Zhifang Yu

Effect of post-harvest heat treatment on proteome change of peach fruit during ripening.

The extracted proteins from the heat-treated peach fruit (dipped in hot water at 48°C for 10min and then stored at room temperature (20°C-25°C) for up to 6 days) were used for proteomic analysis in order to understand the response of post-harvest peach fruit to heat treatment during ripening stage at proteomic level. After two dimensional gels electrophoresis (2-DE) was conducted, more than 600 protein spots were detected. Among them, 35 differently expressed spots (P<0.05) were selected to be excised and analyzed using MALDI-TOF/TOF, and finally 30 protein spots were confidently identified according to NCBI database. The results demonstrated that among the thirty protein spots expressed particularly induced by heat treatment, 43% were related to stress response, 17% to cell structure, 13% to protein fate, 7% to glycolytic pathway, 3% to ripening and senescence and 17% to unclassified. All of them are involved in the regulation of peach fruit development and ripening. All these indicated that the self-defense capability of peach fruit was improved by heat treatment. The study will enable future detailed investigation of gene expression and function linked with peach fruit ripening.

Proteomic analysis of peach fruit during ripening upon post-harvest heat combined with 1-MCP treatment

UNLABELLED Regulation of peach fruit ripening by heat combined with 1-Methylcyclopropene (1-MCP) was studied by 2-dimensional gel electrophoresis (2-DE) and Matrix-Assisted Laser Desorption/Ionization Time of Flight tandem Mass Spectrometry (MALDI-TOF/TOF). Proteins from peach fruits after harvest (CK) and treated by heat combined with 1-MCP (HM) were then stored at room temperature for 0, 1, 3 and 5days. Among the identified 42 protein spots, the differential abundant proteins belonged to pathways of defense and response (35.71%), energy and metabolism (30.95%), ripening and senescence (14.29%), cell structure (14.29%) and protein fate (4.76%). Compared with separate heat or 1-MCP treatment, pectinesterase inhibitor (PEI) and heat shock protein (HSP) appeared, and abscisic stress ripening-like protein (ASR) disappeared after the treatment, while HM specifically increased the abundances of glutathione peroxidase (GPX), peroxiredoxin, calmodulin, and decreased those of cytosolic malate dehydrogenase, d-3-phosphoglycerate dehydrogenase (GAPDH) and glutamine synthetase. HM treatment protected fruit cells by enhancing the capabilities of stress response and defense, inhibiting substance and energy metabolism, limiting cell calcium loss. The results suggest that the self-defense capability of peach fruit was boosted by HM treatment. This study is informative in exploring the influences of HM on peach fruit ripening by demonstrating that 1-MCP and heat functioned synergistically. BIOLOGICAL SIGNIFICANCE To analyze the functions of differentially expressed proteins and to elucidate the response of early-maturing melting peach fruit (cv. Huiyulu) during ripening, we herein, for the first time, studied the effects of HM treatment on involved protein profiles by a proteomic approach with 2-DE and MALDI-TOF/TOF. This study successfully verified that HM functioned synergistically rather than simply superimposed on the proteome level. In addition, this study explains the molecular mechanism regarding peach fruit development and ripening on the proteome level, offers new insights into relevant physiological mechanism, and provides theoretical evidence for reinforcing quality control of post-harvest peach fruit in practice.

Efficacy of different sanitizing agents and their combination on microbe population and quality of fresh-cut Chinese chives.

UNLABELLED The objective of this study was to evaluate the efficacy of individual sanitizing agents (sodium hypochlorite, SH; peracetic acid, PA; chlorine dioxide, CD) and the combination of CD and PA on reducing the total aerobic bacteria, coliforms as well as their effects on ascorbic acid (Vc), chlorophyll, and a* value of Chinese chives. All sanitizing treatments significantly (P < 0.05) reduced microorganisms compared to the control. After treatment with single SH, PA, and CD, the reduction of the total aerobic bacteria on Chinese chives was <1.0 log CFU/g (where colony-forming units is CFU), approximately 1.68 to 2.22 log CFU/g, and approximately 0.99 to 2.85 log CFU/g, respectively. The greatest reduction of total aerobic bacteria achieved by the combination of 40 ppm CD, 150 ppm PA for 8 min, was 2.45 log CFU/g. This treatment had a slight discoloration effect as indicated by a* value and chlorophyll content; and is therefore the optimal combination for reducing microorganisms on Chinese chives. PRACTICAL APPLICATION Fresh-cut vegetables are known to be susceptible to contamination; and subsequent growth of microorganisms result in quality concerns. Chinese chive leaves are hollow, cylindrical, and are more inclined to accumulate microbes. Currently, there is limited information on the decontamination of Chinese chives. This research focused on the evaluation of sanitation options for fresh-cut Chinese chives; and the information obtained should be applicable and useful in other fresh-cut vegetables.

Differential protein profiles of postharvest Gynura bicolor D.C leaf treated by 1-methylcyclopropene and ethephon.

Proteins were extracted from G. bicolor that had been treated with 1-methylcyclopropene and ethephon and then stored at room temperature for 1, 3 and 7days. More than 300 protein spots were detected by 2-DE and 38 differentially abundant spots (P<0.05) were excised and analysed by using MALDI-TOF/TOF. Thirty-three proteins were finally confidently identified. According to the Clusters of Orthologous Groups of proteins, the proteins identified were classified into those responsible for metabolism (75.8%), information storage and processing (9.1%) and cellular processes and signaling (12.1%). Compared with ethephon and control treatments, 1-methylcyclopropene specifically increased the abundances of superoxide dismutase, peroxidase, carbonic anhydrase, nucleoside diphosphate kinases, glyceraldehyde 3-phosphate dehydrogenase, RuBisCO and ribulose bisphosphate carboxylase/oxygenase activase. 1-Methylcyclopropene protected leaf chloroplast and cells by enhancing stress response and defense, and delayed senescence by inhibiting substance and energy metabolisms. Therefore, 1-methylcyclopropene allowed better self-defense and delayed senescence of G. bicolor leaf.

Effect of Incorporation of Nature Chemicals in Water Ice-glazing on Freshness and Shelf-life of Pacific Saury (Cololabis saira) During –18 °C Frozen Storage

BACKGROUND Microbial spoilage and lipid oxidation are two major factors causing freshness deterioration of Pacific saury (Cololabis saira) during frozen storage. To provide a remedy, the effects of several natural chemicals incorporated alone or in combination in traditional water ice-glazing on the freshness and shelf-life of Pacific saury during frozen storage at -18 °C were investigated. Pacific sauries were subjected to individual quick freezing followed immediately by dipping into cold tap water (control) or solutions containing nisin, chitosan, phytic acid (single-factor experiment) or their combinations ((L9 (34 ) orthogonal experiment) for 10 s at 1 °C and then packaged in polypropylene bags before frozen storage at -18 °C. The storage duration tested was up to 12 months. RESULTS All ice-glazing treatments with individual chemicals could significantly (P < 0.05) inhibit the accumulation of thiobarbituric acid-reactive substances (TBARS), total volatile basic nitrogen (TVB-N) and histamine as well as the increase in bacterial total viable count (TVC) compared with controls, while the combination treatments gave even better effects. The L9 (34 ) orthogonal experiment showed that the optimal combination was A2 B1 C2 (i.e. 0.5 g L-1 nisin, 5 g L-1 chitosan and 0.2 g L-1 phytic acid). The TBARS, TVB-N, histamine and TVC values in A2 B1 C2 -treated samples remained far below the maximum acceptable limit for good-freshness fish after 12 months of frozen storage at -18 °C. CONCLUSION The incorporation of natural chemicals tested herein in ice-glazing could inhibit microbial spoilage and lipid oxidation and therefore maintain the freshness of Pacific saury during frozen storage. Under the optimal conditions, the shelf-life of Pacific saury could be extended up to 12 months at -18 °C. The study indicated that the combination treatment with natural chemicals could be commercially utilized to maintain the freshness and prolong the shelf-life of Pacific saury.

Responses of Dynamic Proteome Changes in Zizania Latifolia to Fresh-Cut Operation during Room Temperature (25 °C) Storage

In order to explore the molecular mechanism of fresh-cut operation accelerating senescence and quality deterioration of Z. latifolia, the response of dynamic proteome change in Z. latifolia to fresh-cut operation during room temperature (25 °C) storage was studied. 35 protein spots were identified to change significantly (p<0.05) from the total 660 protein spots on the gels by MALDI-TOF/TOF. Compared with the control, 29 proteins showed similar expression pattern after fresh-cut operations in spite of the difference in abundance between two treatments. Meanwhile, six spots (plant basic secretory protein, adenosine kinase, C2 domain, class III peroxidases, LbH_gamma_CA_like, small Ras-related GTP-binding protein), which were down-regulated in whole Z. latifolia, increased after fresh-cut operation during storage. Fresh-cut operations that accelerate senescence and quality deterioration of Z. latifolia might be due to the production and transduction of wounding signals, acceleration of carbohydrate and nucleotide catabolism, disorder of energy homeostasis, enhancement of free radical damage, as well as degradation of cell structure.