Objectives of the current study were to evaluate meat ultra-structure and tenderness variation at different chilling regimes and aging times. Hot boned longissimus lumborum of 18 Chinese crossbred ...cattle were divided into 4 portions per side. One portion underwent very fast chilling (VFC, at −21°C to achieve core temperature of 0°C, then transferred to another incubator at 2°C), whereas other treatments were held at 14, 7 and 0°C for 10h postmortem, respectively. At 10h postmortem, all muscles were vacuum aged at 2°C for 21d. Cold shortened muscles had greatest absolute amount of tenderization during aging. VFC caused lowest sarcomere length, with super-contractions, ruptured Z-lines and myofibril cleavage, but improved myofibril fragmentation index (MFI), with no significant negative effect on toughness. Overall, aging improved the meat quality of cold shortened beef. Moreover, it should be prudent in some applications to apply VFC to excised muscles from a food safety perspective, and to improve tenderness compared to cold-shortened muscles.
► Very fast chilling (-21°C to get core temperature 0°C) regime was applied to study its effect on meat quality. ► VFC caused lower WB shear force compared to those chilled at 0°C. ► VFC caused super-contraction, ruptured Z-lines, & myofibril cleavage. ► Ageing counteracted the toughening effect of cold-shortening on beef quality.
This study was to determine the bacterial diversity and monitor the community dynamic changes during storage of vacuum-packaged sliced raw beef as affected by
and
.
and
were separately incubated in ...vacuumed-packaged raw beef as bio-protective cultures to inhibit the naturally contaminating microbial load. Dynamic changes of the microbial diversity of inoculated or non-inoculated (control) samples were monitored at 4°C for 0 to 38 days, using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE).
The DGGE profiles of DNA directly extracted from non-inoculated control samples highlighted the order of appearance of spoilage bacteria during storage, showing that
and
emerged early, then
shared the dominant position, and finally,
showed up became predominant. Compared with control, the inoculation of either
or
significantly lowered the complexity of microbial diversity and inhibited the growth of spoilage bacteria (p<0.05). Interestingly, we also found that the dominant position of
was replaced by indigenous
after 13 d for
-inoculated samples. Plate counts on selective agars further showed that inoculation with
or
obviously reduced the viable counts of
,
spp. and
during later storage (p< 0.05), with
exerting greater inhibitory effect. Inoculation with both bio-protective cultures also significantly decreased the total volatile basic nitrogen values of stored samples (p<0.05).
Taken together, the results proved the benefits of inoculation with lactic acid bacteria especially
as a potential way to inhibit growth of spoilage-related bacteria and improve the shelf life of vacuum-packaged raw beef.
Chicken skin is considered the most susceptible to bacterial contamination during slaughter. It is rich in bushy feather follicles with complex internal structures that can absorb bacteria via ...cross-contamination during slaughter. Until now, the microstructural changes and local bacterial composition of feather follicles during slaughter have not been thoroughly investigated. This study used hematoxylin-eosin (HE) staining of the tissue paraffin section to investigate the structure of the feather follicles on chicken skin. In addition, the biopsy sampling method was employed for the high-throughput sequencing of 16S RNA genes to study the composition and source of bacterial contamination during slaughter. The results show that the feather follicles on chicken skin form a closed cavity structure during the slaughtering process. The volume of the irregular follicle cavity was about Ø: 200 μm × D: 1040 μm, which provides a place for the bacteria to absorb and resist the cleaning and disinfection during the slaughtering process. The composition of bacteria in the feather follicle was mainly
Acinetobacter
(37%),
Psychrobacter
(8%),
Macrococcus
(5%), and
Comamonas
(2%). The heat map obtained via the species abundance analysis of the feather follicle samples as well as the slaughter environment samples suggests that the gastrointestinal feces contaminated the feather follicles on the chicken skin mainly during the evisceration, defeathering, and chilling processes, and the last-stage chilling water also caused severe cross-contamination to the feather follicles during the chilling process.
Currently, the metabolomic research on water-holding capacity (WHC) of beef during postmortem aging is still insufficient. In this paper, the kit method was adopted for energy metabolites testing, ...the ultra-high-performance liquid chromatography (UHPLC) system was used for sample separation, and the mass spectrometer was applied to collect the primary and secondary spectra of the samples. The results showed that lactic acid reached saturation at day 2 postmortem, while energy metabolites changed significantly within day 2 postmortem (p < 0.05). Based on these findings, it was suggested that the energy metabolism qualities of the beef had already achieved a largely stable state at around day 2 postmortem. Then, through metabolomic analysis, 25 compounds were differentially abundant at days 0, 0.5, 1, and 2 during postmortem aging. Within the period of day 0−2 postmortem, the purine metabolism in beef was relatively active until 0.5 d postmortem, while glycolysis metabolism remained active until day 2 postmortem. The functions of the identified metabolites contribute to a more detailed molecular view of the processes behind WHC and are a valuable resource for future investigations into the flavor of postmortem beef.
Objectives of the present study were to evaluate the effects of suspension method and aging time on quality traits of Chinese fattened cattle M. Longissimus dorsi (LD). At the end of the slaughter ...line, the right sides of carcasses were re-hung from the pelvic bone obturator foramen, while the left sides remained hung by Achilles tendon suspension (AS). LD muscles were aged for 1, 7, 14 and 21days and were then evaluated for quality index. Pelvic suspension (PS) significantly decreased the WBSF of beef muscle at 1d and 7d postmortem compared with AS. The tenderness with PS at 7d postmortem was similar with that of AS at 14d. Moreover, PS increased sarcomere length and decreased purge loss of LD significantly. In addition, aging time had a significant effect on pH, meat color, Warner–Bratzler shear force, and myofibril fragmentation index of LD muscle. To conclude, PS is valuable to be introduced to the beef industry in China for rapid (within 7days) improvement of beef tenderness and decreased aging time of Chinese fattened cattle.
•Pelvic suspension (PS) decreased purge loss compared to Achilles tendon suspension.•PS improved tenderness rapidly by sarcomere lengthening (within 7days postmortem).•Tenderness was affected by myofibril fragmentation index after 7days postmortem.•Pelvic suspension decreased aging time (about 7days) of Chinese fattened cattle.
The residue of veterinary medicine and brown meat essence in meat and meat products is an important factor that affects food safety. Therefore, there is of great significance to review the harmful ...residues in meat and meat products and develop rapid and accurate detection technologies, which will favor control of these harmful residues and guarantee the safety of meat. This review summarizes antibacterial drugs and leanness-enhancing agents that are commonly used in animal husbandry and analyzed the application range, advantages, and disadvantages, key influencing factors of surface-enhanced Raman spectroscopy, liquid chromatography-mass spectrometry, and immunoassay in the detection of antibiotics and leanness-enhancing agents. This review is anticipated to provide guidance for the safety control and veterinary medicine and leanness-enhancing agents residues detection of meat and meat products.
This study investigated the effect of different acute heat stress (HS) levels on chicken meat quality and ultra-structure.
Chickens were randomly divided into 7 groups to receive different HS ...treatments: i) 36°C for 1 h, ii) 36°C for 2 h, iii) 38°C for 1 h, iv) 38°C for 2 h, v) 40°C for 1 h, vi) 40°C for 2 h, and vii) un-stressed control group (25°C). Blood cortisol level, breasts initial temperature, color, pH, water holding capacity (WHC), protein solubility and ultra-structure were analyzed.
HS temperatures had significant effects on breast meat temperature, lightness (L*), redness (a*), cooking loss and protein solubility (p<0.05). The HS at 36°C increased L*24 h value (p<0.01) and increased the cooking loss (p<0.05), but decreased a*24 h value (p<0.05). However, as the temperature increased to 38°C and 40°C, all the values of L*24 h, cooking loss and protein denaturation level decreased, and the differences disappeared compared to control group (p> 0.05). Only the ultimate pH24 h at 40°C decreased compared to the control group (p<0.01). The pH in 36°C group declined greater than other heat-stressed group in the first hour postmortem, which contributed breast muscle protein degeneration combining with high body temperature, and these variations reflected on poor meat quality parameters. The muscle fiber integrity level in group 40°C was much better than those in 36°C with the denatured position mainly focused on the interval of muscle fibers which probably contributes WHC and light reflection.
HS at higher temperature (above 38°C) before slaughter did not always lead to more pale and lower WHC breast meat. Breast meat quality parameters had a regression trend as HS temperature raised from 36°C. The interval of muscle fibers at 24 h postmortem and greater pH decline rate with high body temperature in early postmortem period could be a reasonable explanation for the variation of meat quality parameters.
The objectives of this study were to explore the expression patterns of myosin heavy chain (MyHC) genes of different skeletal muscles from Chinese cattle, and to investigate the relationship between ...myofiber characteristics and meat quality of M. longissimus lumborum (LL), M. psoas major (PM), and M. semimembranosus (SM) from Chinese Luxi and Qinchuan cattle.
Three major muscles including LL, PM, and SM from Chinese Luxi cattle and Chinese Qinchuan cattle were used in this study. The myofiber characteristics were measured by histochemical analysis. The MyHC isoforms expression was evaluated by real-time quantitative polymerase chain reaction. Quality traits including pH value, meat color, cooking loss, Warner-Bratzler shear force (WBSF) and sarcomere length were determined at day 5 postmortem.
PM muscle had higher pH value, a* value, sarcomere length and lower WBSF value compared to LL and SM muscles (p<0.05). Numbers of type I myofiber and the relative expression of MyHC I mRNA in PM muscle were higher than those of LL and SM muscles (p<0.05). Myofiber diameter of PM muscle was lower than that of LL and SM muscles, regardless of myofiber types (p<0.05).
According to the stepwise linear regression analyses, tenderness was influenced by myofiber characteristics in all three examined muscles. Tenderness of beef muscles from Qinchuan and Luxi cattle could be improved by increasing numbers of type I myofiber.
ObjectiveTo understand the epidemic characteristics of Listeria monocytogenes （L. monocytogenes） from livestock and poultry in China， the contamination and prevalence of L. monocytogenes in livestock ...and poultry food in China was systematically reviewed via a meta-analysis. The findings can provide data that can help in the prevention and control of L. monocytogenes during the production of livestock and poultry meat.MethodsThe relevant literature on the detection rate of L. monocytogenes in livestock and poultry food published from 2001 to 2022 in China was searched by inputting key search terms on PubMed， Web of Science， Wanfang Database， CNKI， and other data platforms. The meta-analysis was performed using Stata software.ResultsA total of 277 Chinese and English research articles were selected， representing a total of 110 066 samples and a combined L. monocytogenes detection rate of 7.2% （95%CI： 6.4%-8.0%）. The subgroup analysis of different regions showed that the detection rates of this pathogen in Jilin
The aim of this study was to investigate the biological inhibiting effect of a beef‐derived Latilactobacillus sakei (RS‐25) on the spoilage of beef steaks in overwrapped packaging during the 12 days ...of storage at 4°C. Beef quality as well as microbial indicators were determined at different intervals during the storage after the inoculation of RS‐25 at the 6 log CFU/g, and the high‐throughput sequencing was applied to investigate the changes of microbial community structure during the storage. The inoculation of RS‐25 on beef had no effect (p > .05) on pH, TBARS, and TVB‐N during storage indicating the weak effect of such strain on the eat quality. Furthermore, the rise of L* and the delayed decline of a* and b* reveal the protection effect of RS‐25 on the meat color. RS‐25 reduced the re‐contaminated Salmonella typhimurium by 1.16 log CFU/g (p < .01), and the growth of Brochothrix thermosphacta was also inhibited but no inhibition was found on the Pseudomonas spp. at the first 6 days of storage. The inhibiting effect of RS‐25 was covered by the rapid growth of other microorganism during the following 6 days of storage. Consistent with the microbial counts results, high‐throughput sequencing analysis confirmed that the inoculated L. sakei RS‐25 was dominant at first 6 days, and then replaced by Pseudomonas spp. The findings obtained from the current study may provide basic information for the further application of bioprotective bacteria in preservation of beef steaks in the overwrapped packaging.
Biological inhibiting effect of a beef‐derived Latilactobacillus sakei on the spoilage of steaks was investigated. The effect of LAB on the microflora structure of overwrapped packaging was investigated by sequencing analysis. Inoculation of LAB at 6 log CFU/g had a limited inhibitory effect on the dominant Pseudomonas during storage.
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