Changes in physicochemical characteristics and volatile compounds of apricot (Prunus armeniaca L. cv. Bergeron) during storage and post-harvest maturation

The effects of storage and post-harvest maturation on the physicochemical characteristics and volatile constituents of Bergeron apricot were investigated during the 2007 season over two experiments. Fruits, harvested at two distinct stages of maturity, in two different experimental orchards, were stored in cold chambers at +1 °C for up to 3 weeks and then subjected to a post-harvest maturation in ripening chambers at 20 °C and 60–70% RH up to 7 days. Firmness, soluble solids (SS), titratable acidity (TA), and the levels of the main volatiles were determined. Physicochemical changes included a significant decrease of firmness during both storage and post-harvest maturation whereas the levels of SS and TA were found to be very similar. The results also indicated that, whatever their initial stage of maturity at harvest, the rates of softening of apricots during storage and/or post-harvest maturation were very comparable. During post-harvest maturation, the levels of C₆-compounds decreased drastically whereas, at the same time, those of esters, lactones and terpenic compounds greatly increased. During storage at 1 °C, a decrease of C₆-compounds was also observed. As regards other compounds, there were some statistically different results between samples but the changes observed for lactones, esters and terpenic compounds were relatively small in comparison to those observed during post-harvest maturation at 20 °C. The results also showed that, at the end, qualitative and quantitative differences can be observed in the “ready-to-eat” apricots according to their initial stage of maturity at harvest. On average, apricots harvested at the most advanced stage of maturity have, on average, the highest levels of soluble solids and the highest levels of volatile compounds of interest.     

Characterization of aroma potential of apricot varieties using different extraction techniques

Aroma compounds are presents in raw foods, freely and glycosidically-bounded (aroma precursors). In the present work, the volatile fraction of eight varieties of apricot were analyzed using simultaneous distillation extraction (SDE), solid phase extraction (SPE) with reverse phase (C18), liquid–liquid extraction (LLE) and headspace-solid phase microextraction (HS-SPME). The free aroma compounds were identified by GC–MS, finding common compounds such as linalool, α-terpineol, β-ionone and γ-decalactone and specific compounds due to the extraction method used. The ANOVA showed a significant effect in the extraction techniques and on the varieties in the free aromatic fraction from apricot as well. In spite of a large number of volatile compounds extracted by SPE, the technique that allowed for the most number of compounds to be extracted was SPME.     

基于SPME-GC-MS对不同品种大米挥发性物质分析

以4种不同品种大米为研究对象,采用固相微萃取-气相色谱-质谱法（SPME-GC-MS）对不同品种大米挥发性成分进行分离鉴定,比较不同大米品种挥发性成分的差异性,并对香气物质进行主成分分析。结果表明：大粒溪香挥发性成分种类最多为52种,大粒香、帅优63和金麻粘分别为39种, 37种和28种。4种大米主要挥发性成分基本相同,主要成分为烷烃、醛类、酯类,且相对含量均以烷烃类最高。大粒溪香、大粒香、金麻粘、帅优63烷烃类相对含量分别为58.56%、37.26%、47.27%、61.65%。根据4种大米发性物质相对含量和种类以及主成分分析,说明不同品种间大米风味物质对大米香气品质存在较大影响。     

Characterization of Volatile Fraction of Saffron from Central Italy (Cascia,Umbria)

Saffron, the world’s most expensive spice, is valuable for its color, taste, aroma, and properties, which are influenced by the postharvest treatments. In this research solid-phase micro-extraction coupled with gas chromatography-mass spectrometry was performed to analyze saffron produced in the area of Cascia, central Italy. The samples were dried under different conditions as a function of time and temperature. The main volatiles in addition to safranal were isophorone, 4-ketoisophorone, and 2,2,6-trimethyl-1,4-cyclohexanedione. In some samples, two new compounds (2,4,4-trimethyl-1-pentene and 1,3,3-trimethyl-7-oxabicyclo[4.1.0]heptane-2,5-dione) were identified. Their content increased with drying temperature and time and they could be characteristic of saffron produced in the selected geographical area. Moreover the results confirmed that the drying conditions strongly influenced saffron volatile profile.     

Analysis of the volatile profile and identification of odour-active compounds in Bayonne ham

The aim of this work was to reliably identify odour-active compounds in dry-cured ham using powerful analysis methods for the volatile fraction. For this purpose, dynamic headspace gas chromatography combined with eight-way olfactometry using a panel of eight sniffers was used. One- and two-dimensional gas chromatography coupled with mass spectrometry and (or) olfactometry were also used. More than 600 compounds from the volatile fraction of dry-cured ham were identified and their biochemical origins are discussed. They covered a wide diversity of structures and chemical functions. Only 29 of them proved odour-active. Comparison of the results of GC–O analysis with those obtained by orthonasal sniffing of the dry-cured ham helped to gain a better understanding of how these substances contributed to the overall aroma of the product. Thus, “Fruity–Floral”, “Green–Vegetable” or “Plastic–Chemical” odours intensively perceived by GC–O have been poorly perceived by orthonasal sniffing. By contrast, “Animal–Meat products” or “Butter–Lactic–Cheesy” odours have been much better perceived by orthonasal sniffing. These results indicate that to understand the interactions between odour-active compounds, experimental doping with carefully selected odour-active compounds will be necessary.     

Impact of processing steps on the composition of volatile compounds in cheese powders

Changes in the composition of volatile compounds during processing of cheese powders, made from Emmental and Danbo cheese were analysed by dynamic headspace gas chromatography–mass spectrometry. Samples comprised cheese, melted cheese slurry, the slurry heat treated using three different time and temperature combinations, and the spray‐dried cheese powder. About 100 volatile compounds were identified. During melting of the cheese the level of some volatile compounds increased significantly; heat treatment mainly leads to a loss of compounds and spray drying leads to a substantial reduction of volatile compounds, with the exception of a range of aldehydes that increased. The final cheese powders could, however, be distinguished according to cheese type.     

Determination of volatile compounds and quality parameters of traditional Istrian dry-cured ham

The aim of this work was to determine the characteristics of Istrian dry-cured ham by instrumental methods and sensory analysis. The aroma-active compounds of Istrian dry-cured ham from 2010 and 2012 were investigated by using headspace-solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). Samples of biceps femoris were also evaluated by measuring physical and chemical characteristics. 92 volatile aroma compounds of Istrian dry-cured ham were found. Volatile compounds belonged to several chemical groups: aldehydes (51.4; 51.3%), terpenes (16.5; 16.4%), alcohols (15.5; 13.2%), ketones (8.6; 7.4%), alkanes (3.8; 5.7%), esters (1.3; 1.6%), aromatic hydrocarbons (0.8; 3.9%) and acids (0.6; 0.9%). Principal component analysis (PCA) showed that fat content, tenderness and melting texture were positively correlated. Terpenes were strongly correlated with flavour of added spices. Sweet taste and the presence of esters were positively correlated as well as negative odour, raw meat flavour and water content.     

Citrus juice classification by SPME-GC-MS and electronic nose measurements

According to suppliers indications, 76 commercial and 120 self-prepared citrus juices were grouped corresponding to fruit type, cultivar and treatment by linear discriminant analysis of the volatile compounds measured by an electronic nose (EN) instrument and solid-phase micro extraction gas chromatography mass spectrometry (SPME-GC-MS) from the headspace. While the number of available variables for SPME-GC-MS with 311 was rather high and always allowed for reasonable group separation, the number of variables for the EN instrument was limited to 12. Nevertheless, wrong and misleading supplier information was uncovered especially by EN data. Analysis revealed a commercial orange juice grouped close to grapefruit and two pummelos declared as grapefruits, while further conspicuous samples were noted but require more detailed investigations.     

The profile of volatile compounds and polyphenols in wines produced from dessert varieties of apples

The aim of this study was to determine the influence of apple variety (Šampion, Idared and Gloster) on the polyphenol profile, volatile composition and sensory characteristics of apple wines. Apples were harvested from the orchard in Garlica Murowana (Poland) and the experiments were conducted on a laboratory scale. Statistically significant differences were detected in the chemical composition of the analyzed wines. The highest antioxidant activity was found in Šampion wines, which was associated with a relatively high concentration of chlorogenic acid and procyanidins. These samples also contained high amounts of acetaldehyde, ethyl acetate and methanol. Idared wines showed a similar polyphenol profile, but they had lower antioxidant capacity and were characterized by a high level of butanol and acetic acid. Gloster wines were distinguished from other samples by a lower concentration of polyphenols and higher concentration of fusel alcohols. During sensory evaluation, wines produced from Idared apples scored the highest value for overall quality.     

Effect of drying and proline addition on aroma volatile compounds of acid‐hydrolysed rice bran protein concentrate

Rice bran protein concentrate (RBPc) was hydrolysed by 0.5 N aqueous HCl at 95 °C for 12 h. The liquid hydrolysate obtained was prepared as hydrolysate powder by spray drying. Aroma volatile compounds in liquid hydrolysate and its hydrolysate powder were tentatively identified by GC‐MS. Furfural and vanillin were found in both hydrolysates with high concentration, and vanillin showed the highest odour activity value. Hexanal was present in only liquid hydrolysate. Concentrations of carboxylic acids and heterocyclic compounds, especially 2‐methoxy‐6‐methylpyrazine, increased after drying. Amino acid composition of the hydrolysate powder showed high aspartic acid and glutamic acid. Aroma volatile compounds of hydrolysate powder prepared by the addition of proline at pH 6.0 (Pro6.0‐H) and pH 7.5 (Pro7.5‐H) before drying were investigated. Furaneol was found only in Pro6.0‐H, but it was not detected in Pro7.5‐H and hydrolysate powder without proline addition. Pro7.5‐H had higher furfural and vanillin concentrations than Pro6.0‐H.     

SPME-GC-MS法分析芽菜中的挥发性风味成分

采用顶空固相微萃取方法提取3个不同厂家芽菜中挥发性风味物质,然后结合气相色谱-质谱联用技术对提取的挥发性风味物质进行分离鉴定.通过对固相微萃取的纤维头、萃取温度和萃取时间的选择来优化其实验条件.采用气-质联用技术从三种样品中一共鉴定出67种挥发性风味物质.主要包括醇类、酸类、酯类和烷烃类化合物等.研究表明,顶空固相微萃取以及气-质联用技术可以很好来分析芽菜中挥发性风味物质,并说明不同品牌芽菜其挥发性风味物质存在一定差异.     

SPME-GC-MS法分析猪肉味香精中的挥发性成分

论文采用固相微萃取结合GC - MS法分析了制备的猪肉香精中的香气成分,摸索了最佳的萃取条件和GC - MS分析条件,鉴定出了猪肉香精中的主要香气成分.首先用三种萃取头对制备的猪肉味香精中挥发性成分进行萃取,结合GC - MS分析图谱选取一个适合的萃取头;再做直接萃取和顶空萃取两种萃取方式进行对比,选择一个较好的萃取方式.发现选用75μm (Carboxen/PDMS)的萃取头采用顶空萃取的方式对萃取本猪肉味香精香气成分效果最佳.最后通过GC - MS分析萃取的猪肉香精的挥发性成分,得出了较好的GC - MS分析条件,共鉴定出44种挥发性香气成分,主要为呋喃类、醛类、烃类、酮类、噻吩、噻唑类等重要肉味化合物,其中醛类和呋喃类最多,是形成猪肉风味的主要成分.最后对制备的猪肉味香精用SPME法提取香气成分,进行GC - MS分析制备的猪肉味香精,鉴定出44种挥发性香气成分,主要为呋喃类、醛类、烃类、酮类、噻吩、噻唑类等重要肉味化合物.     

固相微萃取-气相色谱-质谱分析青钱柳叶挥发性成分

采用固相微萃取（SPME）和气相色谱-三重串联四极杆质谱联用仪（GC-QQQ-MS）相结合的方法对两个产地（江西修水野生和浙江文成人工栽培）的青钱柳叶挥发性成分进行研究,并比较了它们在挥发性化学成分及含量上的差异。结果表明:在两个产地的青钱柳叶中共鉴定出91种挥发性成分,其中两者共有挥发性成分45种,且主要是碳氢化合物类、醇类、醛类、酯类、酮类、醚类和萘类化合物,但两个样品在挥发性成分的具体组成和含量上存在一定的差异。野生青钱柳叶的挥发性成分主要是β-瑟林烯（18.52%）、石竹烯（8.11%）、β-甜没药烯（6.01%）、β-榄香烯（5.36%）、顺-香叶基丙酮（4.02%）等,人工栽培青钱柳叶的挥发性成分主要是β-波旁烯（11.05%）、β-瑟林烯（10.91%）、石竹烯（7.03%）、苯甲醇（7.01%）、2,6-二甲基-6-（4-甲基-3-戊烯基）-双环[3.1.1]庚-2-烯（5.36%）、2,6,11-三甲基十二烷（5.16%）等。      

四川白口仔姜在贮藏过程中挥发性成分的变化

为研究仔姜在沙土贮藏过程中挥发性风味物质的变化,将采收的仔姜经过挑选、分级、杀菌处理后埋藏在沙土中,并于11℃贮藏,采用固相微萃取—气相色谱—质谱联用测定不同时期贮藏过程中仔姜的挥发性风味物质。结果表明:贮藏过程中从仔姜中共检测出77种挥发性成分,分别为烃类(47种)、醇类(16种)、酮类(1种)、醛类(4种)、醚类(9种),其中烃类、酮类物质总量在贮藏过程中(10,20,30d)无显著差异(P0.05),醇类物质总量在20d时显著降低,30d后显著升高。贮藏过程中仔姜有10种挥发性成分的含量随着贮藏时间延长显著升高,分别为左旋-α-蒎烯、莰烯、2,6-二甲基-2,6-辛二烯、反-β-金合欢烯、别香橙烯、2-茨醇、α-松油醇、香茅醇、香茅醛、柠檬醛,在30d时这些物质含量分别是新鲜样品的5.09,7.89,6.73,10.48,153.75,11.11,8.21,11.73,24.96,14.65倍。     

基于SPME-GC-MS和化学计量法分析长沙臭豆腐卤水挥发性风味物质

采用固相微萃取—气相色谱—质谱联用(SPMEGC-MS)法测定长沙5种品牌臭豆腐卤水的挥发性风味物质,结合仙农熵、相关系数和主成分分析等化学计量法对不同品牌卤水的挥发性成分进行分析与比较,以探讨各卤水之间风味异同情况及原因,并找出其共有的"臭"味成分。结果共检测到154种挥发性风味物质,其中5种商品臭豆腐卤水(分别标记为STB1、STB2、STB3、STB4和STB5)分别检出76,37,29,74,35种,占各自卤水挥发性物质总峰面积的87.09%,78.75%,63.14%,70.31%,46.83%。5种卤水中,酸类、酚类和杂环类化合物都是其挥发性化合物中的主要成分,其中乙酸、丙酸、苯酚、对甲基苯酚、吲哚和3-甲基吲哚等是试验卤水所共有的特殊风味物质,且相对含量较高,推测它们为卤水的"臭"味所在。化学计量分析表明,主成分分析能有效地区分5种卤水,但STB3和STB5部分区域叠加,推断这2个品牌卤水在原料和配比上有很大的相似性。     

Sensory characteristics of spoilage and volatile compounds associated with bacteria isolated from cooked and peeled tropical shrimps using SPME-GC-MS analysis

The spoilage potential of six bacterial species isolated from cooked and peeled tropical shrimps (Brochothrix thermosphacta, Serratia liquefaciens-like, Carnobacterium maltaromaticum, Carnobacterium divergens, Carnobacterium alterfunditum-like and Vagococcus penaei sp. nov.) was evaluated. The bacteria were inoculated into shrimps, packaged in a modified atmosphere and stored for 27 days at 8 °C. Twice a week, microbial growth, as well as chemical and sensory changes, were monitored during the storage period. The bacteria mainly involved in shrimp spoilage were B. thermosphacta, S. liquefaciens-like and C. maltaromaticum whose main characteristic odours were cheese-sour, cabbage-amine and cheese-sour-butter, respectively. The volatile fraction of the inoculated shrimp samples was analysed by solid-phase microextraction (SPME) and gas chromatography coupled to mass spectrometry (GC-MS). This method showed that the characteristic odours were most likely induced by the production of volatile compounds such as 3-methyl-1-butanal, 2,3-butanedione, 2-methyl-1-butanal, 2,3-heptanedione and trimethylamine.     

芥末油中挥发性成分的提取与分析

为了鉴定芥末油中的挥发性成分,采用固相微萃取提取了市售4种芥末油中的挥发性成分,并利用气相色谱-质谱联用对所得挥发性成分进行了分离与鉴定。采用质谱、保留指数和标准品进行定性,共鉴定出11种挥发性成分,其中酯类最多,为6种;4种芥末油中共有的成分是二硫化碳、烯丙基氯、异硫氰酸环丙酯、异硫氰酸甲酯、异硫氰酸烯丙酯和硫氰酸烯丙酯。采用邻二氯苯为内标对4种芥末油进行了定量,其中含量较高的有异硫氰酸烯丙酯(7487.01~22025.36μg/g样品)、硫氰酸烯丙酯(1074.69~4013.81μg/g样品)、异硫氰酸环丙酯(21.24~49.74μg/g样品)、硫氰酸甲酯(5.80~19.77μg/g样品)等。在鉴定出的成分中,由异硫氰酸烯丙酯转化或降解的产物有硫氰酸烯丙酯、异氰酸烯丙酯、二硫化碳和二烯丙基硫醚。     

Nitrogen addition influences formation of aroma compounds,volatile acidity and ethanol in nitrogen deficient media fermented by Saccharomyces cerevisiae wine strains

The effects of nitrogen addition into nitrogen deficient/depleted media on the release of aroma compounds post-fermentation were investigated in three commercial yeast strains of Saccharomyces cerevisiae which highlight the yeast strain effect as well as nitrogen effects. By comparing the two timings of nitrogen addition, prior to fermentation or later at stationary phase (72 h), it was shown that nitrogen addition at stationary phase significantly decreases ethanol and acetic acid formation and significantly increases the following compounds: 2-phenylethanol, ethyl isobutyrate, 2-phenylethyl acetate, ethyl 2-methylbutyrate and ethyl propionate in the three strains, and also isovaleric acid, isoamyl alcohol and ethyl isovalerate in both PYCC4072 and UCD522. The strain EC1118 produced significantly less medium chain fatty acids, hexanoic, octanoic and decanoic acids and their respective esters after nitrogen addition. Therefore, timing of nitrogen addition to a ferment media can vary the concentration of certain aroma compound and might provide a means for varying wine composition.     

基于挥发性风味物质分析的小麦储藏年份鉴别方法研究

目的 基于挥发性风味物质分析鉴别小麦储藏年份。方法 采用固相微萃取-气相色谱-质谱法对小麦籽粒样品进行检测,采用主成分分析、凝聚层次聚类并结合偏最小二乘法判别分析对不同储藏年份的小麦样品的挥发性风味物质种类和含量进行分析,建立基于挥发性风味物质分析的小麦储藏年份鉴别模型。结果 对收获期为2018年至2022年共5个年份的小麦样品进行检测,检出挥发性风味物质73种,包括醇类、醛类、酮类、杂环化合物、酸类、酯类、醚类、烃类和酚类物质。基于变量投影重要性筛选出37种对主成分分类贡献较大的差异化合物,其中γ-辛内酯、γ-庚内酯、γ-己内酯、γ-壬内酯、1-庚醇、1-己醇和1-戊醇含量与小麦储藏年份呈正相关,被确定为特征差异化合物。结论 不同储藏年份小麦中挥发性风味物质含量存在差异,基于特征差异化合物构建的分类模型有望用于小麦储藏年份的快速、准确鉴别,为小麦的品质鉴别提供一定的技术支撑。     

啤酒风味物质研究进展

近年来,啤酒产业不断发展,人们对啤酒的风味要求不断提高。啤酒的风味是衡量其品质的关键指标,种类繁多的挥发性和非挥发性成分是啤酒具有特有风味的主要原因。啤酒因原料、酵母、发酵工艺、贮藏等条件的不同,成品风味有很大差异。本文综述了啤酒风味物质的组成,从啤酒的香气成分、苦味成分和不良风味3个方面阐述风味物质的来源。啤酒花中萜烯类化合物、酵母发酵产生的酯和高级醇是啤酒重要的香气来源。麦汁、干加酒花、添加功能性原料、无醇的新型啤酒等新技术的应用也对啤酒的香气有一定协同作用。啤酒花中的α-酸、β-酸及多酚物质赋予啤酒特有的苦味。酒花添加量、添加时间,啤酒过滤和灭菌对啤酒苦味具有一定的影响。啤酒的酿造过程中产生的双乙酰、含硫化合物和贮藏期间产生的老化味会使啤酒产生不良风味。超高压技术对降低啤酒不良风味有一定作用。通过本综述,有望推动改进啤酒生产配方、提升啤酒风味、改进工艺和贮藏条件等方面研究的深入进行。