Search Results (9)

Anthocyanin-rich steamed purple sweet potato (SPSP) is a suitable raw material to produce smart packaging films. However, the application of SPSP-based films is restricted by the low antimicrobial activity of anthocyanins. In this study, SPSP-based smart packaging films were produced by adding mandarin essential oil (MEO) as an antimicrobial agent. The impact of MEO content (3%, 6%, and 9%) on the structures, properties, and application of SPSP-based films was measured. The results showed that MEO created several pores within films and reduced the hydrogen bonding system and crystallinity of films. The dark purple color of the SPSP films was almost unchanged by MEO. MEO significantly decreased the light transmittance, water vapor permeability, and tensile strength of the films, but remarkably increased the oxygen permeability, thermal stability, and antioxidant and antimicrobial properties of the films. The SPSP-MEO films showed intuitive color changes at different acid-base conditions. The purple-colored SPSP-MEO films turned blue when chilled shrimp and pork were not fresh. The MEO content greatly influenced the structures, physical properties, and antioxidant and antimicrobial activities of the films. However, the MEO content had no impact on the color change ability of the films. The results suggested that SPSP-MEO films have potential in the smart packaging of protein-rich foods. Full article

Fresh pork tenderloin was stored at −3 °C under different static magnetic fields (SMF) of 0, 4, and 10 mT (control, MF-4, and MF-10) to investigate their physicochemical properties changes during storage of 8 days. The initial equilibrium temperature of the samples stored with 4 mT MF was found to be −2.3 °C, which was slightly lower (0.3 °C) than that the control value. The super-chilling phenomenon on the pork was then observed, as the samples stored under the magnetic field did not freeze throughout storage period, but the control experienced a sudden change in temperature after 138 h and then froze. The preservation effect of MF-4 on meat quality was the best in all treatment groups. MF-4 achieved a higher water-retention rate, with drip and cook losses of 6.5% and 29.0% lower than the control, respectively. Meanwhile, the MF-4 effectively delayed the color change in the meat during the storage and the texture hardening after cooking, and effectively controlled the growth of the total volatile saline nitrogen content on the samples. In addition, MF-4 delayed the reduction in myofibrillar protein solubility, sulfhydryl content, and emulsification capacity, indicating that this field inhibited the denaturation of myofibrillar protein. This study can be considered as an application reference of magnetic fields during meat storage at a super-chilled temperature. Full article

There is an ongoing trend to design new kinds of food packaging materials with excellent properties which are environmentally friendly enough. The aim of this study was to prepare and characterize egg white protein (EWP)-based composite films with and without ε-polylysine (Lys), as well as to compare their physical–chemical properties, structural properties, degradation and antibacterial properties. The results showed that with the addition of Lys, the composite films showed a decreasing tendency of the water permeability due to the enhanced interaction between proteins and water molecules. As indicated by the structural properties, stronger cross-linking and intermolecular interactions happened with increasing concentration of Lys. In addition, the composite films presented excellent antibacterial activities against Escherichia coli and Staphylococcus aureus on chilled pork in the presence of Lys. Therefore, our prepared films might be used as a freshness-keeping material with an application in meat preservation. The biodegradation evaluation demonstrated that the composite films were environmental-friendly and have potential applications in the field of food packaging. Full article

A biodegradable photodynamic antibacterial film (PS-CF) was prepared using the casting method, with κ-Carrageenan (κ-Car) as the film-forming substrate and curcumin-β-cyclodextrin (Cur-β-CD) complex as photosensitizer. Chilled pork samples were coated with PS-CF and stored at 4 °C to investigate the effects of PS-CF combined with LED light irradiation (425 nm, 45 min) (PS+L+) on pork preservation during 10 days of storage. The total viable count (TVC) of bacteria, total volatile basic nitrogen value (TVB-N) and the pH of pork treated with PS+L+ were all lower than the control, and the water-holding capacity (WHC) was higher. Ten days later, the TVB-N value was 12.35 ± 0.57 mg/100 g and the TVC value was 5.78 ± 0.17 log CFU/g, which was within the acceptable range. Sensory evaluation determined that the color, odor, and overall acceptability of pork treated with PS+L+ were significantly better than the control. These findings suggest that PS+L+ treatment effectively extended the shelf life of chilled pork from ~4–5 to 10 days. Correlation analysis showed that the sensory quality of the chilled pork significantly correlated with total bacterial counts, TVB-N and thiobarbituric acid reactive substances (TBARS) (p < 0.05), suggesting that these biomarkers could be used as standard indicators for evaluating the freshness of chilled pork. These findings demonstrate the effectiveness of Cur-β-CD photodynamic antibacterial film for the preservation of chilled pork and provide a theoretical basis for the application of the film for the preservation of fresh food in general. Full article

The purpose of this study was to develop a quantitative baseline of indicator organisms and Salmonella by bio-mapping throughout the processing chain from harvest to final product stages within a commercial conventional design pork processing establishment. Swab samples were taken on the harvest floor at different processing steps, gambrel table, after polisher, before final rinse, after the final rinse, post snap chill, and after peroxyacetic acid (PAA) application, while 2-pound product samples were collected for trim and ground samples. The samples were subjected to analysis for indicator microorganism enumeration, Aerobic Count (AC), Enterobacteriaceae (EB), and generic Escherichia coli (EC), with the BioMérieux TEMPO^®. Salmonella prevalence and enumeration was evaluated using the BAX^® System Real-Time Salmonella and the SalQuant™ methodology. Microbial counts were converted to Log Colony-forming units (CFU) on a per mL, per g or per sample basis, presented as LogCFU/mL, LogCFU/g and LogCFU/sample, prior to statistical analysis. All indicator microorganisms were significantly reduced at the harvest floor (p-value < 0.001), from gambrel table to after PAA cabinet location. The reduction at harvest was 2.27, 2.46 and 2.24 LogCFU/mL for AC, EB and EC, respectively. Trim sample values fluctuated based on cut, with the highest average AC count found at neck trim (2.83 LogCFU/g). Further process samples showed the highest AC count in sausage with a mean of 5.28 LogCFU/g. EB counts in sausage (3.19 LogCFU/g) showed an evident increase, compared to the reduction observed at the end of harvest and throughout trim processing. EC counts showed a similar trend to EB counts with the highest value found in sausage links (1.60 LogCFU/g). Statistical microbial process control (SPC) parameters were also developed for each of the indicator microorganisms, using the overall mean count ($\stackrel{=}{\mathrm{X}}$), the Lower control limit (LCL) and Upper control limit (UCL) at each sampling location. For Salmonella prevalence, a total of 125/650 samples were found positive (19%). From those positive samples, 47 samples (38%) were suitable for enumeration using the BAX^® System SalQuant™, the majority detected at the gambrel table location. From those enumerable samples, 60% were estimated to be between 0.97 and 1.97 LogCFU/sample, while the rest (40%) were higher within the 2.00–4.02 LogCFU/sample range. This study provides evidence for the application of indicator and pathogen quantification methodologies for food safety management in commercial pork processing operations. Full article

Yersinia enterocolitica is a dangerous foodborne human pathogen that mainly causes gastroenteritis. Ideal methods for the detection of pathogens in food should be rapid, sensitive, specific, and cost effective. To this end, novel in vitro nucleic acid identification methods based on clustered, regularly interspaced short palindromic repeats (CRISPR)-associated protein (Cas) endonuclease have received increasing attention. In this study, a simple, visual, and ultrasensitive method, based on CRISPR/Cas12a with recombinase polymerase amplification (RPA), was developed for the detection of Y. enterocolitica. The results show that a specific attachment invasion locus gene (ail) can be rapidly detected using a CRISPR/Cas12a-RPA-based system. Application of the method to raw pork, which was artificially infected with Y. enterocolitica, achieved an estimated detection limit of 1.7 CFU/mL in less than 45 min, and this was 100 times lower compared with qPCR. The results indicated that the CRISPR/Cas12a-RPA system has good potential for monitoring pathogenic Y. enterocolitica in the chilled meat supply chain. Full article

Stunning is a statutory pre-slaughter process that may affect the quality of pork. The objective of this study was quantification of the effects of stunning (ES vs. CO₂ stunning) on selected quality attributes of pork, using a meta-analytical approach. Data from 18 publications with 46 individual experiments were combined using a random-effect model to estimate the effect size of stunning on the initial and ultimate pH (pH₁, pH_u); drip loss (DL); colour (lightness—L*, redness—a*, yellowness—b*); and tenderness (expressed as Warner–Bratzler shear force, WBSF) of pork. In overall, loins from ES showed significantly lower pH₁ (by 0.08 units); greater DL (by 0.68 p.p.); higher L* (by 1.29 units); and a* (by 0.80 units) as they compared to those from CO₂ stunning. In subgroups, a greater-than-overall negative change in pH₁, pH_u, DL, L* and a* was detected with the application of the head-to-back (HB) stunning method. Additionally, alterations in DL and L* may be magnified with the application of conventional chilling (Conv.) to ES pigs. There was no effect of stunning on WBSF but, due to a low number of research in the database, the reliability of these results may be misleading. These results provide evidence that the differences between these two stunning methods in DL and L* may be diminished by the application of the head-only (HO) or head-to-body (HBO) method, followed by the fast chilling of carcasses. Full article

The aim of this research was to evaluate the effect of acid whey on changes in the fatty acid profile, oxidative stability, physico-chemical parameters, and microbiological and sensory quality of traditional organic uncured fermented Polish bacon after production and during chilling storage. Three different treatments of fermented bacon were produced: C—control bacon with a nitrite curing mixture; T—bacon with a nitrate curing mixture; and AW—bacon with acid whey and NaCl. The acid whey used in the production of uncured fermented pork bacon positively changed the sensorial characteristics, directly after the ripening process, and had a positive effect in terms of a decrease in the pH of the product. All of the fermented bacon treatments in general were of good microbiological quality. A higher lactic acid bacteria (LAB) level was observed in the AW treatment after the fermentation process, and the bacteria number did not change during storage, whereas in the C and T treatments, the LAB level increased during storage (p < 0.05). The application of acid whey did not limit the formation of secondary oxidation products (TBARS) during bacon ripening (1.68 mg MDA kg⁻¹), but had a reduced value during storage time (0.73 mg MDA kg⁻¹). The highest polyunsaturated fatty acid (PUFA) levels, after ripening and after four weeks of refrigerated storage, were found in the C treatment. In the AW treatment, it was found that the PUFA level increased; likewise, the content of n-3 and n-6 fatty acids increased, while saturated fatty acids (SFAs) decreased during storage (p < 0.05). The opposite tendency was observed in the C treatment. After four weeks of storage, the PUFA/SFA ratio was the lowest in the nitrate treatment, and higher values of the PUFA/SFA ratio were obtained in the acid whey and nitrite treatment (p < 0.05). Full article

The aims of this study were to develop the magnolol–chitosan films and study the positive effect of the combination of magnolol and chitosan. The addition of magnolol made the magnolol–chitosan films exhibit higher density (1.06–1.87 g/cm³), but the relatively lower water vapor permeability (12.06–7.36 × 10⁻¹¹·g·m⁻¹·s⁻¹·Pa⁻¹) and water content (16.10–10.64%). The dense and smooth surface and cross-section of magnolol–chitosan films were observed by environmental scanning electron microscopy (ESEM) images. The interaction of magnolol and chitosan was observed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). After the addition of magnolol, the antioxidant capacity of magnolol–chitosan films was increased from 18.99 to 82.00%, the growth of P. aeruginosa was inhibited and the inhibition percentage of biofilm formation was increased from 30.89 to 86.04%. We further verified that the application of magnolol–chitosan films on chilled pork significantly reduced the increases in pH value, inhibited the growth of microorganisms and extended the shelf life. Results suggest that magnolol had a positive effect on magnolol–chitosan films and could be effectively applied to pork preservation. Full article