电子舌在鲜榨橙汁掺假识别中的应用研究

在鲜榨橙汁中分别添加不同比例的橙汁饮料,采用电子舌检测技术对其口味进行识别,对传感器所获得的响应信号进行主成分分析(PCA)、辨别因子分析(DFA)和偏最小二乘回归分析(PLS)。与PCA相比,DFA对样品的区分效果更好,随着掺假比例的增加,样品分布呈现一定的规律性;PLS分析法显示:橙汁饮料的不同掺入比例与电子舌响应信号有较好的相关性,相关系数为0.963 8;PLS模型预测误差值在1.85%~2.20%。证明电子舌技术能够有效的用于鲜榨橙汁掺假的鉴别。     

Detection of orange juice adulteration by tangelo juice using multivariate analysis of polymethoxylated flavones and carotenoids

Reverse phase HPLC has been applied to quantify levels of polymethoxylated flavones and carotenoids in orange and tangelo juices. Lower levels of sinensetin and tetramethyl‐o‐scutellarein and higher levels of heptamethoxyflavone and tangeretin relative to nobiletin indicated the addition of tangelo to orange juice. β‐Cryptoxanthin and its esters, identified by positive ion electrospray mass spectrometry, were present in larger amounts relative to β‐carotene in tangelo than in orange juice. Using canonical discriminant analysis, the addition of 100 g kg^?1 tangelo to orange juice can be detected. © 2002 Society of Chemical Industry     

常见果汁掺假检测技术的研究进展

对常见果汁掺假进行理化检测技术进行了综述。     

基于近红外光谱和随机森林方法鉴别蜂蜜真伪

目的建立蜂蜜样品真伪鉴别的近红外光谱快速检测方法,为今后蜂蜜检验工作提供可靠参考依据。方法采用积分球透反射模式采集样品近红外光谱数据,以Savitzky-Golay 1阶微分方法对原始光谱进行预处理,以随机森林方法建立光谱数据与蜂蜜真伪的定性判别模型。结果所建立的判别模型中训练样本判别正确率为100%,测试样本判别正确率为95%。结论近红外透反射光谱技术应用于蜂蜜真伪鉴别的可行性,同其他分析方法相比具有操作简单、速度快、效率高、无污染、费用低、无需复杂前处理等优点。     

Unsuitability of data acquired from blended samples for testing orange juice purity

Non-blended juices (83) obtained directly from Spanish oranges and several computer-simulated blends of these juices were used as reference samples for the detection of orange juice dilution. Amino acids (16), absorbances at different wavelengths (3), minerals (3), ash and isocitric acid were determined in each non-blended juice. The values of these characteristics in blended samples were calculated from the proportions of juices used in simulating each blend. When using non-blended juices for reference, no significant erroneous rejection (less than 1% working at the 99% confidence level) of pure juices and quite good detection of diluted samples were observed. By contrast, the use of reference sets of blended samples led to the erroneous rejection of many pure juices (74% of non-blended juices when the reference set was constituted by binary blends).     

浓缩还原橙汁饮料中果汁含量快速检测方法探究

果汁含量是浓缩还原橙汁的主要质量指标,也是判定其是否掺假的重要依据。本研究发现:不同产地、不同果汁含量的浓缩还原橙汁饮料中,可溶性物质在325nm紫外波长处有特征吸收,并且与22种常用添加剂溶液的紫外吸收有明显区分;采用自主研制的快速检测设备,将橙汁中可溶性物质按分子量大小分离,325nm下连续检测,得到橙汁可溶性物质按分子量大小分布的紫外特征吸收峰,其峰面积与橙汁含量呈现正相关;以100%巴西浓缩还原橙汁为标准参照,用外标法计算果汁含量。该方法样品前处理简单,只需过滤、超声,即可经凝胶色谱柱分离、检测;色谱柱分离和325nm的检测波长,有效避免了22种常用添加剂对果汁含量检测的干扰;该方法精密度高(RSD<6.0%)、线性关系好(R2=0.9988)、抗干扰性强,可用于果汁含量大(等)于10%的橙汁饮料中原果汁含量的快速、大批量检测。      

Targeted and non-targeted detection of lemon juice adulteration by LC-MS and chemometrics

Economically motivated adulteration (EMA) of lemon juice was detected by LC-MS and principal component analysis (PCA). Twenty-two batches of freshly squeezed lemon juice were adulterated by adding an aqueous solution containing 5% citric acid and 6% sucrose to pure lemon juice to obtain 30%, 60% and 100% lemon juice samples. Their total titratable acidities, °Brix and pH values were measured, and then all the lemon juice samples were subject to LC-MS analysis. Concentrations of hesperidin and eriocitrin, major phenolic components of lemon juice, were quantified. The PCA score plots for LC-MS datasets were used to preview the classification of pure and adulterated lemon juice samples. Results showed a large inherent variability in the chemical properties among 22 batches of 100% lemon juice samples. Measurement or quantitation of one or several chemical properties (targeted detection) was not effective in detecting lemon juice adulteration. However, by using the LC-MS datasets, including both chromatographic and mass spectrometric information, 100% lemon juice samples were successfully differentiated from adulterated samples containing 30% lemon juice in the PCA score plot. LC-MS coupled with chemometric analysis can be a complement to existing methods for detecting juice adulteration.     

近红外光谱结合化学计量学技术在食品掺假分析中的应用

近红外光谱结合化学计量学技术由其独特的技术优势在食品掺假分析领域已得到广泛应用。本文对近红外光谱结合化学计量学技术的原理及特点进行论述, 并综述了近10年来应用较为广泛、实用性较强的化学计量学方法, 偏最小二乘法、人工神经网络及支持向量机结合近红外光谱技术在食品掺假分析中应用, 展望了该技术的发展前景。     

温州蜜柑汁的超滤分离工艺研究

利用PVDF膜对柑桔汁进行了超滤分离实验,研究了不同预处理方法对超滤分离的影响、超滤的适宜工作条件及膜的清洗方法。结果表明:PVDF膜对150目筛滤离心过滤后的果汁表现出较强的抗污染能力;超滤分离柑桔汁的最佳工作条件为:操作压力为0.2MPa,温度为40℃,流速为1m/s;0.1%NaOH 和0.5%U10溶液是理想的超滤膜清洗剂。     

荧光法鉴别苹果汁掺伪的研究

利用荧光分光光度计研究几种不同品牌100％苹果汁的荧光特性以及苹果汁中常见的掺伪物质的荧光特性.通过分析3D扫描图谱,确定最佳工作波长为激发波长379nm,发射波长463nm.配制一系列浓度梯度的标准溶液,并测定其在最佳工作波长下的荧光强度,得到标准曲线及对应的标准曲线方程.同时,试验结果表明掺伪物质在最佳工作波长下并没有明显的荧光特性,不会干扰苹果汁饮料中原果汁含量的测定,但苹果汁的荧光强度随温度升高而有所降低.     

Nondestructive determination of soluble solids content and pH in tomato juice using NIR transmittance spectroscopy

The potential of near-infrared (NIR) transmittance spectroscopy to nondestructively detect soluble solids content (SSC) and pH in tomato juices was investigated. A total of 200 tomato juice samples were used for NIR spectroscopy analysis at 800–2400 nm using an FT-NIR spectrometer. Multiplicative signal correction (MSC), and the first and second derivative were applied for pre-processing spectral data. The relationship between SSC, pH, and FT-NIR spectra of tomato juice were analyzed via partial least-squares (PLS) regression. PLS regression models were able to predict SSC and pH in tomato juices. The r _c, RMSEC, RMSEP, and RMSECV for SSC were 0.92, 0.0703°Brix, 0.150°Brix, and 0.138°Brix, respectively, whereas those values for pH were 0.90, 0.0333, 0.0316, and 0.0489, respectively. It is concluded that the combination of NIR transmittance spectroscopy and PLS methods can be used to provide a technique of convenient, versatile, and rapid analysis for SSC and pH in tomato juices.     

果胶酶对玫瑰香橙汁澄清效果的影响

以果胶酶为澄清剂,研究果胶酶用量、pH、温度和时间对玫瑰香橙汁澄清度的影响。通过单因素试验,并利用Box-Benhnken中心组合设计,进行澄清条件优化。结果表明,果汁透光率测定最佳波长为685 nm,澄清最佳工艺参数为果胶酶用量0.09 g/L,酶解温度31 ℃,果汁pH值为3.9,酶解时间120 min。在此最佳条件下,玫瑰香橙汁的透光率为98.00%。     

The debittering of navel orange juice using polymeric films

ABSTRACT:  In order to better understand and optimize the sorption of limonin (the major navel orange juice bitter principle) by various plasticized polymeric films, a sorption and plasticizer migration study was carried out using high-performance liquid chromatography (HPLC) and gas chromatography (GC). Low molecular weight (LMW) poly (vinyl chloride) (PVC) plasticized with dioctyl adipate (DOA) gave the best results for both limonin sorption and low DOA migration. Thick films did not significantly sorb more limonin than thin films in the timeframe of our experiments, as the absorption involved rapid surface sorption followed by slow bulk diffusion. The debittering efficiency was a 1000-fold greater than that obtained with current polystyrene divinylbenzene resin beads, with potential for industrial scale debittering.     

中红外光谱在食品掺假检测中的应用

中红外光谱 (MIR)以其在 40 0 0 - 40 0cm-1处的指纹吸收特性广泛应用于机电、医药等领域。随着计算机技术和化学计量学方法的发展 ,MIR在食品领域的应用研究也已展开。本文仅就其在食品掺假检测中的应用加以概述     

橙汁混浊稳定性的研究进展

橙子榨汁后,果肉颗粒、细胞壁碎片、橙油微滴、橙皮苷结晶、细胞色素及一些无定形物质不均匀的分散于水中,使橙汁呈现特殊的不透明或混浊状态,即\     

元素分析/液相色谱-碳同位素比值质谱法在纯正 苹果汁掺假鉴别中的应用

目的建立一种鉴别检测苹果汁掺假情况的元素分析/液相色谱-同位素比值质谱法(elemental analysis/liquid chromatography-isotope ratio mass spectrometry,EA/LC-IRMS)。方法通过对不同产区不同种类118个纯正苹果汁的糖、有机酸、果糖、葡萄糖、二糖、寡糖碳同位素比值(δ~(13)C值)的测定,建立纯正苹果汁同位素数据库进而提出纯正苹果汁应满足的δ~(13)C值要求。结果有机酸和糖差值Δδ~(13)CO-S在-1.38‰至1.09‰范围内,果糖和葡萄糖差值Δδ~(13)CF-G在-0.70‰至0.57‰范围内,而各组分最大差值Δδ~(13)Cmax4.36‰。对市售105个苹果汁进行检测,采用本方法检出32个阳性样品,而采用本实验室的糖浆标志物法仅检出12个阳性样品。结论本方法大大提高了苹果汁的掺假鉴别,有很大的实际应用潜力。     

不同杀菌方式对橙汁色泽的影响不同杀菌方式对汁色泽的影响

橙汁经过不同杀菌处理后,CIEL＊、CIEb＊、CIEC＊、Hue升高,CIEa＊、OJ值略有降低,同时类胡萝卜素、维生素C含量降低,褐变指数升高。相关性分析表明,类胡萝卜素的变化与橙汁指数OJ值呈极显著正相关。杀菌后的橙汁色泽发生明显变化,褐变指数增加。此外,煮沸杀菌对橙汁色泽的影响最大,高温高压杀菌次之,而微波杀菌对橙汁色泽的影响相对较小。     

近红外光谱技术在液态食品掺假检测中的应用

近些年,食品安全事故有增多趋势,而在众多针对食品掺假的检测技术中,近红外光谱技术因其快速、方便等优点而受到关注。本文主要综述了近红外技术在牛奶、蜂蜜和食用油等液态食品掺假检测研究的发展状况,并分析了如今所存在的问题和未来的发展方向。      

保健型橙汁酸奶的研究与开发

以橙汁、生乳为主要原料，研究了营养保健型橙汁酸奶的制作工艺。采用正交试验方法，确定最佳工艺参数．该产品具有较高的营养价值。