电子鼻检测不同品种和加工类型的柑橘汁

为了探索一种通过气味快速区别橙汁和橘汁以及在线监测橙汁加工品质的方法,应用电子鼻对不同品种的橙汁和橘汁的香气进行区分,研究酸橙汁加工过程中各工艺操作对香气成分的影响,并对不同加工类型的酸橙汁进行区分。通过对所获得的数据进行主成分分析及偏最小二乘回归分析,结果显示,不同品种的橙汁和橘汁的香气品质存在差异, 橙汁经过一系列加工工艺后香气发生了明显变化,浓缩还原汁的香气品质要逊于非浓缩橙汁（NFC橙汁）,28%、38%、48%和63.5% 4种不同可溶性固形物质量分数的还原汁在电子鼻传感器上的信号经拟合后有良好的线性关系,以55%还原汁为盲样,判别结果为57.95%,误差为5%。使用电子鼻可以很好的区分不同品种、不同加工类型的柑橘汁,还可以应用于橙汁加工过程中的品质控制。     

战氏生物农药残留降解剂对茶树中6种农药残留降解效率的研究

为了研究战氏生物农药残留降解剂对茶树中多菌灵、炔螨特、吡虫啉、联苯菊酯、甲氰菊酯、阿维菌素6种农药残留的降解效率,在茶树上喷施添加战氏生物农药残留降解剂的农药,同时喷施未加该生物农药残留降解剂的农药做对照,研究降解剂在第1、 5、 10、 15 d对上述农药的降解效率。结果显示,战氏生物农药残留降解剂对多菌灵、炔螨特、吡虫啉、联苯菊酯、甲氰菊酯等5种农药有较好的降解作用,降解周期为1～15 d,降解效率为37.3%～100%,对阿维菌素降解效果不明显。该项研究为战氏生物农药残留降解剂在茶树中的运用和推广提供了一定的理论依据。     

低糖姜脯加工过程对甲基硫菌灵和多菌灵残留的影响

为研究低糖姜脯加工过程对生姜中甲基硫菌灵和多菌灵残留量的影响,以江永香姜为原料,通过浸药方式强化初始残留量,采用液相色谱串联质谱法测定各主要加工工序中2种农药残留量的变化,并计算2种农药在各工序中的加工因子。结果表明,在低糖姜脯加工过程中,除2次干燥工序,其他加工工序对甲基硫菌灵和多菌灵的残留水平均有一定的降低作用,全果清洗步骤多菌灵的去除率为31.1%,甲基硫菌灵的去除率高达62.3%;去皮工序甲基硫菌灵和多菌灵的去除率分别为82.0%和72.9%,漂烫工序甲基硫菌灵和多菌灵的去除率分别为36.8%和77.3%,硬化、超声辅助加热渗糖和上胶衣过程均对甲基硫菌灵和多菌灵的去除有一定的积极影响。在整个加工过程中,各工序姜脯样品的加工因子均小于1,低糖姜脯成品中的甲基硫菌灵和多菌灵的加工因子分别为0.010和0.023,表明整个加工过程可以显著降低姜脯中甲基硫菌灵和多菌灵的残留量(P<0.05)。本研究结果为生姜加工工艺的优化和农药残留的膳食暴露风险评估提供了数据支撑和参考。     

三峡库区浓缩橙汁加工成本及效益分析

柑橘是三峡库区最主要的经济作物之一,随着栽培面积的增长、管理水平的提高,柑橘产量增长速度较快,产能过剩的风险也越来越大。根据三峡库区柑橘生产现状,对浓缩橙汁加工的成本和经济效益进行了综合分析,结果显示目前浓缩橙汁加工无法满足企业和果农双赢的目标,不符合库区柑橘产业发展需求,建议将新型非浓缩还原橙汁(NFC)作为三峡库区橙汁加工的首选产品。     

高压脉冲杀菌集成冷冻浓缩加工果汁的工艺

为了最大限度的保留果汁原有的生鲜风味和营养,采用高压脉冲电场杀菌和冷冻浓缩这两种非热加工的集成技术,应用在果汁浓缩加工中,其中高压脉冲电场技术可以有效地抑制微生物生长,而冷冻浓缩可以有效地钝化酶活力。将该系统非热力加工工艺应用于浓缩橙汁,经感官评定分析,结果表明,产品品质明显优于巴氏杀菌橙汁。     

新型杀虫剂锐劲特在水稻上的残留动态研究

在河北、浙江两地同时进行了锐劲特在水稻上的残留动态试验。结果表明，锐劲特在稻田水和植株中的半衰期为3－4d，在土壤中的半衰期为15d，施用为建议剂量1倍量的25％锐劲特悬浮剂拌种，收获后糙米、稻壳中锐劲特原体及4种代谢物残留量均未超过最高残留限量。     

我国推出水果农残新标准

目前,我国已制定了79种农药在32种(类)农副产品中农药最高残留限量的国家标准。其中有关水果农药残留最高限量的新标准,每公斤应少于或等于毫克数为:百菌清1,倍硫磷0.05,苯丁锡5,草甘膦0.1,除虫脲1,代森锰锌3(梨果),滴滴涕0.1,敌百虫0.1,毒死蜱1,对硫磷不得检出,多菌灵0.5,二嗪磷0.5,氟氰戊菊酯0.5,甲拌磷不得检出,甲萘威2.5,甲霜灵1(小粒水果),抗蚜威2.5,克菌丹15,六六六0.1,氟氯氰菊酯0.2,氯菊酯2,氰戊菊酯0.2,炔螨特5(梨果),噻螨酮0.5(梨果),三唑酮0.2,三唑锡2(梨果),杀螟硫磷0.5,双甲脒0.5(梨果),四螨嗪1,辛硫磷0.05,溴氰菊酯0.1(皮可食…     

小麦田土壤中炔草酯GC-ECD检测方法研究及残留行为特征

采用乙腈振荡提取,GC-ECD测定,建立了小麦田土壤中炔草酯残留量的测定方法。在0.01~2.0 mg·kg-1质量浓度范围内,气相色谱峰面积与炔草酯质量浓度呈良好的线性关系,相关系数为R2=0.999 4。外标法定量,土壤中添加炔草酯质量分数分别为0.01、0.1 mg·kg-1和0.5 mg·kg-1,平均回收率分别为95.91%、89.50%和75.35%,相对标准偏差分别为2.66%、7.64%和4.23%,最低检出浓度为0.01mg·kg-1。检测结果表明,该测定方法前处理简便快速、成本低、结果准确,能够满足土壤中炔草酯残留量的分析要求。在山东和湖南开展的2年两地土壤田间试验结果表明,炔草酯在土壤中30 d的消解率均超过99%,理论半衰期为2.7~3.9d,属于易降解农药。     

气相色谱法对茶园土壤中3种农药残留量的检测

通过对来自六种不同茶园土壤的三种农药残留量的监测,对茶园环境质量现状进行了较系统的调查,并进行了茶园的污染评价。本研究以丙酮为提取剂,样品经提取和浓缩后,采用毛细管柱气相色谱分离,电子捕获检测器(ECD)检测农药残留,外标法定量。不同种类茶园土壤的农药残留量是不同的。用气相色谱法分析茶园土壤中农药残留,全面了解茶园中拟除虫菊酯类农药残留量现状,有利于更好地采取行之有效的措施降低农药残留量,对促进茶叶的出口贸易也起到重要的作用。     

40%阿维菌素·炔螨特EC防治火龙果田间红蜘蛛试验初报

为了解40%阿维菌素·炔螨特EC在火龙果种植上防治红蜘蛛的效果和使用剂量,以1.8%阿维菌素EC和73%炔螨特EC作为对照,进行田间防效试验。结果表明:使用40%阿维菌素·炔螨特EC有效成分用量为200～400 mg·kg-1,对火龙果红蜘蛛的防治最好,药后3天的防效为79.97%～86.05%,速效性好,药后13天的防效为85.46%～95.11%,持效性长,药剂处理范围内对作物和环境安全,可以在火龙果种植生产上推广应用。     

Capillary electrophoresis and high-performance liquid chromatography determination of polyglutamyl 5-methyltetrahydrofolate forms in citrus products

The 5-methyltetrahydrofolate (5mTHF) polyglutamates in citrus products were analyzed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Folate species were purified from citrus products and concentrated from 2- to 100-fold using combined folate-affinity chromatography and C18 extraction. Seven polyglutamyl 5mTHFs were found in most not-from-concentrate (NFC) orange juices (OJ) in total amounts of approximately 1 nmol/mL, with varying distributions of individual polyglutamates. Folate amounts and distributions were also measured in orange fractions, single-strength OJ from concentrate, NFC grapefruit juice, and citrus peel molasses. Models containing ascorbic acid had folate thermal degradation rates one-seventh that of models without ascorbic acid. Pasteurization studies demonstrated that folate loss was <2% for commercial OJ pasteurization conditions (i.e., 93 degrees C for 5 s, 88 degrees C for 15 s, and 82 degrees C for 30 s). Both methods were precise, reproducible, and potentially faster than traditional analytical procedures requiring enzymatic deconjugation and microbial assays.     

高压CO2处理保持非还原桃汁的品质

采用高压CO2（high pressure carbon dioxide,HPCD）处理非还原（not from concentrate,NFC）桃汁,分析HPCD处理后NFC桃汁pH值、可溶性固形物、色泽、酚类和抗氧化活性等品质特性的变化,讨论HPCD对NFC桃汁品质的影响。NFC桃汁的pH值和可溶性固形物含量分别为3.82和10.3°Brix,HPCD处理后没有显著变化;HPCD处理后NFC桃汁颜色变暗,色泽参数L、a、b值显著降低,对应的褐变度提高;NFC桃汁中的主要酚类物质有儿茶素、绿原酸、新绿原酸和阿魏酸,HPCD处理后酚类物质含量没有显著变化;采用FRAP和1,1-二苯基苦基苯肼（1,1-diphenyl-picrylhydrazyl,DPPH）清除率2种方法测定NFC桃汁的抗氧化活性,2种方法的测定结果都表明 HPCD 处理后 NFC 桃汁的抗氧化活性提高,并且随着处理时间的延长而逐渐提高。以上结果表明HPCD能较好的保持NFC桃汁的品质,为非热加工技术应用于果蔬加工提供理论基础。     

Processing and storage effects on orange juice aroma: a review

Freshly squeezed orange juice aroma is due to a complex mixture of volatile compounds as it lacks a specific character impact compound. Fresh hand-extracted juice is unstable, and thermal processing is required to reduce enzyme and microbial activity. Heating protocols range from the lightly heated not from concentrate, NFC, to the twice heated, reconstituted from concentrate, RFC, juices. Thermal processing profoundly effects aroma composition. Aroma volatiles are further altered by subsequent time-temperature storage conditions. Heating reduces levels of reactive aroma impact compounds such as neral and geranial, and creates off-flavors or their precursors from Maillard, Strecker, and acid catalyzed hydration reactions. Off-flavors such as 4-vinylguaiacol, p-cymene, and carvone are the products of chemical reactions. Other off-flavors such as butane-2,3-dione, guaiacol, and 2,6-dichlorophenol are indicators of microbial contaminations. Since most orange juice consumed worldwide is processed, the goal of this review is to summarize the widely scattered reports on orange juice aroma differences in the three major juice products and subsequent aroma changes due to packaging, storage, and microbial contamination with special emphasis on results from GC-O studies.     

Effect of storage temperature on the degradation of dimethoate in fortified orange and peach juices

The effect of storage temperature on dimethoate degradation in fortified orange and peach juices was studied. The insecticide was aseptically injected into packed orange and peach juices and stored at 40, 15, and 0 degrees C. Samples were taken at regular time intervals and were examined for dimethoate residues. The residues were determined with a simple gas chromatographic method; the recoveries of dimethoate from orange and peach juices were found to be from 88 to 114% for both products. The limits of determination were 0.004 and 0.003 mg/kg, respectively. From the experimental data, rate constants, half-lives, and activation energies for the decomposition of dimethoate in orange and peach juices were evaluated. During the storage of fruit juices in refrigerated rooms (0 degrees C) half-lives of dimethoate were found to be largely extended, being 1733 days for orange juice and 2310 days for peach juice. Corresponding times for storage at 15 degrees C were 533 days for both juices and for storage at 40 degrees C 24 days for orange juice and 24.6 days for peach juice. The activation energy for dimethoate in orange juice was 22.3 kcal/mol and for peach juice, 21. 2 kcal/mol.     

Particle size distribution of orange juice cloud after addition of sensitized pectin

The effect of the addition of commercial pectin to orange juice that was de-esterified by alkaline treatment or pectinmethylesterase was evaluated. Pectin at various degrees of esterification (DE) was added to reconstituted frozen orange juice concentrate, and the extent of cloud loss was determined after centrifugation. Of the five pectin treatments, percent transmittance (% T) of juice remained <5%, except for the pectin treatment with a residual methoxyl content (% DE) of <5%. Addition of 100--600 ppm of 5% DE pectin to juice resulted in % T between 36 and 73%. Despite the absence of clarification, increases in cloud particle size were observed and depended on the % DE, the amount of pectin added, and the method used to modify the pectins.     

Effect of processing techniques at industrial scale on orange juice antioxidant and beneficial health compounds

Phenolic compounds, vitamin C (L-ascorbic acid and L-dehydroascorbic acid), and antioxidant capacity were evaluated in orange juices manufactured by different techniques. Five processes at industrial scale (squeezing, mild pasteurization, standard pasteurization, concentration, and freezing) used in commercial orange juice manufacturing were studied. In addition, domestic squeezing (a hand processing technique) was compared with commercial squeezing (an industrial FMC single-strength extraction) to evaluate their influences on health components of orange juice. Whole orange juice was divided into soluble and cloud fractions after centrifugation. Total and individual phenolics were analyzed in both fractions by HPLC. Commercial squeezing extracted 22% more phenolics than hand squeezing. The freezing process caused a dramatic decrease in phenolics, whereas the concentration process caused a mild precipitation of these compounds to the juice cloud. In pulp, pasteurization led to degradation of several phenolic compounds, that is, caffeic acid derivatives, vicenin 2 (apigenin 6,8-di-C-glucoside), and narirutin (5,7,4'-trihydroxyflavanone-7-rutinoside) with losses of 34.5, 30.7, and 28%, respectively. Regarding vitamin C, orange juice produced by commercial squeezing contained 25% more of this compound than domestic squeezing. Mild and standard pasteurization slightly increased the total vitamin C content as the contribution from the orange solids parts, whereas concentration and freezing did not show significant changes. The content of L-ascorbic acid provided 77-96% of the total antioxidant capacity of orange juice. Mild pasteurization, standard pasteurization, concentration, and freezing did not affect the total antioxidant capacity of juice, but they did, however, in pulp, where it was reduced by 47%.     

利用苹果浓缩汁生产中的蒸发冷凝水制备营养水饮品

为再利用苹果冷凝水,该文以苹果浓缩汁实际生产中的蒸发冷凝水为原料,采用化学及仪器分析方法确定其成分组成与含量;在此基础上利用超滤、反渗透等膜分离技术手段对其进行净化和营养物质的浓缩,继而将此冷凝水开发成一种天然的植物水饮料。试验结果表明：苹果浓缩汁生产中的冷凝水其还原糖、总酸、香气成分、总酚质量浓度依次为150、98.5、166、1.046μg/mL;未检出铅、砷、汞,而嗜酸耐热菌超标,为43 CFU/100mL,但采用超滤膜分离技术（40℃,0.06 MPa）可去除苹果冷凝水中的嗜酸耐热菌,使其含量小于1 CFU/100mL;采用反渗透膜分离技术（0.5 MPa、5℃）可使苹果汁加工的冷凝水中营养成分浓缩,对还原糖、总酸、香气、总酚成分的截留率分别为95.07%、97.61%、87.71%、94.52%;以此浓缩液为原料,再适量添加维生素B和C即可制备富含苹果香气的营养水饮品。研究结果可为苹果浓缩汁企业再利用其浓缩工序的蒸发冷凝水和节约水资源提供思路以及试验基础数据。     

Extraction parameters and capillary electrophoresis analysis of limonin glucoside and phlorin in citrus byproducts.

Limonin glucoside (LG) and phlorin were extracted from citrus fruit tissues and assayed by capillary electrophoresis (CE). LG was determined in dried [1.20 +/- 0.10 mg of dry weight (dw)] and wet peel residues (1.16 +/- 0.04 mg of dw), orange juice finisher pulp (0.58 +/- 0.03 mg of dw), dried grapefruit seeds (2.70 +/- 0.15 mg of dw), and 50 degrees Brix molasses (2225 +/- 68 mg/L). Phlorin was purified from orange peel residue and grapefruit albedo, and concentrations were determined in some citrus products. Phlorin and LG were extracted from residues with water/pectinase or with water solutions of methanol and ethanol. Efficient LG extraction from grapefruit seeds (2.40 +/- 0.15 mg/g) was achieved with 50-65% methanol, solvent polarity P' approximately equal to 7-8. Extracts were purified and concentrated by adsorptive resins and HPLC to obtain 95% pure compounds of LG and phlorin. CE analysis did not require extract purification beyond filtration. LG and phlorin migrated as anions in electropherograms containing peaks representing other citrus flavonoids and limonoid glucosides.     

Isolation of antioxidant compounds from orange juice by using countercurrent supercritical fluid extraction (CC-SFE).

Antioxidants from orange juice are isolated by the use of countercurrent supercritical fluid extraction (CC-SFE) and characterized by reversed-phase liquid chromatography (RPLC) coupled to mass spectrometry (MS) and diode-array detection (DAD). A pilot-scale SFE plant equipped with a packed column has been employed for countercurrent extraction and fractionation of raw orange juice with carbon dioxide. Several experiments have been performed in order to study the effect of the countercurrent conditions on the content of antioxidative compounds. In this study, the main variable that has been considered is the solvent-to-feed ratio (S/F) because it plays an essential role in the extraction efficiency. The values tested covered a wide range of sample and solvent (CO(2)) flow rates. In each experimental run, two different extracted fractions and the residual nonextracted juice were obtained and characterized. Different flavonoids have been identified in the fractions obtained after CC-SFE. The possibility of using this process for antioxidant compounds enrichment is discussed.