Combined Effects of Pressure Cooking and Enzyme Treatment to Enhance the Digestibility and Physicochemical Properties of Spreadable Liver Sausage.

This study aimed to determine the effect of enzyme, guar gum, and pressure processing on the digestibility and physicochemical properties of age-friendly liver sausages. Liver sausages were manufactured by adding proteolytic enzyme (Bromelain) and guar gum, and pressure-cooking (0.06 MPa), with the following treatments: control, without proteolytic enzyme; T1, proteolytic enzyme; T2, proteolytic enzyme and guar gum; T3, pressure-cooking; T4, proteolytic enzyme and pressure-cooking; T5, proteolytic enzyme, guar gum, and pressure-cooking. The pH was high in the enzyme- and pressure-processed groups. The pressure-processed groups had lower apparent viscosity than other cooking groups, and it decreased during enzyme treatment. Hardness was lower in the enzyme- and pressure-processed groups than in the control, and the T4 was the lowest. Digestibility was the highest in T4 at 82.58%, and there was no significant difference with that in T5. The general cooking group with enzyme and guar gum also showed higher digestibility than the control (77.50%). As a result of the sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the enzyme- and pressure-treated groups (T4, T5) were degraded more into low-molecular-weight peptides (≤37 kDa) than the control and other treatments. Viscoelasticity showed similar trends for viscous and elastic moduli. Similarly, combined pressure processing and enzymatic treatment decreased viscoelasticity, while guar gum increased elasticity but decreased viscosity. Therefore, the tenderized physical properties and improved digestibility by enzyme and pressurization treatment could be used to produce age-friendly spreadable liver sausages.

Physiochemical properties of reduced-fat duck meat emulsion systems: effects of preemulsification with vegetable oils and duck skin.

The effects of commercial vegetable oils and duck skin on quality characteristics of a reduced-fat duck meat emulsion were examined. The cooking loss, emulsion stability, and hardness were lower for emulsions preemulsified with vegetable oils and duck skin (P < 0.05) than for the control. Storage modulus (G') and loss modulus (G″) of reduced-fat duck meat emulsions treated with corn, grape seed, soy, and olive oils were similar to the values of control; the highest G' and G″ values were reported for the reduced-fat duck meat emulsion treated with coconut oil. Myofibril protein solubility was the highest for the reduced-fat duck meat emulsion treated with coconut oil and duck skin (P < 0.05). Replacing of pork back fat with different vegetable oils for emulsification may impart superior quality to reduced-fat duck meat emulsion. We recommend preemulsion with vegetable oils and duck skin to enhance the quality characteristics of reduced-fat duck meat emulsion.

Synergistic bactericidal effect of clove oil and encapsulated atmospheric pressure plasma against Escherichia coli O157:H7 and Staphylococcus aureus and its mechanism of action.

We investigated the bactericidal effect of clove oil and encapsulated atmospheric pressure plasma (EAP), individually or in combination, against Escherichia coli O157:H7 and Staphylococcus aureus. The bactericidal effect of the combined treatment was also investigated in inoculated beef jerky. For both pathogens, clove oil and EAP single treatments resulted in less than 3.0-log reductions, whereas the combined treatment resulted in more than 7.5-log reductions. The disc-diffusion assay and gas chromatography-mass spectrometry showed no changes in both the clear zone diameter and chemical composition of clove oil before and after the EAP treatment. Significant changes in cell membrane permeability and cell morphology resulting from the combined treatment of clove oil and EAP were evidenced by increased in UV absorption of cell supernatants, increased cell staining with propidium iodide, and changes in cell structure revealed by transmission electron microscopy. The synergistic bactericidal effects of clove oil and EAP against both pathogens were also observed in inoculated beef jerky, but the treatments were less effective against S. aureus, presumably due to thicker peptidoglycan layer. Experiments also demonstrated that the synergistic bactericidal effects between clove oil and EAP are due to clove oil increasing the susceptibility of the bacteria to subsequent EAP treatment, and does not involve alteration of the antibacterial activity of clove oil by EAP.

Effects of replacing pork fat with grape seed oil and gelatine/alginate for meat emulsions.

The effects of using grape seed oil in combination with gelatine and alginate on the physicochemical characteristics of meat emulsions were examined. Four different meat emulsions were manufactured and half the conventional fat was substituted with pre-emulsified grape seed oil with gelatine and/or alginate: T1, only grape seed oil; T2, grape seed oil and gelatine; T3, grape seed oil and alginate, T4, grape seed oil, gelatine, and alginate. Meat emulsion containing only pork back fat was compared as control. Results revealed that T4 was moister, lighter, more viscous, and stable in emulsion than control and value of ash contents of T4 was higher than those of control. Moreover, the value of fat content, pH, firmness, chewiness, toughness, and lipid oxidation of the T4 meat emulsion were lower than those of control. The meat emulsions with emulsified grape seed oil were more principally elastic than viscous and appearent viscosity was the highest in T4. In conclusion, instead of using each ingredient alone, pre-emulsified grape seed oil, gelatine, and alginate can replace partial pork fat with in meat emulsion formulations results in optimized meat processing properties.

Increase in nitrite content and functionality of ethanolic extracts of Perilla frutescens following treatment with atmospheric pressure plasma.

This study investigated the effect of atmospheric pressure plasma (APP) treatment on nitrite content and functionality of plant extracts. Ethanolic extracts of Perilla frutescens (EEP) were prepared and treated with APP for 60min. Nitrite content increased from 0 to 45.8mg/l in EEP after APP treatment for 60min. Antimicrobial activity of EEP against Clostridium perfringens and Salmonella Typhimurium was increased by APP with no influence on antioxidative activity (p<0.05). Lyophilized EEP (LEEP) treated with APP for 60min contained 3.74mg/g nitrite. The control (LEEP without APP) contained no nitrite. The minimum inhibitory concentration (MIC) of LEEP for C. perfringens was 200µg/ml. The control did not inhibit C. perfringens growth between 25 and 1000µg/ml. MICs of LEEP and the control against S. Typhimurium were 25 and 50µg/ml, respectively. New nitrite sources with increased antimicrobial activity can be produced from natural plants by APP treatment.

Enhancement of antioxidant effects of naringin after atmospheric pressure dielectric barrier discharge plasma treatment.

Naringin is the natural chief bitter flavonoid found in Citrus species. Herein, bitter naringin was treated with atmospheric pressure plasma to afford two new converted flavonoids, narinplasmins A (2) and B (3), along with the known compound, 2R-naringin. The structures of the two new naringin derivatives were elucidated on the basis of spectroscopic methods. The antioxidant activity of all isolates was evaluated based on 1,1-diphenyl-2-picrylhydrazyl and peroxynitrite (ONOO(-)) scavenging assays. The new flavanone glycoside 2 containing a methoxyalkyl group exhibited significantly improved antioxidant properties in these assays relative to the parent naringin.

Comparison of quality traits of meat from korean native chickens and broilers used in two different traditional korean cuisines.

With the aim of investigating the differences in the quality traits between Korean native chicken (Hanhyup, KNC) and broilers commonly used in two different traditional Korean cuisines, the chemical composition and sensory properties of breast and thigh meat from the two chicken strains were assessed. KNC for baeksuk (chicken meat braised in soup with various Oriental medicinal plants; KNL), KNC for samgyetang (similar to baeksuk but young chickens and ginseng are used; KNS), broiler for baeksuk (BL), and broiler for samgyetang (BS) were used as treatments in this study. KNL and KNS contained higher protein but lower fat content than BL and BS. The L* values of breast and thigh meat, but not the a* values, were significantly different between KNS and BS, whereas significant differences in both values were observed between KNL and BL. Compared to the other three types of chickens, KNS contained the highest total and insoluble collagen content, and KNL and BL showed higher inosine-5'-monophosphate content in their meat. Overall, KNL and KNS contributed darker, less tender meat with higher protein and less fat content together with more n-3 fatty acids, as opposed to their counterparts used for the same cuisines. Based on the results of the sensory analysis, even though there are some differences in physiochemical traits, different chicken sources do not differ in overall sensory quality. This information can help consumers to understand better the meat available for their preferred traditional cuisines.

Effects of combined treatments of electron-beam irradiation and addition of leek (Allium tuberosum) extract on reduction of pathogens in pork jerky.

This study investigated the combined effect of electron-beam irradiation and addition of leek (Allium tuberosum R.) extract on pork jerky inoculated with selected foodborne pathogens. Prepared pork jerky samples (control and samples with 1.0% leek extract) were inoculated with pathogens and subsequently irradiated at 0, 0.5, 1, 2, 3, and 4 kGy doses. In comparison with the control, samples with 1.0% leek extract showed significant reduction in the numbers of Escherichia coli, Listeria monocytogenes, and Salmonella Typhimurium. No viable counts were detected for Salmonella Typhimurium in both control and leek-extract samples, and for E. coli and L. monocytogenes in the leek-extract sample exposed to 3 kGy irradiation dose. The D(10) values for E. coli, L. monocytogenes, and Salmonella Typhimurium observed in the irradiated samples with leek extract were 0.39, 0.34, and 0.32 kGy, while the D(10) values in those without leek extract were 0.65, 0.65, and 0.39 kGy, respectively. Therefore, our results clearly showed that irradiation combined with leek extract was effective in reducing pathogens, suggesting that a low dose of irradiation combined with the addition of a natural antimicrobial agent can enhance the microbial safety and shelf-life of pork jerky.