Yifei Wang

Fresh pork is susceptible to microbial contamination and lipid oxidation, which leads to food safety and quality issues. This study aimed to develop a kappa-carrageenan (KC) coating embedded with cinnamon essential oil (CEO) for antimicrobial and antioxidant purposes in pork meat. The uncoated controls and coated samples were subjected to microbial (total viable count, lactic acid bacteria, and H₂S-producing bacteria), chemical (DPPH and pH), and physical (surface color) analyses during refrigerated storage at 4 °C for 7 days. It was observed that KC coatings exhibited a better preservation effect on pork meat after the addition of CEO. The KC–CEO coatings were effective in retarding the growth of total viable count, lactic acid bacteria, and H₂S-producing bacteria. In a DPPH test, the level of lipid oxidation in pork meat was also significantly (p < 0.05) reduced by the KC–CEO coatings. Furthermore, these coatings displayed pronounced activity in inhibiting the adverse alterations of pH value and surface color. Practically, KC–CEO-coated samples still exhibited an attractive bright red color at the end of refrigerated storage. Taken together, the developed KC–CEO coatings exerted pronounced antimicrobial and antioxidant activities in pork, thus providing a potential approach to preserving perishable meat.

Utilization of sublethal concentrations of cinnamon essential oil (CEO) for food preservation has been proposed. However, exposure to stressful, sublethal growth conditions may induce bacterial tolerance to homologous or heterologous stressing agents. Hence, the ability of CEO to stimulate bacterial stress response was evaluated in the current work. Staphylococcus aureus was exposed to 1/4 and 1/2 of the minimum inhibitory concentration (MIC, 500 μL/L) of CEO for 18 h. It was found that overnight habituation to CEO failed to induce direct tolerance and cross-tolerance to lactic acid (pH 4.5), NaCl (10 g/100 mL) and high temperature (45 °C) in S. aureus. Likewise, S. aureus cells subjected to successive habituation with increasing amounts (1/16 MIC to 2× MIC) of CEO developed no direct tolerance. Taken together, CEO has no inductive effect on the acquisition of stress tolerance in S. aureus.

Bioactive edible coatings based on chitosan (Ch) were developed by incorporating clove oil (CO) and/or ethylenediaminetetraacetate (E), with the aim of promoting the microbial quality of meat. The antimicrobial mode of Ch‐based coatings was also explored in terms of membrane permeability. Results showed that the addition of CO and/or E provoked a significant (P < 0.05) increase in diameter of inhibition zones. In the growth inhibition assay, Ch + CO + E solution exhibited the highest inhibition rates of Escherichia coli and Staphylococcus aureus (99.17 and 96.42%, respectively). A pork slice coating test showed that CO and/or E incorporated coatings could moderate the growth of total microbes and maintain acceptable sensory characteristics of pork in 7 days of storage at 4C. The coatings of Ch, Ch + CO and Ch + CO + E improved both lightness and red color stability of pork. Furthermore, four kinds of coating solutions induced the release of intracellular components, indicating the damage of cell membranes. This study suggests the potential utilization of Ch + CO and Ch + CO + E coatings for antimicrobial purposes in refrigerated pork.Practical Applications: Increasing demands for food quality and safety have boosted the development of bioactive edible coatings and films to maintain quality attributes of food products in recent years. Edible coatings based on polysaccharides have shown great promise. Microbial growth on the food surface is a principal cause of food spoilage. Hence, the antimicrobial efficiency of edible coatings is of prime importance. In this study, clove oil (CO) and ethylenediaminetetraacetate (E) were incorporated into chitosan (Ch) coating to improve its antimicrobial activity. Results from in vitro and in vivo tests demonstrated that Ch + CO and Ch + CO + E coatings could be utilized as active packaging materials for refrigerated pork.

BACKGROUND: Essential oil of cinnamon (CM) is a potential alternative to chemical fungicides. Thus this work aimed to investigate the possible effects of CM microemulsions on decay developments and qualitative properties of pears.RESULTS: The decay incidence of samples treated with 500 µg L⁻¹ microemulsion was significantly reduced by 18.7% in comparison to that of 500 µg L⁻¹ non‐microemulsion after 4 days' storage at 20 °C. In the vapor phase, the CM microemulsion with the lowest concentration had the best control for decay incidence and lesion diameter. The interval between inoculations also influenced decay development. Pears treated with Botrytis cinerea and immediately followed by CM microemulsion showed the lowest decay incidence. Moreover, in the natural decay experiment, the percentage of rotted pears was 3.8% in the CM microemulsion treatment and 5.8% in the control. CM microemulsion delayed the loss of ascorbic acid, yet it had no significant influence on pear qualities such as firmness and color.CONCLUSION: CM microemulsion may be an alternative way to control the gray mold of pears without a negative influence on its qualities. © 2013 Society of Chemical Industry

By exchanging the N domain and C domain of hEGF and hTGF-alpha genes by PCR, two chimeras E-TGF(EGF(1-32)-TGF-alpha(34-50))and T-EGF(TGF-alpha(1-33)-EGF(33-53))were constructed. The wild and chimeric molecules were expressed in E.coli under phoA system. The expressed hEGF, hTGF-alpha and two chimeras were purified. The EGF receptor competitive binding affinity of the four molecules was hEGF > hTGF-alpha and E-TGF > T-EGF and the cell proliferation stimulating activity of them was hTGF-alpha and E-TGF > T-EGF > hEGF. The result suggests that the N domain of hEGF and hTGF-alpha may play a major role in receptor binding activity and C domain of them may be responsible for stimulating cell proliferation.