微波复热时间和功率对速冻全麦豆沙包品质的影响

以速冻全麦豆沙包为研究对象,考察微波复热时间(40、50、60、70、80 s)和微波功率(480、560、640、720、800 W)对感官评分、出品率、高径比、比容、质构和色泽的影响.结果显示,随着微波复热功率增加或微波复热时间延长,感官评分、高径比、比容呈先上升后下降趋势,弹性、损失率呈下降趋势.质构结果显示随着微波复热功率的增加,硬度、咀嚼性先下降后上升,而微波时间延长使得硬度、咀嚼性不断下降.色泽结果显示,微波时间对L^*值、a^*值、b^*值有显著影响(p<0.05),而微波时间对L值、b值影响不明显(p≥0.05).当微波复热功率和时间分别为640 W、60 s时,微波复热的速冻全麦豆沙包软甜可口,颜色嫩白,麦香浓郁.     

微波功率对月柿果片微波间歇干燥中水分迁移及品质的影响

目的：探讨微波间歇干燥对月柿果片水分动态和微观结构的影响。方法：选取不同微波功率（280,350,420,490,560 W）对月柿果片进行微波间歇干燥,对干燥过程中月柿果片的水分动态和迁移进行监测,以及对月柿果片的色泽、质构、微观结构进行测定分析。结果：新鲜月柿中的水分主要以结合水（T₂₁）、不易移动水（T₂₂）和自由水（T₂₃）3种形式存在,分别对应3个明显的水峰。随着干燥时间的延长,不易移动水和自由水的横向弛豫时间显著降低。L^*、a^*、b^*值随着微波功率的增加显著减小,ΔE、硬度、弹性、咀嚼性随着微波功率的增加而增加。随着微波功率的增加,果片的组织结构收缩塌陷越明显。结论：较低的微波功率能得到品质较佳的月柿干制品。     

响应面法优化慈姑脆片微波加工工艺

以慈姑为原料,采用微波加工方式制成即食慈姑脆片,考察了装载量、切片厚度、微波功率对慈姑脆片脆度、硬度及b*值的影响,并采用响应面试验优化微波加工工艺。结果表明,即食慈姑脆片微波加工最佳工艺条件为:慈姑片装载量52 g,切片厚度2.4 mm,微波功率210 W,最终慈姑脆片脆度为1873.47 g,所得慈姑脆片色泽鲜亮均匀、酥脆爽口、具有慈姑独特风味。通过比较微波干燥、恒温干燥、热风联合微波干燥和热泵干燥的慈姑脆片主要特性,结果表明微波干燥的慈姑脆片主要特性比较优良。     

微波-热风联用制取笋干工艺条件优化

为获得干燥时间短、干燥品质好的笋干,以竹笋为原料,在单因素试验的基础上,根据中心组合试验设计原理,分析微波干燥功率、微波干燥时间和热风干燥温度3 个因素对笋干感官评分、总干燥时间、复水比、色差和硬度指标的影响,以确定微波-热风联用制取笋干最佳工艺条件。结果表明,制取笋干的最佳工艺条件为：微波干燥功率6.3 W/g、微波干燥时间60 s、热风干燥温度65 ℃。在此条件下得到的笋干感官评分85.6、总干燥时间200 min、复水比6.17,干制品色差ΔE* 19.99、复水制品色差ΔE* 13.92、干制品硬度19 511.23 g、复水制品硬度20010.71 g,该工艺研究结果可为笋干产业化发展提供理论支持。     

熟化紫薯片微波干燥特性及数学模型

以熟化紫薯片为研究对象,利用可调微波干燥机干燥熟化紫薯片,探讨不同微波功率、装载量和切片厚度对熟化紫薯片的干燥特性、水分有效扩散系数及色泽的影响,通过SPSS软件对试验数据进行数学模型拟合,得到熟化紫薯片微波干燥模型。结果表明,熟化紫薯片的微波干燥过程表现为恒速干燥;微波功率、装载量和切片厚度对熟化紫薯的微波干燥特性均有一定影响,微波功率和装载量对其影响最为显著;微波功率越大、装载量越小、切片厚度越小,物料的干燥速率越大。熟化紫薯片微波干燥过程中的水分有效扩散系数随着微波功率与切片厚度的增大、加载量的减小而增大,其最大值为1. 135 4×10^-8m²/s,其平均活化能为4. 893 8 W/g;当微波功率较大、装载量较小时得到的干燥熟化紫薯片品质较差,而切片厚度对其影响不显著。所选用的6个模型中,Modified Page模型具有最大的确定系数R²(0. 999 7),最低的RMSE(0. 006 1)和最小的χ² (0. 000 5),是熟化紫薯片微波干燥的最佳模型,可有效描述熟化紫薯片微波干燥...     

南美白对虾冷风干燥过程中的品质变化研究

冷风干燥是一种重要的水产品干燥方法。该文主要研究南美白对虾在冷风干燥过程中水分含量、复水率、质地、微观结构、色泽及感官评分的变化。结果表明:随着干燥时间的延长,南美白对虾水分含量逐渐降低,复水率显著增加;硬度、咀嚼度不断增大;肌纤维聚集,纤维束间空隙逐渐变大,但干燥16 h的样品仍保持较为完整的纤维结构;冷风干燥16 h时,虾的a~*值达到最大,色泽最红,咀嚼性好,风味浓郁,感官评分最高。     

微波干制甘薯片规律的研究

研究了微波功率、装载量、切片厚度等因素对微波干燥甘薯片的影响,获得了微波干燥甘薯片失水特性及能耗特性,并建立了微波干燥甘薯片的数学模型.研究结果表明:甘薯微波干燥可分为加速、恒速、降速三个阶段;功率与切片厚度增加、装载量减少时,脱水率明显提高;功率增加、装载量与切片厚度减少时,能耗增加,但变化不显著.根据相关系数R2、卡方检验值x2和均方根误差RMSE得出,Page模型最适合用于描述甘薯片的微波干燥过程.     

真空微波干燥对南美白对虾虾仁品质的影响

试验研究了真空微波干燥南美白对虾虾仁的工艺,观察微波功率、预干燥时间、装载量对虾仁品质的影响,并在此基础上采用混合正交的实验方法进一步优化真空微波干燥虾仁的条件。实验结果表明,微波功率、预干燥时间、装载量对南美白对虾虾仁的复水比、水分活度、弹性和感官评分都有一定的影响,其中影响的主次顺序为微波功率最大,装载量次之,预干燥时间最小。最适宜的真空微波干燥条件为微波功率500 W,装载量100 g,预干燥时间20 min得到的产品感官评分最高。     

风味山药脆片脆化工艺的优化

为探讨风味山药脆片的最佳干燥工艺,以山药为原料,以感官评分和脆度为评价指标,采用单因素实验和正交试验研究切片厚度、微波功率、微波时间和装载量对风味山药脆片品质的影响。结果表明,青柠味、番茄味、香辣味三种不同风味的山药脆片最佳的真空微波干燥工艺为:真空度-90 kPa,切片厚度1 mm,微波功率1.5 kW,微波时间12 min,装载量1750 g/m2。在该工艺下,研制的风味山药脆片味道独特、口感好、品质佳。青柠味山药脆片的脆度为520.33 g/s,感官评分为90.67分;番茄味山药片的脆度为523.67 g/s,感官评分为89.33分;香辣味山药脆片的脆度为525.00 g/s,感官评分为90.00分。     

鲜地黄片的微波真空干燥工艺研究

研究了微波功率、真空度、切片厚度、装载量对微波真空干燥鲜地黄片特性的影响,设计了四因素三水平的正交实验,通过比较干燥时间、还原糖得率和多糖得率等指标,优化工艺参数。结果表明,微波干燥过程分升速、恒速和降速三个过程;影响鲜地黄片微波真空干燥特性的因素主次为:切片厚度>微波功率>真空度>装载量。较优组合是:切片厚度12mm,微波功率800W,真空度0.06MPa,装载量150g。     

Isolation,Composition, Structure,Properties, Modifications,and Uses of Yam Starch

Starch is the major carbohydrate in yam tubers and can amount up to 80% of the dry matter. The starch quality determines the quality of food and industrial products made from yam tubers. This review summarizes the present knowledge of the isolation, composition, structure, property, modifications, and uses of starches from diverse yam species. Compared with other tuber and root starches, there is a lack of systematic information on the yam starches. This hinders the further development of yams as sustainable crops as well as the value‐added processing of the starches. Therefore, suggestions on how to better understand and utilize these starches are provided.     

Mineral contents of some southern Italian wines. II. Determination of Li, Na, Mg, K, Ca, Co, As, Rb, Sr, Ag, Sb, Ba

Following our study of the mineral contents of some Southern Italian wines, this work reports on the detection of 12 elemental components. The elements were determined using ICP-AES, flame atomic emission or absorption spectroscopy. The values determined for Li, Na, Mg, K, Ca, Rb, Sr and Ba were within the usual ranges for wines (average values for these elements were: 0.010, 26.2; 94.4; 888; 94.0; 3.30, 0.82 and 0.11 mg/l respectively). All the wines contained low levels of As, the concentrations of which were always under 0.20 mg/l, the maximum level permitted by E.E.C. standards. The measuring of Co, Ag, and Sb led us to ascertain, in all the wines, concentrations lower than 0.01 mg/l for Co and Ag and below the instrumental detection level for Sb (0.06 mg/l). In a previous study wines from D.O.C. areas of Southern Italy were analysed by the technique of inductively coupled plasma atomic emission spectroscopy (ICP-AES), for 14 minerals. This paper deals with further investigation of the mineral composition of the same wines for different metal constituents, analysed by ICP-AES, flame atomic emission, or atomic-absorption spectroscopy (two techniques). The first technique was applied to the detection of Co, As, Sr, Ag, Sb, and Ba. The alkaline metals Li, Na, K, and Rb were determined by flame atomic emission, a technique which possesses better detection limits for these elements. For Mg and Ca the atomic absorption methods were applied.     

卷烟中锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量分析

采用微波消解-电感耦合等离子体质谱法测定了41个牌号烤烟型卷烟和雪茄烟样品烟丝中的锂、铬、镍、铜、砷、硒、钼、镉、铊和铅含量,并按照类型和价位对卷烟中这10种有害元素含量进行了统计分析。结果发现:①卷烟中锂和铜的含量较高,铊的含量很低,铬、镍、镉、铅、砷、硒和钼7种元素的平均含量为0.55～4.42μg/g;②雪茄烟中铬、镍、砷、钼、镉、铊和铅的含量一般高于烤烟型卷烟,而硒元素的含量则相反,但差别较小;烤烟型卷烟中锂和铜的含量与雪茄烟没有显著差异;③高档卷烟中的锂、镍、镉、铊和铬含量较低,而砷、铅的含量较高;不同价位卷烟的铜、硒和钼含量差异不显著。     

Survey of trace elements (Al,As, Cd,Cr, Co,Hg, Mn,Ni, Pb,Se, and Si) in retail samples of flavoured and bottled waters

Concentrations of eleven trace elements (Al, As, Cd, Cr, Co, Hg, Mn, Ni, Pb, Se, and Si) were measured in 39 (natural and flavoured) water samples. Determinations were performed using graphite furnace electrothermetry for almost all elements (Al, As, Cd, Cr, Co, Mn, Ni, Pb, and Si). For Se determination hydride generation was used, and cold vapour generation for Hg. These techniques were coupled to atomic absorption spectrophotometry. The trace element content of still or sparkling natural waters changed from brand to brand. Significant differences between natural still and natural sparkling waters (p < 0.001) were only apparent for Mn. The Mann–Whitney U-test was used to search for significant differences between flavoured and natural waters. The concentration of each element was compared with the presence of flavours, preservatives, acidifying agents, fruit juice and/or sweeteners, according to the labelled composition. It was shown that flavoured waters generally increase the trace element content. The addition of preservatives and acidifying regulators had a significant influence on Mn, Co, As and Si contents (p < 0.05). Fruit juice can also be correlated to the increase of Co and As. Sweeteners did not provide any significant difference in Mn, Co, Se and Si content.     

Varied Composition of Tocochromanols in Different Types of Bran: Rye,Wheat, Oat,Spelt, Buckwheat,Corn, and Rice

The profiles of tocopherol (T) and tocotrienol (T3) homologues in 37 samples of seven different types of bran (rye, wheat, oat, spelt, buckwheat, rice, and corn), available on the Polish market, were studied. Tocochromanols were identified and quantified by reverse phase-high-performance liquid chromatograph/fluorescence detector and reverse phase-ultra performance liquid chromatography-electrospray ionization/mass spectrometry. Only rice bran contained all eight tocochromanol types. Corn bran lacked β-T3; rye, wheat, oat, and spelt bran lacked γ-T3 and δ-T3; and buckwheat bran lacked β-T3, γ-T3, and δ-T3. In buckwheat and corn bran tocopherols predominated (98 and 78%, respectively); whereas rye, wheat, oat, spelt, and rice bran were rich in tocotrienols (78, 76, 66, 87, and 66%, respectively). The average total tocochromanol contents in the oat, corn, spelt, buckwheat, wheat, rye, and rice bran were 5.5, 16.2, 15.8, 14.7, 12.8, 10.7, and 9.1 mg/100 g of dry weight, respectively. Tocochromanol concentrations in samples of the same type bran from different sources varied considerably. Better labeling of bran products to reflect this variation would assist with control of vitamin E daily dietary requirements.     

Optimization of extraction conditions of total phenolics, antioxidant activities, and anthocyanin of oregano, thyme, terebinth, and pomegranate

The purpose of this study was to evaluate the total phenolic extracts and antioxidant activity and anthocyanins of varieties of the investigated plants. These plants include oregano, thyme, terebinth, and pomegranate. The optimum extraction conditions including temperature and solvent of the extraction process itself were investigated. Total phenolic and anthocyanin extracts were examined according to Folin-Ciocalteu assay and Rabino and Mancinelli method, respectively. The effect of different extracting solvents and temperatures on extracts of phenolic compounds and anthocyanins were studied. Plant samples were evaluated for their antioxidant chemical activity by 2, 2-diphenyl-1-picrylhydrazl assay, to determine their potential as a source of natural antioxidant. Results showed that all tested plants exhibited appreciable amounts of phenolic compounds. The methanolic extract (60 °C) of sour pomegranate peel contained the highest phenolic extract (4952.4 mg/100 g of dry weight). Terebinth green seed had the lowest phenolic extract (599.4 mg/100 g of dry weight). Anthocyanins ranged between 3.5 (terebinth red seed) and 0.2 mg/100 g of dry material (thyme). Significant effect of different extracting solvents and temperatures on total phenolics and anthocyanin extracts were found. The methanol and 60 °C of extraction conditions found to be the best for extracting phenolic compounds. The distilled water and 60 °C extraction conditions found to be the best for extracting anthocyanin.     

ICP-MS测定饼干中的铅、砷、铬、镉、铜、锌、铁和锰

探讨了应用电感耦合等离子体质谱仪测定饼干中铅、砷、铬、镉、铜、锌、铁和锰8种重金属元素的方法。运用微波消解系统对样品进行消解,以铋、锗、钪和铟作为内标物,用ICP-MS对消解液进行检测,并采用国标方法对其结果进行验证。利用加标回收率试验和国家标准物质小麦(GBW 10052)检测试验考察了方法的准确性和可靠性。结果表明,该方法所测元素在标准溶液浓度范围内呈线性关系,相关系数均大于0.999,方法检出限在0.002~0.500 mg/kg之间,相对标准偏差均小于6.55%,本法与国标方法测量结果的相对偏差在3.73%~8.40%之间,加标回收率在88.0%~106%之间,标准物质的测定值与标准参考值符合要求。     

The effect of storage of canned juices on content of the metals Fe, Cu, Zn, Pb, Sn, Al, Cd, Sb and Ni

The increase in concentration of iron, copper, zinc, lead, antimony, aluminium, cadmium, tin and nickel over a 2 year's time of juices of peach (prunus persica), pear (pyrus communis), apricot (prunus vulgaris) and apple (malus pumila) was determined. The results show a considerable increase in Fe, Cu, Pb, Zn and Sn with time, while the change in Al, Cd, Ni and Sb is negligible.     

Analysis of cheese for histamine, tyramine, tryptamine, histidine, tyrosine, and tryptophane

A method is described for determining the content of selected biologically active amines (histamine, tyramine, tryptamine) and amino acids (histidine, tyrosine, tryptophane) in cheeses by high performance liquid chromatography. The amines and amino acids were quantified by employing a counter ion-containing mobile phase and by comparing peak areas of high performance liquid chromatography charts for sample cheeses versus standard cheeses containing known amounts of added amines based on dual injections of samples and standards. Recovery of amines and amino acids varied from 87.5 to 111%. Histamine, which has been associated with food poisoning in concentrations of 185 mg/100 g in Swiss cheese and 180 to 500 mg/100 g in fish, was found in concentrations above 500 mg/100 g in Swiss cheese. The high performance liquid chromatography analytical method should be useful for screening to detect cheese samples containing toxic amounts of histamine and for research studies designed to determine the cause and effect relationships for histamine production in cheese.     

接装纸中汞、砷、铅等8种元素的分析研究

本文利用电感耦合等离子体发射光谱仪(ICP-AES法)同时测定接装纸样品中铅、铜、镉、铬、锡、锑元素含量,汞、砷元素含量采用冷原子吸收光谱法和银盐法测定.结果表明接装纸样品中锡元素含量最高,铜次之,汞、砷、铅相比,砷元素含量较高,部分样品中砷、铅元素含量超出食品包装用纸的最高限量标准.采用ICP-AES法同时测定接装纸6种元素,操作简便,重复性好,回收率高.此外,本文还对接装纸荧光物质和脱色程度进行了测定分析,从随机抽检的47份国产、进口接装纸样品看,进口白色接装纸无荧光,国产白色接装纸有荧光,珠光色接装纸个别有荧光,纸边为白色的接装纸荧光程度不一.脱色试验表明,进口接装纸,国产印刷型接装纸、珠光纸不脱色,涂布型接装纸均有不同程度的脱色.