乳酸菌饮料中嗜酸乳杆菌的实时荧光定量PCR检测方法

目的：为快速准确检测乳酸菌饮料中的嗜酸乳杆菌,建立实时荧光定量聚合酶链式反应（polymerase chain reaction,PCR）检测方法。方法：根据嗜酸乳杆菌NCFM的SPIDR保守区域设计特异性引物与探针,借助建立的实时荧光定量PCR方法进行特异性、灵敏度、重复性以及抗干扰能力验证,并利用模拟样品对方法进行检验,最后对市售的实际样品进行检测。结果：该方法的特异性较好;方法的绝对灵敏度达到3pg,相对灵敏度达103 CFU/mL;重复性检测表明相对标准偏差在2.6%以下。同时进行杂菌干扰实验,在纯基因组水平和培养物水平混合大肠杆菌,扩增均无明显影响,表明建立的方法抗干扰能力较好。利用建立的实时荧光定量PCR方法对模拟样品进行检测并建立标准曲线,得出R2为0.987,线性较好,可进行实际样品的检测。对市售的11 份样品进行检测,其中6 份含有嗜酸乳杆菌菌株,5份不含嗜酸乳杆菌菌株,标记嗜酸乳杆菌的样品全部检测出嗜酸乳杆菌且含量在5.83×102～3.68×104 CFU/mL之间。结论：建立的实时荧光定量PCR方法可快速、准确地检测出乳酸菌饮料中嗜酸乳杆菌。     

实时荧光聚合酶链式反应法检测食品中猪源性成分

针对猪线粒体细胞色素b基因序列设计特异的引物和探针,建立食品中猪源性成分实时荧光聚合酶链式反应检测方法,并经特异性和敏感性试验验证其可行性。结果表明：该体系可扩增猪肉DNA片段,长度为98bp,其他常见畜、禽肉成分均无法正常扩增。该体系灵敏度低至1pg,且阴性样品扩增后的Ct值限制在35循环以后。对于各模拟肉类样品中掺杂的猪源性成分,其检测限均达1%,经市售加工食品检测验证,表明所建立的猪引物探针体系具有特异性好、灵敏度高、快速、高效等优点,可用于对食品中猪源性成分的掺假鉴别检测。     

果汁DNA提取方法比较及柑橘属植物分子生物学检测技术的研究

以橙汁为研究对象,选取市售100%橙汁及橙汁饮料各3种,采用CTAB法、SDS-CTAB法以及改良CTAB法提取其DNA,对所提取的DNA的浓度、纯度及扩增效率进行比较;同时选取橙UDP-葡糖基转移酶蛋白基因设计柑橘属植物特异性扩增引物,通过定性PCR检测其特异性和灵敏度,并应用于果汁中柑橘属植物的检测。实验结果证明,由改良CTAB法获得的DNA模板质量较高,适用于果汁中DNA的提取。UGT基因引物可对柑橘属植物产生特异性扩增,最低检测限为10pg/μL。将该引用物用于市售橙汁的检测,其检测结果为阳性,从而证明UGT基因特异性引物可用于果汁中的柑橘属植物成分的检测及鉴伪研究。     

实时荧光PCR法检测奶制品中常见谷物成分

建立Taqman实时荧光PCR法对奶制品中掺加物大米、玉米、小麦、高粱、大麦等谷物源性成分的初筛检测体系。方法 以常见掺加物大米、玉米、小麦、高粱、大麦等谷物的叶绿体rbcL基因作为靶基因,通过BLAST软件比对,选择其同源保守区域设计引物和探针。经通用性、特异性、灵敏性试验对探针和引物可行性进行验证,并通过模拟含谷物奶粉及市售奶类制品检测对其实际检测能力进行验证。结果 所建立体系可扩增大米、玉米、小麦、高粱、大麦等常见的谷物掺加物的DNA提取物,与市售奶制品的主成分牛奶、羊奶以及其常见添加物香蕉、红枣、菠萝、草莓、西红柿、花生、大豆等动植物源性成分无交叉扩增(Ct＞35)。对小麦纯DNA提取物检出限为0.01ng。对分别掺加5种谷物成分的模拟奶制品检出限均可达0.5%,对市售的14份奶类食品中的谷类成分的检测结果均与食品标签相符。结论 本研究建立的Taqman实时荧光PCR体系具有通用、相对特异、灵敏、实用等优点,可用于奶制品中掺加或掺杂掺假谷物源性成分的快速定性检测。     

果汁中柑橘属成分实时荧光PCR检测方法

通过分析20条不同柑橘属植物的trnL基因序列,设计柑桔属植物特异性扩增引物。通过对苹果、梨、葡萄等多种水果成分的特异性筛选,建立检测柑桔属植物成分的SYB Green实时荧光PCR检测方法,该方法对柑桔DNA的检测低限为0.1pg/μL。用该方法检测10种橙汁及其饮料商品,结果表明,该方法能够检测到橙汁中的柑桔属植物成分。该方法可用于果汁或食品中柑桔属植物成分的鉴别。     

实时荧光PCR技术快速检测奶制品中掺入的大米源性成分

目的:建立基于实时荧光PCR技术的奶制品中掺入大米源性成分的快速检测方法。方法:以水稻的根部表达基因(gos9)为靶基因设计特异性引物和探针,经特异性实验和灵敏度实验验证引物探针可行性,并经模拟含大米奶粉及市售奶类制品检测验证其实际检测能力。结果:该引物探针体系只针对大米DNA进行扩增,与奶类主成分牛、羊及其它谷类和植物性食物DNA均无交叉扩增;最低能检测到0.1ng的大米DNA,对含大米粉的模拟混合奶粉样品,检出限可达0.1%(W/W)。将其应用于21份市售奶制品样品检测,对含大米源性成分的奶制品扩增阳性,检测结果与食品标签相符。结论:该实时荧光PCR检测体系具有快速、特异、灵敏的优点,可以准确鉴定出奶制品中大米成分,适用于奶类中掺加大米源性成分的检测。     

实时荧光PCR技术快速检测食品中的牛源成分

目的:建立基于实时荧光PCR技术的食品中牛源性成分快速检测方法.方法:以牛线粒体细胞色素b为目的基因,设计特异性引物和探针,通过特异性、灵敏性实验,及模拟混合肉样和市售肉制品检测,对该体系进行验证.结果:该牛源荧光PCR检测体系具有很好的特异性及灵敏性,可检测1pg牛源DNA的存在,对于各模拟肉类样品中掺杂的牛源性成分,其检测限低至0.5％,且经市售加工食品验证具有较好的应用能力.结论:所建立的牛引物探针体系具有特异性好、灵敏度高,快速高效等优点,可用于对食品中牛源性成分的掺假鉴别检测.     

实时荧光聚合酶链式反应检测肉制品中的鸭源性成分

通过鸭的肌动蛋白β-actin保守基因设计可特异检测鸭肉成分的引物和探针,建立实时荧光聚合酶链式反应（polymerase chain reaction,PCR）技术检测鸭肉的方法,并通过模拟肉样和市售样品检测方法的准确性和适用性。结果表明：该方法可以特异性检测出麻鸭和草鸭成分,而对猪、牛、羊、鸡等DNA均没有扩增,检测灵敏度可达到1 pg DNA;通过模拟肉样检测确定最低质量分数检测限为0.01%;市售样品的检测结果表明,该方法能很好地应用于市场,满足市场检测需求。     

环介导等温扩增技术快速检测植物蛋白饮料中大豆成分

目的 建立植物蛋白饮料中大豆成分环介导等温扩增（Loop-mediated isothermal amplificantion,LAMP）快速检测技术方法。方法 根据大豆Lectin基因保守序列,设计大豆成分环介导等温扩增检测特异性引物和反应体系,对方法特异性、灵敏度和稳定性进行测试,并以实时荧光PCR方法为参比方法,对32种植物蛋白饮料进行检测应用验证。结果 本研究建立的LAMP方法特异性强,稳定性好,最低检出限为0.1%（以质量分数计）;通过参比方法验证,方法特异性和灵敏度为100%,不存在假阳性和假阴性。结论 本研究建立的LAMP技术快速检测植物蛋白饮料大豆成分的方法具有操作简单、快速准确、检测成本低等优点,可为植物蛋白饮料大豆成分掺杂掺假提供一种快速检测方法。     

市售橙汁类饮料总抗氧化活性的比较

比较市售橙汁类饮料的总抗氧化活性。采用ABTS法对11种市售橙汁类饮料的总抗氧化活性进行测定，并分析其总抗氧化活性与所含抗坏血酸、多酚类以及类胡萝卜素的关系。结果：100％橙汁的总抗氧化活性比调配得到的橙汁类饮料要高，调配得到的橙汁类饮料由于添加了VC和β-胡萝卜素也具有较高的抗氧化活性。样品总的抗氧化活性与多酚类的含量之间存在着较好的相关性，说明多酚类物质可能是市售橙汁类饮料的主导抗氧化活性成分。     

Antioxidant activity of pasteurized and sterilized commercial red orange juices

Blood orange juice is a typical Italian product whose red color is primarily associated with anthocyanin pigments. Two orange-based products are present on the market: pasteurized pure juice with 40 days of shelf life, and sterilized beverage containing minimum 12% of concentrated fruit juice. The aim of the present paper is to verify the relationships between the antioxidant properties and the anthocyanins content in a sampling of pasteurized and sterilized commercial red orange juices. The anthocyanins composition was determined by HPLC-MS/MS, while the antioxidant activity was evaluated by the Briggs-Rauscher reaction, selected in order to acquire information at acid pH values, by three radical scavenging assays (DMPD, 2-2'-azinobis-(3-ethylenbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), DPPH), and by FRAP assay to monitor the ferric reducing power. Results showed that antioxidant activity, particularly when measured by ABTS method, is positively related to the content of anthocyanins and that the reduction of anthocyanins content, typical of commercial long-shelf life juices, leads to a remarkable loss of antioxidant power.     

Analysis of sterols: a novel approach for detecting juices of pineapple,passionfruit, orange and grapefruit in compounded beverages

Direct GC/MS analysis of the hexane extracts of fruit juices provides an efficient means for demonstrating that very different sterol patterns exist in the juices of pineapple, passionfruit and the two citrus fruits, orange and grapefruit. Ergostanol and stigmastanol were found to be the sterol markers for pineapple juice, while passionfruit juice was characterised by the presence of an unidentified but unique sterol referred to as compound C. Juices of orange and grapefruit yielded very similar sterol profiles. They were readily distinguished from pineapple and passionfruit juices by a higher stigmasterol/campesterol ratio. Valencene/nootkatone response ratio in the hexane extracts was employed to aid in the differentiation of the two citrus juices. Matrix effects on the determination of sterol and sesquiterpenoid distributions were found to be insignificant. Although natural variation and absolute uniqueness of the sterol profile for each of the four fruit juices were not established due to the relatively small number of fruit samples examined, the results of several compounded beverages clearly point to the potential usefulness of sterol profiles for detecting juices of orange, grapefruit, pineapple and passionfruit in mixed drinks. © 1998 SCI.     

Instrumental measurement of orange juice colour: a review

Colour of orange juice is provided by carotenoids, which belong to one of the main classes of natural pigments, although the colour of particular orange varieties, blood oranges, is mainly due to anthocyanins. Colour of food influences consumers' preferences. For orange juices, some studies have revealed that the colour of citrus beverages in general is related to the consumer's perception of the quality of these products. The USA attaches great importance to the objective evaluation of orange juice colour, to the point that this attribute is evaluated for the commercial classification of the product on the basis of its quality. Apart from the importance of orange juice colour in relation to the quality of the product, it is important to accurately measure this parameter since it has been demonstrated that colour measurements can be used to estimate the carotenoid content rapidly for quality control purposes. Owing to this factors, several techniques and instruments have been developed over the years. This review assesses these methods and the results gained from them. Copyright © 2005 Society of Chemical Industry     

Fertilisation and pesticides affect mandarin orange nutrient composition

The effects of the application of foliar fertilisation and pesticide on nutritional quality of mandarin orange juices were evaluated using ¹H NMR metabolomics. Significant differences between the use of fertiliser and pesticides during fruit formation were observed, and included changes in sugar, amino acid and organic acid composition. To determine whether the difference in sugar concentration was enough for the consumer to detect, a sensory experiment was performed in which two orange juice samples were prepared to resemble the sweet/sour taste balance of juice from mandarin oranges in which foliar fertilisation was either applied or not. In a test using non-trained individuals, 68% could correctly identify which juice had a sourer, or less sweet, taste. The implications of this study could impact citrus growers, and ultimately aid in development of fruit with superior sensory quality.     

Characterisation of volatile aroma compounds of orange juices by three dynamic and static headspace gas chromatography techniques

The influence of collection of volatiles by different headspace sampling techniques was compared for different orange juices, including one fresh unpasteurised, two reconstituted commercial juices and one juice freshly hand extracted in the laboratory. Dynamic headspace sampling from stirred juice samples (DH + S) and notably by purge and trap (PT) sampling gave the highest levels of analysed volatiles, but the composition of the isolated volatiles from the different types of juices varied depending on the volatiles collection method. Aroma sampling by dynamic headspace method without stirring (DH) gave results that reflected the equilibrium aroma composition as determined by static headspace better than that obtained by PT sampling. Totally, 67 aroma constituents were identified among all the orange juices. The largest amount of volatiles was isolated from the fresh commercial, unpasteurised juice, followed by the two reconstituted juices and the hand extracted juice. Limonene was the major constituent of all commercial juices comprising 72–93% of the total peak area of isolated volatiles, meanwhile its amount in the freshly hand extracted juices ranged from 25 to 62% depending on the method of isolation. Qualitatively, the aroma profiles of the freshly extracted oranges and the fresh, commercial unpasteurised juice were described by 62 and 55 aroma compounds, respectively, which included large proportions of esters and aldehydes. Only 41 and 34 aroma compounds, mainly terpenes, were identified in the reconstituted orange juices.     

Quantitative bioactive compounds assessment and their relative contribution to the antioxidant capacity of commercial orange juices

Dietary recommendations for healthy eating include the consumption of fruit juices whose health effects are ascribed, in part, to carotenoids, phenolic compounds and vitamin C. These bioactive compounds have been implicated in the reduction of degenerative human diseases, mainly due to their antioxidant potential. Orange juice is characterized by substantial accumulation (apart from ascorbic acid) of flavonoids and carotenoids. Commercial orange juice is the main human dietary source of antioxidant compounds in developed countries. The qualitative and quantitative determination of carotenoid, flavonoid and vitamin C content of Spanish commercial orange juices was achieved by high‐performance liquid chromatography. The health‐related properties of bioactive compounds contained in orange juice are based on their antioxidant activity. The antioxidant capacity of these juices was assessed by 2,2‐diphenyl‐1‐picrylhydrazyl stable radical scavenging and was compared with a freshly squeezed orange juice. In addition, the relative contribution of the different bioactive compounds to the antioxidant activity of orange juices was calculated. Total vitamin C was found to be the major contributor to the antioxidant potential of the orange juices studied, followed by flavonoid and carotenoid compounds. Ascorbic acid, total vitamin C and β‐cryptoxanthin content correlated positively with the free‐radical scavenging parameters. No significant differences, in terms of antioxidant capacity, were found between commercial traditional pasteurized orange juices and freshly squeezed orange juice. Copyright © 2003 Society of Chemical Industry     

气质联用结合多元分析法比较甜橙汁与宽皮柑橘汁的香气成分差异

比较宽皮柑橘汁和甜橙汁中香气物质的差异性,为宽皮柑橘制汁加工提供数据基础。榨取常见甜橙和宽皮柑橘各8个品种的果汁,通过顶空固相微萃取-气相色谱-质谱对柑橘汁样品中香气成分进行定性和定量,采用香气活度值(odor active value,OAV)计算特征香气,并利用主成分分析进行比较和区分。结果表明,16种柑橘汁中共检出77种香气成分,其中甜橙汁特有香气物质有14种,宽皮柑橘汁特有香气物质有7种。通过计算得到47种OAV> 1的特征香气成分,其中芳樟醇、正己醛、壬醛对两类柑橘汁的主体香气贡献极大。选取31种香气物质进行主成分分析,两类柑橘汁均可被明显区分开。研究表明两类柑橘汁中萜类化合物的种类和含量均最多,但甜橙汁中的酯类和醇类化合物的种类和含量远高于宽皮柑橘汁。     

Immunochemical behaviour of the proteins of the orange

Gel filtration of the proteins isolated from orange juice showed three fractions. The two with higher molecular weight were used to prepare rabbit immunosera. By testing the immunosera with concentrated orange and lemon juice substantial differences between the proteins of these two citrus fruits were demonstrated. Our research has also shown that these sera can be used for analysis of commercial products.     

Effect of extraction method on quality of orange juice: hand-squeezed, commercial-fresh squeezed and processed

BACKGROUND: Fresh orange juice is perceived to be more wholesome than processed juice. Fresh juice may have flavor and nutrients that differ from pasteurized or processed juice. RESULTS: ‘Hamlin’ and ‘Valencia’ oranges were extracted using a commercial food service juicer, pasteurized or not, resulting in fresh‐commercial juice (FCJ) or pasteurized juice (FCPJ) for comparison with pasteurized processed juice (PPJ) in 2009, and gently hand‐squeezed ‘Valencia’ juice (HSJ) in 2010 for quality attributes. There was higher peel oil, lower pectin content, and less cloud loss in FCJ/FCPJ compared to PPJ and HSJ regardless of pasteurization. Titratable acidity was generally higher and the ratio of solids to acids lower in FCJ/FCPJ or HSJ compared to PPJ. FCJ/FCPJ had generally higher levels of most aroma volatiles than did PPJ and, overall, the highest esters and terpenes, while methanol and ethanol levels were highest in HSJ. For sensory evaluation, FCJ/FCPJ had more peel oil and PPJ more cooked flavor than other samples, while ‘Valencia’ HSJ was preferred over the other juices. CONCLUSION: High peel oil content and thermo‐pasteurization process decreased cloud loss of orange juice. Extraction and finishing processes rather than pasteurization or oil content were major factors in influencing orange juice flavor quality. Copyright © 2012 Society of Chemical Industry     

Determination of volatile, phenolic, organic acid and sugar components in a Turkish cv. Dortyol (Citrus sinensis L. Osbeck) orange juice

BACKGROUND: Orange flavour is the results of a natural combination of volatile compounds in a well‐balanced system including sugars, acids and phenolic compounds. This paper reports the results of the first determination of aroma, organic acids, sugars, and phenolic components in Dortyol yerli orange juices. RESULTS: A total of 58 volatile components, including esters (nine), terpenes (19), terpenols (13), aldehydes (two), ketones (three), alcohols (four) and acids (eight) were identified and quantified in Dortyol yerli orange juice by GC‐FID and GC‐MS. Organic acids, sugars and phenolic compositions were also determined by HPLC methods. The major organic acid and sugar found were citric acid and sucrose, respectively. With regard to phenolics, 14 compounds were identified and quantified in the orange juice. CONCLUSION: Terpenes and terpenols were found as the main types of volatile components in Dortyol yerli orange juice. In terms of aroma contribution to orange juice, 12 compounds were prominent based on the odour activity values (OAVs). The highest OAV values were recorded for ethyl butanoate, nootkatone, linalool and DL ‐limonene. When we compare the obtained results of cv. Dortyol orange juice with the other orange juice varieties, the composition of Dortyol orange juice was similar to Valencia and Navel orange juices. Copyright © 2011 Society of Chemical Industry