Smart Colorimetric Corn Starch Films Combined with Anthocyanin-Loaded Glutenin-Carboxymethyl Chitosan Nanocomplexes for Freshness Monitoring of Chilled Pork

In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.

Extending Shelf Life of Chilled Pork by Combination of Chitosan Coating With Spice Extracts

The effects of spices（cinnamon,rosemary,clove）extracts and chitosan on microbiological growth,drip loss,color,and lipid oxidation of fresh chilled meat stored for 28 days at 4℃were investigated.There were four treatments：control,coated with spices（cinnamon 1.5 g·L^-1＋rosemary 1.5 g·L^-1＋clove 1.0 g·L^-1）,coated with 0.5%chitosan,coated with spices and chitosan.Chitosan coating resulted in significant inhibition of microbial growth（P〈0.05）,while the lowest microbial counts were obtained in the samples containing both chitosan and spices,indicating a possible synergistic effect.Chitosan and its combinations with spices also showed the most intense antioxidative effect when compared to the controls（P〈0.05）.Meanwhile,chitosan coating could decrease water loss and keep better color of chilled meat.The combined spice extracts and chitosan coating could effectively extend the shelf life of chilled meat.

Inhibition Effect of Herbal Preservatives on Listeria monocytogenes on Chilled Pork

This study investigated the growth situation of Listeria monocytogenes on chilled pork and the effect of herbal preservatives on this pathogen. The inhibitions of herbal preservatives were identified. The minimum inhibitory concentrations （MIC） of cinnamon and clove were all 0.79 mg.mL^-1, while the rosemary was 1.58 mg.mL^-1. And the composite herbal preservatives were got through orthogonal experiment. The optimum proportion was as following on agar medium： 1.16 mg.mL^-1 cinnamon＋2.38 mg. mL^-1 rosemary＋3.17 mg. mLl clove （herb combination number 5）, while on chilled pork, the strong inhibition of L. monocytogenes was showed, which demonstrated that the surface application of herb combination resulted in an effective delay of L. monocytogenes growth.

Systematic study of the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China

Background: With increasing media coverage of food safety incidents, such as that of clenbuterol residues in pork, food safety has become a major public health concern in China. Rapidly developing online markets attract increasing numbers of Chinese consumers to purchase food on the Internet. However, the quality and safety of food sold online are uncertain and are less reported on. Objective: This research aimed to systematically study the quality and safety of chilled pork from wet markets, supermarkets, and online markets in China. Results: The chilled pork samples from online markets were fresher than those from wet markets and supermarkets based on the surface redness(a* value). Chilled pork contained high levels of nutritional elements, especially the magnesium and phos0-phorus levels in samples from online markets. The levels of heavy metal element residues and veterinary drug residues in all chilled pork samples were within the standards limits. In addition, huge differences existed in the quality and freshness of the chilled pork samples from online markets according to principal component analysis(PCA). Conclusions: Most chilled pork sold in Chinese markets was qualified and safe. It is necessary to establish an effective online market supervision system for chilled pork.

Controlled release and antibacterial activity of nanofibers loaded with basil essential oil-encapsulated cationic liposomes against Listeria monocytogenes

In recent years,the development of functional packaging from natural active compounds has been a promising strategy for microbial control in foods.In this study,the basil essential oil(BEO)was applied as the principal antibacterial agent,and a controlled-release nanofibrous system was engineered with responsiveness to bacterial phospholipase.It indicated that encapsulation by cationic liposome significantly improved the dispersity and stability of BEO during the electrospinning process,and the prepared BEO-loaded cationic liposomes(BCLs)could maintain structural integrity in polymer nanofibers.The resulting BCLs-loaded nanofibers showed an effective antibacterial activity against L.monocytogenes.Additionally,it is worth noting that incorporation of soybean lecithin in nanofiber substrate could accelerate the release of loaded antibacterial agents when exposed to L.monocytogenes,thus obtaining an enhanced antibacterial activity.This could be attributed to the increased sensitivity of nanofibers to the degradation by bacterial phospholipases after incorporation with soybean lecithin.Finally,the application test showed that the prepared antibacterial nanofibrous mats could help maintain the quality of chilled pork during 4-days storage,which indicated their promising potential as active packaging.Given the serious threat of L.monocytogenes to food safety,the present antibacterial nanofibers have wide application prospect for improving microbial safety of chilled meat.