氧化及不同离子强度下猪肉肌原纤维蛋白结合风味物质的研究

文章研究了猪肉肌原纤维蛋白氧化导致其结构功能发生改变及氧化和不同离子条件下其结合风味物质的能力变化。实验选择了2-甲基丁醛、3-甲基丁醛、己醛、辛醛、壬醛等5种风味物质,利用顶空结合气相色谱观察肌原纤维蛋白结合风味物质的能力。结果表明：经氧化的肌原纤维蛋白二级结构及功能发生了变化。氧化处理的肌原纤维蛋白对2-甲基丁醛和壬醛有促释放的作用,对3-甲基丁醛、己醛和辛醛的作用呈2,2-偶氮二(2-甲基丙基咪)二盐酸盐(AAPH)浓度依赖性。Na+的添加促进了氧化蛋白对己醛的释放,而Na⁺、K⁺、Ca²⁺和Mg²⁺的添加促进了氧化蛋白对2-甲基丁醛、3-甲基丁醛、辛醛和壬醛的吸收。因此,在肉及肉制品的加工贮藏过程,氧化易造成蛋白结构和功能的改变,进而影响蛋白质结合风味物质的能力;另外,氯化钠在肉制品中被其它盐部分替代造成蛋白质所处的离子环境发生改变,导致蛋白质结合风味物质的能力改变,从而使肉制品风味发生改变。     

Distribution of volatile compounds in lean and subcutaneous fat tissues during processing of dry fermented sausages

The distribution of volatile compound among lean and fat tissues during processing of dry fermented sausages manufactured with either nitrite or nitrate was studied. Twelve volatile compounds were quantified by multiple headspace solid-phase microextraction (multiple HS-SPME) in combination with gas chromatography and mass selective detector (GC–MS) in the lean and fat tissues. The lean tissue contained the highest amount of volatile compounds derived from the lipid oxidation process (heptanal, octanal, nonanal, 1-octen-3-ol, 2-pentanone and 2-heptanone), amino acid degradation reactions (2 and 3-methylbutanal) and esterase activity (ethyl 3-methylbutanoate and ethyl hexanoate). However, the compounds pentanal and hexanal showed similar concentration in both tissues. Few differences were observed in the concentration of volatile compounds due to curing agents throughout the ripening stages although they disappeared after vacuum storage. In conclusion, the main tissue contributing to the flavour development in sausages is the intramuscular fat and the protein fraction. However, the fat tissue contributes to flavour perception due to the solubilization of volatile compounds in it.     

Generation of flavour compounds in fermented sausages-the influence of curing ingredients, Staphylococcus starter culture and ripening time

The volatile profiles of fermented sausages made with either Staphylococcus xylosus or Staphylococcus carnosus starter cultures were studied with regard to the influence of salt concentration, ripening time and three different combinations of curing ingredients-nitrate, nitrite or nitrite/ascorbate. Emphasis was laid on volatile compounds originating from degradation of branched-chain amino acids. Volatile compounds were collected using dynamic headspace sampling and were identified by gas chromatography/mass spectrometry (GC/MS). Development in water activity, water loss and pH was monitored throughout maturation. Curing salts had a pronounced effect on the level of volatile compounds. In particular, curing with nitrate instead of nitrite resulted in a striking difference. Generally, nitrate increased the level of volatile compounds compared to nitrite, whereas ascorbate had only a small influence. The concentration level of NaCl had a considerable effect on the amount of volatile compounds but the effect was highly related to the ripening stage. Most compounds, but not all, increased in concentration as ripening proceeded. Major differences in the development of volatile compounds were observed depending on whether S. xylosus or S. carnosus were used as starter culture. In particular the effects of nitrate was much more predominant in the sausages made with S. carnosus than S.xylosus.     

亚硝酸钠对干腌肉块脂肪酸氧化源醛类挥发性化合物的影响

研究亚硝酸钠对干腌肉块脂肪氧化源醛类挥发性化合物的影响,结果表明添加亚硝酸钠的干腌肉块脂肪氧化源的醛类物质含量和其中的己醛含量低于无硝腌制干腌肉块。通过Fe2+-亚油酸模型的挥发性化合物检测结果表明亚硝酸钠对抑制亚油酸的氧化起到显著作用,说明亚硝酸钠可以通过螯合金属离子而发挥抗氧化作用。     

Effect of ionic strength of different salts on the binding of volatile compounds to porcine soluble protein extracts in model systems

The effect of different salts on the binding ability of porcine soluble protein extracts was studied using solid-phase microextraction (SPME) and GC/MS analysis. Previously, the effect of the different salts (NaCl, KCl, MgCl₂ and CaCl₂) on the volatile compound headspace concentration in water solution was determined. KCl produced a similar salting out effect as NaCl increasing the volatile compound headspace concentration up to 5–10 times. However, MgCl₂ and CaCl₂ did not produce a salting out effect on the volatile compounds studied. Finally, NaCl and KCl produced a significant reduction on the binding ability of sarcoplasmic protein extracts to branched aldehydes, hexanal and methional while no effect was produced on octanal and 2-pentanone. On the other hand, the effect of MgCl₂ and CaCl₂ was much lower even at high ionic strength, except for the branched aldehydes where the presence of MgCl₂ at 1.0 ionic strength produced the complete liberation of the volatile compound bound. Consequently, the partial NaCl substitution in meat products by other salts must be considered not only due to their salting out effect but also due to their effect on protein binding ability.     

顶空吹扫捕集-气相色谱-质谱法分离鉴定强化高温火腿中的挥发性风味物质

采用顶空吹扫捕集法提取、气相色谱-质谱联用技术分离鉴定强化高温加工过程中腌制结束、成熟中 期、成熟结束、后熟中期、后熟结束期火腿中的挥发性风味化合物,并研究新工艺过程中挥发性风味物质的发展 规律,并采用相对气味活度值判定其特征性风味化合物。结果表明：挥发性风味成分种类与传统工艺相似,但相 对含量有所不同,尤其是酸类、酯类;同时新检测出茚、二苯并呋喃、2,3-二甲基萘等化合物;相对气味活度法 判定其主体挥发性成分为3-甲基丁醛、二甲基二硫化合物、2-壬烯醛、2-辛烯醛、辛醛、壬醛、庚醛、戊醛、己 醛、1-辛烯-3-醇、1-庚醇11 种。     

基于顶空气相离子迁移色谱对鸭肉腥味特征物质的鉴定

为探究鸭肉在60℃和90℃两种温度煮制后的腥味特征物质，以鸭胸、鸭腿及鸭锁骨为研究对象，基于顶空气相色谱-离子迁移谱（headspace-gas chromatography-ion mobility spectrometry,HS-GC-IMS）技术结合嗅闻评价、电子鼻测定及风味物质评价分析确定鸭肉腥味特征物质。结果表明，在两种温度处理下，90℃处理的各部位鸭肉腥味重于60℃，且不同处理组鸭肉样品的腥味特征具有一定差异，电子鼻分析结果也验证了不同处理组鸭肉样品气味存在一定差异。同时基于HS-GC-IMS技术共鉴定出61种挥发性物质，鉴定发现不同处理组鸭肉样本中挥发性物质种类基本一致，而相对含量存在部分差异。结合嗅闻评价结果与风味物质的相对气味活性值共筛选出12种腥味特征物质，分别为壬醛、辛醛、庚醛、癸醛、戊醛、己醛、(E)-2-辛烯醛、(E)-2-庚烯醛、2-甲基丁醛、3-甲基丁醛、2-庚酮和1-辛烯-3-醇，这些物质之间发生的交互作用对鸭肉腥味形成具有重要贡献，并且因种类和含量的不同使得两种温度处理的鸭肉样品各具特征腥味。     

Proteolytic and lipolytic modifications during the manufacture of dry-cured lacón,a Spanish traditional meat product: Effect of some additives

The extractability of sarcoplasmic and myofibrillar proteins, the myofibrillar proteins and their degradation products, classical nitrogen fractions, free amino acids, acidity of the fat, and free fatty acids were determined throughout the manufacturing process of dry-cured lacón, a traditional dry-salted and ripened meat product made in the northwest of Spain from the foreleg of the pig, following a similar technological process to that of dry-cured ham. The effect of the use of additives (glucose, sodium nitrite, sodium nitrate, sodium ascorbate and sodium citrate) on the proteolytic and lipolytic changes was also studied.     

Effect of irradiation on colour and lipid oxidation of dry-cured hams from free-range reared and intensively reared pigs

The effect of irradiation dose (0, 5 and 10 kGy) of vacuum-packaged Iberian dry-cured ham slices from pigs fed on concentrate (CON) or free-range reared (FRG) was studied in relation to TBA-RS, hexanal content and instrumental colour changes. TBA-RS values increased after irradiation in the two sets of hams and the increase was dose-dependent. FRG samples showed higher TBA-RS values than CON samples in all treatments, although differences in the rate of formation of thiobarbituric acid-reactive substances were different in the two types of hams, being higher in CON samples than in FRG ones. Irradiation of dry-cured ham slices significantly increased hexanal contents in both sets of hams. Irradiation produced statistically significant increases in vacuum-packed dry-cured ham slices lightness (L^⁎-value), yellowness (b^⁎-value) and chroma (C^⁎-value). Irradiation resulted in significantly lower hue angle (h°) values and higher a^⁎-values in both sets of hams indicating a redder colour of irradiated samples than non-irradiated, and these changes were greater in FRG samples than in CON samples. Differences in composition characteristics of raw material could play an important role in the irradiation-induced changes on colour and lipid oxidation of vacuum-packaged dry-cured ham slices.Industrial relevanceIberian ham is dry-cured meat product with a high sensory quality due to pig fattening feature and the characteristics of its processing. Both factors lead to a product with characteristic cured red colour of the lean, an intense, characteristic and pleasant flavour, unique in dry-cured hams, derived from intense lipid oxidative phenomena. New commercialization formats of dry-cured Iberian hams include vacuum-packed sliced ham. Although the low Aw, NaCl and nitrite/nitrate contents make dry-cured ham not adequate for the growth of pathogens and spoilage microorganisms (cocci gram+ and yeast), those may be present on the surface of whole hams and reach the sliced product during the final boning, slicing and packaging operations even with the observation of strict hygienic procedures despite the implementation of modern technologies and HACCP systems, constituting a permanent risk of contamination. Dry-cured Iberian ham, as a result of its chemical characteristics, is a product with a long shelf-life at refrigeration temperature, however the risk of spoilage or pathogen growth could increase in the case of temperature abuse for a long stored period. Finally, due to health concerns, salting and curing process of dry-cured Iberian hams tend to a reduction in levels of NaCl and nitrite used. That could increase the risk associated to microorganism presence in dry-cured sliced hams. The use of irradiation could minimizes this risk, however irradiation could have important effects on overall quality of dry-cured Iberian products in which colour and extent of lipid oxidation and lipid oxidation-derived volatile compounds play an important role in consumer acceptation of the product.     

Effect of pork meat proteins on the binding of volatile compounds

The binding ability of pork meat proteins (sarcoplasmic, myofibrillar and isolated actin and actomyosin) was determined by measuring the relative headspace concentration of the volatile compounds in the presence of each protein (expressed as percentages of the free volatiles relative to a standard solution without protein) using solid-phase microextraction (SPME) and gas chromatography analysis. The sarcoplasmic homogenates bound higher quantities of the volatile compounds assayed (3-methylbutanal, 2-methylbutanal, 2-pentanone, hexanal, methional and octanal) than myofibrillar homogenates. The addition of salts also affected the binding ability of sarcoplasmic and myofibrillar proteins. Actomyosin was able to bind all the assayed volatile compounds although the binding depended on protein concentration and conformation, and it was highly affected by frozen storage. On the other hand, G-actin was unable to bind any of the assayed volatile compounds although the polymerized form (F-actin) bound higher quantities of the volatile compounds.     

基于电子鼻和气相色谱-质谱联用技术分析不同贮藏时间羊肉火腿香气成分

采用电子鼻和顶空固相微萃取-气相色谱-质谱联用技术,对贮藏0、30、60、90、120、150?d和180?d的干腌羊肉火腿挥发性香气成分进行分析和检测。电子鼻测定结果表明不同贮藏时间羊肉火腿整体风味存在差异;气相色谱-质谱共鉴定出7?类94?种挥发性香气成分,烃类和醛类相对含量显著高于其他风味物质;偏最小二乘法表明3-甲硫基丁醛、戊醛、己醛、5-甲基己醛、壬醛、苯甲醛、2-甲基-2-十一烷硫醇、1-戊醇、1-辛烯-3-醇、2-辛酮、丁二酮、2-壬酮、乙酸、2,6-二甲基吡嗪等为羊肉火腿贮藏过程中特征风味物质。研究结果对了解羊肉火腿贮藏过程中风味构成及变化规律具有参考价值,有助于推进羊肉火腿的工业化进程。     

Nitric oxide inhibits the formation of zinc protoporphyrin IX and protoporphyrin IX

The aim of this study was to elucidate the mechanism by which curing agents, especially nitrite, inhibit the formation of zinc protoporphyrin IX (ZPP) in dry-cured hams such as Parma ham. The oxidation–reduction potential of model solutions was increased by the addition of nitrite, but it was not clear whether the formation of ZPP is inhibited by the oxidizing property of nitrite. The effect of nitric oxide (NO) produced from nitrite on the formation of ZPP was examined. The amount of ZPP formed was decreased by the addition of NO donors. The amount of protoporphyrin IX (PPIX), which is the precursor of ZPP, was also decreased by the addition of NO donors. It is concluded that NO produced from nitrite inhibited the formation of PPIX and ZPP was therefore not formed in cured meat products with the addition of nitrite or nitrate.     

Effect of salt content and processing conditions on volatile compounds formation throughout the ripening of Iberian ham

Volatile compounds evolution throughout the ripening of dry-cured Iberian hams with different salt content (6% vs. 3% of salt w/w) and processing temperature conditions (traditional processing vs. modified processing) was studied using solid-phase microextraction coupled to a direct extraction device (SPME-DED). Traditional processing implied an increase in the temperatures (28 °C) during an intermediate period (drying phase) of the processing, while in the modified process temperature was maintained at 19 °C. Enhanced temperatures in the traditional processing did not increase compounds from lipid oxidation such as hexanal, heptanal, octanal or nonanal. Salt level did not show any effect on volatiles during processing except for 2-pentylfuran during the drying stage (day 177). Although none of the volatile compounds monitored showed significant differences in the final sampling, the ratio between hexanal and octanal plus nonanal, that of hexanal and 3-methylbutanal plus 2-methylbutanal and that of hexanal and γ-octalactone were significantly higher in hams processed under modified system, in which the temperature is lower in the drying stage.     

腌制剂不同影响中式发酵香肠挥发性成分的组成

利用固相微萃取-气相色谱-质谱联用提取并分析发酵香肠中的挥发性物质,并探讨3 种不同的腌制剂（硝酸钠、亚硝酸钠、亚硝酸钠和抗坏血酸钠）对香肠风味物质,尤其是来源于支链氨基酸的风味成分的影响。结果表明腌制剂确实会对香肠中的风味物质含量产生一定的影响,且硝酸钠作为腌制剂更有利于乙酸乙酯、丁酸、2-丁酮、2-戊酮、2-庚酮、正己醇、正戊醇等风味物质的形成。     

Biochemical activities of Micrococcaceae and their effects on the aromatic profiles and odours of a dry sausage model

Micrococcaceae are used as starter cultures in fermented meat, it is therefore important to determine their biochemical activities and especially their aroma producing potential. With this aim, 19 strains of Micrococcaceae were studied in a dry-sausage model. Odours of the samples were assessed by a trained panel. Volatile compounds were analysed by dynamic headspace gas chromatography–mass spectrometry. Strains belonging to the speciesStaphylococcus warneriorStaphyloccocus saprophyticusthat were both lipolytic and unable to reduce nitrate, developed putrid, nauseous or bread odours. These samples were characterized by high desorption of aldehydes (heptanal, hexanal, octanal), 3-hydroxy butan-2-one and 2, 3-butanedione. The highest dry-cured odour was developed with the inoculation of strains ofStaphylococcus carnosusandStaphylococcus xylosuswhich had low lipolytic and proteolytic activities and did not produce acetoin but effectively reduced nitrate. Their inoculation in the sausage model was associated with the greatest desorbtion of 3-methyl butanal, methylketones and ethyl esters and the lowest desorption of alkanes and 3-hydroxy butan-2-one and 2, 3-butanedione.     

Influence of saliva on temporal volatile flavour release from red bell peppers determined by proton transfer reaction-mass spectrometry

The effect of saliva on temporal volatile flavour release from rehydrated red bell peppers was evaluated. The addition of 40% artificial saliva (w/w) was studied using a model mouth combined with proton transfer reaction-mass spectrometry. Saliva reduced the maximum headspace concentration during temporal release of 2-methylpropanal, 2/3-methylbutanal and hexanal by 42% on average. This was attributed to an effect of saliva on both the thermodynamic and kinetic component of flavour release, as saliva resulted in an average decrease of 25% for these compounds in equilibrium headspace analysis. A preliminary comparison of model mouth and in-nose analysis showed that the model mouth mimicked temporal release under mouth conditions quite well.     

Volatile Compounds and Chemical Changes in Ultrapasteurized Milk Packaged in Polyethylene Terephthalate Containers

The volatile compounds profile and chemical stability of ultrapasteurized 2% milk bottled in amber polyethylene terephthalate (PET) were studied along with its shelf life of 60 d at 5 °C. Identification of volatile compounds using a solid‐phase microextraction (SPME) technique with gas chromatography‐mass spectrometry was performed in situ in the commercial product. Chemical stability was determined by measuring dissolved oxygen, free sulfhydryl groups, ascorbic acid, and headspace oxygen. The classes of volatile compounds identified were ketones, aldehydes, hydrocarbons, fatty acids, alcohol, and miscellaneous compounds. Volatile compounds found consistently during the storage period were 2‐heptanone, methoxy‐phenyl‐oxime, decane, 1‐ethyl‐2,4‐dimethyl‐benzene, D‐limonene, 2‐nonanone, octanoic acid, dodecane, and 4‐(1,1,3,3, ‐tetramethylbutyl) phenol. Possible products of lipid oxidation, such as hexanal, octanal, and nonanal, were also positively identified. Chemical stability of PET‐bottled milk was demonstrated by the insignificant changes in pH or TA, with the exception of ascorbic acid concentration, which degraded in the product at 60 d of refrigerated storage. Sensory evaluation of the milk samples revealed that there is no noticeable oxidized or rancid off‐flavor at 60 d of storage.     

STATIC HEADSPACE CAPILLARY GC METHOD FOR DETERMINING CHANGES OF VOLATILES FROM HEATED CHICKEN BREAST MEAT

Volatile compounds generated during heat processing are associated with the flavor quality of cooked muscle foods. A static headspace GC method using a capillary column was developed for the analysis of volatiles from chicken breast meat previously heated to end-point temperatures (EPTs) of 60 to 80C at 5C intervals. A semi-automatic static headspace GC system with a fused silic capillary column (5% bonded methyl phenyl silicone, 50 m × 0.25 mm × 0.25 μm) was incorporated. Up to 23 peaks were detected. Major volatiles including propanal, pentanal, hexanal, heptanal and octanal increased as the EPT increased, especially between 60 and 70C. The effect of cooking EPT on volatile generation was determined more accurately by using the capillary column than by the packed column reported previously. Controlling EPT is important in ensuring the flavor quality and stability of precooked poultry meat products.     

加热温度对牦牛肉肌原纤维蛋白与葡萄糖或果糖美拉德反应挥发性成分的影响

为探讨不同反应温度和糖种类对牦牛肉肌原纤维蛋白与糖产生美拉德反应时挥发性物质的影响。将牦牛肉肌原纤维蛋白与葡萄糖或果糖于50、70、90、110、130℃下加热,在顶空瓶中直接反应或坩埚中间接反应,并采用气相色谱-质谱联用仪(GC-MS)对挥发性物质进行测定。结果表明:在顶空瓶中直接反应并检测相比在坩埚中反应再转至顶空瓶中检测的制样方式检测出的挥发性物质的种类多、相对含量高;反应温度越高,美拉德反应产物中挥发性风味物质的种类越多、相对含量也越高;当反应温度为130℃时,葡萄糖或果糖与肌原纤维蛋白反应产生的挥发性风味物质的种类分别为40种和44种,相对含量分别为93.59%和98.72%;在130℃时,于顶空瓶中直接反应,两种糖的美拉德反应都可以产生的重要肉味挥发性化合物:壬醛、己醛、辛醛、十六醛、十八醛、2,3戊二酮和2-乙酰基呋喃。