Elucidation of potential relationship between endogenous proteases and key flavor substances in dry-cured pork coppa

Dry-cured meat products are considerably popular around the world due to unique flavor.Proteolysis is one of the enzymatic reactions from which flavor substances are derived,which is affected by endogenous proteases.The purpose aimed to reveal the potential relationship between endogenous proteases and key flavor substances in dry-cured pork coppa in this paper.The dynamic changes of endogenous proteases activity,free amino acids,and volatiles during dry-cured pork coppa processing were characterized.The results showed that 5 kinds of free amino acids,Glu,Lys,Val,Ala,and Leu,were identified as significant contributors to taste.Meanwhile,key volatiles,such as hexanal,nonanal,octanal,benzaldehyde,3-methyl butanoic acid,2-methyl propanoic acid,and ethyl octanoate,greatly contributed to the flavor characteristics of dry-cured pork coppa.Further partial correlation analysis was performed to better elucidate the relationship among parameters.The results revealed that close relationship between endogenous proteases and key substances.RAP not only significantly affected the accumulation of key active-amino acids,but also affected the accumulation of ethyl octanoate,2,3-pentanedione,and 2,3-octanedione by regulating the accumulation of octanoic acid and Leu.In addition,cathepsin B and D,DPP II,DPP IV and RAP notably affected accumulation of hexanal.

Smart Colorimetric Corn Starch Films Combined with Anthocyanin-Loaded Glutenin-Carboxymethyl Chitosan Nanocomplexes for Freshness Monitoring of Chilled Pork

In this study,intelligent,pH-responsive colorimetric films were prepared by encapsulating anthocyanins in nanocomplexes prepared from glutenin and carboxymethyl chitosan.These nanocomplexes were added to a corn starch matrix and used in the freshness monitoring of chilled pork.The effects of anthocyanin-loaded nanocomplexes on the physical,structural,and functional characteristics of the films were investigated.The addition of anthocyanin-loaded nanocomplexes increased the tensile strength,elongation at break,hydrophobicity,and light transmittance of the films while decreasing their water vapor permeability.This is because new hydrogen bonds are formed between the film components,resulting in a more homogeneous and dense structure.The colorimetric film has a significant color response to pH changes.These films were used in experiments on the freshness of chilled pork,in which the pH changes with changing freshness states.The results show that the colorimetric film can monitor changes in the freshness of chilled pork in real time,where orange,pink,and green represent the fresh,secondary fresh,and putrefied states of pork,respectively.Therefore,the intelligent colorimetric film developed in this study has good application potential in the food industry.

Impact of Low-temperature Storage on Volatile Flavor Compounds in Prepared Pork Products

[Objectives]This study was conducted to explore the dynamic changes of volatile flavor compounds in prepared pork during storage at different low-temperature conditions.[Methods]Prepared pork was stored at 4,-4 and-18℃.The volatile flavor compounds of prepared pork were determined by solid-phase microextraction-gas chromatography-mass spectrometry(SPME-GC-MS)at days 0,7,14,21 and 28,and relative odor activity value(OAV),principal component analysis(PCA)and cluster analysis(CA)were combined to analyze changes in volatile flavor compounds of prepared pork during storage.[Results]The total number of volatile flavor compounds gradually decreased with the prolongation of the storage period,and OAV analysis identified 22 key flavor compounds(OAV≥1).The results of PCA and CA showed that 2-methyl-1-butanol,1-octen-3-ol,linalool,cineole,hexanal and nonanal were the main key flavor components,and the degree of flavor degradation was low under both superchilling and freezing conditions.After 28 days of storage,the alcohol content in the chilling group was significantly higher than other two groups,and the overall content of volatile flavor compounds was also significantly higher than other two groups,indicating that the-4℃chilling storage was more favorable for maintaining the overall flavor of prepared pork.[Conclusions]This study provides a theoretical basis for finding a better storage method for prepared meat products.

Effects of the degree of oral processing on the properties of saliva-participating emulsions:using stewed pork with brown sauce as the model

This work investigated the changes in properties of saliva-participating emulsions during different oral processing stages(the whole process from intake to swallowing was divided into five stages,i.e.,20%,40%,60%,80%and 100%stage).The stewed pork with brown sauce was masticated and the emulsion was collected for the determination of emulsion stability,droplet size,ζ-potential,interfacial tension,and microstructure.The results showed that the emulsion stability increased gradually during the oral processing and reached the highest level near the swallowing point.The droplet size of emulsion showed a significant downward trend(P<0.05).Microstructure observations also found different degrees of reduction in fat droplets size at different stages of oral processing.In addition,theζ-potential of food boluses emulsion was decreased from-16.4 mV to-41.2 mV and the interfacial tension decreased by 52.6%before and after oral progressing.In conclusion,the oral processing of stewed pork with brown sauce was essentially a process in which fat was constantly emulsified,and saliva might act as an emulsifier.This study provides new insights on understanding the oral processing process and sensory changes of fat.

Flavor release from traditional dry-cured pork during oral processing

The rate of flavor release in the mouth from traditional dry-cured pork was evaluated in this study.It was hypothesized that a slow steady release of flavor would occur on chewing and hydration.To test this,high salt dry-cured pork was chewed and held in oral cavity without swallowing for 4 different chewing stages(B,NC_(30),C_(30),EC).Saliva and food bolus from 16 healthy subjects were collected during oral processing,and analyzed for saliva flow rate,total saliva protein content,saliva pH,conductivity,saliva and sodium,and taste components.Results show that oral processing behavior and salivary release have important effects on flavor release of dry-cured pork.Sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)analysis showed that oral processing has a certain effect on the protein composition and concentration in saliva.This study suggests that the interaction between food and saliva that accompanies chewing can lead to significant changes in sensory perception during oral processing.

Genetic dissection and genomic prediction for pork cuts and carcass morphology traits in pig

Background As pre-cut and pre-packaged chilled meat becomes increasingly popular,integrating the carcasscutting process into the pig industry chain has become a trend.Identifying quantitative trait loci(QTLs)of pork cuts would facilitate the selection of pigs with a higher overall value.However,previous studies solely focused on evaluating the phenotypic and genetic parameters of pork cuts,neglecting the investigation of QTLs influencing these traits.This study involved 17 pork cuts and 12 morphology traits from 2,012 pigs across four populations genotyped using CC1 PorcineSNP50 BeadChips.Our aim was to identify QTLs and evaluate the accuracy of genomic estimated breed values(GEBVs)for pork cuts.Results We identified 14 QTLs and 112 QTLs for 17 pork cuts by GWAS using haplotype and imputation genotypes,respectively.Specifically,we found that HMGA1,VRTN and BMP2 were associated with body length and weight.Subsequent analysis revealed that HMGA1 primarily affects the size of fore leg bones,VRTN primarily affects the number of vertebrates,and BMP2 primarily affects the length of vertebrae and the size of hind leg bones.The prediction accuracy was defined as the correlation between the adjusted phenotype and GEBVs in the validation population,divided by the square root of the trait’s heritability.The prediction accuracy of GEBVs for pork cuts varied from 0.342 to 0.693.Notably,ribs,boneless picnic shoulder,tenderloin,hind leg bones,and scapula bones exhibited prediction accuracies exceeding 0.600.Employing better models,increasing marker density through genotype imputation,and pre-selecting markers significantly improved the prediction accuracy of GEBVs.Conclusions We performed the first study to dissect the genetic mechanism of pork cuts and identified a large number of significant QTLs and potential candidate genes.These findings carry significant implications for the breeding of pork cuts through marker-assisted and genomic selection.Additionally,we have constructed the first reference populations for genomic selection of pork cuts in pigs.

Effect of dietary magnolia bark extract supplementation in finishing pigs on the oxidative stability of meat

Background:Magnolia bark extract(MBE)is a natural supplement with antioxidant,anti-inflammatory,and antimicrobial activities.Its properties suggest that the dietary supplementation in livestock could improve the quality of products.Therefore,the aim of this study was to investigate,for the first time,the effect of dietary MBE supplementation(0.33 mg/kg)in finishing pigs on the oxidative stability of meat.Oxidative stability is of paramount importance for pork,as it affects storage,retail,and consumer acceptance.For the purpose,the fatty acid profile,cholesterol,fatsoluble vitamins,antioxidant enzymes(catalase,glutathione peroxidase,and superoxide dismutase),non-enzymatic antioxidant capacity(TEAC,FRAP,and Folin-Ciocalteu assays),color stability,and lipid stability of pork were assessed.Results:Concerning carcass characteristics,dietary MBE did not affect cold carcass yield,but reduced(P=0.040)the chilling weight loss.The meat from pigs fed MBE had a lower(P=0.031)lightness index than the control meat.No effect on intramuscular fat,cholesterol,and fatty acid profile was observed.Dietary MBE did not affect the content of vitamin E(α-tocopherol andγ-tocopherol)in pork,whereas it reduced(P=0.021)the retinol content.The catalase activity was 18%higher(P=0.008)in the meat from pigs fed MBE compared with the control group.The MBE supplementation reduced(P=0.039)by 30%the thiobarbituric acid reactive substances(TBARS)in raw pork over 6 d of aerobic refrigerated storage.Instead,no effect on lipid oxidation was observed in cooked pork.Last,the meat from pigs fed MBE reduced Fe3+-ascorbate catalyzed lipid oxidation in muscle homogenates,with a lower(P=0.034)TBARS value than the control group after 60 min of incubation.Conclusions:Dietary MBE supplementation in finishing pigs delayed the lipid oxidation in raw meat.This effect was combined with an increased catalase concentration.These results suggest that dietary MBE could have implications for improving the shelf-life of pork.

Effects of Heat Treatment on Processing Characteristics of Pork

[Objectives]This study was conducted to explore the effects of heat treatment on processing characteristics of pork.[Methods]The effects of low-temperature long-term cooking(LTLT),high-temperature vacuum cooking,high-temperature cooking and high-temperature steaming on some indexes of pork products were studied,and principal component analysis was carried out.[Results]LTLT had significant effects on the total sensory score,moisture content,cooking loss rate,a value,shear force,and TBARS of pork,and the corresponding optimal product indicators were 71.40 points,72.36%,14.20%,4.79,7089.87 g,and 0.05 mg/kg,respectively.The microstructure changes in the LTLT group were relatively small,as the muscle fiber structure was relatively dense and uniform,and the gaps between muscle fibers were small.A total of 30 volatile flavor compounds were detected in the four groups,mainly alcohols,alkenes,alkanes,lipids,ketones,and aldehydes,and the LTLT group had more types and high contents.PCA analysis showed that the sensory evaluation,moisture content,elasticity,a value and LTLT were positively correlated with principal component 1.[Conclusions]Various indexes comprehensively showed that the LTLT group had better meat color,flavor,texture characteristics and lower oxidation degree than traditional cooking and steaming methods,which provides a theoretical reference for its large-scale application in the processing of prepared meat products.

Silage Fermentation Technology and Its Effects on Growth Performance of Local Pigs

This paper first introduced the silage fermentation technology,including the selection of strains and activation expansion technology,the screening of high-quality fermentation raw materials,and the comparative experiment of fermentation process.It discussed feeding methods for sows and growing-finishing pigs at different breeding stages.In addition,it analyzed the effects of fermented silage on the growth performance of local pigs at various stages.Finally,it is concluded that silage fermentation can improve the water retention performance of pork,improve the quality of pork from local pigs,increase economic benefits,and achieve the purpose of saving costs and increasing efficiency.

高效液相色谱-串联质谱法对猪肉中四种大环内酯类药物残留量的测定

A simple and sensitive method was developed for the simultaneous determination of four macrolides in pork using high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).Homogenized sample was extracted with NaH2PO4 buffer and acetonitrile solution,and defatted with n-hexane.Further cleanup was performed on a Sep-Pakt C18 solid-phase extraction cartridge.The compounds were determined by LC-MS/MS operated in positive electrospray ionization mode.The limits of detection(LODs) were 0.5 μg/kg.The average recoveries at three spiked concentration levels of 1.0,5.0,10.0 μg/kg were in the range of 70%-110%,with the intra-day RSD of less than 12.9% and inter-day RSD of less than 13.4%.

气相色谱-离子阱二级质谱法测定猪肉中的氢化泼尼松和甲基氢化泼尼松残留

建立了固相萃取-气相色谱-离子阱二级质谱（GC-MS/MS）测定猪肉中氢化泼尼松和甲基氢化泼尼松残留量的分析方法。待测药物用乙腈提取,C18柱净化,K2Cr2O7氧化,GC-MS/MS测定。采用DB-5毛细管柱分离,电子轰击电离源二级质谱监测模式检测,外标法定量。方法的线性关系良好,线性相关系数均大于0.99,线性范围为2-50μg/kg;氢化泼尼松和甲基氢化泼尼松的回收率为56%-84%。两种药物的检测限和定量限均分别为1μg/kg和2μg/kg。

Isolation and Drug Resistance Analysis of Swine Salmonella

In this study, 68 fresh pork samples were collected from several major wholesale markets in Dalian City of Liaoning Province to isolate Salmonella using SS agar medium as selective medium. Salmonella isolates were identified with colony morphology observation and PCR method. The resistance of Salmonella iso- lates to 15 antibiotics was analyzed by broth microdilution susceptibility test. Accord- ing to the result, 12 Salmonella strains were isolated from 68 fresh pork samples, indicating a detection rate of 17.64%; 83.33% of Salmonella strains isolated from fresh pork samples could at least resist one antibiotic; Salmonella strains exhibited the strongest resistance to florfenicol （75.0%）, sarafloxacin hydrochloride （66.7%）, neomycin sulfate （66.7%） and doxycycline hydrochloride （66.7%）, followed by oxyte- tracycline （58.3%）, gentamicin sulphate （58.3%） and mequindox （58.3%）; Salmonella strains exhibited relatively low resistance to ciprofloxacin lactate （50.0%）, en- rofloxacin （50.0%）, ciprofloxacin hydrochloride （50.0%）, amoxicillin （16.7%） and col- istin sulphate （16.7%）. Salmonella in fresh pork samples from wholesale markets in Dalian Economic ＆ Technological Development Zone exhibited a high detection rate, and the isolated Salmonella strains showed extremely high resistance to various an- tibiotics. The strong drug-resistance of Salmonella can also be transmitted through the food chain from the food to the people, which should attract sufficient attention.

Study on Pork Quality and Safety Traceability System and Relevant Management Systems

It is the key to construct the traceability mechanism of quality responsibility for ensuring the quality and safety of animal products. In this study, after defining the concept of traceability system and analyzing its function mechanism, the design ideas of pork quality and safety traceability system based on bar code and Internet were put forward, including network structure, system process, business process and information identifica- tion. Then the relevant management systems were proposed.

Effects of Probiotics on Growth, Pork Quality and Serum Metabolites in Growing-finishing Pigs

A total of 72 growing-finishing pigs（56 days old） were used to investigate the effects of dietary probiotics on growing performance, pork quality and serum metabolites. Using single factorial experiment design, pigs were allotted to three groups（four pens/group and six pigs/pen）. Diet treatments were a corn-soybean meal（control group） and a corn-soybean meal with 1% probiotics（probiotics group） or 80 mg kg-1colistin sulfate（antibiotics group）. Pigs were slaughtered when pigs of the lightest averaged 90 kg（157 days of age）. There was no difference（p＆gt;0.05） in average daily gain or feed/gain, and the average daily feed intake of the antibiotics group was higher than that of the probiotics and the control groups（p＆lt;0.05）. Diet supplemented with probiotics reduced the drip loss and cooking loss of pork（p＆lt;0.05）. Dietary supplementation with probiotics significantly decreased the content of triglycerides, lowdensity lipoprotein and urea nitrogen in serum（p＆lt;0.05）, and increased the content of high-density lipoprotein in serum（p＆lt;0.05）. These results suggested improving effects of dietary probiotics on pork quality and serum metabolism in growing-finishing pigs.

A Solution on Pork Quality Traceability from Farm to Dinner Table in Tianjin City,China

In order to meet government supervision of pork production safety as well as consumer＇s right to know what they buy and protect the public safety of pork food, this study adopts animal identification, intelligent personal digital assistant （PDA） reading and writing, general packet radio service （GPRS）, and other information technologies, proposes a pork tracking and traceability inferstructure based on pork production substrace flow and data flow, designs the metadata structure and related datatbases for farming, slaughtering, and retailing sector based on intensive pig farming and smallhold pig farming, develops three different data-recording systems, and finally establishes a public network platform for the information inquiry in light of ＂the administrative rules on identification and rearing files for animal and poultry＂ in China. The farming process information system supplies early warning for the usage of drugs and feed additives based on data of every individual pig and timely uploading all events data to remote traceability database when pigs are sold; the PDA data collecting system can collect farming events data for pigs fed by farmers and submit to the center database by GPRS; the web-based Tianjin＇s pork traceability platform can integrate all identifications and related pork quality data from farming, slaughtering to marketing by online, and achieve pork tracking from product origin to consumption and tracing in the turnover direction. It is feasible to realize pork quality traceability by identification technologies developed and/or integrated, metadata specifications designed, three data-recording systems deyeloped, and web-inquiring platform established. Some individual technical bottlenecks will be resolved with the development of communication technologies. The full implementation in Tianjin, China, will supply technical support for guaranteeing the quality and safety of pork production and meeting consumer＇s demands.

A Review of Factors Influencing Intramuscular Fat Content in Porcine Meat

Intramuscular fat （IMF）, an important flavor precursor of porcine meat, is closely related to pork quality traits such as pH, color, tenderness, water-holding capacity （WHC） and juiciness, and thus is one of the important factors affecting pork quality. Pork IMF content is not only associated with swine breed on heredity, but also influenced by the alteration of nutrients in diet. These may give a possibility for researchers to improve the IMF content and pork quality by their work on swine breed or heredity, and nutrition regulation in diet. Therefore, this article summarizes the effects of swine breed and nutrition regulation on IMF content briefly to provide some information for future researches.

Comparative studies on the biochemical characteristics of natural actomyosin isolated from PSE and normal pork

Biochemical changes of natural actomyosin from fresh pale, soft, exudative (PSE) and normal pork were studied,and the effects of different storage temperatures and different incubation temperature and times on sample superprecipitation,total sulfhydryl (-SH) content, and ATP (adenosine triphosphate) sensitivity were investigated. The results demonstrated that ATPase activity and thermal stability of PSE actomyosin were lower than those of normal pork; and that PSE actomyosin had higher -SH content than that of normal pork at all incubation temperatures and times tested.

Effect of Lactobacillus salivarius H strain isolated from Chinese dry-cured ham on the color stability of fresh pork

The aim of this research is to investigate the effect of lactic acid bacteria(LAB)on color stability of fresh pork.Of the seven LAB strains isolated from the Chinese dry-cured hams,H strain was identified as Lactobacillus salivarius(CCTCC M2010374)by serial biochemical tests and 16S rRNA analysis.The fresh pork samples were immersed in the H strain and Lactobacillus fermentum extracts for 1 min after ultrasonic cells disruption and samples immersed in sterile 0.9%(m/V)saline was served as a control group,then samples were vacuum packaged and stored at 4◦C.Nitrate oxide synthase(NOS)and metmyoglobin(MetMb)reductase were found in the cells extracts of H strain.After 6 days of storage,H strain group was found to be associated with the highest CIE a*values(P<0.05)and the lowest MetMb(41%).L.salivarius H strain has thus shown a beneficial effect on the color stability of fresh pork.Further research is necessary to elucidate its mechanism.©2013 Beijing Academy of Food Sciences.Production and hosting by Elsevier B.V.All rights reserved.

Influences of dietary protein sources and crude protein levels on intracellular free amino acid profile in the longissimus dorsi muscle of finishing gilts

Background： The current study was carried out to determine effects of dietary protein source and crude protein（CP）level on carcass characteristics, meat quality, and muscle amino acid（AA） profile in finishing gilts. The experiment was designed as a 2 × 2 factorial arrangement with two sources of dietary proteins（cottonseed meal, CSM vs. soybean meal, SBM） and two levels of CP（12 % vs. 14 %, as-fed basis）. Seventy-two crossbred gilts（89.5 ± 0.9 kg） were allotted to one of four dietary treatments in a randomized complete block design for a period of 28 d. All diets were formulated to be isoenergetic and similar concentrations of standardized ileal digestible essential AA covering the nutrient requirements of pigs.Results： Growth, carcass characteristics and meat quality were not affected by dietary protein source nor crude protein level（P ＆gt; 0.10） except that average daily feed intake was increased by CSM diets（P = 0.03）. Gilts offered reduced protein diets had lower muscle p H45min（P 〈 0.05）. Neither dietary protein source nor crude protein level influenced N deposition. However, reduced protein diets decreased N intake, N excretion, and serum urea nitrogen content, whilst improved N efficiency（P 〈 0.01）. CSM diets increased N intake（P = 0.04）,but did not depress N efficiency. The concentrations of phenylalanine, tryptophan, cysteine and tyrosine（P 〈 0.05） of the longissimus muscle were decreased when gilts offered CSM diets, while muscle intracellular free valine concentration was increased（P = 0.03）. The gilts offered reduced protein diets had greater intracellular concentrations of free methionine, lysine, and total AA in muscle（P 〈 0.05）.Conclusion： These results suggest that CSM could replace SBM as a primary protein source in finishing pig diets in terms of performance, N efficiency, carcass characteristics, and meat quality, but decrease the concentrations of muscle specific AA. Furthermore, the reduced protein diet played an important role in increasing muscle intracellular concentrations of specific free amino acids（FAA）, and in reducing the relative ratios of specific FAA to lysine in longissimus dorsi muscle of pig, whose biological meaning needs further studies.

An empirical analysis on the impact of environmental regulations on pork trade:evidence from China

This paper uses the gravity model to examine the effect of environmental regulations on pork trade flows between different regions within China.We apply a linear programming tool to estimate pork trade flows from 2000 to 2008,and discuss the environmental acts on livestock pollution and income level to proxy environmental regulations.We use OLS regression and panel data with dummy variable in the cross-sectional GLS estimation.Our results indicate that the gap of environmental regulations between trade partners has a positive relationship with pork trade flows,and the difference in environmental regulations changes the traditional comparative advantage pattern to some extent.This paper provides convincing evidence for the pollution haven effect on livestock in China.