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.

抗冻蛋白对冷冻猪肉品质的影响

研究抗冻蛋白(antifreeze proteins,AFP)对猪肉冷冻过程中品质变化的影响。以商业抗冻剂海藻糖(4 mg/m L)的抗冻效果为参考,以未添加AFP组为对照组,研究不同添加量(0.05、0.1、0.2、0.3 mg/mL)AFP对冷冻猪肉品质、肌原纤维蛋白理化性质、微观结构和水分分布的影响。结果表明:AFP可以减少冷冻猪肉的水分损失,有利于维持猪肉色泽和微观结构;在冷冻贮藏过程中,0.3 mg/mL AFP组猪肉的蒸煮损失、解冻损失及色泽的保护效果最好,其次是0.2 mg/mL AFP组和4 mg/mL海藻糖组;0.2、0.3 mg/mL AFP组剪切力和肌原纤维蛋白总巯基含量显著高于未添加AFP组(P<0.05);核磁共振成像验证了AFP的渗入降低了猪肉中结合水和不易流动水损失;扫描电子显微镜结果显示,0.2 mg/mL AFP使猪肉肌纤维排列整齐,更加紧凑和致密。总体而言,添加AFP对改善冷冻猪肉品质有积极作用,是一种潜在的安全、高效冷冻保护方法。

日粮中添加枯草芽孢杆菌对高氧气调包装猪肉蛋白质和脂质氧化的影响

为探究日粮添加枯草芽孢杆菌对猪肉抗氧化能力以及高氧气调包装贮藏期间猪肉肉色、蛋白质氧化、脂质氧化和感官品质的影响,选取对照组(只饲喂基础日粮)和处理组(基础日粮添加枯草芽孢杆菌)的三元杂交(杜洛克×长白×大约克)猪各6只,屠宰后取背最长肌测定抗氧化酶活性,其余背最长肌样品进行高氧气调包装,4℃冷库贮藏,分别在0、5、10、15、20?d测定肉色、丙二醛(malondialdehyde,MDA)、羰基和巯基含量,并进行感官评价。结果表明:与对照组相比,处理组能够显著提高超氧化物歧化酶、谷胱甘肽过氧化物酶和过氧化氢酶活性(P<0.05),增强猪肉的抗氧化能力;日粮中添加枯草芽孢杆菌可以显著改善高氧气调包装猪肉的肉色(P<0.05);在低温贮藏期间,处理组能够显著降低MDA含量(P<0.05),抑制高氧气调包装猪肉的脂肪氧化;日粮中添加枯草芽孢杆菌能够显著抑制高氧气调包装猪肉的蛋白质氧化、羰基的生成和巯基损失(P<0.05),同时显著提高猪肉打开包装前的颜色和打开包装后的总体喜爱度评分(P<0.05)。综上,在日粮中添加枯草芽孢杆菌可提高猪肉的抗氧化能力、改善猪肉在高氧气调包装中的肉色、抑制蛋白质和脂质氧化,提高猪肉的食用品质。

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.

Pork Meat Quality of Preto Alentejano and Commercial Largewhite Landrace Cross

This work aimed to evaluate the physical-chemical characteristics of pork from a local breed （Portuguese black pork called Preto Alentejano） and a commercial breed. Sixteen animals were used, 4 females and 4 males from each breed. Animals had 80-100 kg of live weight. The longissimus muscle between the 5th thoracic vertebra and the 10th lumbar vertebra was used in the analysis. Samples were analysed for protein, fat, pigments, ashes, dry mater, water-holding capacity, and texture. Results of fat and pigments contents indicate signiifcant （P〈0.05 and P〈0.01） differences for all treatments. For protein, ashes, dry mater, water-holding capacity and texture, no signiifcant differences were found for sex. In the analysis of fatty acids composition, ten were detected, being the main ones C16：0, C18：0, C16：1, C18：1, C18：2. There was a predominance of monounsaturated fatty acids （MUFA）, followed by saturated （SFA） and polyunsaturated （PUFA）. Differences were signiifcant for sex （P〈0.01） and breed （P〈0.01）. Preto Alentejano breed and females presented the higher percentages of SFA （P〈0.01） and MUFA （P〈0.001） fatty acids. Differences between breeds might be due to breed production system and feed differences.

Interactions between pork consumption,CagA status and IL-1B-31 genotypes in gastric cancer

AIM: To explore potential interactions among Helicobacter pylori (H. pylori), CagA status, interleukin (IL)-1B-31 genotypes, and non-cardiac gastric cancer (GC) risk.

Prediction of Fresh Pork Quality using Hyperspectral Scattering Imaging(HSI) Technique

In this study, fresh pork tenderness, drip-loss, pH value and color parameters （ CIE, a ＊ , b ＊ and L ＊ values） were simultaneously predicted using hyperspectral scattering imaging （HSI） technique. The hyperspectral scattering images of dO fresh pork samples were collected at the wavelength of 400 -I 100 nm, and the scattering profiles were fitted via Lorontzian distribution （ LD ） function to give three parameters a （ asymptotic value ）, b （peak value ） and c （ full width at b/2）. Stepwise discrimination was performed to determine the optimal wavelengths combinations. The LD parameters combinations （a, b and c） of optimal wavelengths were used to establish multi-linear regression （MLR） models to predict the pork attributes. The models were able to predict pork with high correlation coefficients of 0.92 for drip-loss, 0.94, 0.92 and 0.98 respectively for color parameters （ a ＊ , b＊ and L ＊ ）, and for tenderness and pH value the models gave the correlation coefficients of 0.69 and 0.76, respectively. These results showed that the hyperspectral scattering technique was capable of predicting quality parameters of perk. The study provides an efficient means for rapid and nondestructive determination of pork quality simultaneously.

The Inhibiting Effect of Bone Protein Hydrolysates on Lipid Oxidation in Pork Patties

Bone protein hydrolysates were prepared by limited alcalase hydrolysis （5 h）. The hydrolysates were formulated （0-3%, w/w） into pork patties to determine the antioxidant efficacy. 0.02% BHA （butylated hydroxyanisole） was used as a positive control. Lipid oxidation in patties during storage was analyzed by measuring the TBARS and protein carbonyl content. The results showed that bone protein hydrolysates possessed significant antioxidant activity, and antioxidant activity increased with the increasing hydrolysates concentration. Sensory evaluation indicated that bone protein hydrolysates improved the color and decreased lipid oxidation flavor of pork patties. The 2% bone hydrolysates possessed the highest antioxidant activity and better sensory quality, and its effect was closed to 0.02% BHA.

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.

Inhibition of Heterocyclic Aromatic Amines in Pork Chops Using Complex Marinades with Natural Antioxidants

Five marinades were developed using natural antioxidants. Based on a consumer test of the appearance, three marinades were chosen for further investigation: an oregano, an acerola and a Dijon marinade, the Dijon marinade containing acerola, sumac and oregano. A barbecue and a sumac marinade were not included in the further study. In a home use test, consumers barbecued pork chops with the three marinades. Most of the consumers preferred the oregano and the Dijon marinade, while the acerola marinade was less liked. After controlled cooking using both direct and indirect heat to a core temperature of 65°C and 80°C, the content of the heterocyclic aromatic amines (HCA) PhiP, MeIQx, DiMeIQx, Harman and Norharman was analysed. All of the marinades reduced the content of MeIQx and DiMeIQx, although only with indirect heat, while PhiP was reduced using both grilling methods. Surprisingly, in particular the content of Harman—and to a lesser extent Norhaman—was very high in the Dijon-marinated chops. The results demonstrated that it was possible to develop well-liked marinades that can reduce the formation of selected HCAs.

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.

THE INVISCID AND NON-RESISTIVE LIMIT IN THE CAUCHY PROBLEM FOR 3-D NONHOMOGENEOUS INCOMPRESSIBLE MAGNETO-HYDRODYNAMICS

In this paper,the inviscid and non-resistive limit is justified for the local-in-time solutions to the equations of nonhomogeneous incompressible magneto-hydrodynamics （MHD）in R3.We prove that as the viscosity and resistivity go to zero,the solution of the Cauchy problem for the nonhomogeneous incompressible MHD system converges to the solution of the ideal MHD system.The convergence rate is also obtained simultaneously.

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.

Analysis of Pork Price Cycle and Its Relationship with CPI

Since the second half of 2015,the price of pork has come into a new round of rising cycle,especially from January to April of 2016,pork prices continued rising.Excessive rising of pork prices sparks people’s concern about CPI rising.It is of practical significance to discussing the fluctuation cycle of pork price and its relationship with CPI.In this context,we do empirical research on pork cycle and price fluctuations with CPI relationships.From January 2000 to March 2016,based on a total of 195 samples,using Eviews6.0 metrology software,we draw the following conclusions:fluctuations in the price of pork did Granger cause CPI,the impact of pork price fluctuations on the CPI was significant and the effect significantly was enhanced after certain lag;CPI did not Granger cause pork price fluctuations,CPI had no significant effect on the price of pork;pork price was affected by its own large contribution,and there was a certain time lag effect of the impact;CPI had a positive impact on itself,for its contribution is relatively large.Finally we put forward relative strategies.

Maillard reaction in Chinese household-prepared stewed pork balls with brown sauce:potentially risky and volatile products

The stewed pork balls with brown sauce(SPB-BS)in China is well known for its delicacy and preferred by consumers.Maillard reaction(MR)is widespread in SPB-BS due to the use of sugar,meat and sauce in the thermal process.However,there is a lack of research on its risk and flavor by MR.By solid phase extraction combined with HPLC-MS,4 kinds of harmful compounds including acrylamide(AA),heterocyclic aromatic amines(HAAs),4-methylimidazole(4-MEI)and furan were analyzed in SPB-BS and their amounts ranged 0.05–0.50 mg/kg.The quantitative formula was proposed to evaluate the risk value of the SPB-BS,after taking into account the content,acceptable daily intake(ADI)and carcinogenicity of each compound.The risk values were in range of 0.57–37.93,suggesting that the risk caused by MR in SPB-BS was low.By head space-solid phase microextraction combined with GC-MS,57 volatile compounds in SPB-BS were identified with the dominant contribution of alcohols,aldehydes,acids and esters.Based on the structures of these compounds and the composition of SPB-BS,lipid oxidation and MR are inferred to be responsible for the formation of the harmful and volatile compounds.In addition,the added sauces and oil provides the main precursors to form the harmful and volatile compounds in SPB-BS,so it is necessary to point out a balance between them in the further study.

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.