温度对蜂蜜品质流变学检验法的影响

研究了温度对蜂蜜和糖蜜粘度的影响，旨在进一步完善蜂蜜品质流变学检验法。     

Selected Physical Properties of Lime Bee Honey in Order to Discriminate Between Pure Honey and Honey Adulterated with Glucose

The refractive index, conductivity, optical rotation, thermophysical parameters, and infrared spectra of bee honey samples, as well as the content of β-carotene and potassium, were determined with a view to discriminate between pure honey and honey adulterated with glucose. The glass transition temperature and the optical rotation may be used for qualitative assessment of honey adulteration with glucose. Another indication of lime honey adulterated with glucose was the β-carotene content below 20 ppm and the potassium content below 200 ppm. The minimum detectable amount of glucose adulterant was 25 g in 100 g honey.     

Prediction of Adulteration in Honey Using Rheological Parameters

Honey is a sweet substance that can be adulterated easily with inexpensive sweeteners by making syrup. Water being the second major constituent of honey, makes its flow behavior one of the important parameter for quality determination. In the present study, the rheological characteristics of honey samples adulterated with different concentrations of jaggery syrup were studied using rotational rheometer with parallel plate geometry. The viscosity of honey and adulterated honey samples was determined by varying temperature and percentage of jaggery concentration. All the adulterated honey samples behaved as non-Newtonian fluid. The viscosity increased linearly with increase in concentration of adulteration and varied from 2.48–4.80 Pa s as adulteration increased from 5 to 30%. Oscillatory tests were performed to find the possible effect of storage time on different honey samples. It was found that adulteration decreased the shelf life of honey, thus rheology can be considered one of the important parameters to determine adulteration of honey.     

The Composition,Rheological and Thermal Properties of Tajonal (Viguiera Dentata) Mexican Honey

Samples of Tajonal honey (Viguiera dentata) from Yucatan, Mexico with different moisture contents were studied for their physicochemical, crystallization, rheological, and thermal characteristics. The presence of crystals changed the flow behavior from Newtonian to non-Newtonian. A characteristic glass transition temperature (Tg') was found for each sample, and it was observed to be dependent of the initial moisture content but independent of the storage period. The temperature and latent heat of fusion were not affected by the crystallization phenomenon, while both the moisture content and the glucose/water ratio were useful indexes for crystal growth in honey. Crystallization process can be controlled by harvesting the product with higher moisture contents without exceeding the limits established by international regulations.     

Rheological Properties of Honey from Burkina Faso: Loss Modulus and Complex Viscosity Modeling

This study evaluated the rheological behavior of Burkina Faso honey and the use of exponential and polynomial models to predict the influence of chemical composition and temperature on the viscoelastic parameters: complex viscosity (η*) and loss modulus (G’’). Samples were first characterized by evaluating: water activity, 5-hydroxy methyl furfural, sugars (fructose, glucose, and sucrose), electrical conductivity, moisture, and color. Dynamic rheological properties were obtained at different temperatures (5, 10, 15, 20, 25, 30, and 40°C). All the honeys displayed Newtonian behavior. Complex viscosity and loss modulus can be predicted based on the chemical composition and temperature using polynomial models (R² > 98.00%).     

Properties of Dried and Intermediate Moisture Honey Products: A Review

This review discusses the processing techniques proposed for the production of dried and intermediate moisture honey products, as well as their properties. Stickiness is the major problem in the drying of sugar rich products like honey, that depend on the type of sugar and temperature of operation, which are related to the glass transition temperature. Some additives are usually added to the sugary feed to increase the glass transition temperature and concurrently the sticky point temperature. In the case of honey-fruit spreads, nutritional and sensory characteristics can be enhanced by replacing part of sugar with honey. Co-crystallization of honey with sucrose could be used to preserve the honey flavor. These diversified honey products provide better taste and nutrition to the consumer besides enhancing the utilization of honey.     

温度对烟用乳胶粘度的影响

为探讨不同温度对烟用乳胶粘度特性的影响,对7种18个烟用乳胶样品进行了实验。从4℃到30℃改变烟用乳胶的温度,测定其相应的粘度值,用SPSS软件进行处理,作拟和优度检验,得出了各烟用乳胶温度与粘度的线性方程。结果表明,烟用乳胶的粘度与温度呈负相关。在烟用乳胶生产和使用中应根据这一特性来控制其质量。     

Effect of Soluble Solids Concentration and Temperature on Thermo-Physical and Rheological Properties of Mango Puree

Thermo-physical and rheological properties of mango pulp were evaluated at different temperatures (20, 40, 60, and 80°C) and total soluble solids concentrations (15, 20, 32, and 40°Brix). Thermal properties were primarily dependent on the moisture content of the sample, and increased with temperature and decreased with soluble solids concentrations. Density showed a reverse trend. Glass transition temperatures increased with an increase in soluble solids concentrations indicating better stability. Empirical models developed for each thermal property as a function of temperature and soluble solids concentrations (R² > 0.90) generally showed better predictions than published models. Mango puree exhibited pseudo-plastic behavior during steady shear measurements, and the power law model well described their flow behavior. Consistency coefficient increased with soluble solids concentrations and decreased with temperature. The flow behavior index ranged between 0.27 and 0.38 but did not show a clear trend either with soluble solids concentrations or temperature. Small amplitude oscillatory shear measurements revealed that mango puree behaved like a weak gel and demonstrated visco-elastic properties.     

Chemical Composition and Temperature Influence on the Rheological Behaviour of Honeys

The purpose of this work was to examine the viscoelastic properties of Spanish honeys with various sugar contents [fructose (32–42 g/100 g honey), glucose (24–35 g/100 g honey), sucrose (0.0–3.4 g/100 g honey)]; concentrations (79–83 °Brix), and moisture levels (16–19 g/100 g honey) at different temperatures (5, 10, 15, 20, 25, 30, and 40°C). Honey showed Newtonian behaviour, presenting a highly viscous part (loss modulus was much greater than the elastic modulus). The loss modulus (G″) and viscosity increased with moisture content and a decrease with temperature. Exponential and power law models were applied to fit loss modulus and viscosity data. Polynomial models were proposed to describe the combined effect of temperature, fructose, glucose, sucrose content, other sugars, non-sugar substance, and moisture content.     

缓冲预处理对玻璃化转变温度的影响

利用调制式差示扫描量热仪对牛肉糜和牛肉肌动球蛋白在低温情况下的玻璃化转变温率进行了实验研究，发现肌动球蛋白在－10℃和－3℃附近有两次明显的吸热峰值，并且添加的羧甲基纤维素钠、海藻酸钠和明胶对DSC曲线无明显影响。从牛肉糜和牛肉肌动球蛋白的DSC曲线变化看，出现双吸热峰值与缓冲预处理过程无关。     

Effect of Temperature and Soluble Solids Content on the Viscosity of Beetroot (Beta vulgaris) Juice Concentrate

The study investigates the viscosity of clarified beetroot juice as dependent on temperature and soluble solids content. Rheological research was carried out using a rotational rheometer with a system of coaxial cylinders. Flow curves were obtained in the temperature range from 10 to 60°C and at the soluble solids content of 50° to 67.1°Bx. The concentrate under study showed a Newtonian behaviour. Dynamic viscosity ranged from 5.2 to 320 mPa·s and depended on soluble solids content and temperature of measurement. The effect of temperature was described using an Arrhenius equation. Activation energy values were between 24.68 and 39.96 kJ/mol. The effect of soluble solids content was described employing a power-law function and an exponential function. In addition, two equations were proposed to describe the combined effect of temperature and soluble solids content on the viscosity of beetroot juice concentrate.     

Influence of water activity and molecular mobility on peroxidase activity in salt and sorbitol-maltodextrin systems

Solvent composition, system mobility and viscosity play a central role in the regulation of enzymatic activity.The aim of this study was to investigate the individual and combined effect of water activity (a_w), bulk viscosity and glass transition temperature () on the activity of horseradish peroxidase (HRP) in buffered solutions. For this purpose, the water activity of the solutions was modulated using both a ionic (sodium chloride) and a non-ionic (sorbitol) ligand and viscosity changed upon the addition of maltodextrin.In viscous solutions characterized by different compositions, the effectiveness of a solute in the inhibition of the HRP activity was dependent both on the chemical properties of the solution, as described by a_w, and on the mobility of the system, as described by the inverse of viscosity and T − . Viscosity was the most important factor in the inhibition of HRP activity in solutions characterized by the same value, but when was changed, due to changes in the solutes composition, the latter became a key factor in the regulation of the enzyme activity.In salt-maltodextrin systems the water activity reduction limited HRP activity with higher efficiency at low viscosities whilst in sorbitol-maltodextrin systems, characterised by different values, the a_w lowering by sorbitol addition resulted in the increase of HRP activity depending on its effect on .     

浓缩豆乳的粘度变化及控制方法的研究

豆乳在浓缩时，随着豆乳固形物的增加，粘度也急剧增加。降低浓缩豆乳的粘度是制造速溶豆粉，大豆炼乳的技术关键。探讨了反复抽提法，加抗坏血酸法，酶解法的效果，分析了粘度的形成机理和影响因素，结果认为采取适度分解豆乳中的蛋白质，调整ＰＨ，并加以高温短时处理，可有效地降低浓缩豆乳的粘度，豆乳风味同时得到改善。     

水分含量对草莓玻璃化转变温度的影响

在冻干和低温保存中,玻璃化转变温度是一个非常重要的参数。本文用差示扫描量热仪测量得到不同湿基水分含量的草莓汁的玻璃化转变温度。实验发现水分含量较高时(>50%),草莓发生的是部分玻璃化转变,不同湿基水份含量草莓汁的Tg’基本相同,水分对其的影响较小。而水分含量较低时(<45%),草莓降温时往往出现完全玻璃化转变,不同湿基水分含量草莓的Tg有很大不同,完全玻璃化转变温度随着水分含量的减少而升高,拟合得到Tg随水分变化的公式。     

Effects of Drying Air Temperature on the Structural Properties of Garlic Evaluated During Drying

Second order phase transitions may occur in foodstuffs during the convective drying process. These transitions involve physicochemical changes, which influence both structural properties and drying behavior. The aim of this study was to examine the effects of drying air temperature and the second order phase transition of garlic on the changes in particle density, apparent density, apparent porosity, effective diffusivity, and cracking produced during drying. Garlic slices were dehydrated at three air temperatures (40, 50, and 60°C). The moisture content (X), inside temperature (T_i), surface temperature (T_s), apparent (ρ_b) and particle (ρ_p) densities of garlic slices were measured during drying. Porosity (?) was calculated based on the data collected for ρ_p and ρ_b. Glass transition temperatures (T_g) and micrographs were obtained for both raw and dehydrated garlic. A critical point in the intersection of T_i, T_s, and T_g was found; this point was identified as a second order phase transition. Diffusivity and slope changes in ρ_b, ρ_p, and ? with respect to moisture content were found to be related to this critical point. Experimental data for ρ_b, ρ_p, and ? was fitted to a nonlinear equation with three exponential terms with respect to moisture content, with an R² > 0.85. Less dense products were found to be more porous, with more cracking, higher moisture diffusivity, and lower T_g at the end of the drying process.     

亚麻籽胶性能研究——亚麻籽胶的粘度和乳化性

亚麻籽胶即富兰克胶,是一种纯天然、多功能、营养型植物胶。可做为增稠剂、乳化剂、保湿剂及发泡稳定剂、悬浮稳定剂广泛应用于各类食品加工行业。亚麻籽胶的粘度、亚麻籽胶的乳化性及其与胶液浓度、温度、胶液组成的关系进行了研究。     

蜂蜜中蔗糖转化酶测定方法探讨

本文确定了3，5－二硝基水杨酸比色法测定蜂密中蔗糖转化酶的最佳实验条件，该法操作简便，快速，杂质干扰少。     

均质与热处理对脱脂搅拌型酸奶的流变性影响

就部分工艺条件对脱脂搅拌型酸奶的流变性影响进行了研究。结果表明,随着乳固体含量的增高,酸奶的粘度增高,但当乳固体含量增加到11．5％或13．0％时,酸奶的粘度并无显著提高;乳固体为10％时,抗剪切能力最好。在蛋白质含量不变的情况下添加乳清粉,用质量分数为0．41％乳清粉代替1％脱脂奶粉制得的酸奶,其抗剪切能力明显比全部用脱脂奶粉制得的酸奶好。均质和热处理条件是影响酸奶粘稠度的重要因素。均质的最佳压力为20Mpa,温度为60℃。原料乳的最佳条件是95℃、5min,经过这样处理的原料乳酪蛋白在酸奶中可以完全凝固,乳清蛋白因充分受热而完全变性沉淀,可以使搅拌型酸奶的粘度增加,抗剪切能力也比较好。     

Quality Characteristics and Glass Transition Temperature of Hydrocolloid Pre-Treated Frozen Pre-Cut Carrot

The effect of hydrocolloid pre-treatment, i.e., pectin, carboxy methyl cellulose, xanthan gum and sodium alginate on textural properties, drip losses and sensory quality as well as on glass transition temperature (T_g′′′) of the frozen-thawed pre-cut carrots was studied. Untreated frozen samples showed detrimental effects in texture and also excessive drip losses while the carrot tissue integrity was well retained in the hydrocolloid pre-treated samples. As the concentration of the hydrocolloid increased, hardness and fracturability were also found to increase. However, adhesiveness was observed to follow a reverse trend. Xanthan gum (0.4%) resulted in higher texture retention than other hydrocolloids used as well as than the control samples. Hydrocolloids imparted lightness and higher red and yellowness to the carrot samples due to reduced solute mobility and moisture conditioning effects. Overall acceptability of the hydrocolloid pre-treated samples was found to be more than the experimental control samples. All the hydrocolloids were found to be effective in increasing the T_g′′′ to an extent, ?2.73 to ?0.28°C compared with T_g′′′ (?5.4°C) of untreated carrot samples. T_g′′′ increased to almost 74% in CMC (0.4%) pre-treated samples. The maximum enhancement was found in carboxy methyl cellulose followed by pectin, sodium alginate, and xanthan gum. The threshold concentrations in terms of sensory attributes were determined for optimal conditioning of the product prior to freezing.