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。     

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).     

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.     

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。     

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.     

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     

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。     

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。     

Studies on non-enzymic browning in orange juice using a model system based on freshly squeezed orange juice

An orange juice based model system was set up wherein variables such as the addition of glucose, lysine, sorbitol and L -ascorbic acid and changes in pH and storage temperature were introduced to study their effects on L -ascorbic acid degradation and on browning. The addition of glucose, lysine and sorbitol did not have a significant effect on L -ascorbic acid degradation, whereas added L -ascorbic acid acted solely as a reserve material. In terms of browning, a change in pH and storage at elevated temperature produced a synergistic effect in the development of brown colour which was enhanced by the introduction of additives. Based on the results obtained, L -ascorbic acid appears to be the precursor in the non-enzymic browning occurring in this type of sample due to the formation of reactive carbonyl compounds produced upon its degradation which tend to polymerise, or to react with nitrogenous compounds, to give brown pigments.     

粒粒橙饮料的研制

以柑桔为主要原料，对粒粒橙的生产工艺和生产配方进行了研究，得出了既保持柑桔的原有风味。使产品清凉爽口、酸甜适宜，又保证产品安全性的两次杀菌生产工艺。以及使产品稳定性好、果粒悬浮均匀、产品感观效果好的以琼脂为稳定剂的配方。     

橙汁乳酸饮料的研制

以桔子汁为主要原料,研制乳酸饮料,运用正交实验确定其最佳工艺参数为乳酸菌接种量为5%、加糖量为7%、发酵温度为42℃、发酵时间为24h。所得产品口感良好、性质稳定、富含VC,是一种营养保健的大众饮品。     

橙汁品质评价国内外研究现状

橙汁是世界上最受欢迎的果汁饮料.就国内外橙汁的研究现状进行了综述,介绍了主要的国际标准及国内标准,重点阐明了橙汁品质评价及鉴伪分析的研究进展,分析了当今研究中存在的问题,提出感官评价与其特征成分进行相关性分析,实现定性和定量综合描述,是未来研究工作以及产品标准制定的发展趋势.     

橙汁非酶褐变机制及控制措施

阐述了橙汁非酶褐变的机制：美拉德反应、焦糖化反应、抗坏血酸的氧化分解和多酚类化合物氧化缩合反应。通过对橙汁原料选择、杀菌方式、贮藏方式、褐变抑制剂添加及加工中吸附树脂使用的分析,重点综述了在橙汁加工储藏过程中控制非酶褐变的措施。     

序列式柑桔压榨机机构运动学的计算机仿真

对序列式柑桔压榨机的主要机构进行运动学分析,推导了柑桔压榨机的机构运动学参数的表达式,提出了用计算机对它们的运动学仿真方法。该仿真方法为柑桔压榨机的机构的动力学分析打下了基础,可迅速地检查设计参数的合理性及工作性能。     

加工和储藏条件对橙汁芳香成分的影响

橙汁的怡人香气是由多种挥发性化合物混合而成。鲜榨橙汁经热加工后性质更稳定,但对芳香物质影响较大。热处理会降低香气活性化合物含量,并产生异味物或其前体物。乙烯基愈创木酚、对伞花烃和香芹酮等异味物都是化学反应的产物,而丁二酮、愈创木酚和2,6-二氯苯酚则是微生物污染物。文中简述了橙汁的芳香物质组成,重点介绍了不同的加工方法、包装、储藏和微生物污染对橙汁芳香物质的影响的研究进展,并探讨了研究中存在的问题和未来的研究方向。     

橙汁储藏期非酶褐变控制与感官评定

橙汁作为世界上销量最大的果汁类饮品,其储藏过程中的褐变一直是研究领域的一大难题.综述了目前抑制橙汁褐变的一些方法,并介绍了橙汁储藏过程中的感官评定方法,为橙汁褐变的研究提供一定的理论基础.     

利用氨基酸分析仪对橙汁中脯氨酸定量研究

利用氨基酸分析仪对橙汁饮料中的游离脯氨酸进行测定,结果表明,橙汁饮料中含有一定量的脯氨酸,其含量差异较大,含量范围在0～919mg/L之间。分析果汁含量和脯氨酸含量之间的关系,结果表明,其含量的大小不能作为橙汁饮料中天然果汁含量多少的判定依据,要综合考虑其他的检测因子才能判定是否掺假。     

橙汁的果汁含量测定及与其6种特征指标相关性的比较

测定了19个橙汁样品的果汁含量,并比较了GB/T16771-1997《橙、柑、桔汁及其饮料中果汁含量的测定》中所规定的6个特征指标(钾、总磷、氨基酸态氮、L-脯氨酸、D-异柠檬酸、总黄酮)含量与果汁含量的相关性。结果表明,6个特征指标的含量和果汁含量都具有不同程度的相关性,其中钾含量与果汁含量相关性最大,相关系数达0.6873;氨基酸态氮含量与果汁含量相关性最小,相关系数为0.3768,但均未达到显著相关水平。     

高压脉冲电场杀菌技术在橙汁中的应用

食品冷杀菌技术是一类不用热能杀死微生物,不影响食品营养、质构、色泽和风味的新兴杀菌技术。主要阐述了高压脉冲电场杀菌（PEF）的基本原理和优点,讨论了其在橙汁中的应用,并对比了PEF处理和热处理（90℃,15s）对橙汁微生物的杀灭效果及橙汁理化指标的变化。