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Li Z.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Zhang P.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Zhang K.,Dalian Polytechnic University | Ren Z.,National Engineering and Technology Research Center for Preservation of Agriculture Products
Nongye Jixie Xuebao/Transactions of the Chinese Society of Agricultural Machinery | Year: 2011

In order to investigate the effect of 1-methylcyclopropene combined with controlled freezing-point storage on grape texture, the change of 'ZANA' grape flesh texture parameters was studied by using texture profile analysis with a texture analyzer. The result showed that softening of grape fruit was delayed by 1.0 μL/L 1-methylcyclopropene combined with controlled freezing-point storage. The hardness, springiness, cohesiveness, chewiness and marketable fruit rate of grape fruit treated by 1-methylcyclopropene are higher than cold storage and controlled freezing-point storage. The hardness of grape has a good positive correlation with resilience. The springiness of grape has good positive correlations with resilience, chewiness and springiness. The marketable fruit rate of grape has a good linear relationship with fruit hardness. In conclusion, TPA test can reflect the change of grape fruit texture during storage and fit for evaluation of the quality of stored grape.


Fan X.,U.S. Department of Agriculture | Guan W.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Sokorai K.J.B.,U.S. Department of Agriculture
Radiation Physics and Chemistry | Year: 2012

Fresh-cut Iceberg lettuce packaged in modified atmosphere packages and spinach in perforated film bags were irradiated with gamma rays at doses of 0, 1, 2, 3, and 4kGy. After irradiation, the samples were stored for 14 days at 4°C. O 2 levels in the packages of fresh-cut Iceberg lettuce decreased and CO 2 levels increased with increasing radiation dose, suggesting that irradiation increased respiration rates of lettuce. Tissue browning of irradiated cut lettuce was less severe than that of non-irradiated, probably due to the lower O 2 levels in the packages. However, samples irradiated at 3 and 4kGy had lower maximum force and more severe sogginess than the non-irradiated control. In addition, ascorbic acid content of irradiated lettuce was 22-40% lower than the non-irradiated samples after 14 days of storage. The visual appearance of spinach was not affected by irradiation even at a dose of 4kGy. Consumer acceptance suggested that more people would dislike and would not buy spinach that was treated at 3 and 4kGy as compared to the non-irradiated sample. Overall, irradiation at doses of 1 and 2kGy may be employed to enhance microbial safety of fresh-cut Iceberg lettuce and spinach while maintaining quality. © 2011.


Yan R.,U.S. Department of Agriculture | Yan R.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Mattheis J.,U.S. Department of Agriculture | Gurtler J.,U.S. Department of Agriculture | And 2 more authors.
Postharvest Biology and Technology | Year: 2014

A UV-C treatment system (two treatment chambers connected by an inclined belt to rotate apricots between chambers) was tested in a commercial setting. Escherichia coli ATCC 25922, used as a surrogate for E. coli O157:H7 to determine the system's antimicrobial efficacy, was inoculated onto fruit surfaces at a population of 6.8log CFU/fruit. UV-C dosage was evaluated by attaching film dosimeters to six fixed locations on each apricot. Results suggested that reduction of inoculated E. coli ATCC 25922 populations on the apricot fruit by UV-C treatment was small (only 0.5-0.7logs). There were large variations in UV-C doses among varying apricot surface locations. Approximately 1/3 of apricots had individual surfaces receiving less than 0.2kJm-2 UV-C exposure, even though fruit received, on average, more than 1kJm-2. Low reductions of E. coli may be attributed, in part, to non-uniform UV-C exposure. This study demonstrates the need to use a fruit rotation device more capable of delivering uniform UV-C dosage to the surface of apricots for inactivating bacteria in a commercial setting. © 2014.


Guan W.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Huang L.,U.S. Department of Agriculture | Fan X.,U.S. Department of Agriculture
Journal of Food Science | Year: 2010

Recent studies showed that sodium acid sulfate (SAS) and levulinic acid (LA) in combination with sodium dodecyl sulfate (SDS) was effective in inactivating human pathogens on Romaine lettuce. The present study investigated the effects of LA and SAS in combination with SDS (as compared with citric acid and chlorine) on the inactivation of E. coli O157:H7 and sensory quality of fresh-cut Iceberg lettuce in modified atmosphere packages during storage at 4 °C. Results showed that LA (0.5% to 3%) and SAS (0.25% to 0.75%) with 0.05% SDS caused detrimental effects on visual quality and texture of lettuce. LA- and SAS-treated samples were sensorially unacceptable due to development of sogginess and softening after 7 and 14 d storage. It appears that the combined treatments caused an increase in the respiration rate of fresh-cut lettuce as indicated by higher CO2 and lower O2 in modified atmosphere packages. On the positive side, the acid treatments inhibited cut edge browning of lettuce pieces developed during storage. LA (0.5%), SAS (0.25%), and citric acid (approximately 0.25%) in combination with SDS reduced population of E. coli OH157:H7 by 0.41, 0.87, and 0.58 log CFU/g, respectively, while chlorine achieved a reduction of 0.94 log CFU/g without damage to the lettuce. Therefore, compared to chlorine, LA and SAS in combination with SDS have limited commercial value for fresh-cut Iceberg lettuce due to quality deterioration during storage. © 2010 Institute of Food Technologists®.


Guan W.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Fan X.,U.S. Department of Agriculture | Yan R.,National Engineering and Technology Research Center for Preservation of Agriculture Products
Postharvest Biology and Technology | Year: 2012

This study investigated the effects of ultraviolet-C (UV-C) light applied to both sides of mushrooms on microbial loads and product quality during storage for 21d at 4°C. Microflora populations, color, antioxidant activity, total phenolics, and ascorbic acid were measured at 1, 7, 14 and 21d of storage. Additionally, the inactivation of Escherichia coli O157:H7 by UV-C was determined. Results showed that UV-C doses of 0.45-3.15kJm -2 resulted in 0.67-1.13logCFUg -1 reduction of E. coli O157:H7 inoculated on mushroom cap surfaces. UV-C radiation also reduced total aerobic plate counts by 0.63-0.89logCFUg -1 on the surface of mushrooms. Although mushrooms treated with UV-C had more severe browning with increasing dosage after initial treatment, the control mushrooms also browned as indicted by lower L* and higher a* values after 21d of storage at 4°C. In addition, the UV-C treatments apparently inhibited lesion development on the mushroom surface. During the first 7d, irradiated mushrooms had lower antioxidant activity, total phenolics, and ascorbic acid content compared to non-radiated samples. However, irradiated mushrooms reached similar amounts of these nutrients as the control after 14d of storage at 4°C. In summary, UV-C radiation could potentially be used for sanitizing fresh button mushrooms and extending shelf-life. © 2011.


Guan W.,National Engineering and Technology Research Center for Preservation of Agriculture Products | Fan X.,U.S. Department of Agriculture
Journal of Food Science | Year: 2010

Tissue browning and microbial growth are the main concerns associated with fresh-cut apples. In this study, effects of sodium chlorite (SC) and calcium propionate (CP), individually and combined, on quality and microbial population of apple slices were investigated. " Granny Smith" apple slices, dipped for 5 min in CP solutions at 0%, 0.5%, 1%, and 2% (w/v) either alone or in combination with 0.05% (w/v) SC, were stored at 3 and 10 °C for up to 14 d. Color, firmness, and microflora population were measured at 1, 7, and 14 d of storage. Results showed that CP alone had no significant effect on the browning of cut apples. Even though SC significantly inhibited tissue browning initially, the apple slices turned brown during storage at 10 °C. The combination of CP and SC was able to inhibit apple browning during storage. Samples treated with the combination of SC with CP did not show any detectable yeast and mold growth during the entire storage period at 3 °C. At 10 °C, yeast and mold count increased on apple slices during storage while CP reduced the increase. However, high concentrations of CP reduced the efficacy of SC in inactivating E. coli inoculated on apples. Overall, our results suggested that combination of SC with 0.5% and 1% CP could be used to inhibit tissue browning and maintain firmness while reducing microbial population.Practical Application: Apple slices, which contain antioxidants and other nutrient components, have emerged as popular snacks in food service establishments, school lunch programs, and for family consumption. However, the further growth of the industry is limited by product quality deterioration caused by tissue browning, short shelf-life due to microbial growth, and possible contamination with human pathogens during processing. Therefore, this study was conducted to develop treatments to reduce microbial population and tissue browning of " Granny Smith" apple slices. Results showed that an antimicrobial compound, sodium chlorite, is effective in not only eliminating microbes but also inhibiting tissue browning of apple slices. However, the compound caused tissue softening and its antibrowning effect was short-lived, lasting only for a few days. Combination of the compound with a calcium-containing food additive was able to improve firmness and freshness of apple slices while reducing population of Escherichia coli artificially inoculated on samples and inhibiting the growth of yeast and mold during storage. © 2010 Institute of Food Technologists®.

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