不同解冻方式对伊拉兔肉挥发性风味物质的影响

为探究不同解冻方式对伊拉兔肉挥发性风味物质的影响,采用顶空-固相微萃取结合气相色谱-质谱联用技术,对低温解冻、自然空气解冻、流水解冻、微波解冻和超声波解冻5 种方式处理的伊拉兔肉挥发性风味物质进行定性及定量分析。结果表明：不同解冻方式对兔肉挥发性风味物质的变化有一定的影响,共检测到解冻兔肉挥发性风味物质71 种,其中醛类26 种、酮类6 种、烃类14 种、醇类12 种、酯类8 种、酸类4 种、呋喃类1 种,且醛类所占的比例最高（＞70%）,其次是酮类、烃类及醇类化合物（＞5%）,酯类及呋喃类化合物所占的种类少且相对含量低（＜3%）。与鲜肉相比,流水解冻、微波解冻及超声波解冻处理兔肉醛类相对含量分别增加了19.385%、4.694%和18.285%,而低温解冻则下降了6.930%;低温解冻和微波解冻处理兔肉酮类相对含量分别增加了72.843%和14.554%,而超声波解冻则下降了72.932%;微波解冻后兔肉挥发性烃类变化与低温解冻相似;仅超声波解冻检出兔肉的特征风味物质2-戊基呋喃;自然解冻处理兔肉主要挥发性风味物质与鲜肉最为接近,对其风味的保持最好。解冻处理与伊拉兔肉挥发性醛类物质的相对含量呈现正相关,相关系数为0.584,而与醇类物质呈现显著负相关（P＜0.05）,相关系数为－0.835。     

不同解冻温度对滩羊肉熟制后风味的影响

将实验组新鲜滩羊羊腿肉先进行-60℃静止空气冻结,分别采取25、10、5℃静止空气解冻处理,对照组进行冷藏(3℃,24 h)处理,然后将样品熟制。利用固相微萃取-气相色谱-质谱法(SPME-GC-MS)测其挥发性风味物质,并使用主成分分析法对挥发性风味物质进行分析。结果表明,通过主成分分析可以从8类挥发性风味物提取2个主成分,其累积贡献率为97.362%,即将8种挥发性风味物质归为三大类:酸类、酯类、杂环类、醇类;醛类、醚类、酮类;烃类。且经过冻结、解冻处理的滩羊肉熟制后不会增加新的挥发性风味物质类型,随着解冻温度的降低,滩羊肉熟制后的风味物质种类逐渐增多,其中增加的挥发性风味物质:烃类5种、酯类3种、酸类1种、酮类2种。     

柠檬果肉真空冻结过程中挥发性风味成分变化

目的：探索柠檬果肉真空冻结过程中挥发性风味成分的变化规律。方法：利用电子鼻（E-nose）和气质联用（GC-MS）技术分别对新鲜、真空冻结10,20,30 min的柠檬果肉样品的挥发性风味物质进行分析。结果：E-nose可从整体上分析柠檬果肉中不同类别的挥发性风味成分,主成分分析和线性判别分析可区分新鲜和不同冻结时间的样品;GC-MS分析发现真空冻结过程中柠檬果肉挥发性风味物质的种类和含量均显著下降（P<0.05）;柠檬果肉中的主要挥发性风味物质主要是烯烃类、醇类、醛类化合物,其在真空冻结过程中的损失均呈先快后慢的趋势,通过热图和聚类分析可将真空冻结过程中所出现的挥发性风味成分划分为四大类;真空冻结10 min后,D-柠檬烯损失率最高;真空冻结20 min后,烯烃类、醇类和醛类化合物含量下降较为显著,酮类化合物含量变化不明显;真空冻结30 min后,出现了2,4-二甲基苯甲醛和2,4-二叔丁基苯酚新生挥发性风味成分。结论：柠檬果肉中绝大多数挥发性风味成分在真空冻结过程中呈明显下降趋势,并有部分新物质生成。     

基于GC-IMS和电子鼻分析牛肉腐败进程中挥发性风味物质的变化

为探究牛肉腐败进程中挥发性风味物质的变化规律,本研究以不同保藏时间的牛肉为研究对象,通过气相色谱-离子迁移谱（GC-IMS）技术和电子鼻分析其挥发性风味物质。结果表明,通过GC-IMS共检出55种挥发性风味物质,主要包括12种酮类物质、10种醇类物质、9种酯类物质、8种醛类物质和4种烃类物质。GC-IMS和电子鼻分析表明,牛肉腐败过程中挥发性风味物质含量呈显著上升趋势,其中醇类、醛类、酯类、酸类、呋喃、吡咯、噻唑、胺类、吡嗪和醚类物质持续增加;酮类、烃类和含硫化合物逐渐增加,在第7 d时达到峰值,而后逐渐下降。PCA和PLS-DA分析表明,牛肉腐败过程中挥发性风味物质发生了显著性变化。通过VIP值共筛选出16个差异性风味物质,随着保藏时间的延长,正己醛-D、正己醛-M、丁醛-M、丁醛-D、四氢吡咯-M、异戊醇-D、异戊醇-M、正丙醇-D、2,3-丁二酮等刺激性、不愉快风味物质的含量逐渐增加,可作为区分牛肉腐败进程的潜在生物标志物。本研究为牛肉腐败进程的监测提供一定的理论依据。     

新鲜牛肉冷藏过程中挥发性成分的变化

以新鲜牛肉为研究对象,测定其4℃冷藏过程中总挥发性盐基氮(total volatile basic nitrogen,TVB-N)和菌落总数的变化,并采用采用吹扫/捕集-热脱附-气质联用分析技术,研究在此贮藏过程中挥发性成分种类及含量的变化。结果表明:TVB-N值和菌落总数在贮藏期间呈增长趋势,在贮藏第6天时,TVB-N值已超过新鲜肉最高限值,菌落总数也已接近国家标准。挥发性物质中酸类、醇类和酮类物质含量呈逐渐增加的趋势;醛类物质先增加后又降低;芳香烃类物质含量则随时间延长呈下降趋势;胺类物质于贮藏后期,第8天时被检出。因此,牛肉挥发性成分的变化在一定程度上可以反应其新鲜度。     

干燥温度对紫苏挥发性物质组成的影响

采用气相色谱-质谱和电子鼻相结合的方法,评价干燥温度对紫苏中挥发性物质组成和风味的影响。电子鼻分析显示：55 ℃干燥获得产品的风味与新鲜紫苏冻干后的风味非常相似,与其他温度干燥获得产品风味有一定区别。气相色谱-质谱分析显示：新鲜紫苏冻干后总共检出25 种挥发性物质,其中紫苏酮含量最高为173 μg/g,根据生理代谢途径特征可以判定该紫苏为PK（perillaketone）型。干燥温度对紫苏中挥发性物质组成有不同影响,其中55 ℃干燥样品保留的挥发性物质种类最多,典型的挥发性物质如紫苏酮、芳樟醇、香芹酮等均有检出,较好保留了紫苏的风味。因此,55 ℃是紫苏较适宜的干燥温度。     

电子鼻结合顶空固相微萃取-气相色谱-质谱联用技术对干制乌贼挥发性成分分析

以乌贼为研究对象,采用电子鼻技术,结合顶空固相微萃取-气相色谱-质谱（headspace-solid phasemicroextraction-gas chromatography-mass,HS-SPME-GC-MS）联用技术,分析晾晒和热风烘干处理对乌贼挥发性风味物质的影响。结果表明,电子鼻分析结果能够很好地区分新鲜、晾晒和热风烘干3 种乌贼样品的风味。采用主成分分析、负荷加载分析以及线性判别分析可以量化主成分贡献率、传感器识别效应和样品间的风味区分度。HS-SPME-GC-MS分析结果表明,3 种样品共检出116 种不同的挥发性风味物质。其中新鲜乌贼为52 种,晾晒乌贼为64 种,热风烘干乌贼为71 种。新鲜乌贼经干制加工后,风味物质变化明显,产生新的醛类、烃类以及吡嗪类物质,而胺类物质的相对含量相对减少。吡嗪类物质在热风烘干乌贼中相对含量很高,是构成其特有的挥发性风味的主要贡献物质。     

湖南腊肉加工过程中挥发性风味成分的变化分析

以湖南腊肉为研究对象,分析加工过程中挥发性风味物质的变化规律。利用固相微萃取-气相色谱-质谱联用仪,分别对腌制后、一阶段烘干后、二阶段烘干后和烟熏后的湖南腊肉4 个阶段的挥发性风味成分进行定性和半定量分析。结果表明,湖南腊肉样品加工过程中共鉴定出78 种挥发性风味物质,腌制后、一阶段烘干后、二阶段烘干后和烟熏后4 个加工阶段分别鉴定出37、52、55 种和67 种挥发性风味成分,主要为醛类、酯类、酮类和酚类。腌制后样品的挥发性风味化合物较少,且含量不高;烘干时酮类物质种类增多,醛类和酯类物质的含量大幅增加,酸类物质含量也有增长的趋势,而醇类物质变化不大;烟熏后酚类物质的种类和含量变化最大,酚类物质的含量由最初的5.97 μg/kg增加到1 019.33 μg/kg。     

基于固相微萃取-气相色谱-质谱法分析热风干燥对草鱼肉挥发性风味物质的影响

目的 探索热风干燥不同温度条件下草鱼鱼块挥发性风味成分变化。方法 研究设置3种热风温度(30、40、50℃)干燥草鱼鱼块不同时间(2、4、6、12 h),采用固相微萃取气相色谱-质谱法(solid-phase microextraction gas chromatography-mass spectrometry, SPME-GC-MS)分析挥发性物质,PCA、PLS-DA和HCA进行多元统计分析。结果 新鲜草鱼和不同温度(30、40、50℃)热风干燥草鱼鱼块分别检测出28、44、39和36种挥发性风味成分,其主要为脂肪氧化型风味物质,包括醛类、醇类、酮类、芳香化合物、酸类、酯类和烃类,对草鱼风味的改良和增香具有一定作用,其中醇类和醛类物质含量较多。在干燥过程中,草鱼片内挥发性化合物的种类总体呈现增加的趋势,其峰面积(浓度)呈现先上升后下降的趋势。多元数据分析表明,不同干燥温度下草鱼肉风味物质具有显著的差异,PC1和PC2之和为41.8%。此外,除去芳香族化合物,其中3-羟基-2-丁酮、1-辛烯-3-醇、己醛、己醇、2-辛烯-1-醇、棕榈酸、壬醛、2,7-辛二烯-1-醇、辛醇、壬醇等10种挥发性物质对干燥草鱼肉的整体风味贡献较大,可以被作为热风干燥草鱼肉中的标志性风味物质。结论 挥发性风味成分是热风干燥草鱼片过程中非常重要指标,可用于草鱼热加工样品的监测和品质评价。     

荔枝汁结冰-解冻浓缩过程中品质的变化规律

以灭菌后的荔枝汁为原料,采用结冰-解冻浓缩工艺将其浓缩,研究了浓缩过程对荔枝汁的可溶性固形物含量、褐变度和可滴定酸度的影响,并运用气相色谱-质谱联用法对浓缩过程中的荔枝汁的挥发性风味物质进行测定,探讨其品质的变化规律。结果表明:荔枝汁中可溶性固形物的含量和褐变度随解冻所得的荔枝汁总体积的增加而逐渐降低;浓缩过程中,挥发性风味物质的相对含量的变化趋势因物质类型不同而不尽相同。综合考虑理化指标与风味物质的变化规律,可将解冻过程中荔枝汁总体积的40%(v/v)处选定为浓缩汁与剩余液的分界点,得到的浓缩汁中风味较高。     

Lipolytic and proteolytic properties of dry-cured boneless hams ripened in modified atmospheres

We studied proteolytic and lipolytic properties of dry-cured boneless ham (porcine quadriceps femoris) made with chilled (10°C, 48 h) or frozen/thawed meat (frozen at -20°C frozen for 90 days and followed by thawing at 10°C for 48 h) were determined. Dry-cured meats were stored in modified atmosphere packages (100% N(2) and a mixture of 75% N(2)+25% CO(2)) at 15°C with the intention of reducing ripening space. Results showed that dry-cured hams made with frozen/thawed raw meat had more salt, volatile fatty acids and free fatty acid content after salting and smoking. Whereas, samples prepared with chilled meats contained more nitrogenous compounds (water-soluble nitrogen, non-protein nitrogen, and free amino acids). Volatile and free fatty acid contents in all samples significantly increased with storage. Acetic acid was the predominant volatile fatty acid. To confirm lipolytic activity in dry-cured ham stored in modified atmospheres, we calculated the lipolytic coefficient. The lipolytic coefficients of all samples were positive values and significantly (P<0.05) increased with storage indicating lipolysis in samples were still active. Furthermore, nitrogenous compounds in dry-cured ham significantly (P<0.05) increased with storage indicating proteolysis in samples were not affected by modified atmosphere storage. Aerobic, anaerobic and lactic acid bacteria counts in dry-cured meats were stable to modified atmospheres storage for 20 weeks at 15°C. Flavor, texture and color score in sensory evaluation for dry-cured ham made with chilled meat were significantly higher than that made with frozen/thawed meat. All samples had high overall acceptance scores in sensory evaluation. Results in this study suggested that dry-cured boneless ham stored in modified atmospheres for 20 weeks at 15°C was another feasibility to ripen the meat without affecting lipolysis, proteolysis, microbiology and sensory quality.     

不同解冻方式对鳀鱼鲜度及挥发性风味物质的影响

为了探究不同解冻方式(微波解冻、超声辅助解冻、盐水解冻、冷藏室解冻)对鳀鱼(Anchovy)鲜度及挥发性风味物质的影响,分析了样品不同解冻方式的解冻时间、持水力、菌落总数及挥发性盐基氮(TVB-N),同时进行了感官评价、电子鼻分析和挥发性风味物质的鉴定.结果表明:微波解冻耗时最短(22.4 min),微波解冻后鳀鱼持水...     

Meat and storage effects on processing characteristics of beef roasts

Two experiments were done to determine the effect of storage conditions and meat cut on the processing characteristics of beef roasts. The first experiment examined the effect of storage condition (fresh/frozen), cap on/off, thawing regime and holding time post thawing on purge, brine uptake, cook yield and colour of raw and cooked roasts. The second experiment examined the effect of meat cut (insides/flats) and chilled storage for up to 8 weeks on processing characteristics of roast beef. Purge was greater for insides stored frozen without cap and air thawed. Frozen thawed cuts had increased brine retention after injection, after tumbling and after cooking. Flats had less purge and higher cook yields when manufactured into roast beef. Raw and cooked colour was not significantly affected by most factors investigated. Raw meat was more red than meat that had been frozen.     

顶空固相微萃取-气相色谱-质谱联用分析延边牛不同肌肉组织的挥发性风味物质

为探究延边牛不同肌肉组织的挥发性风味物质,以6 头同一月龄、同一生长条件的延边牛屠宰后的臀肉、眼肉、上脑、里脊、脊肋排和牛腩6 个部位为材料,采用顶空固相微萃取结合气相色谱-质谱联用对其挥发性风味物质进行检测,通过峰面积归一法确定各成分的相对含量,确定不同部位肌肉关键性挥发性风味物质。结果表明：共检测出醛类、醇类、酮类、烷烃类、酯类、胺类和烯烃类共79 种挥发性化合物,其中脊肋排29 种、里脊40 种、上脑28 种、臀肉25 种、牛腩29 种、眼肉35 种;6 个部位间挥发性化合物的种类及含量存在明显差异,与其他部位相比,牛腩中醛类和胺类化合物的相对含量最高,里脊的酯类与醇类化合物相对含量最高,脊肋排的烯烃类与烷烃类化合物相对含量最高,酮类化合物并没有在脊肋排中被检测到,臀肉中富含较多的酮类化合物。     

等离子体活化水作为解冻介质对牛肉杀菌效能及品质的影响

目的:研究低温等离子体活化水（plasma-activated water,PAW）作为解冻介质对牛肉微生物安全及生鲜品质的影响。方法:采用射频等离子体发生装置,处理水量为300 mL,以高压电源处理时间（40、60、80、100、120 s）为试验因素,制备不同处理时长的PAW。将放置至常温（25 ℃）的PAW作为冷冻牛腱子肉的解冻介质,以介质与样品4:1的质量比例静置浸泡解冻10 min,测定牛肉和解冻介质中的菌落总数、亚硝酸根含量、pH,及牛肉保水性（汁液损失率、持水力）、脂质氧化和蛋白质流失状况。结果:随着等离子体活化水制备时间的延长,其减菌效果显著增强（P<0.05）,解冻后牛肉中的菌落总数可降低0.91 lg (CFU/g)。将等离子体活化水作为解冻介质可显著增强牛肉的持水力（P<0.05）,汁液损失率最多可降低1.83%,脂质氧化程度可降低0.0944 mg/kg,蛋白流失可减少0.085 mg/mL,牛肉经解冻后,亚硝酸根含量最高为3.38 mg/kg,仍小于定量限,解冻后肉品pH最大仅增加0.06,即该解冻方式并不会对牛肉的亚硝酸根、pH产生显著影响（P<0.05）。本研究为低温等离子体活化水在肉制品解冻方面的应用提供了一定的理论依据和数据参考。     

酸汤对酸汤牛肉特征风味及品质的影响

研究酸汤（红酸汤、白酸汤、混合酸汤（红酸汤＋白酸汤））煮制对牛肉感官品质、pH值、色泽、水分含量、蒸煮损失率、嫩度、质构等理化特性的影响,并结合气相色谱-离子迁移谱分析酸汤牛肉挥发性成分,评价酸汤牛肉综合品质。结果表明,与对照组比较,酸汤可显著提高牛肉的嫩度和水分含量,降低牛肉蒸煮损失率、硬度、咀嚼性、胶黏性,改善牛肉的色泽和感官品质。白酸汤牛肉蒸煮损失率、硬度、胶黏性、咀嚼性最低,水分含量最高,红酸汤牛肉水分含量次之。红酸汤牛肉与白酸汤牛肉嫩度无显著差异,红酸汤可以显著提高牛肉红度值和黄度值。混合酸汤对牛肉亮度值提升效果较好。红酸汤和白酸汤中乳酸质量浓度最高,分别为23.27、4.90 mg/mL。酸汤牛肉中共鉴定出挥发性风味物质55 种,不同酸汤牛肉挥发性成分存在明显差异;与对照组比较,酸汤煮制牛肉可降低醛类物质相对含量,增加酯类、酸类和酮类物质相对含量,其中,红酸汤牛肉酯类和酸类物质相对含量较高,醛类物质相对含量较低,感官评分最高,口感风味最佳。红酸汤牛肉主要特征风味物质为乳酸乙酯、丁醛、乙酸、苯甲醛（二聚体）、2-甲基丙酸等;白酸汤牛肉主要特征风味物质为丙醇、2-丁酮、3-戊酮、丙酸等;混合酸汤牛肉以酮类物质为主要特征风味物质。与对照组相比,酸汤牛肉中部分风味物质增加,形成酸汤牛肉特有的特征风味。综上所述,红酸汤牛肉挥发性风味成分丰富,感官评价及综合品质更好,红酸汤是制作酸汤牛肉的适宜选择。     

High Hydrostatic Pressure Effects on Rapid Thawing of Frozen Beef

High hydrostatic pressure (HHP) during thawing of frozen beef was investigated by measuring temperature changes in frozen beef and the pressurization fluid. Frozen ground beef sample variables were pressure levels (140, 210, 280, and 350 MPa), times (5, 15, and 30 min), sample diameters (55, 65, and 80 mm), and initial temperatures (7, 11, 18 and 22°C). Properties of cooked patties were compared between beef thawed using HHP and using conventional thawing (atmospheric pressure at 3°C). Pressures of 210 to 280 MPa provided a critical processing range that effectively thawed the beef. Sample size and initial temperature did not affect thawing rate. The lowest temperature at which the beef was efficiently thawed was-24+2°C. HHP treated beef thawed much faster than controls. HHP thawing resulted in similar color and texture to controls.     

Thawing of lamb loin chops in air and CO(2). Effect on colour and drip

Colour retention and drip loss was assessed during retail display for chilled lamb chops displayed fresh or stored in CO(2) for 7 weeks before display, and for chops frozen for various times and thawed in air or CO(2). A sensory panel found fresh lamb chops to have an acceptable display life of 1 day, while chops which had been frozen for 1 day and then thawed lasted 2 days. Holding chops for 7 weeks in a CO(2) atmosphere at - 1·5°C improved display life to 3 days, but frozen chops held for 7 weeks before thawing had deteriorated in colour, and only one group was acceptable on the initial day of display. Initially there were no differences in Hunter L values (brightness) due to treatment, but chilled chops or those frozen for 1 day showed a greater increase in L values by the second day than those frozen for 7 weeks, after which there was no change in brightness. Hunter a values (redness) were higher in chilled chops and those thawed after 1 day's frozen storage than those frozen for 7 weeks before thawing. Hunter b values (yellowness) were greater at all times in chilled chops held for 7 weeks and varied amongst the other treatments. The measured per cent drip from chops frozen for only 1 day was greater on thawing than drip from chops frozen for 7 weeks before thawing. Drip during display, assessed by a sensory panel, increased more in those chops stored either chilled or frozen for 7 weeks before display.     

Combined effect of freeze chilling and MAP on quality parameters of raw chicken fillets

The effect of short-term frozen storage prior to thawing on the quality of freeze-chilled chicken fillets was investigated, as was the effect of modified atmosphere packaging (MAP). Four process treatments were used: (1) fresh chicken chilled at 4 degrees C without previous freezing, (2) freeze-chilled for 7 days and thawed at 4 degrees C, (3) chilled at 4 degrees C packaged under MAP (70% N(2)-30%CO(2)), and (4) packaged under MAP, freeze-chilled for 7 days and thawed at 4 degrees C. Microbiological, chemical and sensory analyses were conducted on samples for a period up to 15 days. Freeze-chilled fillets gave a lower total viable count (TVC) at a given sampling day than chilled fillets. MAP, as expected, delayed microbial growth. The Pseudomonads were the dominant microbial species in fillets under aerobic conditions. MAP reduced the populations of Pseudomonads by 2-4 log cfu/g. Lactic acid bacteria (LAB) and Enterobacteriaceae increased progressively for all treatments throughout storage. Yeasts and molds were inhibited by MAP and by freeze chilling. Total volatile basic nitrogen (TVB-N) values increased rapidly for the chilled fillets but remained significantly lower for the freeze-chilled and the MA-packaged samples. MAP and especially freeze chilling enhanced drip loss. MAP did not affect redness or yellowness of product while freeze chilling decreased product redness. Lightness was not affected by either MAP or freeze chilling. Based on taste, which proved to be the most sensitive sensory attribute, shelf life of product ranged from 6 to 7 days for all treatments leading to the conclusion that freeze chilling is a suitable technology for fresh chicken fillets enabling their distribution as a frozen product and upon subsequent thawing at their final destination, their retail display as chilled products. MAP in combination with freeze chilling had a negligible effect on product quality.