果汁中添加外源糖检测技术的研究进展

果汁中添加外源糖检测技术是果汁鉴伪中重要组成部分,其潜在应用对于果汁质量与安全控制至关重要。本文综述国内外关于果汁添加外源糖检测技术的现状与最新进展,介绍红外光谱法、稳定性同位素法、核磁法、色谱法等检测技术的最新研究进展。分析评述各种检测方法的优缺点,为果汁鉴伪研究工作的开展提供理论参考。     

果汁中微生物检测技术的研究进展

微生物是影响果汁质量安全的重要因素,目前果汁微生物检测的方法主要是传统的培养基培养法,且检测的微生物种类较少,没有覆盖到影响果汁品质的多数微生物。随着果汁工业的迅速发展,消费者对食品安全需求的提高,急需寻求多种快速、简便方法相结合检测果汁中的微生物。本文介绍了当前微生物的检测方法,包括形态学方法、生理生化试剂盒、免疫学技术、仪器分析技术和分子生物学技术等,分析了各方法的优缺点和适用性,为果汁中微生物的检测分析提供参考。     

果汁饮料中原果汁含量检测技术的现状

综述了果汁饮料中果汁含量检测技术的现状与进展,分析比较了现行的各种果汁含量的检测方法,系统介绍了各种新型检测技术在果汁含量测定中的应用。     

我国果汁掺假检测技术研究现状

果汁由于其营养丰富且口感较好深受广大消费者的喜爱,但果汁加工原料成本较高,某些生产者在加工过程中添加外来物质或稀释来掺假,以此谋取高额利润,给消费者的健康带来了危害。文章介绍了我国及国际果汁的检测标准,总结了常见检测指标和检测方法,对新型果汁检测技术发展现状进行了综述,并展望了我国果汁掺假检测技术的发展前景。     

动态显色法鲎试验用于果汁细菌内毒素活性检测及干扰分析

目的建立一种定量检测果汁细菌内毒素活性的方法,准确评估果汁潜在的内毒素污染风险。方法采用动态显色法东方鲎(Tachypleus amebocyte lysate, TAL)试验对常见的4种果汁(橙汁、桃汁、苹果汁和葡萄汁)细菌内毒素活性进行检测,对果汁样品中的干扰因素进行识别与排除,最后使用抗增液排除β-葡聚糖等类似物质带来的假阳性结果。结果市售果汁(n=36)的细菌内毒素活性范围为0.2～209.5 EU/mL,自榨果汁(n=12)的细菌内毒素活性范围为0.4～4.2EU/mL,加标回收率范围均在50%～200%之间,符合药典要求。结论动态显色法TAL试验适用于常见的4种果汁(橙汁、桃汁、苹果汁和葡萄汁)细菌内毒素活性的检测,为果汁的健康风险评价和卫生监管提供参考。     

果汁饮料和加果汁清凉饮料的制造方法

果汁饮料是指含果汁50％以上的饮料,加果汁的清凉饮料是指含果汁10～50％的饮料。在生产工艺上除了原材料的配比不同外没有什么大的差别。制造果汁饮料和加果汁清凉饮料的技术关键是配制调整液,包括酸味、香味和色泽的调配。使之产生清凉感、色鲜、味美。应该特别注意的是:加工过程中微生物的污染;由使用水引起的化学的、物理的变化;由酶作用引起的果汁分离和透明化、褐变现象等。     

核磁共振氢谱法测定果汁中主要糖类的含量

该研究以邻苯二甲酸氢钾和柠檬酸分别作为定量内标和外标,结合水峰压制技术,建立了核磁共振氢谱法快速、同步、准确定量果汁中葡萄糖、果糖和蔗糖的含量。该方法果糖的检出限为0.005 g/L,定量限为0.018 g/L;葡萄糖的检测限为0.006 g/L,定量限为0.021 g/L;蔗糖的检出限为0.009 g/L,定量限制为0.030 g/L。葡萄糖、果糖、蔗糖在0.025～6.40 g/L线性关系良好（R²>0.999）;外标法加标回收率为100.9%～104.7%,内标法加标回收率为102.1%～108.6%,测量精密度相对标准偏差<1%;测定方法重复性好。与GB 5009.8—2016《食品安全国家标准食品中果糖、葡萄糖、蔗糖、麦芽糖、乳糖的测定》高效液相色谱法测定结果误差在±5%以内,满足方法的可行性验证要求。相比于国标方法该方法样品前处理简单,在测定结果准确的基础上,极大地节约了时间与人力,可实现果汁中葡萄糖、果糖和蔗糖同时定性定量检测,可广泛应用于果汁质量控制,同时为建立果汁核磁共振指纹图谱真实性鉴别技术奠定了良好基础。     

温控辅助离子液体分散液液微萃取-高效液相色谱检测果汁中杀菌剂残留

建立温控辅助离子液体分散液液微萃取结合高效液相色谱-二极管阵列检测器法检测果汁中7 种杀菌剂农药残留的新方法。对影响萃取效果的因素萃取剂和分散剂类型及体积、溶解温度、萃取时间和离心时间进行优化。在优化后的方法条件下,7 种杀菌剂富集倍数可达64～101;方法检出限在4.3～13.0 μg/L之间;在0.02、0.05 mg/L和0.10 mg/L三个水平下加标,果汁（苹果汁、梨汁、葡萄汁、桃汁和橙汁）的平均加标回收率在70.0%～116.2%范围内,相对标准偏差均小于9.8%,能满足多种果汁中杀菌剂农药多残留检测的要求。     

4种柑桔汁的缓冲能力与氮及灰分的二元线性回归关系

果汁含量是果汁的一项重要指标,但目前果汁含量检测方法还不完善,即使有一些检测方法,检测手段也比较繁琐、费时,同时费用较高。对于同一种果汁而言,果汁缓冲能力与果汁的含量呈线性相关关系,但同一类水果不同品种之间缓冲能力是否存在差异以及缓冲能力与水果的那些内在指标密切相关还不清楚。作者选择了南丰蜜桔,砂糖橘、皇帝柑和平远脐橙4种柑桔类水果,制备了相应的柑桔汁,并分别采用检测添加柠檬酸后H+浓度变化的方法检测了其果汁的缓冲系数,采用凯氏定氮法检测了其果汁中氮含量,采用灰化法检测了其灰分质量分数,结果显示这4种柑桔汁缓冲系数与氮含量和灰分呈二元线性相关,回归方程的建立能为利用缓冲能力检测果汁含量的方法提供理论依据。     

浆果果汁真伪鉴别技术研究进展

以蓝莓、树莓为代表的浆果类水果素有“黄金水果”的美誉,由于产量低、保质期短和价格高昂,浆果果汁掺假、造假、错误标签等导致的食品质量和安全争议不断发生,果汁真伪鉴别技术面临巨大挑战。目前,常用的浆果真伪检测方法主要是常规理化法和传统的分子生物学方法,这些方法在浆果果汁鉴定上各有优缺点。如理化方法的优势在于浆果的质量控制和品质评价,对产品中植源性成分的识别易受个体生长发育、加工条件等外部因素的影响;而基于DNA的分子生物学方法更多的用于果汁中植源性成分的识别。面对浆果果汁掺假造假现象,本文综述了近年来常用于浆果及其果汁质量控制和真伪鉴别技术的研究进展,主要包括感官技术、理化技术和分子生物学技术。     

Statistical Evaluation of Data for Detecting Adulteration of California Navel Orange Juice

Compositional data from California early-, mid-, and late-season navel orange juice, concentrate and two-stage pulpwash were analyzed by various statistical techniques (ratios, regression, chi-square, Linear combination, and discriminant analysis) for detecting adulteration. These techniques were evaluated according to applicability for detecting three types of adulteration: (1) addition of sugar and/or citric acid, (2) addition of excess or unauthorized pulpwash, and (3) addition of other constituents intended to mask the dilution. Most parameters were significantly affected by time of harvest following commercial maturity. Two-stage pulpwash showed small but significant differences from corresponding single strength juice. Product differences were of about the same magnitude as the differences due to harvest date.     

Characteristics of Israeli Citrus Peel and Citrus Juice

Data on the composition of Israeli orange juice, grapefruit juice, orange peel and grapefruit peel were analyzed. Significant differences were found mainly between the juice and peel in the content of isocitric acid, ash, minerals, total pectin, total flavonoids, chlorides, phosphates, chloramine-T number and arginine. The significance of these findings in detecting juice adulteration with peel extract solids is discussed. The chemical and amino acids characteristics of the citrus products analyzed may be used to establish guidelines required for detecting citrus juice adulteration.     

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.     

Detection of adulteration in citrus juice beverages

The detection of adulteration in citrus juices is a challenge to industry and regulatory agencies. Early work was directed towards detecting citric acid added to lemon juice. More recently, efforts have been made to develop methods of detecting adulteration in orange juice and to determine orange juice content in diluted orange beverages.     

Differentiation of Frozen and Unfrozen Beef Using Near-Infrared Spectroscopy

Freezing and thawing affects the quality of meat. The present paper focuses on using near-infrared (NIR) diffuse reflectance spectroscopy to detect whether beef has been frozen and thawed. Intact beef and drip or centrifuged meat juice of M longissimus dorsi slices from 40 cattle were used as samples. The meat juices were analysed using dry extract spectroscopy by infrared reflection (DESIR). From centrifuged juice 80 samples were classified 100% correctly, using crossvalidation, into frozen or unfrozen beef by the K nearest neighbours method. This was obtained by high-order principal components from 400–2500 nm spectra. Other multivariate techniques, smaller wavelength ranges and detecting refrozen, thawed beef also gave results between 90 and 100%. Analyses of drip loss, exudative properties, water-holding capacity and dry matter of meat juice supported the interpretation of the NIR measurements. The results showed that NIR might be used as a screening method to differentiate unfrozen and frozen beef. © 1997 SCI.     

苹果汁的掺假鉴定

从糖、有机酸、氨基酸、稳定性同位素、类黄酮、阳离子及光谱学等方面全面探讨了真假苹果汁的鉴定方法，为苹果汁加工业提出了一系列行之有效的鉴定掺假方法。     

蓝莓野果浓缩汁及蓝莓野果汁饮料生产技术的研究开发

以大兴安岭野生蓝莓为原料生产蓝莓野果浓缩汁和蓝莓野果汁。采用灭酶护色 ,真空浓缩 ,无菌灌装等加工工艺可使蓝莓野果浓缩汁保持良好色泽及药理作用。以蓝莓野果浓缩汁为原料 ,选择适当稳定剂及采用超微细化工艺处理 ,可获得口味良好、营养丰富、质量稳定的蓝莓野果汁饮料。     

余甘子清汁饮料加工工艺研究

对余甘果汁清汁饮料生产中存在的出汁率低、贮藏期易产生沉淀和褐变等关键技术及配方进行研究，为余甘子果汁饮料的产业化生产提供科学依据。     

Detection of fruit juice adulteration in apple and pear juice

A method has been developed to detect the adulteration of pear juice with apples and apple juice with pears. In different varieties of apples and pears and in several commercial juices the flavonoids were examined by HPLC with respect to their quality and quantity. The chalcones phloretin glucoside and phloretin xyloglucoside are typical compounds found in apples (detection limit 7 ng). They are suitable indicators for detecting adulteration of pear juice with apples. Isohamnetin glucoside cannot be detected in apples (detection limit 10 ng), but can be used to detect pears in apple juice. The extract or juice was purified with the aid of a polyamide column. The evaporated eluate of methanol was analysed by HPLC (gradient: acetonitrile/1% acetic acid). An RP-18 column and a UV-detector were used. Additionally, the UV spectra of the compounds indicating an adulteration were recorded by a diode array detector.