Effects of chitosan-based packaging film crosslinked with nanoencapsulated star anise essential oil and superchilled storage on the quality of rabbit meat patties

In this paper, the effects of chitosan film containing star anise essential oil nanofiltration (CFSAO) and superchilled (SC) temperature on the changes of physicochemical and microbiological indexes of rabbit meat patties within 15 days of storage were studied. The total aerobic bacteria counts, malondialdehyde content, protein carbonyl content, total sulfhydryl content, and metmyoglobin content continued to grow throughout the entire experimental period, and the maximum absorption peak at the soret region of myoglobin gradually decreased. Along with the storage time extended, the brightness and redness of rabbit meat significantly decreased (P < 0.05), while the yellowness significantly increased (P < 0.05). The results of storage experiments showed that chitosan composite films and SC temperature had good inhibition on lipid oxidation, myoglobin oxidation and degradation, sulfhydryl content reduction, and microbial growth of rabbit meat after 15 days of storage, and could slow down the change of rabbit meat color.

Oxidized myoglobin: Revealing new perspectives and insights on factors affecting the water retention of myofibrillar proteins

The impact of oxidized myoglobin (Mb) on myofibrillar protein (MP) oxidation and water retention was investigated. Results showed that the oxidation of Mb increased with increasing concentration of oxidized linoleic acid (OLA). In the presence of 100 mmol/L OLA, hemin iron decreased by 62.07 % compared to the control group. Further investigation showed that mild oxidation of Mb (≤10 mmol/L OLA) increased the water retention and the absolute value of the zeta potential of MP, whereas excessive oxidation (>10 mmol/L OLA) decreased these properties. With the increase of Mb oxidation, the carbonyl content in MP increased, and α-helices changed to random helix. And the tertiary structure changed. Pearson correlation analysis suggested that oxidized Mb affected the water retention of MP, which was closely related to hemin iron and non-hemin iron. In conclusion, OLA induced Mb oxidation, further promoted MP oxidation and affected its water retention.

Meat quality and sensory traits in rabbits fed with two different percentages of bovine colostrum

The nutritional, antimicrobial, and antioxidant properties of bovine colostrum (BC) have encouraged its use in animal nutrition as a functional food in recent years. Nonetheless, the potential implications of BC supplementation on meat quality remain to be thoroughly assessed. To address this, thirty-nine New Zealand White rabbits (n = 13/group) were fed different dietary regimens until slaughter.: commercial standard diet for the control group (C) and C with 2.5% and 5% w/w of BC for BC-2.5 and BC-5 groups, respectively. Rabbits were slaughtered at 91 days of age and meat quality, and sensory characteristics were evaluated at days 2 (48 h after slaughter), 5, and 10 of refrigerated storage at 4 °C. The addition of colostrum in the diet resulted in a reduction of the total viable count, albeit only at the highest concentration and at the final detection, whereas for Lactobacillus spp. and Pseudomonas spp., there was little or no effect. The colour coordinates showed no differences between the groups, but they varied over time according to diet. Some differences between groups emerged in the definition of sensory attributes but did not affect the overall liking and overall scores of individual descriptors. These results indicate that the use of colostrum in rabbit feeding does not significantly impart meat quality and sensory attributes, but the potential of this valuable by-product for the food industry needs further investigation.

An underlying softening mechanism in pale, soft and exudative - Like rabbit meat: The role of reactive oxygen species - Generating systems

This work investigated the role of reactive oxygen species (ROS) - generating systems on the softening of the pale, soft and exudative-like (PSE-like) rabbit meat during aging. PSE-like meat was induced by incubation of post-mortem rabbit Longissimus thoracis et lumborum at 37 °C for 3 h. During aging, PSE-like meat samples had higher values in peroxides value, thiobarbituric acid-reactive substances, metmyoglobin percentage, ferrylmyoglobin content, non-heme iron content, hydroxyl radical content and ROS concentration compared with the normal ones, suggesting that PSE-like incubation could activate lipid-oxidizing system, myoglobin-mediated oxidation system, together with metal-catalyzed oxidation system. Additionally, higher protein carbonyl content was observed in PSE-like meat, along with a significant loss in sulfhydryl group. The results of SDS-PAGE suggested that more serious protein degradation occurred in PSE-like meat. It is plausible that the activated ROS-generating system played an underlying role in the softening texture during the aging period of PSE-like meat.

Influence of freeze-thawed cycles on pork quality

OBJECTIVE

This study was conducted to determine the effect of freeze-thawed cycles (Fresh meat, F-T 1 cycle and F-T 2 cycles) on the quality characteristics of porcine longissimus dorsi muscle.

METHODS

A total of 20 three-crossbred pigs (Duroc×[Large White×Landrace]) were randomly obtained from a commercial slaughterhouse in Thailand. Muscle samples were immediately taken from 10 to 11th of the longissimus dorsi for histochemical analysis. The muscles were cut into 2.54 cm-thick chops. A minimum of 20 chops were used for each treatment (fresh meat, freeze-thawed 1 and 2 cycles). Individually chops were packaged in polyethylene bags and frozen at -20°C for 6 months followed by thawing in refrigerator at 4°C for 24 h (the 1st freeze-thawed cycle). The freeze-thawed procedure was repeated for two cycles (the 2nd freeze-thawed cycle). Thawing loss, shear force value, citrate synthase activity and muscle fiber characteristics were determined on the muscles.

RESULTS

Results showed that increasing of freeze-thawed cycle increased the thawing loss (p<0.01) and citrate synthase activity (p<0.001). Shear force value of fresh meat was higher than freeze-thawed 1 and 2 cycles (F-T 1 cycle and F-T 2 cycles). Freeze-thawed cycles affected muscle characteristics. Muscle fiber area and muscle fiber diameter decreased with an increasing number of freeze-thawed cycles (p<0.001), while the thickness of endomysium and perimysium were increased (p<0.001).

CONCLUSION

Repeated freeze-thawed cycles degraded muscle fiber structure and deteriorated pork quality.

Hemin from porcine blood effectively stabilized color appearance and odor of prepared pork chops upon repeated freeze-thaw cycles

This study was designed to evaluate changes in color following pork chop supplementation with porcine hemin, astaxanthin and paprika red in response to repeated freeze-thaw processes. Surface color analyses revealed that hemin significantly enhanced the appearance of the pork chops (P < 0.05), and the coloring efficiency of 0.10% hemin was similar to that of 0.20% astaxanthin and 0.08% paprika red. Sensory evaluations conducted on both raw and fried chops showed that hemin and astaxanthin significantly enhanced the overall acceptability of the chops before and after cooking. The color stability of the pork chops was also evaluated, and the results suggested that the hemin-colored chops were the most stable among the three, upon repeated freeze-thaw cycles. The electronic nose showed that the odor of the hemin-colored samples after 0, 3, and 7 freeze-thaw cycles was better than that of the other two groups. In conclusion, hemin may be a superior supplement for the large scale preparation of prepared pork chop.

A comprehensive insight into the effects of microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation on the discoloration of rabbit meat during retail display

The effects of the retail display temperature (8 °C, 3 °C and - 1 °C) on the discoloration of the Longissimus thoracis et lumborum of rabbits and the associations among such effects with microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation were investigated. The total aerobic count, total volatile basic nitrogen content, metmyoglobin content, protein carbonyl content, and contents of thiobarbituric acid-reactive substances steadily increased during retail display. Moreover, the lightness and redness of the rabbit meat significantly (P < 0.05) declined over time, whereas the yellowness increased considerably (P < 0.05) with prolonged retail time. Canonical correlation analysis suggested that microbial spoilage, myoglobin autoxidation, lipid oxidation, and protein oxidation jointly affected rabbit meat color. Linear mixed models further revealed that microbial spoilage, myoglobin autoxidation, lipid oxidation and protein oxidation positively affected yellowness, and they inversely impacted lightness and redness.

Effects of different thermal temperatures on the shelf life and microbial diversity of Dezhou-braised chicken

This work investigated the effects of different thermal temperatures (84 °C for 35 min, 95 °C for 30 min, and 121 °C for 20 min) on the shelf life and microbial diversity of Dezhou-braised chicken. During refrigerated storage at 4 °C, the increase rate of total viable counts, pH and TVB-N value, was lower in 95 °C-treated and 121 °C-sterilized groups, when compared with 84 °C-treated group. Electronic nose revealed that the fresh odor of Dezhou-braised chicken treated by 84 °C and 95 °C could be maintained during storage. Additionally, 95 °C contributed to the maintenance of good texture of chicken. High throughput sequencing showed that Bacillus and Clostridium were only very active in 84 °C-treated samples, but not in 95 °C-treated and 121 °C-sterilized samples. Taken together, 95 °C can be developed as one potential thermal treatment temperature for Dezhou-braised chicken, due to its positive effects on maintaining fresh odor and texture together with extending shelf life while also protecting food safety.

Ribose-induced Maillard Reaction as an Analytical Method for Detection of Adulteration and Differentiation of Chilled and Frozen-thawed Minced Veal

Quality control of meat products is one of the main concerns of consumers, governmental control authorities, and retailers. The purpose of this study was to employ ribose-induced Maillard reaction in detection of meat adulteration and differentiation of fresh-chilled from frozen-thawed minced veal. The browning intensity was assessed through measuring the absorbance at 420 nm with a spectrophotometer as well as the direct analysis of the color and pH. The results showed that CIE b*, CIE a*, and A420* values in the extract of fresh-chilled veal were significantly (p<0.05) higher than frozen-thawed samples. The extract of frozen meat samples stored at -18°C became significantly darker and more yellowish compared to -4°C. The results showed that the A420* value in the frozen-thawed veal stored at -4°C and -18°C was reduced by approximately 17.22±3.53% and 11.68±2.49%, respectively, compared with fresh-chilled veal. The findings also showed that the storage temperature of minced veal and the heating time in this reaction had a significant effect on all tested variables (p<0.0001). The proposed method can be considered as an easy, quick, and inexpensive test for differentiating between the fresh-chilled and frozen-thawed minced veal.

The impact of freezing methods on functional and technological properties of semi-finished rabbit meat products

During storage meat and semi-finished meat products, the decisive factor is the correct implementation of freezing process, because the physical, histological, biochemical, microbiological changes that occur at this time, affect the final quality of product after defrosting procedure. Accordingly, studies of the impact of traditional and shock-freezing methods on functional and technological properties of semi-finished rabbit meat products represent scientific and practical interest. The effect of freezing temperature of natural and minced semi-finished rabbit meat products on the duration of cold treatment process has been studied, and the regression equations of their relationships have been obtained and regression curves have been constructed. It has been established that unlike traditional method, by the type of semi-finished products, the duration of cold treatment by shock-freezing method is 3 - 3.5 times shorter. The optimal freezing parameters have also been selected. It has been shown that the use of shock-freezing method contributes to the reduction of mass losses of semi-finished rabbit meat products, and by the type of semi-finished products, they are 5 - 5.3 lower as compared to traditional method of freezing. The determination of functional properties has revealed that shock-freezing allows for increasing water binding capacity-by 23.2 - 31.9%, water holding capacity-by 20 - 25% and pH by 6.7 - 10.4%. There have been studied microbiological indicators of frozen semi-finished products and their changes during the storage process. It has been established that they meet the safety and hygiene requirements for meat products. The full results obtained indicate the advantage of shock-freezing method as compared to traditional methods, as well as point to the appropriateness of its use when selecting the cold treatment modes for semi-finished rabbit meat products.