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Ding T.,Zhejiang University | Ding T.,Zhejiang Key Laboratory for Agro Food Processing | Ge Z.,Zhejiang University | Shi J.,Agriculture and Agri Food Canada | And 4 more authors.
LWT - Food Science and Technology | Year: 2015

This study investigated the effect of ultrasonic treatment on the physicochemical properties (pH, available chlorine concentration (ACC), oxidation reduction potential (ORP), spectrophotometric characteristics) of slightly acidic electrolyzed water (SAEW). The effects of individual treatments (ultrasound and SAEW) and their combination on microbial loads and quality of cherry tomatoes and strawberries were also studied. The results indicated that a 10min ultrasonic treatment had no effect on pH, ACC, or ORP of SAEW. Ultrasound enhanced the bactericidal activity of SAEW which resulted in 1.77 and 1.29log reductions on total aerobic bacteria, and 1.50 and 1.29log reductions on yeasts and molds, respectively for cherry tomatoes and strawberries. The firmness of cherry tomatoes decreased while all other qualities considered were unaffected. This research indicates that SAEW in combination with ultrasound treatment has potential as a sanitization treatment to improve the efficacy of microbial inactivation on fresh produce without compromising product quality. © 2014 Elsevier Ltd.

Ding T.,Zhejiang University | Ding T.,Zhejiang Key Laboratory for Agro Food Processing | Xuan X.-T.,Zhejiang University | Liu D.-H.,Zhejiang University | And 7 more authors.
International Journal of Food Engineering | Year: 2015

Electrolyzed water offers several advantages over other sanitizers for sanitation of both food contact and non-contact surfaces. However, current electrolyzed water-generating process has low fluid output. To overcome such limitations, a circulating electrolyzed water-generating system has been developed in this study. The effects of NaCl/HCl concentration and electrolysis time were investigated. The free chlorine form (HClO and ClO-) of circulating electrolyzed water, and NaClO with the available chlorine concentrations of 50, 100, 200 mg/L were analyzed by using an ultraviolet spectrophotometer. The results show that the main chlorine form was HClO when the pH of solution was 6.44-6.53. The only ClO- in NaClO solutions when the pH of solution is 11.90. With the dilution of circulating electrolyzed water, the HClO concentration decreased while its proportion account for total available chlorine concentration increased (from 56.99% to 74.29%). The results indicated the potential application of diluted circulating electrolyzed water with high available chlorine concentration. The developed circulating electrolyzed water system in this study could be considered as a potential sanitizer due to its high stability, strong antimicrobial activity with high concentration of HClO and minimized equipment requirements for production. © 2015 by De Gruyter.

Chen Q.,Zhejiang University | Chen Q.,Zhejiang Key Laboratory for Agro Food Processing | Xu S.,Zhejiang University | Wu T.,Zhejiang University | And 6 more authors.
Journal of the Science of Food and Agriculture | Year: 2014

BACKGROUND: Essential oils such as citronella oil exhibit antifungal activity and are potential alternative inhibitors to chemical synthetic fungicides for controlling postharvest diseases. In this study the antifungal activity of citronella oil against Alternaria alternata was investigated. RESULTS: In vitro, citronella oil showed strong inhibition activity against A. alternata. The minimum inhibitory concentration in potato dextrose agar and potato dextrose broth medium was determined as 1 and 0.8 μL mL-1 respectively. In vivo the disease incidence of Lycopersicon esculentum (cherry tomato) treated with citronella oil was significantly (P < 0.05) reduced compared with the control after 5 days of storage at 25 °C and 95% relative humidity. The disease incidence at oil concentrations of 0.2-1.5 μL mL-1 was 88-48%. The most effective dosage of the oil was 1.5 μL mL-1, with 52% reduction, and the oil had no negative effect on fruit quality. Scanning electron microscopy observation revealed considerably abnormal mycelial morphology. CONCLUSION: Citronella oil can significantly inhibit A. alternata in vitro and in vivo and has potential as a promising natural product for controlling black rot in cherry tomato. © 2014 Society of Chemical Industry.

Huang H.,Zhejiang University | Huang H.,Zhejiang Key Laboratory for Agro Food Processing | Sun Y.,Zhejiang University | Sun Y.,Zhejiang Key Laboratory for Agro Food Processing | And 4 more authors.
Food Chemistry | Year: 2014

The traditional method of chemical extraction (i.e., extracts), combined with chemical antioxidant activity assays cannot assess the real antioxidant activity. In vitro digestion (i.e., digesta) with a cellular antioxidant activity (CAA) assay was developed for the determination of antioxidant activity in Chinese bayberry fruits. In this study, pretreatment methods were studied and the results showed that digesta had more free phenolic acids (FPA) but less total phenolic content (TPC) and total anthocyanin content (TAC) than extracts. Antioxidant activity assays, including ABTS, FRAP, DPPH, ORAC and CAA, were compared. Digesta had lower ABTS, FRAP and DPPH values but higher CAA values than extracts. FPA were better correlated with the chemical antioxidant assays in digesta. The correlations were high between TPC and CAA values in digesta (R2 = 0.96) but not extracts (R2 = 0.58). Higher correlations were also obtained between CAA and chemical assays in digesta. © 2013 Elsevier Ltd. All rights reserved.

Cai H.,Zhejiang University | Cai H.,Fuli Institute of Food Science | Cai H.,Zhejiang Key Laboratory for Agro Food Processing | Cai H.,Zhejiang R and nter for Food Technology and Equipment | And 16 more authors.
Journal of Food Safety | Year: 2014

The DNA microarray was employed in this study to investigate the gene expression profiles of Escherichia coli treated by oil in water (o/w) microemulsion in order to better understand the antimicrobial mechanism of the microemulsion as a promising food-grade antimicrobial system. Among 5,440 open reading frames of E.coli, a total of 634 and 501 were highly induced and repressed, respectively. According to the annotation and analysis in the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, it was found that the differently expressed genes were mainly involved in the biosynthesis of cell wall components and membranes, phosphate-related metabolism and some other biosynthetic pathways, suggesting that the main antibacterial mechanisms of the o/w microemulsion were the attacks to the cell surface structure, especially the cell wall, and its influences on the metabolism of phosphate of the E.coli cells through phosphate absorption inhibition. Practical Applications: In the panorama of the increasing need to search for novel strategies in order to prevent foodborne outbreaks, microemulsion systems have been of great interest to researchers for their broad antimicrobial properties. In our group, a series of food-grade or pharmaceutical microemulsion systems based on glycerol monolaurate have been established for antimicrobial applications. It was found that the prepared microemulsions possessed excellent broad-spectrum antimicrobial activities due to the disruption and dysfunction of biological membranes and cell walls, as suggested by the transmission electron microscopy observations and membrane permeability experiments. The antimicrobial mechanisms analysis of the microemulsion mediated by DNA microarray in this work will be of great importance in exploring the structure-activity relationship of the o/w microemulsion at molecular biological levels in future work, in order to provide a guideline in designing food-grade antimicrobial microemulsions. © 2014 Wiley Periodicals, Inc.

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