Rheological Characteristics of Domestic Honeys

采用流变学方法对国产蜂蜜流变特性进行了研究。流变试验数据分析表明国产蜂蜜流变模型为Ｎｅｗｔｏｎ体，而非过去所认为的Ｂｉｎｇｈａｍ体。影响国产蜂蜜粘度的诸因素中，水分的影响最为显著。建立了国产蜂蜜ｗ－ｔ－η图，以充分描述其水分、温度与粘度之间的各种关系     

国产蜂蜜流变特性研究(英)

采用流变学方法对国产蜂蜜流变特性进行了研究。流变试验数据分析表明国产蜂蜜流变模型为Ｎｅｗｔｏｎ体，而非过去所认为的Ｂｉｎｇｈａｍ体。影响国产蜂蜜粘度的诸因素中，水分的影响最为显著。建立了国产蜂蜜ｗ－ｔ－η图，以充分描述其水分、温度与粘度之间的各种关系     

牛奶检验与喷雾干燥中的粘度分析

根据中、澳两国两种牛奶流变试验结果,指出牛奶流变特性受浓度、温度和牛奶品种的影响,可以采用粘度分析法进行新鲜牛奶质量鉴定,并对牛奶喷雾干燥时的温度和浓度选择提出见解。     

食用植物油粘度测试仪器

为研究食用植物油流变性质,选择适宜的粘度计进行测量,以Engler粘度计测量值为对照组进行实验。检验自行设计的滚球式粘度计、落柱式粘度计和从市场上购买的毛细管粘度计的相对可靠性。通过实验,用数理统计分析四种简易粘度测量结果,发现工业测量时用Engler粘度计较方便,商品检验时推荐用落柱式粘度计,食用植物油实验分析时宜用毛细管式粘度计。     

莲藕粉糊的流变特性实验研究

为了研究莲藕粉糊的流变特性参数，以开发莲藕方便食品，采用一套同心圆筒旋转粘度仪测绘了不同浓度、粒度、pH值条件下莲藕粉糊的流变特性曲线，并对浓度、粒度、pH值和温度对莲藕粉糊流变学行为的影响进行了分析研究。结果表明，浓度从2%增至10%时，稠度系数从0.434增至20.302。建立了表观粘度随浓度的变化规律的回归方程，其相关系数高达0.9931。     

细粒魔芋精粉及其复合胶的特性与应用研究

采用胶体磨湿法粉碎工艺制备得到细粒魔芋精粉,在该细粒魔芋精粉中添加10%(w/w)黄原胶制备得到复合胶。对该复合胶及细粒魔芋精粉水溶胶的流变特性以及两者在冰淇淋中的应用进行了比较研究。结果表明,与正常粒度魔芋精粉比较,细粒魔芋精粉的溶胀速度快,溶胶粘度低;相同浓度与测定条件下,复合溶胶的粘度数倍高于细粒魔芋精粉溶胶的粘度,切稀现象也比同粘度魔芋溶胶更为明显;以参考用量为0.25%的复合胶作为稳定剂应用于冰淇淋中时,也同样使冰淇淋浆料粘度显著提高,并导致其产生明显的切稀现象,相应冰淇淋制品的粘稠感明显低于以     

玉米高压淀粉糊流变特性的研究

高压玉米淀粉糊的流变特性为：随含水量提高剪切模量、动态粘度和耗损角都提高；在小于９０Ｈｚ低频波作用下，高压淀粉糊的剪切模量和动态粘度因保压时间延长而增大；在１００Ｈｚ的剪切波作用下，高压淀粉糊的上述特征值则因保压时间延长而减小。     

棉籽粉流变特性的研究

用毛细管流变仪研究了棉籽粉的流变特性。实验结果表明：棉籽粉呈现很强的非牛顿性，剪切速率、温度和含水率对表观粘度影响显著；表观粘度随剪切速率的增大而减小，随温度的升高而减小，随含水率的增大而减小。文中还提出了棉籽粉的粘度模型和半经验公式。     

稻米淀粉糊老化动力学研究

以不同类型稻米为原料，用旋转粘度仪研究较稀浓度淀粉糊的老化动力学，以预测和控制稻米淀粉糊老化。结果表明：稻米淀粉糊呈假塑性流体的特征，随存放时间的延长，其流变指数上升，淀粉糊的刚性增大。用流变指数和一级化学反应动力学模型能较好的描述淀粉糊的老化特性。淀粉糊的老化与其分散相的凝聚、沉淀和连续相的特性有关。淀粉糊中直链淀粉和支链淀粉的相互作用会使其老化进一步加深。     

魔芋葡甘聚糖溶胶流变特性研究

魔芋葡甘聚糖溶胶粘度的对数（lgη）与浓度正相关,表现出非牛顿流体特征。而且在浓度＜0.5%、浓度为0.5%～1.0%、浓度为1%～2%、浓度＞2%时,分别出现稀溶液、中间过渡溶液、浓溶液、冻胶（含部分切变稀化过渡范围）特性。溶胶粘度随温度上升而降低。在增塑剂作用下,浓度增加,流动性增强;补强剂使其粘度增加,而流动性减弱。魔芋葡甘聚糖溶胶流变特性的研究为魔芋高强度可食性薄膜的成膜提供了理论依据。     

Quantification of saccharides in multiple floral honeys using fourier transform infrared microattenuated total reflectance spectroscopy

Fourier transform infrared (FTIR) spectroscopy with microattenuated total reflectance (mATR) sampling accessory and chemometrics (partial least squares and principal component regression) was used for the simultaneous determination of saccharides such as fructose, glucose, sucrose, and maltose in honey. Two calibration models were developed. The first model used a set of 42 standard mixtures of fructose, glucose, sucrose, and maltose prepared over the range of concentrations normally present in honey, whereas the second model used a set of 45 honey samples from various floral and regional sources. The developed models were validated with different data sets and verified by high-performance liquid chromatography (HPLC) measurements. The R (2) values between the FTIR-mATR predicted and HPLC results of the different sugars were between 0.971 and 0.993, demonstrating the predictive ability and accuracy of the procedure.     

Honeys from different floral sources as inhibitors of enzymatic browning in fruit and vegetable homogenates

Honeys from different floral sources were evaluated for their antioxidant content and for their ability to inhibit enzymatic browning in fruits and vegetables. Antioxidant contents of honeys vary widely from different floral sources, as do their abilities to protect against enzymatic browning. Polyphenol oxidase (PPO) activity was reduced over a range of approximately 2-45% in fruit and vegetable homogenates, corresponding to a reduction in browning index by 2.5-12 units. Soy honey was particularly effective when compared to clover honey, which had a similar antioxidant content. When compared to commercial inhibitors of browning, honeys were less effective; however, in combination they added to the effectiveness of metabisulfite and ascorbic acid. Honey has great potential to be used as a natural source of antioxidants to reduce the negative effects of PPO browning in fruit and vegetable processing.     

Effect of sugar on anthocyanin degradation and water mobility in a roselle anthocyanin model system using 17O NMR

The purpose of this study was to try to elucidate the relationship between anthocyanin degradation and water mobility using (17)O NMR. A model system containing anthocyanin from roselles with different sugar concentrations (20, 40, 60%) was used to compare the effect of sugar (sucrose and honey) on the kinetics of anthocyanin degradation and water mobility after heating. Data on the anthocyanin degradation index (DI), half-life of anthocyanin, and activation energy of anthocyanin degradation showed that sucrose was a good anthocyanin protector, especially at high concentration. However, honey led to a severe anthocyanin degradation after its concentration reached 40% or it was heated to temperatures >50 degrees C. Spin-spin relaxation rates (R(2)) of water using (17)O NMR were further used to monitor the water mobility in two sugar systems to explain the differences in browning under the same concentration and water activity. R(2) in sucrose was significantly higher than that in honey after the concentration reached 40%. Apparently, increasing the ability to bind with water molecules favored the stability of anthocyanin in sucrose solution.     

Dynamic flavor release from sucrose solutions

The initial dynamic flavor release from sucrose solutions was modeled. Modeling was based on the theoretical hydration behavior of sucrose, theoretical physicochemical data of flavor volatiles, and process parameters of a headspace apparatus used for model validation. The rate-limiting factor determining the initial flavor release was the hydration of sucrose, which in turn depends on the molarity of sucrose in the solution and, therefore, on the actual amount of nonbound water. Improved solubility of the more hydrophilic compounds due to their orientation toward the hydration shells of the sugar molecules was considered. The viscosity of nonassociated water forming the microregion for mass transfer of volatiles was considered instead of the bulk solution viscosity. Experimental validation of the model by real-time measurements of dynamic flavor release using foodlike flavor concentrations confirmed the above theory. Increasing sucrose concentrations resulted predominantly in increased flavor release, and bulk solution viscosity showed no effect.     

Methods for determinging carbohydrates, hydroxymethylfurfural, and proline in honey: collaborative study.

A modification of the official selective absorption method for honey carbohydrates, 31.124--31.133, was studied collaboratively; the determinations of sucrose, total monosaccharides, disaccharides, and higher sugars by this procedure were satisfactory and were adopted by the AOAC. High pressure liquid chromatography of glucose, fructose, and sucrose in honey showed better precision than the modified official method and gave concordant results; it was also adopted. Two methods for hydroxymethylfurfural do not qualify. A method for proline was also adopted.     

基于红外光谱技术的蜂蜜理化性质快速检测

该论文以116个蜂蜜样品为对象，考察蜂蜜理化指标间的相关性，并采用红外光谱技术结合偏最小二乘回归法建立快速定量模型，探讨模型对蜂蜜理化性质指标的定量能力，比较近、中红外光谱在定量检测中的能力，从数据层融合角度考究光谱融合对定量精度的提升。主要研究结论如下：蜂蜜的部分理化性质间具相互关联性，色差、电导率和pH两两呈正相关，pH和可滴定酸，水分与黏度之间彼此呈负相关；近红外光谱技术（near-infrared spectrum，NIR）和中红外光谱技术（mid-infrared spectrum，MIR）对果糖、葡萄糖、还原糖、果糖/葡萄糖、水分、黏度、pH和色差具有良好的定量分析能力（R²＞0.9），对电导率、蔗糖、麦芽糖和可滴定酸的精度和模型相关系数尚可接受；二者单独对淀粉酶值、脯氨酸的定量结果较差，通过数据融合后，脯氨酸精度有所提升（Rc 0.825，Rp 0.664，RMSEC 38.68，RMSEP 49.57），淀粉酶值无优化（Rc 0.799，Rp 0.695，RMSEC 2.57，RMSEP 3.02）。MIR对糖的定量分析精度略优于NIR。研究证明将近、中红外光谱用于蜂蜜部分理化指标的快速定量是可行的，数据融合对模型产生积极影响，但仍存在很多理论和算法问题需要解决。     

Separation of disaccharides by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry. Application to honey analysis

A new method based on comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC×GC-ToF MS) has been developed for the first time for the analysis of complex mixtures of disaccharides previously converted to their trimethylsilyl oximes (TMSO). Among the different experimental parameters considered for optimization, both the column set combination and the dimensions of the second-dimension column were found to be the most significant with regard to the complete resolution of structurally similar disaccharides. Application of the optimized method to honey analysis allowed the separation of most of the honey disaccharides previously described in the literature. Furthermore, 12 other unknown disaccharides have been separated by this method and characterized from their mass spectral data.     

Improved method for extraction and LC-MS analysis of pyrrolizidine alkaloids and their N-oxides in honey: application to Echium vulgare honeys

A method for analyzing honey samples was developed that enabled the simultaneous detection and identification of pyrrolizidine alkaloids and their N-oxides. Honey samples were treated with methanol or dilute sulfuric acid and then centrifuged to remove insoluble material. Subsequent strong cation exchange, solid-phase extraction of the supernatant provided a fraction that was analyzed for the presence of pyrrolizidine alkaloids and their N-oxides using high-pressure liquid chromatography coupled to electrospray ionization mass spectrometry. The procedure was validated using extracts of Echium plantagineum and authenticated standards of pyrrolizidine alkaloids and their N-oxides from other plant sources. Of several variations of the solid-phase extraction method assessed in this study, the best combination for generic use involved the dilution of honey with 0.05 M sulfuric acid and the subsequent application of the centrifuged solution to solid-phase extraction columns at the rate of a maximum of 10 g of honey per solid-phase extraction column. The method was applied to the analysis of nine floral honeys, five of which were attributed by the apiarist to Echium vulgare. Seven of the honey samples were positive for pyrrolizidine alkaloids and N-oxides characteristic of E. vulgare.