固相微萃取-气相色谱-质谱联用法分析荔枝汁贮藏过程中香气成分的变化

以荔枝果汁为研究对象,研究其在贮藏过程中香气成分的变化,旨在为荔枝汁生产和品质控制提供理论依据。采用SPME/GC-MS法分别对4℃和25℃贮藏的荔枝汁于贮藏4、5、6、7、8周后进行香气成分检测。结果表明：荔枝汁中香气成分总量在4℃和25℃贮藏4周后分别比贮藏前增长39.10%及31.99%。贮藏5周后呈显著下降趋势(P＜0.05),贮藏8周后香气保留率分别为96.17%及74.49%。其中醇类、酸类香气成分均在贮藏4周时含量最高,此后随着贮藏时间延长含量呈缓慢下降趋势;酯类物质在冷藏6周后达到最高,之后出现显著降低趋势(P＜0.05);烯类香气成分随着贮藏时间的延长逐渐减少,呈现显著下降趋势(P＜0.05);醛类香气成分含量在贮藏4周时变化不大,在4℃和25℃贮藏8周后保留率分别为59.86%和55.3%。荔枝汁中几种典型的香气成分如香叶醇、香茅醇、苯乙醇,β-月桂烯,D-柠檬烯,香叶醛的含量也是在贮藏4周达最大,此后逐渐降低。通过对4℃冷藏和25℃常温贮藏的荔枝汁主要香气类型及典型香气成分的比较分析表明,4℃冷藏后香气总量和绝大多数典型香气成分的含量显著高于同期常温贮藏(P＜0.05)。     

橙汁香气物质及其风味在储藏过程中的变化规律研究

分析研究了橙汁在储藏过程中香气成分变化及其对橙汁风味的影响。采用顶空固相微萃取、气相色谱-质谱联用技术对橙汁香气成分进行提取与分析,并结合感官评定确定橙汁风味变化。结果表明:从橙汁中共鉴定出58种香气成分,包括醇类、酯类、萜烯烃类、醛类、酮类和羧酸类等物质,其中主要香气化合物为柠檬烯、己醛、芳樟醇、桧烯、β-月桂烯、松油醇、癸醛、丁酸乙酯、瓦伦西亚橘烯、辛醛和圆柚酮等物质。揭示了橙汁在贮藏过程中主要风味物质的变化规律,即随着贮藏时间的延长,其主要香气成分含量呈下降趋势,风味品质也随之变差。     

鲜榨锦橙汁香气成分的固相微萃取-气质联用分析

采用固相微萃取-气质联用法对鲜榨锦橙汁的香气成分进行分析,并比较不同萃取头对鲜榨橙汁香气成分的萃取差异。结果表明:从鲜榨橙汁中共鉴定出53种香气成分,包括烯烃类、酯类、醇类、醛类和酮类,其中的主要香气化合物为柠檬烯、β-月桂烯、芳樟醇、α-松油醇、4-松油烯醇、丁酸乙酯、辛醛、α-蒎烯、β-水芹烯等物质。     

杀菌方式对无核雪柑汁香气成分的影响

采用固相微萃取-气相色谱-质谱法分析橙汁香气成分,内标法半定量,研究了巴氏杀菌和微波杀菌对无核雪柑汁香气成分的影响。结果表明:无核雪柑鲜榨汁、巴氏杀菌汁、微波杀菌汁分别检测出56种、57种和53种香气成分,含量分别为1304.70、991.51mg/kg和887.67mg/kg,巴氏杀菌后橙汁香气成分总含量高于微波杀菌汁,但微波杀菌后叶醇、十二碳醛、γ-芹子烯等含量均高于巴氏杀菌处理,且未检出异味物质β-松油醇,2种杀菌处理后烃类、酯类物质总含量均下降,酮类物质上升。     

不同贮藏方式对橙汁胞香气成分的影响

为探究不同贮藏方式对橙汁胞贮藏效果的影响,通过充氮（0.06 MPa,4 ℃）贮藏及冷冻（－18 ℃）贮藏72-1锦橙汁胞,分别于2、4、6 个月取样,采用顶空固相微萃取法与气相色谱-质谱联用技术分析橙汁胞香气成分。结果表明：橙汁胞经充氮和冷冻贮藏6 个月后各组分的相对含量变化不大,香气成分仍以烃类物质为主,其次是醇类和酯类物质。贮藏6 个月后,酯类相对含量均减少,且充氮贮藏相对含量高于冷冻贮藏;醇类、酮类相对含量有所增加,烃类、醛类、其他类相对含量变化较小。综合分析可知,充氮贮藏和冷冻贮藏对橙汁胞香气物质的保存效果差异不显著。     

基于电子鼻分析夏橙汁在贮藏过程中香气的变化

目的:研究了夏橙汁在不同贮藏温度和不同贮藏时间情况下橙汁的香气的变化情况.方法:电子鼻采集到夏橙汁的香气成分,并得到电子鼻传感器的响应值.利用PCA与DFA分析方法鉴别出夏橙汁在贮藏过程中香气的变化,以及在不同贮藏温度香气变化.结果:DFA的区分效果优于PCA的区分效果;在-18℃与4℃的低温贮藏条件下,橙汁的香气变化幅度较小,25℃贮藏的条件下香气成分的损失较多,并且三种贮藏温度下,第一、二周香气的响应值变化显著,第三、四周香气的响应值变化小,响应值接近.     

加工单元操作对血橙汁香气成分的影响

以塔罗科血橙汁为研究对象,对手榨汁、精滤汁、杀菌汁和还原汁采用顶空固相微萃取-气相色谱-质谱联用法测定了橙汁香气成分。结果表明,4 种血橙汁分别检出47、55、51 种和14 种香气成分,总含量分别为459.21、1 436.16、1 194.25、118.72 mg/kg,精滤汁比手榨汁多检出莰烯、丁酸甲酯、壬醇、癸醛等物质,杀菌后果汁多检出壬醛,压榨过滤和加热有助于香气的形成,但要控制副作用物质如α-松油醇等的增加,浓缩还原后橙汁香气最差,在生产中可利用回填方式提高产品品质。     

超声波处理对鲜榨橙汁中主要香气成分的影响

为了研究超声波处理对鲜榨橙汁香气的影响,采用固相微萃取技术(SPME)对不同强度超声处理的鲜榨橙汁中的香气成分进行富集,并用气相色谱-质谱联用仪(GC-MS)检测,结果显示:超声波处理对橙汁的香味物质有较大影响,产生两种新的物质(芹子烯、古芸烯),同时有些原有香气物质(如壬醛、香茅醛)消失,大部分香气物质种类不变,而其含量发生变化。对香气物质的定量检测表明:超声处理后柠檬烯含量显著降低,最高下降23.20%;α-松油醇、芳樟醇含量先增加后降低;醛类物质含量也呈先增加后降低趋势;香芹酮含量增多;酯类物质在超声下含量的变化趋势是:先略有下降后显著增加。总体来看,超声处理使得橙汁中的醇类、醛类等物质转化为酯类物质,使得香气更加突出。     

蜜柑鲜汁与巴氏灭菌汁香气成分比较研究

采用顶空-固相微萃取法提取蜜柑鲜果汁与巴氏灭菌果汁的香气成分,用气相色谱-质谱进行分离鉴定,应用色谱峰面积归一化法测定各成分的相对含量。实验结果显示:鲜果汁与巴氏灭菌果汁分别鉴定出78和79个香气成分。蜜柑鲜汁中的主要香气成分是D-柠檬烯(69.82%)、芳樟醇(3.35%)、γ-松油烯(1.61%)、4-松油醇(1.01%)和α-松油醇(0.81%)等;灭菌后的蜜柑汁中的主要香气成分为D-柠檬烯(58.20%)、α-松油醇(8.02%)、γ-松油烯(1.65%)、4-蒈烯(1.29%)、β-松油醇(1.11%)。灭菌后,果汁原有的愉悦的香气成分如丁酸乙酯未检出;α-松油醇、癸醛的含量增加使果汁风味变劣;产生的二甲基硫醚、糠醛、p-乙烯基愈疮木酚也影响果汁品质。     

蜜柚发酵酒与蒸馏酒香气成分的GC-MS分析

为探究巴氏灭菌对新鲜沃尔卡姆柠檬汁香气的影响,采用顶空固相微萃取-气相色谱-质谱联用法（HS-SPME-GC-MS）分析巴氏灭菌前后新鲜柠檬汁的挥发性成分。结果表明,巴氏灭菌前后的柠檬汁中分别共鉴定出86种和94种挥发性成分,主要挥发性风味物质的种类及其相对含量均有不同。巴氏灭菌后,醇类、酯类化合物相对含量分别增加了9.15%和0.86%,而烷烯类、醛酮类物质相对含量分别下降了10.77%、0.40%。巴氏灭菌后原有的挥发性成分有所变化,同时也生成了新的物质,但是柠檬汁中柠檬烯、萜品油烯、β-蒎烯、α-松油醇、4-萜烯醇、月桂烯、香茅醇、1-β-红没药烯等主体挥发性成分没有发生明显变化。     

加工过程中夏橙汁香气成分的SPME-GC-MS分析

采用固相微萃取- 气相色谱- 质谱法对伏令夏橙汁加工过程中5 个关键点样品的主要香气成分进行分析,共鉴定出50 种香气成分,主要为柠檬烯(84.79%～86.92%)、β- 月桂烯(3.87%～5.83%)、α- 蒎烯(1.03%～2.05%)、芳樟醇(0.02%～1.72%)、葵醛(0.15%～0.28%)、辛醛(0.03%～0.52%)和丁酸乙酯(0.12%～0.44%)等。加工过程对夏橙汁香气成分种类和含量有重要影响,5 个样品香气成分种类分别为38 种、36 种、31 种、30 种和20 种。精滤后烃类相对含量增加2.01%,醇类物质下降2.00%;脱气后烃类下降0.95%,醇类下降0.15%;灭菌后香气成分与脱气后相近;浓缩还原对香气影响最大,烃类和醇类比精滤后橙汁分别降低3.85%、1.16%。     

Flavor Evaluation and Volatile Flavor Constituents of Stored Aseptically Packaged Orange Juice

Samples of commercial orange juice packaged aseptically and stored at 21°C and 26°C were evaluated weekly by a sensory panel using hedonic ratings. Flavor scores were significantly lower than control juice and unacceptable after 1 wk at 26°C and 2 wk at 21°C. The flavor score decreased to 50–60% of the starting value during 6 wk storage. The volatile components, α-terpineol and ethyl acetate, increased during storage. A component not identified earlier as a volatile citrus component was identified as 2-(2-butoxyethoxy)ethanol. This and the observed increase in ethyl acetate during storage might have come from the laminated multilayered package liner. Limonene in juice decreased about 40% during storage. Other major volatile components did not change markedly.     

酸化、低温和添加山梨酸盐贮藏橙汁的研究

本文主要研究了酸化、低温和山梨酸盐结合对橙汁贮藏的影响。结果表明,将橙汁酸化到pH2.0和pH2.5,于5℃下贮藏12周,其细菌总数、酵母和霉菌数明显减少。使用0.03％山梨酸或山梨酸钾并酸化到pH2.5的橙汁,可在10℃下贮藏10周以上。但山梨酸盐会使Vc分解。这表明,Vc含量较高的橙汁中,微生物数量也高。     

Influence of different storage conditions on changes in the key aroma compounds of orange juice reconstituted from concentrate

Quantification of aroma compounds in an orange juice reconstituted from concentrate which had been stored at 37 °C for 4 weeks (forced storage) revealed an increase in the concentrations of, in particular, dimethyl sulphide, 2-methoxy-4-vinylphenol, α-terpineol, and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF) in comparison with the same orange juice before storage. On the other hand, clearly lower concentrations were found for octanal, decanal, (R)-α-pinene, linalool, and (E)-β-damascenone after storage, while the concentrations of vanillin and carvone remained nearly constant. Similar results were found for the same aroma compounds after storage of the orange juice at 20 °C for 1 year. Sensory experiments corroborated the importance of 2-methoxy-4-vinylphenol and dimethyl sulphide for the typical stale off-flavour of the stored orange juice, while the omission of e.g., α-terpineol in model mixtures could not be detected. Under both storage conditions (37 °C for 4 weeks or 20 °C for 1 year), the breakthrough odour thresholds of α-terpineol and 4-HDF were not reached, while the concentrations of dimethyl sulphide and 2-methoxy-4-vinylphenol clearly exceeded their breakthrough odour thresholds, thus confirming the crucial role of these odorants for the off-flavour of stored orange juice from concentrate. In addition, changes in the concentrations of selected orange juice odorants at various temperatures and times were investigated.     

超高压和高温短时杀菌对NFC橙汁品质的影响

本文对比了超高压（Ultral high pressure processing,HPP,600 MPa,1 min）和高温短时（High temperature short time,HTST,110℃,8.6 s）杀菌处理对非浓缩还原（Not from concentrate,NFC）橙汁处理前后及4℃、25 d贮藏期内微生物、基本理化指标以及颜色、稳定性、生物活性成分、抗氧化活性等品质的影响,并在贮藏期末对杀菌橙汁进行了感官评价。结果表明,HPP和HTST处理后NFC橙汁菌落总数、霉菌和酵母菌、乳酸菌、嗜冷菌均降低至检测限以下（<10 CFU/mL）,储藏25 d后HPP处理橙汁微生物仍未检出,符合国家果蔬汁饮料行业标准《NY/T 434-2016》,而HTST处理橙汁在贮藏期末菌落总数和霉菌酵母数量开始增加。HPP处理对橙汁色泽的L*、b*值无显著影响（P>0.05）,使a*值显著增大（P<0.05）,总色差ΔE低于HTST处理。HPP处理对橙汁悬浮稳定性的保持和果胶甲基酯酶（Pectin methylesterase,PME）的钝化效果较差,处理后HPP组和HTST组PME残留活性分别为92.31%和14.42%,贮藏末期分别为30.77%和0.03%,贮藏期间HPP组悬浮稳定性下降了95.45%。HPP处理显著提高了NFC橙汁的总酚含量13.50%（P<0.05）,对维生素C含量、DPPH自由基清除能力、FRAP铁离子还原能力、综合感官评价无显著影响（P>0.05）,显著高于HTST处理橙汁（P<0.05）。综上所述,HPP处理有助于保持橙汁的营养和感官品质,保留新鲜风味,比HTST处理更具优势,但对PME酶的钝化效果有待提高。     

Toward validation of process criteria for high-pressure processing of orange juice with predictive models

Mathematical models were developed to predict time to inactivation (TTI) by high-pressure processing of Salmonella in Australian Valencia orange juice (pH 4.3) and navel orange juice (pH 3.7) as a function of pressure magnitude (300 to 600 MPa) and inoculum level (3 to 7 log CFU/ml). For each model, the TTI was found to increase with increasing inoculum level and decrease with increasing pressure magnitude. The U.S. Food and Drug Administration Juice Hazard Analysis and Critical Control Point Regulation requires fruit juice processors to include control measures that produce a 5-log reduction of the pertinent microorganism of public health significance in the juice. To achieve a 5-log reduction of Salmonella in navel orange juice at 20 degrees C, the models predicted hold times of 198, 19, and 5 s at 300, 450, and 600 MPa, respectively. In Valencia orange juice at 20 degrees C, a 5-log reduction of Salmonella was achieved in 369, 25, and 5 s at 300, 450, and 600 MPa, respectively. At pressures below 400 MPa, Salmonella was more sensitive to pressure in the more acidic conditions of the navel orange juice and TTIs were shorter. At higher pressures, little difference in the predicted TTI was observed. Refrigerated storage (4 degrees C) of inoculated navel orange juice treated at selected pressure/time/inoculum combinations showed that under conditions in which viable Salmonella was recovered immediately after high-pressure processing, pressure-treated Salmonella was susceptible to the acidic environment of orange juice or to chill storage temperature. These TTI models can assist fruit juice processors in selecting processing criteria to achieve an appropriate performance criterion with regard to the reduction of Salmonella in orange juice, while allowing for processing flexibility and optimization of high-pressure juice processing.     

采收期、贮藏时间及加工单元操作对赣南脐橙汁苦味物质含量的影响

探讨赣南脐橙采收期、贮藏时间及加工单元操作对橙汁苦味物质(柠檬苦素、诺米林)含量的影响,为降低橙汁苦味提供参考。测定不同采收期与贮藏时间及不同加工单元操作下的橙汁中的苦味物质含量,重点研究橙汁热处理过程中苦味物质的变化并进行动力学模型拟合。结果表明,随着采收期的延长,橙汁中柠檬苦素与诺米林的含量逐渐降低,但在贮藏期间,橙汁中的柠檬苦素与诺米林含量先升高后降低;破碎汁中柠檬苦素与诺米林含量均高于挤压汁,酶解工艺后破碎汁和挤压汁中柠檬苦素含量均大幅升高,而诺米林未被检出;热处理温度越高、pH值越低,橙汁中苦味物质含量越高,当pH值>6.0时,柠檬苦素和诺米林均未在橙汁中检出,同时可用联合反应模型拟合热处理过程中橙汁柠檬苦素和诺米林含量变化。脐橙采收期与贮藏期和加工单元操作特别是热处理条件均对橙汁苦味物质的含量影响较大,后续可通过延迟采收期与贮藏时间、优化取汁方法及控制热处理参数等措施降低橙汁的苦味物质含量。