pressure- or temperature-induced changes were considerably different. Both temperature and pressure-temperature inactivation were only slightly influenced by pH (in the pH-range 5.5–7.5).     

Color of Minimally Processed Potatoes as Affected by Modified Atmosphere Packaging and Antibrowning Agents

Minimal processing of potatoes was studied by using different treatments of cut potatoes in combination with modified atmosphere packaging. Different packaging materials and peeling methods were evaluated. An L-cysteine (0.5%) and citric acid (2%) mixture prevented browning of potatoes effectively. Active modification of the atmosphere inside the package was necessary to achieve extended shelf-life. Nitrogen flushing was more effective than other gas treatments with a highly permeable multilayered polyolefin packaging material. Hand peeling and lye peeling resulted in better quality, but abrasion peeling was undesirable for fresh potatoes. The shelf-life of the minimally processed products could be extended to nearly 3 wk under refrigerated storage.