UHT热处理对牛奶中风味物质的影响

结合固相微萃取(SPME)及气相色谱-质谱(GC-MS)研究UHT热处理后牛奶的风味变化,并与原料牛乳风味特征进行对比。结果表明:新鲜原料乳中可以检测到50种挥发性风味物质,其中酸类最多,其他还包括醛,醇,酮,酚,酯等。牛乳经过137℃,4 s加热杀菌后,挥发性风味物质有75种,除上述风味化合物外,酯类和酮类数量明显增加,其中甲基酮,3-羟基-2-呋喃酮,δ-癸内酯,γ-十二内酯是UHT乳中重要挥发性风味物质,对形成UHT乳特有风味起重要作用。     

预处理对低温压榨花生油风味物质的影响

采用顶空固相微萃取(HS-SPME)和气相色谱–质谱联用(GC-MS)技术检测不同预处理低温压榨花生油中挥发性风味物质,探讨不同预处理低温压榨花生油中醛类、酮类、吡嗪类等挥发性风味物质的种类和相对含量。结果表明:被检测的花生油样品中共鉴定出97种挥发性风味物质,不同预处理方式制得的低温压榨花生油其挥发性风味物质差异很大。脉冲电场预处理低温压榨花生油主要呈味物质为3-羟基-2-丁酮;微波预处理低温压榨花生油挥发性风味物质以吡嗪类和吡咯类物质居多;超声波预处理低温压榨花生油挥发性风味物质主要是酸类。预处理方式对低温压榨花生油挥发性风味物质的影响有显著差异,不同预处理方式可以获得不同风味的低温压榨花生油。     

欧姆加热对豆浆风味物质的影响

为研究欧姆加热对豆浆挥发性物质的影响,采用顶空固相微萃取结合气相色谱-质谱联用技术,对豆浆的风味物质进行分析,利用内标法对各风味物质成分定量分析。通过对比50/30?μm二乙基苯/碳分子筛/聚二甲基硅氧烷（divinylbenzene/carboxen/polydimethylsiloxane,DVB/CAR/PDMS）、100?μm PDMS、65?μm PDMS/DVB 3 种萃取头对豆浆风味物质的萃取效果,筛选出最佳的萃取头,并在最适条件下分析豆浆的风味物质成分,为排除热效应对实验结果的影响,2?种热处理历程尽可能保持一致。结果表明：65?μm PDMS/DVB纤维萃取头较100?μm PDMS和50/30?μm DVB/CAR/PDMS纤维萃取头更适宜豆浆风味物质的测定;从豆浆样品中共检测到35?种挥发性物质,其中醛类物质16?种,醇类物质5?种,酮类物质3?种,酯类物质1?种,杂环烃类物质10?种,主要包括己醛、（E）-2-庚烯醛、1-辛烯-3-醇等,这些物质共同组成豆浆的特征香气;不同加热处理对豆浆风味物质种类的影响不大,但是对特征香气含量有显著影响（P＜0.05）;欧姆加热处理组样品中己醛、1-辛烯-3-醇、（E）-2-辛烯醛的含量分别比传统加热处理组约低45.55%、58.60%、25.56%,且在欧姆加热处理样品组中未检测到（E）-2-己烯醛和正己醇,而这些物质是豆腥味的主要组成成分。因此,利用欧姆加热方式加热豆浆可以显著降低豆浆的豆腥味。本研究可以为欧姆加热技术在豆浆加工业中的应用提供理论依据。     

不同酶处理对鳕鱼挥发性风味物质影响的主成分分析

通过利用多酚氧化酶、脂肪氧化酶和胶原蛋白水解酶3种不同的酶对鳕鱼进行处理,并在实验室条件下,利用顶空固相微萃取、气相色谱与质谱联用技术对处理后的鳕鱼进行挥发性成分分析.实验结果表明,鳕鱼挥发性风味物质的主要成分为醛类、酮类、醇类、酯类、酸类和烷类物质,其中醛类、酮类和醇类是鳕鱼风味的主要成分,鳕鱼经过不同的酶处理后,其...     

油炸对臭豆腐中挥发性风味物质的影响

以长沙臭豆腐为原料,采用顶空固相微萃取结合气相色谱质谱联用（HS-SPME-GC-MS）技术检测臭豆腐油炸前后的挥发性 风味成分,研究油炸对臭豆腐的挥发性风味物质的影响。结果表明,油炸前的臭豆腐中共鉴定出37种挥发性物质,主要由醛类、醇类、 烷类、含硫化合物和呋喃类组成;油炸后的臭豆腐中共鉴定出40种挥发性物质,除上述物质外,还含有苯类、酮类和酸酐类等物质,而 醇类物质较少。与油炸前的臭豆腐相比,油炸后的臭豆腐中醇类、烯类、烷类的相对含量呈递减趋势,酮类、醛类、苯类、其他杂环类化 合物的相对含量呈递增趋势。     

兰州糟肉加工过程中挥发性风味物质的分析

以兰州糟肉为研究对象,分析其加工过程中挥发性风味物质的变化规律。采用固相微萃取-气相色谱-质谱(SPME-GC-MS)联用结合电子鼻技术,分别对原料期、炖煮期、腌制期、蒸煮期4个阶段的挥发性风味物质进行分离鉴定,并通过相对气味活度值(ROAV)法确定关键挥发性风味物质。结果表明:兰州糟肉加工过程中共鉴定出84种挥发性风味物质,4个阶段兰州糟肉挥发性风味物质的种类分别为37,23,23,40种,总相对含量呈现先增加后降低的趋势,在腌制期达到最大。4个阶段共有的风味化合物为5种,分别为四氯乙烯、甲苯、正己醛、2-正戊基呋喃和乙腈。相对气味活度值显示兰州糟肉加工过程中醛类、醇类物质的关键挥发性风味物质占主导地位,对兰州糟肉的风味贡献较大。电子鼻测定结果显示烷烃类、硫化合物风味活性较强。腌制期对兰州糟肉风味的影响较大。     

SPME-GC-MS结合ROAV分析单菌及复配发酵牛乳中关键性风味物质

采用固相微萃取-气相色谱-质谱联用技术检测分析Streptococcus thermophilus与Lactobacillus delbrueckii subsp.bulgaricus单菌及复配发酵牛乳中的挥发性风味物质,结合相对气味活度值(relative odor activity value,ROAV)探讨发酵牛乳中关键性风味物质。结果表明:本实验共鉴定出100种挥发性风味物质,包括酸类、酮类、醛类、醇类、酯类、烷烃类和芳香族类化合物等。主成分分析表明,表征S.thermophilus单菌发酵乳的关键性风味物质是双乙酰、正壬醛和甲苯;表征L.bulgaricus单菌发酵乳的关键性风味物质是正庚醛、丁酸-2-甲基丙酯和1-庚醇;表征S.thermophilus与L.bulgaricus复配发酵乳的关键性风味物质是乙醛、3-甲基正丁醛、乙偶姻、2-壬酮、2-庚酮、醋酸乙烯酯、碳酸庚基苯基酯、甲酸乙烯酯和2-壬醇。相较于单菌发酵,复配发酵的风味物质组成、各组分相对含量及关键性风味物质均发生改变。     

即食豆干加工过程中挥发性风味物质的研究

为研究加工工艺对即食豆干挥发性风味物质的影响,采用固相微萃取(SPME)结合气相色谱-质谱联用(GC-MS)对即食豆干各工艺阶段风味物质进行定性和定量分析。结果表明:在原料、卤制、油炸和杀菌的样品中分别检测出44种、62种、56种、53种物质,含量分别是2560.84μg/kg、3168.53μg/kg、2277.82μg/kg、937.64μg/kg,醛类、醇类、酮类、烷烃类以及其它类构成即食豆干的风味成分;卤制能降低腥味醇类物质含量,增加香气醛类、酮类和其它类物质的含量,使豆干具有焦糖香气,甜香及香辛料香;油炸后具有特征香气的醛类、酮类和醇类等物质含量均有所下降,特征香气成分损失严重;特征风味物质在杀菌后进一步损失,且最终产品中重要豆腥味物质正己醛、1-辛烯-3醇的相对含量(32.63%)较高。因此,即食豆干的加工工艺可进行适当改良,以期获得更高品质的即食豆干产品。     

顶空-固相微萃取方法分析4 种发酵剂制作馒头中挥发性风味物质

采用顶空-固相微萃取方法对传统老酵馒头与单一酵母馒头样品进行预处理,利用气相色谱-质谱法检测样品中的挥发性风味成分。经NIST 08.L质谱数据库检索结合文献对照,从旗舰馒头（传统老酵馒头）中检出59 种挥发性风味成分,天津自制馒头（传统老酵馒头）中检出51 种,安琪馒头（单一酵母馒头）中检出47 种,燕山馒头（单一酵母馒头）中检出43 种,这些挥发性成分中主要包括醇类、烃类、酯类、醛类、酮类、芳香类等。不同发酵剂制作馒头中风味物质的种类及相对含量都存在一定的差异性,这也是使用相同原料不同发酵方法制作馒头产生特别的风味的主要原因。     

马铃薯泥挥发性风味物质研究

采用顶空固相微萃取法(HS-SPME)制备样品,利用气相色谱质谱联用法(GC-MS)分离并鉴定新鲜的及在4℃下冷藏1d的马铃薯泥的挥发性风味物质。由检测结果可知,新鲜样主要风味组分有47种,而冷藏样主要风味组分有37种。新鲜样中最丰富的是醛类化合物,出峰面积相对比例76.94%,其次是呋喃类8.08%,醇类6.85%。冷藏样中出峰面积相对比例较高的是醛、酯、醇类化合物,分别为93.27%、3.45%和1.03%。新鲜样和冷藏样中醛类含量均最高,是由蒸煮阶段不饱和脂肪酸在脂肪氧合酶催化下生成的。     

Effects of Commercial-scale Pulsed Electric Field Processing on Flavor and Color of Tomato Juice

Effects of commercial‐scale pulsed electric field (PEF) processing on the flavor and color of tomato juice during storage at 4 deg;for 112 d were studied. Tomato juice was prepared by hot break at 88°C for 2 min and then thermally processed at 92° for 90 s or PEF processed at 40 kV/cm for 57 μs. The PEF‐processed tomato juice retained more flavor compounds of trans‐2‐hexenal, 2‐isobutylthiazole, cis‐3‐hexanol than thermally processed or unprocessed control tomato juice (P < 0.05). PEF‐processed juice had significantly lower nonenzymatic browning and higher redness than thermally processed or control juice (P < 0.05). Sensory evaluations indicated that the flavor of PEF‐processed juice was preferred to that of thermally processed juice (P < 0.01).     

高压脉冲电场对抗氧化肽荧光特性的影响

以前期研究所得的Gln-Trp-Phe-Met(QWFM,652.78)和Lys-Trp-Phe-Met(KWFM,610.78)抗氧化四肽为研究对象,探究高压脉冲电场技术(pulsed electric field,PEF)对抗氧化肽荧光特性的改变。研究表明,在PEF作用下QWFM和KWFM的荧光强度发生了不同程度的改变,由于两条结构相似的抗氧化四肽中色氨酸前端所连接的氨基酸不同,在相同的PEF处理条件下,QWFM的荧光强度变化更为显著,在电场频率为1 800 Hz和电场强度为15 k V/cm时,其荧光强度变化最显著。通过监测经PEF处理后2 h抗氧化四肽荧光强度的变化,发现抗氧化四肽荧光强度的变化随着时间的延长而逐渐减弱。通过圆二色谱分析和核磁共振波谱技术分析发现维持QWFM中β-折叠的氢键含量有所改变从而导致了β-折叠结构的含量有所减少。这些变化表明PEF技术可能通过改变抗氧化肽的化学结构而改变其荧光特性,为PEF技术应用于抗氧化肽的研究提供了理论基础。     

Shelf‐Life Study of an Orange Juice–Milk Based Beverage after PEF and Thermal Processing

ABSTRACT: The effect of thermal and pulsed electric field (PEF) processing on the shelf life of an orange juice–milk beverage (OJMB) was studied. The intensities of the treatments were selected to produce similar inactivation of pectin methyl esterase (PME), an enzyme responsible for the jellification and loss of fresh juice cloudiness. Physical properties (pH, °Brix, and color), microbial population, PME activity, and volatile compounds of the product were analyzed during a 4‐wk storage at 8 to 10 °C. The pH was not affected by any treatment but decreased during the storage in the untreated sample. The °Brix values were decreased by the 2 treatments. The thermal and PEF treatments initially inactivated PME activity by 90%. During storage, the PME activity remained constant in the 2 treated samples and decreased slightly in the untreated sample. The reductions in bacterial as well as yeast and mold counts were similar after the 2 treatments (4.5 and 4.1 log CFU/mL for thermal against 4.5 and 5 log CFU/mL for PEF). Based on the initial bacterial counts of the control, it was estimated that the shelf lives of the OJMB treated with thermal and PEF processing stored at 8 to 10 °C were 2 and 2.5 wk, respectively. Differences were observed in the color parameters of the OJMB between the 2 treatments in comparison with the control, with a higher difference observed in the thermally processed samples. The relative concentration of volatile compounds was higher in OJMB processed by PEF treatment than that in the thermally processed sample. During storage, the loss of volatile compounds was lower in the PEF sample while thermal and control samples had a similar rate of loss. For an OJMB, treatment with PEF achieved the same degree of microbial and enzyme inactivation as the thermal treatment, but better preserved color and volatile compounds.     

高压脉冲电场在食品工业中的应用

介绍了高压脉冲电场应用于食品工业。高压脉冲电场(HPEF)是一种低能耗、高效率的食品加工技术,在杀菌,干燥,保持风味和营养成分等方面,HPEF技术都表现很好的效果。     

Commercial-Scale Pulsed Electric Field Processing of Orange Juice

Effects of commercial‐scale pulsed electric field (PEF) processing on the microbial stability, ascorbic acid, flavor compounds, color, Brix, pH, and sensory properties of orange juice were studied and compared with those of thermal processing. Freshly squeezed orange juice was thermally processed at 90 °C for 90 s or processed by PEF at 40 kV/cm for 97 ms. Both thermally processed and PEF‐processed juices showed microbial shelf life at 4 °C for 196 d. PEF‐processed juice retained more ascorbic acid, flavor, and color than thermally processed juice (P<0.05). Sensory evaluation of texture, flavor, and overall acceptability were ranked highest for control juice, followed by PEF‐processed juice and then by thermally processed juice (P<0.01).     

Enhanced Anthocyanin Extraction from Red Cabbage Using Pulsed Electric Field Processing

Abstract: This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment on anthocyanin extraction from red cabbage using water as a solvent. Mashed cabbage was placed in a batch treatment chamber and subjected to PEF (2.5 kV/cm electric field strength; 15 μs pulse width and 50 pulses, specific energy 15.63 J/g). Extracted anthocyanin concentrations (16 to 889 μg/mL) were determined using HPLC. Heat and light stabilities of the control and PEF-treated samples, having approximately the same initial concentrations, were studied. PEF treatments enhanced total anthocyanin extraction in water from red cabbage by 2.15 times with a higher proportion of nonacylated forms than the control (P < 0.05). The heat and light stabilities of the PEF-treated samples and control samples were not significantly different (P > 0.05). Practical Application: An innovative pretreatment technology, pulsed electric field processing, enhanced total anthocyanin extraction in water from red cabbage by 2.15 times. Manufacturers of natural colors can use this technology to extract anthocyanins from red cabbage efficiently.     

高压脉冲电场非热杀菌技术对原料乳的预处理

针对国内原料乳质量低下这一问题,运用高压脉冲电场非热杀菌技术对原料乳进行预处理。发现原料乳的细菌总数随电场强度、脉冲数、初始温度的增加而降低,随流速的增加而升高。当出口温度为常温20℃,电场强度E=50kv/cm,脉冲频率为1000Hz,流速为20ml/min时,能使其菌落总数降低2.6个数量级,从四级原料乳提升至一级原料乳,且不改变其营养结构和风味。     

电场处理对大米淀粉理化性质的影响

利用脉冲电场对大米淀粉进行预处理,研究不同电场强度和不同有效处理时间对淀粉颗粒结构特征和理化性质的影响。通过扫描电镜(SEM)发现,淀粉颗粒表面受电场影响遭到破坏。傅里叶变换红外光谱(FTIR)和X射线衍射(XRD)表征结果表明脉冲电场处理大米淀粉不会引入新的官能团,在本实验条件下也不会改变淀粉的晶型结构,是一种物理改性的处理手段。经脉冲电场处理后,大米淀粉糊的透明度由6.2%提高到32.4%,冻融析水率由58.31%降低到22.53%,此外凝沉性和冻融稳定性均有所改善。     

高压脉冲电场(PEF)非热处理的加工原理与安全控制

高压脉冲电场非热处理技术因处理时间短,温升小,能耗低和杀菌效果明显等成为目前杀菌工艺中研究最为活跃的技术之一,而且在功能物质提取与保持物质活性等方面也展现了较好的应用前景。本文着重对该技术在食品加工中的作用原理、工艺过程和加工中的安全质量控制等方面进行阐述。