Evaluation and selection of yeasts as potential aroma enhancers for the production of dry-cured ham

Yeasts play a critical role in the flavor formation of dry-cured ham.In this study,41 yeast isolates from the dry-cured ham at different processing stages were evaluated for their technological properties.Debaryomyces hansenii was the most dominant yeast and has been detected at each phase of dry-cured ham,followed by Candida zeylanoides which was mainly detected in salting phase.Yarrowia bubula and Yarrowia alimentaria were found at the first two-phase of dry-cured ham.All isolates of yeast showed enzymatic activities against milk protein and tributyrin,while only 4 strains displayed proteolytic activity on meat protein.Yeast strains were grown in a meat model medium and volatile compounds were identified.The result showed that inoculated yeast strains could promote the production of volatiles and there were significant differences among strains.D.hansenii S25 showed the highest production of volatile compounds,followed by the strain C.zeylanoides C4.D.hansenii S25 was the highest producer of alcohols showing the highest production of benzeneethanol and 3-(methylthio)-1-propanol.Based on OAV and PLS analysis,D.hansenii S25 was strongly correlated with overall flavor and key volatile compounds of dry-cured ham,which could be selected as potential starter cultures.

Stability and transepithelial transport of oligopeptide(KRQKYD)with hepatocyte-protective activity from Jinhua ham in human intestinal Caco-2 monolayer cells

The study evaluated the stability of an oligopeptide(Lys-Arg-Gln-Lys-Tyr-Asp,KRQKYD)and its transport mechanism by simulating gastrointestinal digestion and a model of human intestinal Caco-2 monolayer cells in vitro.In this study,the effects of environmental factors(temperature,pH and NaCl concentration)and simulated gastrointestinal digestion on the stability of KRQKYD were evaluated by indicators of the levels of alanine transaminase(ALT),aspartate transaminase(AST)and malondialdehyde(MDA)in an alcoholinduced hepatocyte injury model.The results showed that KRQKYD still maintained satisfactory hepatocyteprotective activity after treatment with different temperatures(20-80℃),pH(3.0-9.0),NaCl concentration(1%-7%)and simulated gastrointestinal digestion,which indicated that KRQKYD showed good stability to environmental factors and simulated gastrointestinal digestion.Furthermore,the intact KRQKYD could be absorbed in a model of Caco-2 monolayer cells with a P_(app)value of(9.70±0.53)×10^(-7)cm/s.Pretreatment with an energy inhibitor(sodium azide),a competitive peptide transporter inhibitor(Gly-Pro)and a transcytosis inhibitor wortmannin did not decrease the level of transepithelial KRQKYD transport,indicating that the transport mechanism of KRQKYD was not associated with energy dependent,vector mediated and endocytosis.The tight junction disruptor cytochalasin D significantly increased the level of transepithelial KRQKYD transport(P<0.05),suggesting that intact KRQKYD was absorbed by paracellular transport.

Effect of the Inclusion of Chestnut in the Finishing Diet on Volatile Compounds of Dry-Cured Ham from Celta Pig Breed

The effect of the inclusion of chestnut in pigs ifnishing diet on volatile compounds of dry-cured Celta ham was studied. Twelve hams of each type （from three different pigs ifnishing diets：concentrate （CO）, mixed （MI） and chestnut （CH）） were used. Volatiles were extracted using a purge-and-trap method and analyzed by gas chromatography/mass spectrometry （GC/MS）. Thirty-nine volatile compounds were identified in dry-cured Celta ham samples. Most abundant volatiles in ham samples were aldehydes, which represented respectively, 53% （CO）, 51% （MI） and 46% （CH） of the total volatile composition. With the exception of 2-butenal, 2-methyl, all aldehydes were affected by feeding system. On the other hand, hydrocarbons n-alkanes were the second major group in the volatile proifle of dry-cured Celta hams and represented 28.9, 35.7 and 32.4%of the total volatile composition for CO, MI and CH groups, respectively. Ham samples from chestnut group showed a higher content of alcohols and this result could be related with the inclusion of chestnut in the ifnishing diet of pigs. Principal component analysis showed a good separation among groups. The discriminant analysis selected eight variables （butanoic acid, hexanal, octanal, nonenal （E）, decenal （E）, tetradecane, decane trimethyl and pyridine 2-methyl） and calculated two discriminating functions to predict if chestnut has been included in the ifnishing diet. Thus, it was possible to discriminate between groups fed with ifnishing diets containing chestnuts in their composition （mixed and chestnut group）.

Study Progress on Pests in Dry-cured Ham

Dry-cured ham can become infested with pests during the curing and ag-ing process, which not only damages the ham quality, but also causes economic loss. The advance of study on the effects of ham pests on the ham quality, the main species and distributions of ham pests in process of dry-cured ham were intro-duced in this article.

Charactering the spoilage mechanism of"three sticks"of Jinhua ham

To investigate the spoilage characteristics of Jinhua ham,sensory scores,volatile compounds,biogenic amine,physicochemical parameters and microbial counts were evaluated between normal and spoiled hams.The results showed that off-odors of spoiled hams were dominated by rancid,sour,sulfide and ammonia odors derived from these compounds including butanoic acid,methanethiol and dimethyl disulfide.Total content of biogenic amine in spoiled hams was significantly higher(more than 10-fold)compared with normal hams,and putrescine,cadaverine and histamine were the key components of biogenic amine of spoiled hams.Lower salt content,and higher moisture,TVB-N and thiobarbituric acid reactive substances(TBARS)values were observed in spoiled hams compared with normal hams.The populations of Enterobacteriaceae and Enterococcus of spoiled hams were obviously higher than that of normal hams.High moisture and low salt content caused the abnormal growth of Enterobacteriaceae and Enterococcus in spoiled hams,which contributed to the spoilage of Jinhua ham.

Reducing the Levels of Sodium, Saturated Animal Fat, and Nitrite in Dry-Cured Pork Meat Products: A Major Challenge

The curing of meat is a conservation technique widely used since ancient times to prolong shelf-life. It consists in exposing meat to a mixture of sodium chloride and nitrate/nitrite. Sodium chloride affects the flavor, texture and shelf-life of meat products. Animal fat mainly affects the flavor and texture, and nitrate and nitrite affect the color and flavor, and give cured meat products their typical aroma. Excessive intake of sodium has been linked to arterial hypertension and increased risk of cardiovascular diseases. Excessive intakes of saturated fatty acids in pork fat, and also of nitrite, have been identified as factors promoting some cancers. There is consequently an increasing consumer demand to reduce these ingredients in processed meat and so develop healthier cured meat products. This paper reviews how and to what extent sodium, animal fat rich in saturated fatty acids, and nitrite contents can be reduced in the production of dry-cured hams and dry-fermented sausages.

金华火腿中单增李斯特菌的风险评估

本研究以现代加工工艺条件下生产制作的金华火腿为研究对象,评估了因单增李斯特菌而引起食物中毒的风险。通过调查生猪肉中单增李斯特菌的初始污染率及污染水平,金华火腿生产及销售过程中影响单增李斯特菌生长的参数,如pH、水分活度、温度以及乳酸菌含量等,再结合单增李斯特菌生长模型,模拟其暴露水平,并评估了不同人群因食用即食金华火腿切片而患李斯特菌病的风险。结果显示:金华火腿零售时污染水平为-9.47~7.05 lg CFU/g(90%的置信区间);健康成年人食用即食金华火腿切片的平均患病概率小于10^(-15),易感人群的平均患病概率小于10^(-13)。食用即食金华火腿切片而患李斯特菌病的风险较低,金华火腿的现代加工工艺对于单增李斯特菌的控制水平可以与国际接轨。本研究首次定量模拟了金华火腿从生猪肉到腌制发酵至最终产品的全过程中单增李斯特菌的暴露情况,为发酵火腿中食源性致病菌的风险评估提供了参考模型。

金华火腿中生物活性肽的抗高血压活性研究

干腌火腿在发酵成熟期间蛋白质降解可产生丰富的肽类物质。为探究干腌火腿中多肽的抗高血压活性,从金华火腿中提取多肽,通过体外检测肾素的抑制活性和动物体内灌胃实验,探究火腿多肽潜在的血压调节能力。结果显示:金华火腿多肽具有显著的肾素抑制能力,当火腿多肽质量浓度为10 mg/mL时,其肾素抑制率为62.21%。在SHR大鼠体内,当火腿多肽质量浓度为20 mg/mL时,灌胃处理组大鼠的收缩压和舒张压比未灌胃处理组显著降低(P<0.05),其血压控制效果与5 mg/mL卡托普利相近,且持续时间更长。结论:金华火腿多肽具有良好的抗高血压活性,为进一步开展干腌火腿中生物活性肽的生理调节功能研究奠定了理论基础。

金华火腿中生物活性肽的血管紧张素转化酶调节功能及其分离纯化

为了探究干腌火腿中生物活性肽的降血压功能,以金华火腿为原料,提取其生物活性肽成分,并通过分离纯化鉴定具有血管紧张素转化酶(ACE)调节功能的生物活性肽。结果表明:经Sephadex G-25分子排阻色谱分离后,金华火腿生物活性肽可分为A、B、C、D共4个组分,其中组分C的ACE抑制活性最强,达到31.8%。将组分C经离子交换柱分离后,金华火腿多肽可分为C1、C2、C3、C4共4个组分,其中C2组分的ACE抑制活性显著高于其它组分,活性高达49.0%(P<0.05)。经Nano-LC-ESI-MS/MS鉴定得到C2中含有8条多肽,经ACE活性测定,序列IESDLERAEE在8条多肽中活性最强,ACE抑制活性达到59.1%。结论:金华火腿多肽具有良好的体外调节ACE活性的功能,为进一步开展其体内血压调节功能研究奠定了基础。

Inhibition of 3-hydroxy-3-methyl-glutaryl-coenzyme A reductase enzyme by dipeptides identified in dry-cured ham

High cholesterolemia is a key risk factor for the development of cardiovascular diseases,which are the main cause of mortality in developed countries.Most therapies are focused on the modulation of its biosynthesis through 3-hydroxy-3-methylglutaryl-coenzyme A reductase(HMG-CoAR)inhibitors.In this sense,food-derived bioactive peptides might act as promising health alternatives through their ability to interact with crucial enzymes involved in metabolic pathways,avoiding the adverse effects of synthetic drugs.Dry-cured ham has been widely described as an important source of naturally-generated bioactive peptides exerting ACEI-inhibitory activity,antioxidant activity,and anti-inflammatory activity between others.Based on these findings,the aim of this work was to assess,for the first time,the in vitro inhibitory activity of HMG-CoAR exerted by dipeptides generated during the manufacturing of dry-cured ham,previously described with relevant roles on other bioactivities.The in vitro inhibitory activity of the dipeptides was assessed by measuring the substrate consumption rate of the 3-hydroxy-3-methylglutaryl CoA reductase in their presence,with the following pertinent calculations.Further research was carried out to estimate the possible interactions of the most bioactive dipeptides with the enzyme by performing in silico analysis consisting of molecular docking approaches.Main findings showed DA,DD,EE,ES,and LL dipeptides as main HMG-CoAR inhibitors.Additionally,computational analysis indicated statin-like interactions of the dipeptides with HMG-CoAR.This study reveals,for the first time,the hypocholesterolemic potential of dry-cured ham-derived dipeptides and,at the same time,converges in the same vein as many reports that experimentally argue the cardiovascular benefits of dry-cured ham consumption due to its bioactive peptide content.

金华火腿发酵过程中微生物区系研究

本实验对金华火腿传统工艺发酵过程中微生物的数量及种类的变化进行了较详细深入的研究,检测了一年中金华火腿表面和深部微生物的数量变化规律、微生物的种类,并检测了发酵过程中水分、含盐量和pH值的动态变化。研究结果表明:金华火腿前期内部及表面微生物数量极少,晾晒时表面微生物数量增加,进入发酵室后内部微生物也很快增加达到106CFU/g,火腿成熟生香时期,内部微生物数量降至103CFU/g以下,优势菌相是葡萄球菌,其次是乳酸菌;内部酵母菌群中占优势的菌种主要有类筒假丝酵母、汉逊德巴利酵母、赛道威汉逊酵母、红酵母等,火腿表面的霉菌数量影响着内部的微生物。最初的阶段,二者一起增加,当霉菌的数量增加到一定水平时,抑制内部微生物的生长,使其数量减少;当霉菌数量减少时,内部微生物数量就会增加,发酵前期青霉菌占优势,主要有意大利青霉、简单青霉、灰绿青霉、柑桔青霉等。发酵后期,为曲霉菌占优势,主要包括萨氏曲霉、灰绿曲霉、黄柄曲霉等。金华火腿独特的风味与该地区特有的微生物区系有一定关系。

中西方干腌火腿风味成分比较及形成机理分析

风味对干腌火腿的质量十分重要 ,它与生产所用原料、生产工艺和参数密切相关。文中比较了金华火腿与欧洲几种著名火腿的风味成分 ,结果显示 ,中西方火腿的风味组成相似 ,醇、醛、酮、酯、含硫化合物、含氮化合物、烷、烯烃类物质是干腌火腿的共有成分 ,但各成分的含量在中西方火腿中存在明显差异 ,金华火腿中烷、烯烃含量最高 ,欧洲的几种火腿中醛类物质含量最高。文中同时分析了干腌火腿中各风味成分的特征和可能的形成机理。

金华火腿生产过程中脂质氧化及脂肪氧合酶变化特点研究

60只重量为6.2～6.9kg的原料腿按传统工艺加工金华火腿。分别于原料腿、盐后、晒后、成熟中期、成熟结束、后熟-1和后熟-2七个工艺点随机取5只腿的股二头肌为样品,分析TBA值、羰基值、共轭二烯值及脂肪氧合酶活力的变化,同时用响应曲面法研究加工过程中主要因子对脂肪氧合酶活力的影响。结果显示:TBA值在晒后达到最高,羰基值、共轭二烯值在盐后达到最高,在其它工艺步骤变化不明显。脂肪氧合酶活力从原料腿的8.00U/min·g蛋白上升到盐后的12.55U/min·g蛋白,之后不断下降,至后熟-2酶活为4.87U/min·g蛋白。温度、盐含量和硝酸盐含量是脂肪氧合酶活力的显著影响因子,且温度与盐和硝酸盐含量之间的交互作用对酶活产生显著影响。利用所得回归方程预测加工过程中的实际酶活在成熟中期达到最高,该酶活可解释20%左右的脂肪氧化水平,说明生产过程中脂肪氧合酶在脂肪氧化中不起主导作用,脂肪氧化以自动氧化为主。

采用同时蒸馏提取法分析不同加工时期金华火腿香味成分

腌制时间对金华火腿的风味与质量十分重要 ,文中采用同时蒸馏提取法比较了成熟火腿(发酵 1a)和生火腿 (未经发酵 )中的风味成分 ,分别得到了 77种和 62种化合物。结果显示 ,成熟火腿中的醛醇类物质 (3 4种 )尤其是烯醛和烯醇的种类和数量明显多于生火腿 (1 5种 )。同时 ,文中还讨论分析了各类组分及它们的风味贡献。

肌肉非蛋白氮和游离氨基酸在金华火腿加工过程中的变化

以60只浙江兰溪当地杂交猪后腿为原料,按传统工艺加工金华火腿,分析了股二头肌中非蛋白氮(Non-proteinnitrogen,NPN)和游离氨基酸(Freeaminoacids,FAA)浓度随加工时间而变化的规律。结果表明,肌肉中的NPN和FAA含量都随金华火腿加工进程逐渐升高;NPN在后熟期和晒腿期间升高速度最快,而FAA在成熟过程中升高最快,成品火腿的蛋白质降解指数在14～20之间;成品火腿中的FAA占NPN的70%以上,其中以Arg、Glu、Leu、Lys、Ala和Val等含量较高。FAA总含量比腌制前提高13.8倍,火腿中大部分FAA浓度为腌制前的10～20倍,其中增加比例较大的FAA有Lys、Asp、Ser、Tyr和Ile等。火腿中大部分游离氨基酸的浓度多倍于其感觉阈值,因此可能对火腿风味的形成有重要贡献。

金华火腿传统工艺过程挥发性风味物质的分析研究

通过对金华火腿传统工艺过程晒后、中温发酵、高温成熟、成熟下架样品中挥发性风味物质的分析测定,研究传统工艺过程中挥发性风味物质的发展规律,结果表明:共有78种挥发性风味物质检出,醛、羧酸、醇、酯、酮、脂肪族和芳香族碳氢化合物、含硫化合物、吡嗪是主要成分;工艺工程中醛和酮的相对含量随温度的升高而逐渐降低,羧酸、酯、吡嗪和含硫化合物的相对含量逐渐增加。金华火腿的高温成熟工艺使来自于美拉德反应的羧酸有显著增加,这是金华火腿与地中海地区干腌火腿最显著的区别,也是金华火腿具有其独特风味的主要原因。

不同等级金华火腿风味特点研究

随机取5条不同等级金华火腿的股二头肌为样品,利用固相微萃取(SPME)和GC/MS系统进行风味成分研究。结果发现,四级火腿中共检测到116种成分,在1～4级火腿中分别检出84、84、83和92种成分。这些成分可归类为烷烯烃、芳香烃、醇、醛、酮、酸、酯、萜烯类、含氧杂环化合物、含氮杂环化合物、含硫化合物、酰胺类物质和胺类物质。主成分分析显示,第一主成分主要由丁酸、3-甲基丁酸、苯酚、丙酸和丁酸乙酯组成,解释了不同等级金华火腿风味变化总方差的71.6%。第二主成分主要由:已醛、戊醛、2-甲基丁醛、3-甲基丁醛、1-辛烯-3-醇、丙酮和2,3-丁二醇组成,解释了不同等级火腿风味变化总方差的20.5%。根据风味成分产生途径,可以认为微生物是影响产品级别的第一要素。

金华火腿发酵成熟现代工艺及装备研究

跟踪金华火腿传统工艺方法，研究火腿发酵成熟现代工艺、研制工艺装备；发酵成熟现代工艺保持“低温脱水、中温发酵、高温成熟”传统工艺特色，按照“强化高温成熟、缩短工艺时间”原则正交试验，并优化现代工艺参数。结果表明：现代发酵成熟45～80d比传统工艺时间缩短55．5％～70％；火腿脱水率和工艺时间与温、湿度密切相关，80d火腿脱水率（29．43％±1．16％）已超过传统工艺水平，风味达到传统一级火腿水平，且火腿肉面没有霉菌斑点；现代发酵成熟工艺装备能实现温湿度和进风量等工作参数的自动控制，以火腿脱水率为目标函数进行的现代工艺回归优化结果与火腿感官品质评定结果有良好的一致性。

金华火腿传统加工过程中游离氨基酸和风味物质的变化及其相关性

通过对金华火腿传统加工过程中游离氨基酸 (FAA)和挥发性风味物质的分析 ,研究确定FAA的形成变化与温度条件、NaCl含量及其传统特色风味的相关性。结果表明 :加工过程中FAA与温度变化呈正相关 (R2 =0 91) ,高温成熟期温度升高使各种FAA和挥发性风味物质显著增加 ;成熟后期和后熟过程中 ,NaCl含量大幅度提高使蛋白质水解酶活性降低 ,其与FAA提高呈负相关 (R2 =0 98) ;特定比例的各种FAA产生金华火腿滋味和风味特性 ;来自于Maillard反应的挥发性风味物质与温度提高和FAA的显著增加呈正相关。

应用响应曲面法研究金华火腿生产过程中磷脂酶的变化

取 6 0条杂交猪后腿作原料按传统金华火腿生产工艺进行生产 ,分别在原料、盐后、晒后、成熟中期、成熟后期、后熟 (1)、后熟 (2 )工艺段随机取 5条腿的股二头肌作为样品测定潜在的磷脂酶活力 ,结果显示潜在的磷脂酶活力在生产过程中不断下降 ,原料中酶活为 3 0 5 ,到后熟 (1)酶活为 0 . 16 ,在后熟 (2 )已测不到酶活。利用响应曲面法研究磷脂酶在生产过程中实际酶活的变化情况并建立酶活变化数学模型 ,结果表明 ,温度和盐含量是影响磷脂酶活力的显著因子 ,通过模型预测 ,生产过程原料中的实际酶活为 0. 2 1,盐后为 0 . 13,之后酶活不断提高 ,到成熟后期达最高 ,为 0 . 4 1,之后再开始下降。