Publications by authors named "Lixian Zhu"

54 Publications

Lactic Acid and Peroxyacetic Acid Inhibit Biofilm of O157:H7 Formed in Beef Extract.

Foodborne Pathog Dis 2021 Jul 1. Epub 2021 Jul 1.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, China.

The objective of this study was to evaluate the inhibitory effect of lactic acid (LA) and peroxyacetic acid (PAA) on the biofilm formation of O157:H7 in beef extract (BE). BE medium was used as the growth substrate in this study, to make the control effect closer to the situation of the factory. The biofilm inhibitory efficacy of LA and PAA was tested by using a crystal violet staining assay and microscopic examination. And then, extracellular polymeric substance (EPS) production, metabolic activity, and real-time polymerase chain reaction assay were used to reveal the biofilm inhibition mechanism of LA and PAA. The results showed that both LA and PAA significantly inhibited biofilm formation of O157:H7 at minimum inhibitory concentrations (MICs) ( < 0.05). At MIC, LA and PAA showed different effects on the biofilm metabolic activity and the EPS production of O157:H7. Supporting these findings, expression analysis showed that LA significantly suppressed quorum sensing genes ( and ) and adhesion genes (), while PAA downregulated the transcription of extracellular polysaccharide synthesis genes ( and ) and the global regulatory factor . This result revealed that LA and PAA had different biofilm inhibitory mechanisms on O157:H7; LA inhibited the biofilm formation mainly by inhibiting metabolic activity, while PAA inhibited EPS production. This study provided a theoretical basis for the control of O157:H7 biofilm in the actual production process.
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http://dx.doi.org/10.1089/fpd.2021.0012DOI Listing
July 2021

Effects of spraying lactic acid and peroxyacetic acid on the quality and microbial community dynamics of vacuum skin-packaged chilled beef during storage.

Food Res Int 2021 04 10;142:110205. Epub 2021 Feb 10.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; National R&D Center for Beef Processing Technology, Tai'an, Shandong 271018, PR China. Electronic address:

A long shelf life for fresh meat products is very important both to processors, retailers and consumers. In this work, the effect of repeat acid spraying on the shelf life of vacuum skin-packaged (VSP) chilled beef, as well as the quality and microbial community dynamics was evaluated. Carcasses were sprayed with 300 ppm peroxyacetic acid (PA) or 3% lactic acid (LA) three times during the chilling process, or one more time of LA spray before packaging (LLA). Quality, sensory attributes and microbial load of VSP beef during 32 days of storage at 4 °C were evaluated. The results showed that quality and sensory scores decreased over time for all treatments, but LLA treated samples were still above the rejection threshold at the end of the storage period. Moreover, the total volatile basic nitrogen value and the total viable counts were 15.0 mg/100 g and 7.2 log CFU/g for the control group, while acid treated groups remained below these two values until the end of the storage period. In particular LLA treated beef steaks exhibited the best preservation potential even at the end of storage. This is attributed to the reduction of Proteobacteria in LLA beef steaks shown by the bacterial diversity analysis via high-throughput sequencing, as well as the lower counts of B. thermosphacta and Enterobacteriaceae during storage. This indicates that LLA treatment has the potential to achieve a shelf life extension of VSP steaks without impacting on quality.
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http://dx.doi.org/10.1016/j.foodres.2021.110205DOI Listing
April 2021

Inhibition of Biofilm Formation and Related Gene Expression of in Response to Four Natural Antimicrobial Compounds and Sodium Hypochlorite.

Front Microbiol 2020 14;11:617473. Epub 2021 Jan 14.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, China.

The aim of this study was to assess the efficacy of four natural antimicrobial compounds (cinnamaldehyde, eugenol, resveratrol and thymoquinone) plus a control chemical disinfectant (sodium hypochlorite) in inhibiting biofilm formation by CMCC54004 (Lm 54004) at a minimum inhibitory concentration (MIC) and sub-MICs. Crystal violet staining assay and microscopic examination were employed to investigate anti-biofilm effects of the evaluated compounds, and a real-time PCR assay was used to investigate the expression of critical genes by Lm 54004 biofilm. The results showed that five antimicrobial compounds inhibited Lm 54004 biofilm formation in a dose dependent way. Specifically, cinnamaldehyde and resveratrol showed better anti-biofilm effects at 1/4 × MIC, while sodium hypochlorite exhibited the lowest inhibitory rates. A swimming assay confirmed that natural compounds at sub-MICs suppressed Lm 54004 motility to a low degree. Supporting these findings, expression analysis showed that all four natural compounds at 1/4 × MIC significantly down-regulated quorum sensing genes (, , and ) rather than suppressing the motility- and flagella-associated genes (, , and ). This study revealed that sub-MICs of natural antimicrobial compounds reduced biofilm formation by suppressing the quorum sensing system rather than by inhibiting flagella formation.
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http://dx.doi.org/10.3389/fmicb.2020.617473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7840700PMC
January 2021

The mixed application of organic and inorganic selenium shows better effects on incubation and progeny parameters.

Poult Sci 2021 Feb 2;100(2):1132-1141. Epub 2020 Nov 2.

Department of Animal Science and Technology, Shandong Agricultural University, Taian, Shandong 271018, China. Electronic address:

This experiment aims to study the effects of dietary selenium (Se) sources on the production performance, reproductive performance, and maternal effect of breeder laying hens. A total of 2,112 Hyline brown breeder laying hens of 42 wk of age were selected and randomly divided into 3 groups, with 8 repeats in each group and 88 chickens per repeat. The sources of dietary Se were sodium selenite (SS, added at 0.3 mg/kg), L-selenomethionine (L-SM, added at 0.2 mg/kg), and combination of SS and L-SM (SS 0.15 mg/kg + L-SM 0.15 mg/kg). The pretest period was 7 d, and the breeding period was 49 d. Compared with 0.3 mg/kg SS, the addition of 0.2 mg/kg L-SM in the diet significantly increased the hatchability (P < 0.05) and the Se content (P < 0.05) in egg yolk and chicken embryo tissues and improved the activity of yolk glutathione peroxidase (GSH-px) effectively (P < 0.05). Treatment with 0.2 mg/kg L-SM also reduced the content of yolk malondialdehyde (P < 0.05) and significantly improved the antioxidant performance of 1-day-old chicks, as manifested by increased activity of antioxidant enzymes (GSH-px, total antioxidant capacity and the ability to inhibit hydroxyl radicals) in serum, pectoral, heart, and liver (P < 0.05). This treatment decreased the malondialdehyde content (P < 0.05) and increased the expression of liver glutathione peroxidase 4 and deiodinase 1 mRNA (P < 0.05). Adding L-SM to the diets of chickens increased the hatchability of breeder eggs as well as the amount of Se deposited and antioxidant enzyme activity in breeder eggs and embryos. Compared with SS, L-SM was more effectively transferred from the mother to the embryo and offspring, showing efficient maternal nutrition. For breeder diets, the combination of organic and inorganic Se (0.15 mg/kg SS + 0.15 mg/kg L-SM) is an effective nutrient supplementation technology program for effectively improving the breeding performance of breeders and the antioxidant performance and health level of offspring chicks.
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http://dx.doi.org/10.1016/j.psj.2020.10.037DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7858146PMC
February 2021

Beef-Based Medium Influences Biofilm Formation of Escherichia coli O157:H7 Isolated from Beef Processing Plants.

J Food Prot 2021 Jun;84(6):1060-1068

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong, 271018, People's Republic of China.

Abstract: Beef-based medium beef extract (BE) and standard medium tryptic soy broth (TSB) are used as minimally processed food models to study the effects on Escherichia coli O157:H7 biofilm formation. The effects of temperatures (4, 10, 25, 37, and 42°C), pH values (4.5, 5.0, 5.5, 6.0, 7.0, and 8.0), strain characteristics, and the expression of functional genes on the biofilm formation ability of the bacteria were determined. The three tested E. coli O157:H7 strains produced biofilm in both media. Biofilm formation was greater in BE than in TSB (P < 0.05). The strongest biofilm formation capacity of E. coli O157:H7 was achieved at 37°C and pH 7.0. Biofilm formation was significantly inhibited for three tested strains incubated at 4°C. Biofilm formation ability was correlated with swarming in TSB. Biofilm formation was significantly and positively correlated with autoaggregation or hydrophobicity in BE (P < 0.05). At the initial stage of biofilm formation, the expressions of luxS, sdiA, csgD, csgA, flhC, adrA, and rpoS were significantly higher in BE than in TSB (P < 0.05). At the maturity stage, the expressions of luxS, sdiA, csgD, csgA, flhC, csrA, adrB, adrA, iraM, and rpoS were significantly higher in TSB than in BE (P < 0.05). Such information could help in the development of effective biofilm removal technologies to deal with risks of E. coli O157:H7 biofilms in the beef industry.

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http://dx.doi.org/10.4315/JFP-20-385DOI Listing
June 2021

Acid tolerance response of Salmonella during simulated chilled beef storage and its regulatory mechanism based on the PhoP/Q system.

Food Microbiol 2021 May 10;95:103716. Epub 2020 Dec 10.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong, 271018, PR China. Electronic address:

To investigate the persistence of acid tolerance response (ATR) and the regulatory mechanism during chilled storage, Salmonella ATCC 14028 and the △phoP mutant were acid adapted and then incubated in meat extract at 4 °C for 24 days as simulated beef storage. The bacterial population, D values and expression of PhoP/PhoQ linked genes of both strains were determined at 6-day intervals. Although a mild suppression effect on the D values of adapted Salmonella was found during the long-time storage in meat extract at 4 °C, the D value of adapted strains was significantly higher than non-adapted strains, indicating the persistence of ATR during the whole aging and distribution of beef posing a threat to food safety. The fact that low temperature inhibits the formation of ATR at the early adapted stage emphasizes the importance of keeping a low-temperature environment during slaughter. An interaction between the acidic adaptation and phoP gene on D values was found and the expression levels of adiA, adiY, cadA and cadB genes was significantly reduced in the △phoP mutant, suggesting that PhoP/Q system plays an important role in the ATR by sensing the pH and regulating lysine and arginine decarboxylation directly or indirectly.
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http://dx.doi.org/10.1016/j.fm.2020.103716DOI Listing
May 2021

Investigation of the physicochemical, bacteriological, and sensory quality of beef steaks held under modified atmosphere packaging and representative of different ultimate pH values.

Meat Sci 2021 Apr 25;174:108416. Epub 2020 Dec 25.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; National R&D Center for Beef Processing Technology, Tai'an, Shandong 271018, PR China. Electronic address:

The objective was to evaluate the effect of packaging conditions on bacteriological and biochemical changes in beef steaks classified here, as normal ultimate pH (pHu; 5.40-5.79), intermediate pHu (5.80-6.09) or high pHu (≥ 6.10). Steaks were packaged in vacuum packaging (VP) and modified atmosphere packaging with high oxygen (HiO-MAP) or carbon monoxide (CO-MAP). Headspace, bacterial counts, total volatile basic nitrogen, pH, purge loss, surface color, lipid oxidation, and sensory attributes were monitored over a 14-day storage period at 2 °C. HiO-MAP and CO-MAP of high pHu steaks resulted in a bright red color even when observed to be spoilt. Reduced purge loss and lipid oxidation, as well as increased sensory acceptability were observed for steaks with elevated pHu. Higher pHu was also accompanied by an acceleration of microbial proliferation. Of all packaging types investigated, CO-MAP exerted the best preservation, regardless of pHu and based on its antibacterial and antioxidant properties.
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http://dx.doi.org/10.1016/j.meatsci.2020.108416DOI Listing
April 2021

Effect of modified atmosphere packaging on shelf life and bacterial community of roast duck meat.

Food Res Int 2020 11 28;137:109645. Epub 2020 Aug 28.

College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China. Electronic address:

The purpose of this work was to assess the effect of different packaging methods on the shelf life and bacterial communities of roast duck meat. Samples were packaged under the following five conditions: overwrapped packaging (OWP), 100% N (100% N-MAP), 30% CO/70% N (30% CO-MAP), 50% CO/50% N (50% CO-MAP), and 0.4% CO/30% CO/69.6% N (CO-MAP). Physicochemical and microbiological parameters were monitored during 14 days of chilled storage (0-4 °C). Results showed that MAP samples obtained higher and more stable redness, better sensory scores, and lower lipid oxidation, compared with OWP, in which CO-MAP samples had the lowest TBARS values (0.13-0.22 MDA/kg) during storage. Moreover, 30% CO-MAP, 50% CO-MAP, and CO-MAP effectively retarded the onset of bacterial spoilage and extended shelf life by 7 days compared with 100% N-MAP and OWP treatments. Additionally, bacterial succession was significantly affected by the gas composition used in the packages, especially the dominant biota at the end of storage, which played an important role in the spoilage of roast duck meat under specific packaging. On day 14, Pseudoalteromonas spp., Lactobacillus spp., and Pseudomonas spp. became the most predominate genera in OWP, 100% N-MAP, and 50% CO-MAP, respectively. Notably, Vibrio spp. was dominant in both 30% CO-MAP and CO-MAP, indicating 0.4% CO did not exert a further inhibitory effect on this genus. Additionally, the growth inhibition of Pseudoalteromonas spp., Lactobacillus spp., and Leuconostoc spp. by high CO concentration might be the reason for MAP (CO/N) samples having lower levels of TVC. Globally, these results indicate that 30% CO-MAP, 50% CO-MAP, and CO-MAP are promising packaging methods to improve roast duck meat quality and achieve shelf life extension.
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http://dx.doi.org/10.1016/j.foodres.2020.109645DOI Listing
November 2020

Effect of medium voltage electrical stimulation and prior ageing on beef shear force during superchilled storage.

Meat Sci 2021 Feb 24;172:108320. Epub 2020 Sep 24.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; National R&D Center for Beef Processing Technology, Tai'an, Shandong 271018, PR China. Electronic address:

The effect of medium voltage electrical stimulation (ES), prior ageing (0-4 °C, 7 days), and their combination on the decrease of shear force in beef during superchilled storage (-4 °C) for 24 weeks was evaluated, in the context of a high shear force obtained under this storage condition. Both ES and prior ageing significantly reduced the initial Warner-Bratzler shear force, and the combination of ES and prior ageing shortened the storage time needed to reach an acceptable shear force of superchilled beef, which is mainly due to increased myofibrillar degradation as indicated by changes in desmin (P < 0.01, r = 0.35). Additionally, ES and prior ageing did not negatively affect lipid oxidation, total volatile basic nitrogen or water loss of superchilled beef. Consequently, ES combined with ageing for 7 days offered an effective approach for decreasing shear force and ensuring good quality superchilled beef.
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http://dx.doi.org/10.1016/j.meatsci.2020.108320DOI Listing
February 2021

Effects of packaging methods combined with frozen temperature on the color of frozen beef rolls.

Meat Sci 2021 Jan 2;171:108292. Epub 2020 Sep 2.

College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; Centre for Red Meat and Sheep Development, NSW Department of Primary Industries, Cowra, New South Wales 2794, Australia.

Beef rolls for hot pot are usually stored and transported in a frozen state, and the beef color deteriorates quickly. This paper reports on an investigation into the effect of packaging method, freezing temperature and storage time on instrumental color, pH, myoglobin state, lipid oxidation (TBARS) and total volatile basic nitrogen (TVB-N) of beef rolls. It was shown that the color of beef rolls at -18 °C was better than that at -12 °C overall, and the OxyMb% and pH values were higher, while the MetMb% and TBARS were lower with storage at -18 °C. With the extension of storage time, the instrumental color, OxyMb% and pH values of beef rolls decreased. Correspondingly, the MetMb% and TBARS showed an upward trend. However, the TVB-N of all treatments did not exceed the Chinese standard during 180d of storage. The results of this paper provide a number of recommendations for the storage of frozen beef rolls to extend color-shelf life.
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http://dx.doi.org/10.1016/j.meatsci.2020.108292DOI Listing
January 2021

The relationship between myofiber characteristics and meat quality of Chinese Qinchuan and Luxi cattle.

Anim Biosci 2021 Apr 24;34(4):743-750. Epub 2020 Jun 24.

College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, China.

Objective: 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.

Methods: 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.

Results: 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).

Conclusion: 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.
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http://dx.doi.org/10.5713/ajas.20.0066DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7961283PMC
April 2021

Effects of microbiota dynamics on the color stability of chilled beef steaks stored in high oxygen and carbon monoxide packaging.

Food Res Int 2020 08 6;134:109215. Epub 2020 Apr 6.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; National R&D Center for Beef Processing Technology, Tai'an, Shandong 271018, PR China.

The microbiota influence on meat color stability of chilled beef steaks under two modified atmosphere packaging (MAP) systems was studied: HiOx-MAP (80% O/20% CO) and CO-MAP (0.4% CO/30% CO/69.6% N). Steaks were stored for up to 20 days at 2 °C. Headspace gas composition and color stability were evaluated. High-throughput sequencing analyses were performed to characterize bacterial community dynamics. For HiOx-MAP steaks, Pseudomonas spp. became the dominant species, and an increased oxygen consumption caused by these bacteria contributed to metmyoglobin (MetMb) formation from day 10. Functional analysis based on 16S rDNA sequencing predicted higher abundance of genes related to amino acid and lipid metabolism in HiOx-MAP bacterial communities compared to CO-MAP bacterial communities, which probably accelerated meat discoloration. Lactic acid bacteria dominated in CO-MAP steaks, in which Lactobacillus spp. and Lactococcus spp. contributed to improve redness and chroma, and reduce MetMb%, respectively. These findings help our understanding of color stability in CO-MAP steaks in comparison to HiOx-MAP steaks as influenced by the microbial community.
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http://dx.doi.org/10.1016/j.foodres.2020.109215DOI Listing
August 2020

Occurrence and characterization of Shiga toxin-producing Escherichia coli (STEC) isolated from Chinese beef processing plants.

Meat Sci 2020 Oct 15;168:108188. Epub 2020 May 15.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China. Electronic address:

In order to investigate the prevalence, O serogroup, virulence genes and antibiotic resistance of Shiga toxin-producing Escherichia coli (STEC) in two beef plants in China, a total of 600 samples collected from 6 sites (feces, hide, pre-evisceration carcasses, post-washing carcasses, chilled carcasses and meat, 50 samples per site in each plant) were screened for the existence of Shiga toxin-encoding genes by PCR. STEC strains in positives were isolated and characterized for serogroup and antibiotic sensitivity. The PCR prevalence rate in each site was 45.0%, 31.0%, 14.0%, 13.0%, 9.0% and 18.0%, respectively. Sixteen O serogroups including O157, O146 and O76 which are associated with disease were identified. The existence of both stx and stx genes was the most common among the isolated strains (42.3%). Among the overall 26 isolates, seven and three were resistant to at least three and ten antibiotics, indicating a high antibiotic resistance in STEC strains isolated from the study.
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http://dx.doi.org/10.1016/j.meatsci.2020.108188DOI Listing
October 2020

Protein degradation and structure changes of beef muscle during superchilled storage.

Meat Sci 2020 Oct 7;168:108180. Epub 2020 May 7.

College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China. Electronic address:

This study investigated the effect of superchilled storage (-4 °C) on protein degradation and structural changes of beef steaks from M. longissimus lumborum compared with traditional chilling (2 °C) and frozen storage (-18 °C). Traditional chilling induced significantly greater degradation of troponin T and desmin, and more rapid loss of calpain activity, compared to superchilled or frozen storage treatments. The proteolysis of key myofibrillar proteins resulted in a sharp decline of WBSF values during traditional chilled storage. For frozen beef samples, no major changes were observed with respect to protein degradation or muscle structure during storage. However, superchilled samples exhibited wider gaps between muscle fibers at 12 weeks storage, associated with muscle fiber shrinkage.
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http://dx.doi.org/10.1016/j.meatsci.2020.108180DOI Listing
October 2020

Preliminary investigation of the use of Raman spectroscopy to predict beef spoilage in different types of packaging.

Meat Sci 2020 Jul 2;165:108136. Epub 2020 Apr 2.

Centre for Red Meat and Sheep Development, NSW Department of Primary Industries, Cowra, Australia.

In this study, pH, meat color analysis, microbial counts and Raman spectroscopic data were obtained from beef steaks stored at 4 °C for up to 21 days using two different packaging methods: vacuum (VP) and modified atmosphere packaging (MAP). Models using partial least square regression (PLSR), indicated that Raman spectroscopy was able to predict total viable counts (TVC) and lactic acid bacteria (LAB) measured at 21d post mortem (TVC in VP: R = 0.99, RMSEP = 0.61; TVC in MAP: R = 0.90, RMSEP = 0.38; LAB in VP: R = 0.99, RMSEP = 0.54; LAB in MAP: R = 0.75, RMSEP = 0.60). The results of this study demonstrate that Raman spectroscopy may have potential for the rapid determination of meat spoilage.
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http://dx.doi.org/10.1016/j.meatsci.2020.108136DOI Listing
July 2020

Shelf-life and bacterial community dynamics of vacuum packaged beef during long-term super-chilled storage sourced from two Chinese abattoirs.

Food Res Int 2020 04 23;130:108937. Epub 2019 Dec 23.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; National R&D Center for Beef Processing Technology, Tai'an, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China. Electronic address:

This study explored the shelf-life and bacterial community dynamics of beef cuts stored at super-chilled conditions (-1 ± 0.5 °C) for 20 weeks when sourced from two Chinese abattoirs, in order to determine whether domestic beef has equivalent quality as that imported from Australia. The initial total viable counts (TVC) were 4.15 and 4.87 log CFU/cm in beef from abattoirs A and B, respectively at the commencement of the storage period. The TVC of beef from abattoir A was above 6.0 log CFU/cm at 6 weeks and kept below 7.0 log CFU/cm at 20 weeks; while the counts were above 6.0 log CFU/cm at 3 weeks and reached at 7.3~7.6 log CFU/cm in beef from abattoir B. The beef shelf-life was deemed less than 12 and 9 weeks in abattoirs A and B, respectively, based on the total volatile basic nitrogen (TVBN) threshold, although all samples were acceptable organoleptically. High-throughput sequencing showed that the initial bacteria community and bacterial succession during storage were different between the two abattoirs. Carnobacterium spp. and Lactobacillus spp. dominated in both abattoirs throughout 3-9 weeks while Serratia spp. co-dominated in abattoir B, and Lactobacillus spp. and Carnobacterium spp. were dominant for the rest of storage in abattoir A and B, respectively. Overall, the high initial TVC is a concern compared to imported beef from Australia. To achieve comparable shelf-life, domestic super-chilled stored beef would need to be sourced from abattoirs employing effective decontamination technologies or where strict hygiene procedures are adopted.
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http://dx.doi.org/10.1016/j.foodres.2019.108937DOI Listing
April 2020

Effects of spraying lactic acid and peroxyacetic acid on the bacterial decontamination and bacterial composition of beef carcasses.

Meat Sci 2020 Jun 28;164:108104. Epub 2020 Feb 28.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong, 271018, PR China; NSW Department of Primary Industries, Centre for Red Meat and Sheep Development, PO Box 129, Cowra, NSW 2794, Australia. Electronic address:

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http://dx.doi.org/10.1016/j.meatsci.2020.108104DOI Listing
June 2020

Investigation of muscle-specific beef color stability at different ultimate pHs.

Asian-Australas J Anim Sci 2020 Dec 25;33(12):1999-2007. Epub 2020 Feb 25.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, China.

Objective: This study was aimed to investigate the muscle-specific beef color stability at normal and high ultimate pHs.

Methods: The impact of muscle (Longissimus lumborum [LL] vs psoas major [PM]) and pH (normal ultimate pH [Np] vs high pH dark cutting beef [Hp]) on color stability, indicated by basic color traits, metmyoglobin reducing activity (MRA) and oxygen consumption (OC), as well as the lipid oxidation, were determined over 7 days of display at 4°C.

Results: Hp-LL had the highest pH (6.92), followed by Hp-PM (6.01), Np-PM (5.76), and Np-LL (5.52). Hp-LL had increased (p<0.05) a*, chroma and % oxymyoglobin during display. Hp-LL also had the highest metmyoglobin (MMb) reducing activity and OC among all the samples, thus, the greatest color stability, although very dark throughout storage, with lowest values for lightness (L*) and yellowness (b*). Np-LL also exhibited relatively high color stability, as a result of its lower % MMb and OC and higher MRA than psoas muscle samples. The 0.2 unit difference of the pH between Hp and Np psoas muscle, resulted in the difference of the color intensity, not the color stability. Interestingly, high pH psoas muscle (Hp-PM) did not have better color stability than Np-PM, and in fact had lower color stability than even Np-LL. The similar level of OC and lipid oxidation cannot explain the difference in color stability between Hp-PM and Np-LL.

Conclusion: The Hp does not always show better color stability compared with Np beef, which depends on the muscle type. The balance of MRA and OC is important to keep the color in great intensity and stability in the meantime.
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http://dx.doi.org/10.5713/ajas.19.0943DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649401PMC
December 2020

Robot-Assisted Laparoscopic Excision of Complicated Retroperitoneal Tumors with Four Arms Via Retroperitoneal Way: A Unique Minimal-Invasive Approach.

J Laparoendosc Adv Surg Tech A 2020 Oct 9;30(10):1110-1116. Epub 2020 Jan 9.

Department of Urology and The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.

Surgical management of complicated retroperitoneal mass is one of the most challenging urologic oncologic surgeries. This study aims to describe our technique and experience in dealing with retroperitoneal mass. Three patients with complicated retroperitoneal mass were treated with robot-assisted surgery with four arms through retroperitoneal approach. Our standardized anatomic-based "kidney safe first, then mass resection" technique for robot-assisted complicated retroperitoneal mass resection focused on minimizing the chance of renal pedicle injury. Baseline demographics, pathology data, and latest follow-up outcome were obtained. In this retrospectively reviewed case series, all 3 patients were successfully treated with robot-assisted surgery with four arms during retroperitoneal space. One patient received paravertebral mass resection 2 weeks after the robotic surgery. Mean data included operative time of 175 minutes, estimated blood loss was 133 mL, and hospital stay was 4 days. No complications occurred. Robot-assist surgery for complicated retroperitoneal mass with four arms is a safe and feasible way. Mini-invasive treatment for retroperitoneal mass with robotic four arms through retroperitoneal approach is a feasible way. The approach reduces interruption of intracorporeal structure and organs. And patients could benefit from the retroperitoneal approach with a quicker recovery.
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http://dx.doi.org/10.1089/lap.2019.0532DOI Listing
October 2020

Acid Tolerance Response of in Various External pHs with Different Concentrations of Lactic Acid.

Foodborne Pathog Dis 2020 04 18;17(4):253-261. Epub 2019 Nov 18.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, People's Republic of China.

This study evaluated the acid tolerance response (ATR) of two strains of (serotype 1/2a and 4b) and one strain of under different mildly acid conditions. Cells were incubated in combinations of three concentrations of lactic acid medium (3, 4.75, and 15 mM) and three external pH's (pH 5.0, 6.0, and 6.5), plus, a HCl control, and a blank control (pH 7.4). Results showed that lactic acid induced lower log reduction of all three strains when challenged in severe acid conditions (pH 3.0) after being habituated at a pH of 5.5 or 6.0 until the log phase, compared with a pH of 6.5 or the two controls. This indicates that when the pH was either 5.5 or 6.0 this induced a higher ATR of the strains, which may be caused by the ability of the strains to retain intracellular pH (pH) homeostasis with pH maintained in the range of 7.4-7.9. It was also found that a pH of 5.5 resulted in the highest pH of the strains across all incubated conditions, which indicates that the pH may play an important role in the induction of ATR when cells are habituated in lactic acid, and if the higher pH can be maintained, the ATR would be stronger. The concentration of lactic acid has no significant effect on ATR, which it is proposed was due to the pH homeostasis maintained within the cells. However, the difference in ATR among three strains was also significant, which cannot be explained by the stable pH of all tested strains. Therefore, other underlying mechanisms to mediate ATR under different conditions need to be explored in further studies.
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http://dx.doi.org/10.1089/fpd.2019.2730DOI Listing
April 2020

Effect of oxygen concentration in modified atmosphere packaging on color changes of the M. longissimus thoraces et lumborum from dark cutting beef carcasses.

Meat Sci 2020 Mar 2;161:107999. Epub 2019 Nov 2.

College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China. Electronic address:

The objective of this study was to investigate the effect of modified atmosphere packaging (MAP) with different oxygen concentrations on color changes of dark-cutting beef steaks from M. longissimus thoraces et lumborum. Four normal-pH (mean pH = 5.52) and four dark-cutting beef carcasses (mean pH = 6.36) were obtained from a commercial abattoir at 48 h post-mortem. The gas compositions in MAP were as follows: (i) 20% O/20% CO/60% N, (ii) 40% O/20% CO/40% N, (iii) 60% O/20% CO/20% N and (iv) 80% O/20% CO. Steaks were stored in the dark at 2 °C for 14 days. Surface color of dark-cutting beef steaks was improved (P < .05) by 60%O-MAP and 80%O-MAP after 4 days storage, to a level similar to the initial normal-pH steaks. Steaks in 60%O-MAP and 80%O-MAP had lower metmyoglobin reducing activity and higher TBARS values (P < .05), but deeper oxygen penetration depth (P < .05) that may have masked discoloration resulting from metmyoglobin formation under the surface. While both 60%O-MAP and 80%O-MAP improved the appearance of dark-cutting beef, 60%O-MAP may be preferred owing to the lower level of lipid oxidation.
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http://dx.doi.org/10.1016/j.meatsci.2019.107999DOI Listing
March 2020

Shelf-life and microbial community dynamics of super-chilled beef imported from Australia to China.

Food Res Int 2019 06 18;120:784-792. Epub 2018 Nov 18.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China.

The aim of this study was to investigate the shelf-life and microbial community dynamics of super-chilled vacuum-packaged beef striploins imported from Australia to China after approximately five weeks of shipping time and an additional 15 weeks of storage at -1 °C ± 0.5 °C. Data analysis using a mixed model (REML) with time as the fixed effect and portion as a random effect, showed that the only beef quality trait that changed during storage was total volatile basic nitrogen (TVBN; P < .05), which reached the threshold of 15 mg/100 g between 15 and 20 weeks (including 5 weeks of transport). The total viable count (TVC) accounted for 78% of the variance in TVBN, when storage time was included in the model. Sensory scores decreased as storage time extended (P < .05), but were still acceptable at 20 weeks. After 9 weeks, Carnobacterium spp. and Lactobacillus spp. dominated alternately and then Lactobacillus became the most prevalent bacteria. An operational taxominc unit based hierarchical cluster analysis using the unweighted pair-group method with arithmetic means was performed and it was shown that the bacterial communities tended to be consistent as storage time extended. Overall indications are that beef which is safe can be imported into China from Australia and aged for extended periods.
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http://dx.doi.org/10.1016/j.foodres.2018.11.039DOI Listing
June 2019

Effect of superchilled storage on shelf life and quality characteristics of M. longissimus lumborum from Chinese Yellow cattle.

Meat Sci 2019 Mar 17;149:79-84. Epub 2018 Nov 17.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; Centre for Red Meat and Sheep Development, NSW Department of Primary Industries, Cowra, NSW 2794, Australia.

The effect of superchilled storage (SC, -4 °C) on shelf life and quality characteristics of M. longissimus lumborum from Chinese Yellow cattle compared with traditional chilling (TC, 2 °C) and frozen storage (-18 °C) was studied. The shelf life of beef steaks held at -4 °C extended to 12 weeks based on the total volatile basic nitrogen (TVB-N) value, which was 2.4 times longer than steaks stored at 2 °C. As the storage time increased, SC samples showed a lower increase of the total aerobic count (TAC), pH and thiobarbituric acid reactive substances (TBARS) values compared to TC samples. Further, L and a values of SC samples changed more slowly than that of TC samples. Beef steaks held frozen had a longer shelf life than SC steaks, however, the shear force of frozen steaks remained above 55 N throughout the storage time indicative of toughness. Consequently, SC offers an effective approach for maintaining better shelf life and quality of beef steaks.
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http://dx.doi.org/10.1016/j.meatsci.2018.11.014DOI Listing
March 2019

Effect of new generation medium voltage electrical stimulation on the meat quality of beef slaughtered in a Chinese abattoir.

Meat Sci 2019 Mar 14;149:47-54. Epub 2018 Nov 14.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; NSW Department of Primary Industries, Centre for Red Meat and Sheep Development, PO Box 129, Cowra, NSW 2794, Australia.

In this study, a medium voltage electrical stimulation (ES) system with three parameter combinations (A: 1A, 1.55 ms pulse width, 27 s; B: 0.55A, 1 ms pulse width, 34 s; C: 0.55A, 2 ms pulse width, 20s) were applied to beef carcases (n = 24; 319 ± 26.4 kg), in the context of a very slow pH decline rate in the abattoir. All the ES combinations significantly accelerated the rate of pH decline (reflected by [email protected] 6.0, i.e. temperature when pH drops to 6.0), resulting in a tenderness improvement even after 14 days ageing compared to the controls. Sarcomere length was not different between treatments and controls, and it was not a contributor to the tenderness improvement, instead, physical disruption revealed by transmission electron microscopic images may have led to the improvement. Retail colour was significantly improved by either combination B or C after 7 days of ageing. Combination B shows the most promise for commercial application, however, verification on more animals is required before commercial adoption.
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http://dx.doi.org/10.1016/j.meatsci.2018.11.011DOI Listing
March 2019

Effect of different short-term high ambient temperature on chicken meat quality and ultra-structure.

Asian-Australas J Anim Sci 2019 May 26;32(5):701-710. Epub 2018 Oct 26.

Laboratory of Meat Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, China.

Objective: This study investigated the effect of different acute heat stress (HS) levels on chicken meat quality and ultra-structure.

Methods: 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.

Results: 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.

Conclusion: 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.
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http://dx.doi.org/10.5713/ajas.18.0232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6502722PMC
May 2019

The Characterization of Biofilm Formation and Detection of Biofilm-Related Genes in Salmonella Isolated from Beef Processing Plants.

Foodborne Pathog Dis 2018 10 8;15(10):660-667. Epub 2018 Sep 8.

Department of Food Science, College of Food Science and Engineering, Shandong Agricultural University , Tai'an, China .

The biofilm formation behavior of Salmonella isolated from beef processing plants was investigated under varying temperatures (4°C, 10°C, 25°C, 37°C, and 42°C) and pH (4.5, 5.0, 5.5, 6.0, 7.0, and 8.0). The relationships between the presence of biofilm-related genes and the biofilm formation capacity were evaluated. A total of 77 Salmonella strains in 8 different serotypes were assessed: Salmonella Agona (n = 43), Salmonella Senftenberg (n = 13), Salmonella Meleagridis (n = 8), Salmonella Derby (n = 7), Salmonella Kottbus (n = 2), Salmonella Calabar (n = 2), Salmonella Kingston (n = 1), and Salmonella Typhimurium (n = 1). The results showed that all tested Salmonella strains produced biofilm at 25°C and 37°C after 3 d, and Salmonella Kingston and Salmonella Senftenberg had higher biofilm production than other strains under test conditions. Serotype, incubation temperature, pH, and their interactions had significant effects on biofilm formation for Salmonella. The strongest biofilm formation capacity of Salmonella (serovar Agona, Senftenberg, Kottbus, Calabar, Kingston, and Typhimurium) occurred at 25°C and at pH 7.0. Biofilm formation was significantly inhibited for all Salmonella strains incubated at 4°C. The detection rates of genes rpoS, fliC, wcaA, and invA were 100%, and the rates of genes csgB, csgD, csrA, sirA, adrA, gly, fimH, sdiA, ompR, sipB, sipC, luxS, and pfs exceeded 75% among all biofilm producer strains. The detection rate of igaA was significantly different between different biofilm producers. Based on the findings in this study, useful information on biofilm formation of Salmonella isolated from beef processing plants in China is provided, which could help clear the technological hurdle in delaying biofilm production to deal with risks from Salmonella biofilms in the beef industry.
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http://dx.doi.org/10.1089/fpd.2018.2466DOI Listing
October 2018

Proteomic analysis to investigate color changes of chilled beef longissimus steaks held under carbon monoxide and high oxygen packaging.

Meat Sci 2018 Aug 3;142:23-31. Epub 2018 Apr 3.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China. Electronic address:

This study investigated the proteome basis for color stability variations in beef steaks packaged under two modified atmosphere packaging (MAP) methods: HiOx-MAP (80% O/20% CO) and CO-MAP (0.4% CO/30% CO/69.6% N) during 15 days of storage. The color stability, pH, and sarcoplasmic proteome analysis of steaks were evaluated on days 0, 5, 10 and 15 of storage. Proteomic results revealed that the differential expression of the sarcoplasmic proteome during storage contributed to the variations in meat color stability between the two MAP methods. Compared with HiOx-MAP steaks, some glycolytic and energy metabolic enzymes important in NADH regeneration and antioxidant processes, antioxidant peroxiredoxins (thioredoxin-dependent peroxide reductase, peroxiredoxin-2, peroxiredoxin-6) and protein DJ-1 were more abundant in CO-MAP steaks. The over-expression of these proteins could induce CO-MAP steaks to maintain high levels of metmyoglobin reducing activity and oxygen consumption rate, resulting in CO-MAP steaks exhibiting better color stability than HiOx-MAP steaks during storage.
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http://dx.doi.org/10.1016/j.meatsci.2018.04.001DOI Listing
August 2018

Microbial community dynamics analysis by high-throughput sequencing in chilled beef longissimus steaks packaged under modified atmospheres.

Meat Sci 2018 Jul 29;141:94-102. Epub 2018 Mar 29.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Tai'an, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China. Electronic address:

The microbial community dynamics were investigated in this study to understand the spoilage of beef steaks packaged in both modified atmosphere packaging (MAP): 80%O-MAP (80% O/20% CO) and CO-MAP (0.4% CO/30% CO/69.6% N). Steaks were stored at 2 °C for 20 days. Meat physicochemical changes and microbial counts were monitored, and the microbial communities were evaluated by high throughput-sequencing. The microbial diversity for both MAP decreased over time and it was more complex in CO-MAP steaks than that in 80%O-MAP steaks. B. thermosphacta and Pseudomonas spp. were dominant bacteria of 80%O-MAP steaks but Pseudomonas spp. gradually outcompeted the former from day 10. Leuconostoc, Lactobacillus, Lactococcus, Vagococcus and Serratia dominated alternately in CO-MAP steaks during storage, and Lactococcus eventually became the most common bacteria. Predicted metagenomes indicated a higher microbial amino acid and lipid metabolism level in 80%O-MAP compared with CO-MAP at day 20, which may contribute to the dramatic physicochemical deterioration of 80%O-MAP steaks.
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http://dx.doi.org/10.1016/j.meatsci.2018.03.010DOI Listing
July 2018

Association of ultimate pH and stress-related blood variables in cattle.

Meat Sci 2018 May 7;139:228-230. Epub 2018 Feb 7.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China. Electronic address:

The objective of this study was to investigate the relationship between ultimate pH (pHu) and stress-related blood variables. Of 50 cattle in total, blood samples from 6 cattle which exhibited high (≥6.10) pHu (dark-cutting) were collected, along with the same number of low pHu and intermediate pHu cattle (5.40-5.80; 5.80-6.10, respectively) to determine the concentration of plasma cortisol, glucose, lactate, creatine kinase, lactate dehydrogenase, haptoglobin and serum amyloid A protein. Compared to cattle with low pHu, high pHu cattle showed higher plasma cortisol, glucose, lactate, creatine kinase and lactate dehydrogenase levels at exsanguination. But the concentration of haptoglobin and serum amyloid A protein showed no significant differences among three pH groups. These results imply that measuring plasma cortisol, glucose, lactate, creatine kinase, or lactate dehydrogenase levels at exsanguination may be useful to identify the dark-cutting beef condition.
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http://dx.doi.org/10.1016/j.meatsci.2018.02.004DOI Listing
May 2018

Carbon monoxide packaging shows the same color improvement for dark cutting beef as high oxygen packaging.

Meat Sci 2018 Mar 17;137:153-159. Epub 2017 Nov 17.

Lab of Beef Processing and Quality Control, College of Food Science and Engineering, Shandong Agricultural University, Taian, Shandong 271018, PR China; Jiangsu Synergetic Innovation Center of Meat Production and Processing Quality and Safety Control, Nanjing, Jiangsu 210000, PR China.. Electronic address:

In this study, carbon monoxide (CO) modified atmosphere packaging (MAP) was used to increase redness (a*) and lightness (L*) values of dark cutting beef (ultimate pH (pHu)≥6.10), compared to normal pHu beef and intermediate pHu beef (pH: 5.40-5.79; pH: 5.80-6.09, respectively) during 20 d chilled storage. Compared with HiOx-MAP, CO-MAP exhibited similar color improvement effects (increased L*, a*, b* values) for all pHu beef groupings. The metmyoglobin (MetMb) content was lower under CO-MAP than that of HiOx-MAP in normal pHu beef, but opposite effects were observed in dark, high pH beef. This result could not be explained by MetMb reducing ability (MRA) and lipid oxidation, as both parameters were higher in CO-MAP beef than either normal or high pHu beef, compared with HiOx-MAP. In conclusion, CO-MAP was effective to maintain the cherry red color for dark cutting beef, but the color improvement mechanisms might be different with HiOx packaging methods.
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http://dx.doi.org/10.1016/j.meatsci.2017.11.016DOI Listing
March 2018
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