Relating Descriptive Sensory Analysis to Gas Chromatography/Olfactometry Ratings of Fresh Strawberries Using Partial Least Squares Regression

ABSTRACT: Sensory properties of 5 strawberry varieties were related to gas chromatography/olfactometry (GC/ O) analysis using partial least squares regression (PLS). The sour and green sensory aspects were strongly associated with titratable acidity, hexanal, and E-2 hexenal. The caramel/sweet character was differentiated from the strawberry/fruity character by its stronger association with Furaneol, which had a high score in the 2nd PLS dimension. The sensory scores for peach and the GC/O ratings for the peach-like lactones were also associated. The fruity sensory scores and the floral sensory scores were not well correlated with compounds having fruity or floral character. This lack of relationship could partially be explained by covariance among the sensory ratings for the samples.     

Sensory and Chemical Analysis of ‘Shackleton's’ Mackinlay Scotch Whisky

Three cases of Mackinlay's Rare Highland Malt whisky were excavated from the ice under Sir Ernest Shackleton's 1907 expedition base camp hut at Cape Royds in Antarctica in January 2010. The majority of the bottles were in a pristine state of preservation and three were returned to Scotland in January 2011 for the first sensory and organoleptic analysis of a Scotch malt whisky distilled in the late 1890s. Sensory analysis and the higher alcohol and maturation congener profiles describe a lightly peated malt whisky matured in American white oak sherry or wine casks. Analysis of process related compounds together with combined gas chromatography (GC) mass spectrometry and GC‐olfactometry analysis of fermentation related congeners show a distinctly ‘modern’ style of malt whisky. While Scotch malt whisky at the end of the 19th century was generally regarded as heavily peated and harsh in character, Charles Mackinlay & Co. Distillers were producing a malt whisky with an altogether more subtle character at their Glen Mhor distillery near Inverness. The sensory and chemical analysis of this unique whisky artefact significantly changes our understanding of the quality and character of Scotch malt whisky produced by our distilling forefathers.     

Characterization of Important Odorants in Steamed Male Chinese Mitten Crab (Eriocheir sinensis) using Gas Chromatography‐Mass Spectrometry‐Olfactometry

Chinese mitten crab (Eriocheir sinensis) from Yangcheng Lake in Jiangsu Province is a popular species due to its unique pleasant aroma and intensive umami taste. In this study, odorants in steamed male E. sinensis were investigated using the headspace‐monolithic material sorptive extraction technique coupled with gas chromatography‐mass spectrometry‐olfactometry (GC‐MS‐O). A total of 74 volatile compounds were found, and the results of the GC‐MS‐O analysis, combined with odor activity values, showed that trimethylamine (fishy, ammonia‐like odor), (Z)‐4‐heptenal (mushroom‐like odor), and benzaldehyde (paint‐like odor) were the important odorants (IOs) in all 4 of the edible parts of steamed male E. sinensis. Furthermore, heptanal (mushroom‐like odor) was common to the abdomen, claw, and leg meat but was not found as the IO in the gonad. The abdomen meat also contained 3‐methylbutanal (vegetable‐like, grassy odor), while 2 additional IOs were found in claw meat (2‐methylbutanal, which has a mushroom odor and 3‐ethyl‐2,5‐dimethylpyrazine, which has a chocolate‐like, musty odor). Another IO (2‐nonanone, chocolate‐like odor) was also found in leg meat, while (E)‐2‐nonenal (green, fruity odor) was the IO found exclusively in the gonad.     

Quantification of Volatile Compounds in Chinese Ciders by Stir Bar Sorptive Extraction (SBSE) and Gas Chromatography‐Mass Spectrometry (GC‐MS)

A new method for the quantification of volatile compounds in ciders was developed using stir bar sorptive extraction (SBSE) followed by gas chromatography (GC)‐mass spectrometry (MS). The optimized conditions consisted of 10 mL cider sample with NaCl addition to a final concentration of 30% (w/v) extracted by SBSE at 55°C during 60 min, stirring at 1100 rpm. Under the conditions described above, the method linearity was satisfactory, with correlation coefficients (R²) higher than 0.99 in all cases. The detection limits of this method ranged from 0.01 to 6.37 μg/L, and quantification limits ranged from 0.03 to 21.25 μg/L. The recoveries of analyzed compounds varied between 70.92 and 111.38%. The relative standard deviations (RSD) were all below 10%. A total of 54 volatile compounds in six samples from Chinese cider were quantified, mainly esters, alcohols, terpenoids, aromatics, and acids.     

南瓜的感官品质、质构及生化分析

在对127份南瓜材料进行感官鉴定的基础上,选取10份口感明显不同的南瓜材料为研究对象,分别测定其质构指标及生化指标,并分析感官属性和质构指标以及感官属性和生化指标的相关性。结果表明：南瓜的感官属性可以分为3个主成分,第1主成分为粉质、干湿情况和甜度,第2主成分为面度和纤维度,第3主成分为硬度和脆性;南瓜的质构指标也分为3个主成分,第1主成分为硬度、回复性和剪切力,第2主成分为内聚性,第3主成分为黏附性和弹性。感官属性与质构指标及理化指标不同项目之间具有不同的相关性。南瓜感官评价的关键指标为粉质,干湿情况和甜度。     

Analysis of Volatile Compounds in Shochu Koji,Sake Koji,and Steamed Rice by Gas Chromatography‐Mass Spectrometry

The volatile compounds in three types of koji (yellow, white, and black) and steamed rice were investigated using gas chromatography‐mass spectrometry. The objective of this study was to characterize each koji type based on its profile of volatile compounds. From the steamed rice and rice koji samples examined, a total of 29 volatile compounds were identified. Butanal, hexanal, dimethyl trisulfide and cyclohexyl isothiocyanate were detected only in steamed rice. The volatile profile of yellow koji (sake koji) was distinct from those of white and black kojis (shochu koji). On the basis of relative peak areas, alcohols and aldehydes were identified as being more abundant in yellow koji. White and black kojis had similar volatile profiles, and had a greater abundance of furans than yellow koji. We assume that the different suites of volatile compounds identified in shochu and sake kojis impart the respective characteristic flavours to shochu and sake.     

Sensory and compositional attributes of melting‐ and non‐melting‐flesh peaches for the fresh market

A study was conducted to determine differences in sensory and compositional characteristics of melting‐flesh (MF) and non‐melting flesh (NMF) fresh market peach genotypes. Sensory results showed that the NMF fruit (‘Oro A’ and FL 86‐28C) were ‘harder’, less ‘juicy’ and more ‘rubbery’ than their MF (FL 90‐20 and ‘TropicBeauty’) counterparts. A principal component analysis of the sensory data showed a clear distinction between the textural aspects of MF and NMF fruit, but not between their flavour aspects. Likewise, chemical analysis showed that while differences in pH, titratable acidity, and soluble solids were detected among the four genotypes, no consistent grouping could be made based on the MF/NMF nature of the fruit. © 1999 Society of Chemical Industry     

Sensory and chemical characteristics of trans‐resveratrol‐fortified wine

Background and Aims: trans‐Resveratrol (tR) is a grape‐derived polyphenolic that is believed to confer considerable health benefits to humans. Its concentration in wine, however, is highly variable, and thus direct fortification of wine with tR has been proposed to create a high‐value, health‐promoting wine product. This study determines the sensory and chemical characteristics of tR fortified white and red wine. Methods and Results: Riesling and Cabernet Sauvignon wines were enriched with 20 mg/L and 200 mg/L tR. Basic chemical and sensory indicators of wine quality, trans‐ and cis‐resveratrol concentrations, and antioxidant capacity were assessed at bottling and at 6, 18, 31, 44 and 58 weeks post‐bottling. tR concentrations in bottled wine remained relatively stable throughout the 58‐week period of this study. In addition, tR‐enriched wines had a significantly higher antioxidant capacity compared with control wine, and Cabernet Sauvignon fortified at both tR concentrations had greater colour intensity. Basic chemical indicators of wine quality were not affected by tR fortification, and sensory changes were minimal, with higher bitterness intensity in Riesling fortified at 200 mg/L tR the most consistent finding. Conclusions: tR is relatively stable in wine during bottle aging, and tR enrichment up to 200 mg/L results in minimal change to wine quality, particularly with red wine. Significance of Study: This is the first study to investigate the chemical and sensory characteristics of tR‐enriched wines. Results indicate that these products may have considerable potential for the functional food market.     

Quantitative Analysis of Bioactive Compounds from Aromatic Plants by Means of Dynamic Headspace Extraction and Multiple Headspace Extraction‐Gas Chromatography‐Mass Spectrometry

Seven monoterpenes in 4 aromatic plants (sage, cardamom, lavender, and rosemary) were quantified in liquid extracts and directly in solid samples by means of dynamic headspace‐gas chromatography‐mass spectrometry (DHS‐GC‐MS) and multiple headspace extraction‐gas chromatography‐mass spectrometry (MHSE), respectively. The monoterpenes were 1st extracted by means of supercritical fluid extraction (SFE) and analyzed by an optimized DHS‐GC‐MS. The optimization of the dynamic extraction step and the desorption/cryo‐focusing step were tackled independently by experimental design assays. The best working conditions were set at 30 °C for the incubation temperature, 5 min of incubation time, and 40 mL of purge volume for the dynamic extraction step of these bioactive molecules. The conditions of the desorption/cryo‐trapping step from the Tenax TA trap were set at follows: the temperature was increased from 30 to 300 °C at 150 °C/min, although the cryo‐trapping was maintained at ?70 °C. In order to estimate the efficiency of the SFE process, the analysis of monoterpenes in the 4 aromatic plants was directly carried out by means of MHSE because it did not require any sample preparation. Good linearity (r² > 0.99) and reproducibility (relative standard deviation % <12) was obtained for solid and liquid quantification approaches, in the ranges of 0.5 to 200 ng and 10 to 500 ng/mL, respectively. The developed methods were applied to analyze the concentration of 7 monoterpenes in aromatic plants obtaining concentrations in the range of 2 to 6000 ng/g and 0.25 to 110 μg/mg, respectively.     

Characterization of Aroma Compounds in Chinese Bayberry (Myrica rubra Sieb. et Zucc.) by Gas Chromatography Mass Spectrometry (GC‐MS) and Olfactometry (GC‐O)

Abstract: The aroma‐active compounds in Chinese bayberry were identified using gas chromatography‐olfactometry (GC‐O) and GC‐mass spectrometry techniques. The volatile compounds were extracted using Liquid–liquid extraction, solvent‐assisted flavor evaporation and headspace solid‐phase microextraction (HS‐SPME), respectively. On the basis of odor intensity, the most important aroma compounds in Chinese bayberry samples were caryophyllene, menthol, 4‐terpineol, linalool oxide, linalool, benzyl alcohol, α‐methylbenzyl alcohol, β‐phenylethanol, 3‐methylbutanoic acid and acetic acid, and so on. Moreover, HS‐SPME technique was employed to investigate the aroma compounds among immature and mature waxberry fruits. The results showed that terpenes (for example, β‐caryophyllene) was predominant and its concentration represented over 89.9% of the overall compounds, and alcohols, aldehydes, ketones, esters, acids, and others were typically present in lesser amounts. Finally, principal component analysis revealed that there was also significant difference between immature and mature waxberry fruits     

Characterization of Volatile and Semi‐Volatile Compounds in Chinese Rice Wines by Headspace Solid Phase Microextraction Followed by Gas Chromatography‐Mass Spectrometry

The volatile and semi‐volatile compounds of Chinese rice wines were extracted by headspace solid phase microextraction (HS‐SPME) and analyzed by gas chromatography‐mass spectrum (GC‐MS). The original Chinese rice wine samples were diluted with deionized water to a final concentration of 6% (v/v) ethanol and then extracted by HS‐SPME. The samples were pre‐equilibrated at 50°C for 15 min and extracted with stirring at the same temperature for 45 min prior to injection into a GC‐MS. A total of 97 volatile and semi‐volatile compounds were identified from ten Chinese typical rice wine samples, including 13 alcohols, 8 acids, 28 esters, 4 aldehydes and ketones, 17 aromatic compounds, 3 lactones, 6 phenols, 3 sulphides, 9 furans and 6 nitrogen‐containing compounds, of which, 39 compounds were firstly reported in Chinese rice wine. By stepwise linear discrimination analysis, the ten Chinese rice wine samples could be classified into three groups according to the production area, and in particular, the production technologies.     

Differentiation of volatile aroma components in organically and conventionally produced apples by stir bar sorptive extraction combined with gas chromatography and EI/CI TOF mass spectrometry

Volatile aroma components and contents of organically and conventionally produced apples of the cultivars Elstar, Jonagold, Jonagored and Braeburn were studied. In three cultivars investigated, the aroma contents of organically produced apples were significantly lower (Elstar 16%, Jonagold 29%, Jonagored 68%). For Braeburn, no statistically significant difference was observed. In particular, the main aroma components were present at much lower concentrations in organically produced apples. In all apple cultivars, these were hexanal, trans-2-hexenal, 2-methylbutylacetate and hexylacetate. twenty-three aroma components were identified in total, in different relative ratios in the different apple cultivars: saturated esters, saturated and unsaturated aldehydes and alcohols. Some components identified in the conventionally produced cultivars were not present in the organically produced cultivars at all. The aroma components were extracted from juice freshly prepared from the apples by stir bar sorptive extraction (SBSE) technique and characterised by FID gas chromatography and EI/CI TOF mass spectrometry.     

工程重组米质构测定(TPA)与感官评价相关分析

为研究TPA测试在评价、改善工程重组米食用品质中的应用,运用质构仪测定工程重组米的有关质构指标,并分析了工程重组米感官评定与质构指标之间的相关性。结果表明,TPA测试能够使感官评价的品尝指标量化,便于数据处理和分析;感官评价结果与硬度和黏着性呈显著负相关(r=-0.863**、-0.763*),与咀嚼性、弹性、黏聚性和回复性显著正相关(r=0.873**、0.794*0、.844**0、.825**)。弹性、硬度和黏聚性指标对工程重组米感官评定的影响较大,其回归方程能够解释工程重组米感官评价变异的84.8%。     

猕猴桃感官评定与质地剖面分析的相关性

为确定猕猴桃质地的仪器测试方法是否反映人的真实感官,本研究以3种猕猴桃(海沃德、秦美、徐香)为对象,进行感官评定与质地剖面分析指标间的相关性分析。结果表明:3个品种猕猴桃的感官评定与质地剖面分析指标间广泛存在相关性,但相关系数不高(|r|=0.002~0.807)。采用逐步回归分析建立各感官指标的多参数预测模型,发现感官指标预测值与实际值的相关系数均有不同程度提高。预测模型中海沃德、秦美、徐香猕猴桃感官指标预测值与实际值间的相关系数分别为0.377~0.782、0.370~0.895和0.490~0.764。在预测模型的检验中,以总体可接受度为评定标准,其平均相对误差分别为10.04%(海沃德)、9.78%(秦美)和11.09%(徐香)。本研究结果证明利用多质构指标融合可以建立与感官评定更好地相关性。