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.

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.

不同包装方式对冷鲜猪肉品质及假单胞菌生长的影响

【目的】探索冷鲜猪肉贮藏期间品质劣变情况及假单胞菌生长状况,为冷鲜肉贮藏期品质判断提供依据。【方法】采用真空、保鲜盒和热收缩膜3种方式包装冷鲜猪肉,检测4℃下贮藏第0、2、4、6、8天时肉样中假单胞菌菌落数及细菌菌落总数、感官指标、pH值、色差、水分活度值、TVB-N值的变化。【结果】相对于保鲜盒包装,真空包装和热收缩膜包装均能抑制冷鲜猪肉中菌落总数及假单胞菌菌落数增长;贮藏第4天,保鲜盒组肉样的菌落总数达到6.99 lg(CFU·g-1),真空包装组第6天才达到6.46 lg(CFU·g-1);贮藏第6天,保鲜盒组肉样中假单胞菌数最高达到7.58 lg(CFU·g-1),真空包装组和热收缩膜组分别达到了5.00 lg(CFU·g-1)、6.27 lg(CFU·g-1),显著低于保鲜盒组;贮藏期间,3组肉样的TVB-N值均呈现出上升的趋势,保鲜盒组第6天TVB-N值达到158.7 mg·kg-1,真空包装组和热收缩膜组在贮藏第8天时超过150 mg·kg-1;水分活度测定中,第4天真空包装组和热收缩膜包装组AW值大于保鲜盒包装组,贮藏第6天起,各组肉样的水分活度趋于稳定差异不显著(p>0.05);贮藏前2 d,保鲜盒组肉样L*值较高,而贮藏后期,热收缩膜组和真空包装组能维持较高的L*值;保鲜盒组肉样的a*值均整体先上升后下降趋势,热收缩膜组和真空包装组呈下降趋势,真空包装能较好延缓a*值下降;第8天,保鲜盒组肉样pH值最高,已接近7.0,热收缩膜组与真空包装组肉样pH值差异不显著(p>0.05),且均低于6。在反映肉质新鲜度上,猪肉的感官与a*值、pH值、AW值、TVB-N值、假单胞菌数相关性比较大。【结论】真空包装可以能抑制冷鲜猪肉细菌的增长、延缓TVB-N值的增长,在短期内能更好维护冷鲜猪肉的品质。

气相色谱法测定猪肉脂肪的脂肪酸方法优化

比较在3种程序升温条件下的37种混合脂肪酸甲酯标准品的谱图,确定最适合分析猪肉脂肪的脂肪酸的程序升温条件;比较索氏提取法、酸水解辅助提取法、有机溶剂浸提法、超声波辅助提取法提取猪肉脂肪,确定最佳猪肉脂肪提取方法;比较碱法甲酯化、酸法甲酯化、碱皂化酸酯化法、碱皂化三氟化硼酯化法对猪肉脂肪的脂肪酸进行甲酯化处理,确定最佳甲酯化方法。结果表明:最适合分析猪肉脂肪的脂肪酸的程序升温条件为在初始温度140℃条件下保持5 min,以5℃/min升温至220℃保持15 min;最佳提取方法是超声波辅助提取法;最佳甲酯化方法是碱法甲酯化。

冰温贮藏期间淀粉添加对水滑肉品质的影响

水滑肉是中国传统的菜肴,具有爽滑细嫩、鲜香无比的特点。为了探究水滑肉淀粉外壳变化对水滑肉品质的影响,以质构、剪切力、水分含量、回生程度、淀粉热力学特性等为评价指标,研究了在冰温贮藏期间水滑肉品质的变化情况。结果表明:与水煮肉进行对照,在冰温贮藏期间淀粉的添加显著抑制了水滑肉的硬度、咀嚼性及剪切力的增加;水滑肉在贮藏期品质指标劣化,但感官得分优于对照组。在冰温贮藏期间,水滑肉外壳的水分含量、糊化焓值及1047 cm^(-1)和1022 cm^(-1)处的峰强度比值(R_(1047/1022))依次增加了7.29%、327.42%、5.17%,增长幅度均低于淀粉组(P<0.05);肉的存在显著减缓了水滑肉淀粉外壳的回生(P<0.05)。在冰温贮藏条件下,淀粉外壳的回生与水滑肉的质构指标呈现显著正相关(P<0.05),即淀粉外壳的回生会劣化水滑肉的硬度、咀嚼性和剪切力。冰温条件下,肉中水分向淀粉外壳转移可能会延缓淀粉外壳的回生,从而延缓其品质劣化。研究结果可为水滑肉预制菜肴品质研究提供参考。

基于模糊数学评价红菌豆渣对猪肉丸品质的影响

将红菌豆渣添加到猪肉糜中,探讨不同红菌豆渣添加量对猪肉丸色泽、持水性、损失率、流变特性和质构特性的影响,结合模糊数学感官评价法对其作综合评价。结果表明:红菌豆渣猪肉丸的持水率、咀嚼性、硬度、胶着性和储能模量G`值随红菌豆渣添加量的增加而上升,白度值降低,蒸煮损失率先降后略微上升,弹性和回复性变化不明显。当红菌豆渣添加质量分数12%时,产品出品率较高,口感品质好,感官综合评分最高。添加红菌豆渣可以改善猪肉丸的品质,为猪肉丸开发提供新思路。

添加洛神花粉末对苏姜猪肉发酵香肠品质的影响

为研究洛神花粉末在苏姜猪肉发酵香肠中的应用,探讨添加不同量(0.0%、0.5%、1.0%、1.5%、2.0%)的洛神花粉末对其理化品质与加工特性(色差、质构、硫代巴比妥酸值、水分含量、蒸煮损失率、p H值)及感官品质的影响。结果表明,添加洛神花粉末可以起到一定的护色抗氧化作用,随着洛神花粉末添加量的增加,苏姜猪肉发酵香肠的蒸煮损失率和pH值下降幅度逐渐减小,色泽、总体可接受性得分、硬度、弹性、粘聚性、咀嚼性均呈先增大后减小的趋势;洛神花粉末处理组的硫代巴比妥酸值均低于对照组,香肠的水分含量均高于对照组,综合成本及效果考虑,选择洛神花粉末最佳添加量为1.5%。因此,适量添加洛神花粉末能够改善苏姜猪肉发酵香肠的食用品质。

鸡滑液囊支原体PCR检测方法的建立

目前鸡滑液囊支原体(MS)在养鸡生产中时有发生,是一种顽固性、条件性疾病。在多种致病因素的作用易发,给养鸡生产造成了经济损失;为了快速诊断MS,特别是致病性鸡滑液囊支原体,本研究针对MS的VlhA基因设计特异性引物,通过优化反应条件,进行灵敏性试验、特异性试验和重复性试验,建立快速高效检测MS的PCR方法。试验结果表明:该检测技术具有较好的灵敏性、特异性强且CV<3%,具有很好的符合性。

甜橙精油-北五味子提取物复合膜的制备及其在冷鲜猪肉保鲜中的应用

为提高冷鲜猪肉的保鲜能力并延长其货架期,以甜橙精油(orange essential oil,OEO)、北五味子提取物(Schisandra chinensis extract,SCE)为活性成分,羧甲基纤维素钠(sodium carboxymethyl cellulose,CMC-Na)为成膜基质,采用流延法制备复合膜。利用单因素试验和正交试验优选复合膜的配制方法,以色泽、汁液流失率、pH值、感官评价、总挥发性盐基氮含量和菌落总数探究OEO-SCE复合膜对冷鲜猪肉保鲜能力的影响。结果表明,当CMC-Na添加量为1.0 g/100 mL、SCE添加量为0.9 g/100 mL、OEO添加量为0.2%(V/V)时,制备的复合膜综合性能最佳:断裂伸长率为(63.860±0.120)%,抗拉强度为(8.800±0.049)MPa,水蒸气透过率为(2.360±0.070)g·mm/(m^(2)·h·kPa)。用该膜包裹冷鲜猪肉进行保鲜,与未包膜组相比,色泽及感官评分有明显提升,可以有效降低贮藏期内的总挥发性盐基氮含量、pH值、汁液流失率及菌落总数,贮藏期从6 d延长至8 d。由此可见,OEO-SCE复合膜可以抑制冷鲜猪肉在贮藏期内的腐败变质并延长其贮藏期。

基于电子鼻和GC-MS评价腌制时间对猪肉脯品质的影响

为研究肉脯加工中腌制时间对猪肉脯品质的影响,利用气质联用(GC-MS)、电子鼻、质构仪等对不同腌制时间制备的肉脯样品的感官指标、挥发性风味成分等进行检测,并利用模糊数学评定法、主成分分析法(PCA)对感官指标和风味物质进行分析。结果表明,低温(4℃)条件下,腌制时间对猪肉脯的品质具有明显的影响,原料肉腌制8 h后,经过65℃烘烤2.5 h、180℃高温烤制3.5 min制备的猪肉脯硬度适中,色泽诱人,香味浓郁,感官品质最好,且样品中酮类、醛类和杂环类风味物质含量较高。

响应曲面法结合模糊感官评定在细叶韭风味香肠研制中的应用

以猪肉为主要原料,添加细叶韭、食盐、五香粉和土豆淀粉等制成风味独特的细叶韭风味香肠,旨在制作一款健康、美味的香肠产品。以细叶韭用量、土豆淀粉用量、五香粉用量、食盐用量为单因素,以感官评分为指标,进行模糊感官评定和响应面试验设计,最终得出最佳配比:细叶韭用量为2.161%,五香粉用量为2.304%,土豆淀粉用量为20.489%;采用最佳配比制作的细叶韭风味香肠的感官评分最高,为89.744分。在最佳配比方案下生产出的细叶韭风味香肠切片表面平整,组织紧密,口感细腻,有韧性,无粉状感,有细叶韭特有的香味,表面颜色明亮。

静电场对熟猪肉冷冻过程影响的研究

为了研究外加静电场对食品冷冻过程的影响,通过流体力学计算软件CFD模拟静电场下熟猪肉中心温度由5℃降低至-10℃的冷冻过程,同时试验测量了汁液损失率和电导率。结果表明:实验结果与仿真结果吻合,外加静电场会提高相变温度,减少相变潜热的释放,缩短相变时间。外加电场降低了汁液损失率和电导率,可以改善肉类的品质,有利于保证肉类细胞的完整性。

发酵泔水生产育肥猪用生物饲料的研究与应用

以泔水为主要原料,采用桶式固态厌氧发酵生产育肥猪用生物饲料,成功解决了泔水营养物的储存、保质和安全卫生等关键问题。经过5 d发酵,物料的pH低于3.8,保质期可以达到20 d左右,大肠杆菌的残留量低于3.0 CFU/g,完全符合饲料的卫生安全要求。用碳酸钠调节发酵泔水的pH至4.5~5.0,然后与常规配合饲料以2∶3的比例均匀混合,育肥猪的生长速度和饲料转化效率都优于对照的配合饲料,猪肉品质也完全符合国家安全卫生要求。与传统处理工艺相比,不仅改善了养殖场的卫生环境、降低了劳动强度,而且还有很好的经济效益。

猪肉收储政策对我国生猪市场价格波动的影响

猪肉收储政策作为民生商品储备体系的重要组成部分,是做好生猪和猪肉市场保供稳价工作的重要政策工具,对缓解我国生猪市场价格波动具有重要意义。文章基于我国2007—2022年30个省份数据,构建双重差分模型评估自2009年颁布《防止生猪价格过度下跌调控预案(暂行)》及之后一系列猪肉收储政策对我国生猪市场价格波动的影响。结果表明,在控制其他因素后,猪肉收储政策对我国生猪市场价格波动具有显著抑制作用,其作用程度约为0.041;猪肉收储政策对我国生猪市场价格波动的影响具有明显区域异质性,在东部地区该政策效果最强。文章主要考察了猪肉收储政策对生猪市场价格波动的影响,以期为合理控制生猪市场价格提供参考。

新冠肺炎疫情对猪肉价格的影响——基于多期DID模型的考察

以新冠肺炎疫情的突然爆发作为切入点,将疫情爆发地区和未爆发地区视为一次部分省份冲击猪肉价格的准自然试验,采用多期DID模型考察新冠肺炎疫情对猪肉价格的影响,并构建DID-QR模型检验新冠肺炎疫情对猪肉价格的处理效应在不同初始价格增长率和不同制度环境下的表现形式。结果表明,新冠肺炎疫情的爆发导致猪肉价格出现大幅度上涨,平均涨幅约为10%;受疫情影响的猪肉价格呈现上涨、平稳、再上涨、再平稳、下跌的变化趋势,在考察期内仅次月、3月、6月和7月涨幅明显,10月开始出现明显的下降趋势。新冠肺炎疫情的爆发拉大了不同地区猪肉价格水平的差距,且疫情对价格的提升作用在初始农业经济发展水平较低地区和初始经济发展水平较高地区较为明显。为此,政府应根据猪肉价格在不同条件下的异质性,有的放矢的采取平抑措施,并通过建立各产业链环节主体衔接机制和完善公共信息平台的方式,减弱猪肉市场受突发性外部冲击的影响。