Solid-phase extraction and determination of trace aroma and flavour components in cider by GC-MS

Summary Minor volatile compounds are responsible for the aromas of cider. A simple technique for the analysis of these components is described based on solid-liquid phase extraction followed by quantitation by gas chromatography-mass spectrometry (GC-MS). The method is quantitative for analysis of alcohols, esters, lactones, phenols, and medium and long chain-length fatty acid.     

Ultrasound-assisted fermentation for cider production from Lebanese apples

The present work studies the impact of low-intensity ultrasound (US) on Hanseniaspora sp. yeast fermentations. The effect of pulse duration and growth phase on US application was first evaluated using a synthetic medium. The optimal conditions were then applied to apple juice US-assisted fermentation. An US treatment chamber was first designed to allow the recycling of the culture medium. The optimal US pulse duration on the yeast growth rate was of 0.5 s followed by 6 s rest period, and during 6 h of both Lag and Log phases. These US parameters led to a faster consumption of glucose in the medium during the fermentation, compared to the untreated culture. The impact of US was also depending on the growth phase, showing higher sensitivity of the yeast to US during the Lag phase rather than the Log phase. US-assisted fermentation of apple juice showed a significant increase in biomass growth and glucose consumption, along with a significant decrease in the ethanol yield. The fastest growth kinetic (by 52%), and the highest ethanol reduction (by 0.55% (v, v)) were obtained for the treatment during the first 12 h of fermentation, thereby, the stationary phase was reached faster, and the maximum biomass growth rate was 10 folds higher compared to the untreated culture. The results obtained in this study demonstrated the promising efficiency of US-assisted fermentation in stimulating the biomass growth and reducing the ethanol content in alcoholic beverages.     

Chemometric characterisation of Basque and French ciders according to their polyphenolic profiles

Polyphenolic compositions of Basque and French ciders were determined by HPLC-DAD following thiolysis, in order to characterise and differentiate these beverages and then develop a classification system capable of confirming the authenticities of both kinds of cider. A data set consisting of 165 cider samples and 27 measured features was evaluated using multivariate chemometric techniques, such as cluster analysis and principal component analysis, in order to perform a preliminary study of data structure. Supervised pattern recognition techniques such as linear discriminant analysis (LDA), K-nearest neighbours (KNN), soft independent modelling of class analogy (SIMCA), and multilayer feed-forward artificial neural networks (MLF-ANN) attained classification rules for the two categories using the chemical data, which produced satisfactory results. Authentication systems obtained by combining two of these techniques were proposed. We found that SIMCA and LDA or KNN models achieved 100% hit-rates, since LDA and KNN permit the detection of every Basque cider and SIMCA provides a model for Basque cider that excludes all French ciders. Polyphenolic profiles of the ciders provided enough information to be able to develop classification rules for identifying ciders according to their geographical origin (Basque or French regions). Chemical and organoleptic differences between these two types of cider are probably due to the original and distinctive cidermaking technologies used for their elaboration. Using polyphenic profiles, about 80% of French ciders could be distinguished according to their region of origin (Brittany or Normandy). Although their polyphenolic profiles did not provide enough information to achieve an authentication system for Breton and Norman ciders.Abbreviations AVI Avicularin - CQA Caffeoylquinic acid - CAF Caffeic acid - CAT (+)-catechin - CT-1, -2, -3 Unknown flavan-3-ols - DPn Average degree of polymerization of procyanidins - EC (–)-epicatechin - HCA-7 Ferulic acid - HCA-1, -2 ,-3, 4, -5, -6 Unknown hydroxycinnamic acids - HYP Hyperin - IQC Isoquercitrin - PC Total procyanidins - PCM p-Coumaric acid - PCQ p-Coumaroylquinic acid - PL Phloretin - PLG Phloridzin - PLXG phloretin-2-O-xyloglucoside - PPO Polyphenoloxidase - QCE Quercetin - QCI Quercitrin - RUT Rutin - CA Cluster analysis - KNN K-nearest neighbours - LDA Linear discriminant analysis - MLF-ANN Multilayer feed-forward-artificial neural network - PCA Principal component analysis - PC1 First principal component - PC2 Second principal component - PC3 Third principal component - RMSE Root medium square error - SD Standard deviation - SIMCA Soft independent modelling of class analogy - DAD Diode array detector - HPLC High Performance Liquid Chromatography - ND Not detected     

搅拌棒吸附萃取技术与GC-MS联用测定苹果酒挥发性物质

研究了检测苹果酒中挥发性物质的一种新方法—搅拌棒吸附萃取(简称SBSE)气质联用技术。对搅拌速度、搅拌时间、温度及加盐量对搅拌棒萃取效果的影响进行了研究。萃取条件为:10 mL苹果酒样加入3 g NaCl,于55℃下以1100 r/min的转速搅拌60 min。搅拌棒萃取出了苹果酒中80种挥发性物质,对其中的49种物质进行了定量。该方法具有良好的线性,所有标准曲线的线性相关系数均大于0.99。方法检出限为0.01~6.37μg/L,定量限为0.03~21.25μg/L,回收率在70.9%~111.4%之间,相对标准偏差均在10%以内。     

High-performance liquid chromatographic determination of major organic acids in apple juices and ciders

Summary A reversed-phase high-pressure liquid chromatographic method is presented for the simultaneous separation and determination of malic, citric, lactic, succinic and ascorbic acids in apple juices and ciders. After filtration and/or degasification, the organic acids in the sample are separated on a LiChrosorb/C₁₈ column and quantified by using a rapid diode array detector. The method is considered to be a suitable choice for the accurate and precise determination (C.V. 5%) of these compounds.     

Size-based separations of proteins by capillary electrophoresis using linear polyacrylamide as a sieving medium: model studies and analysis of cider proteins

Electrophoretic conditions to separate sodium dodecyl sulfate (SDS)-protein complexes according to their relative molecular mass by capillary electrophoresis (CE) using linear polyacrylamide as a sieving matrix were examined. Five purified proteins with relative molecular masses between 14 400 and 66 200 Da were separated on a coated fused-silica capillary with an internal diameter of 100 microm and an effective length of 24 cm (total length, 32.5 cm). Benzoic acid was added to the solution of purified proteins as internal standard; beta-mercaptoethanol was also added as reducing agent. The running buffer composition was 0.05 M tris(hydroxymethyl)aminomethane (Tris), 0.035 M aspartic acid, 0.1% m/v SDS, 4% m/v acrylamide, the resulting pH being 8.0. The applied voltage was 7 kV (reversed voltage polarity) in order to avoid high current intensities. Under optimized conditions, the five proteins were separated in less than 15 min, with a % relative standard deviation (RSD) between 0.2 and 0.4 for migration times in the same day. Good efficiency (values between 150 000 and 40 000 N/m) and resolution (values between 2 and 2.8) were obtained. The inverse of relative migration times was found to correlate with the logarithm of their relative molecular mass. Finally, cider proteins were analyzed and their relative molecular masses were determined. These results were compared with those obtained by SDS-polyacrylamide gel electrophoresis (SDS-PAGE).     

基于ICP-MS法的苹果酒发酵过程矿质元素的动态分析

利用电感耦合等离子质谱仪(ICP-MS)测定苹果酒发酵的不同时期主要矿质元素含量,分析在苹果酒发酵过程中主要矿质元素的吸收和释放的动态变化。结果表明：发酵液中含有的主要矿质元素有钾、钠、钙、镁、铁、锰、铜、锌、锶、硼等十种,其中钾元素的含量最高,在苹果汁中达到1 853.83 mg·L-1,经过发酵后的含量为1 654.38 mg·L-1。在发酵过程中,各种矿质元素的含量处于不断的动态变化之中,整体看来,在发酵进行72～120 h以及144～216 h,大部分矿质元素的含量变化波动较大;尤其在发酵进行到192 h,大部分矿质元素的含量都达到峰值或谷值,其中铁和锌元素的含量达到峰值,钾、钠、钙、镁、锰、硼六种元素的含量达到谷值。但在随后发酵结束前的24 h内,矿质元素的含量又剧烈反弹。经过发酵过程后,钾、镁、铜、锌、硼等元素的含量显著降低,钠、钙、锰、铁、锶等元素含量变化不显著。对十种元素进行相关性分析,结果表明钙元素和锰元素之间的相关性最高,pearson相关系数达到0.924。试验结果为调控酿酒过程,控制产品质量提供了理论依据。     

基于ICP-MS法的苹果酒发酵过程矿质元素的动态分析

利用电感耦合等离子质谱仪(ICP-MS)测定苹果酒发酵的不同时期主要矿质元素含量, 分析在苹果酒发酵过程中主要矿质元素的吸收和释放的动态变化。结果表明: 发酵液中含有的主要矿质元素有钾、钠、钙、镁、铁、锰、铜、锌、锶、硼等十种, 其中钾元素的含量最高, 在苹果汁中达到1 853.83 mg·L-1, 经过发酵后的含量为1 654.38 mg·L-1。在发酵过程中, 各种矿质元素的含量处于不断的动态变化之中, 整体看来, 在发酵进行72～120 h以及144～216 h, 大部分矿质元素的含量变化波动较大;尤其在发酵进行到192 h, 大部分矿质元素的含量都达到峰值或谷值, 其中铁和锌元素的含量达到峰值, 钾、钠、钙、镁、锰、硼六种元素的含量达到谷值。但在随后发酵结束前的24 h内, 矿质元素的含量又剧烈反弹。经过发酵过程后, 钾、镁、铜、锌、硼等元素的含量显著降低, 钠、钙、锰、铁、锶等元素含量变化不显著。对十种元素进行相关性分析, 结果表明钙元素和锰元素之间的相关性最高, pearson相关系数达到0.924。试验结果为调控酿酒过程, 控制产品质量提供了理论依据。     

Fluorimetric determination of histamine in wine and cider by using an anion-exchange column-FIA system and factorial design study

A study has been performed of the conditions for the reaction of histamine with o-phthaldehyde in a flow injection analysis system employing three channels, using an anion-exchange column to eliminate sample matrix interferences. Factorial design was used to determine which operational parameters should be included in the optimization and their optimal values were found. The method developed shows good selectivity for histamine determination in alcoholic beverages. A linear response of up to 2.0 mg l⁻¹ was observed and the detection and quantification limits were 30 and 101 μg l⁻¹, respectively. The repeatability, measured by the R.S.D. for 10 replicate injections, was 0.84 and 0.52% for histamine solutions of 0.20 and 2.0 mg l⁻¹, respectively. The recoveries obtained in wine and cider samples were close to 100% and a sample frequency of 24 samples per hour was achieved.     

Application of purge and trap extraction and gas chromatography for determination of minor esters in cider

The validation of a method based on the purge and trap technique combined with gas chromatography-mass spectrometry-flame ionization detection has been carried out in order to apply it to the analysis of ciders. Although 49 compounds were identified, our work was focused on the study of nine minor esters, obtaining recoveries ranging between 93% for ethyl decanoate and 117% for ethyl 3-methylbutyrate, and a precision (RSDs) ranging between 2.2% for hexyl acetate and ethyl decanoate and 10.9% for isopentyl acetate. To demonstrate the feasibility of the procedure, the method was applied to the analysis of commercial ciders.