共查询到20条相似文献,搜索用时 15 毫秒
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研究了浓缩橙汁中的碳水化合物组成以及它们对产品的玻璃化转变温度和粘度的影响 .由压榨工艺和酶法工艺制备的浓缩橙汁在含量较少的大分子碳水化合物的组成上存在明显差异 ,而在含量占优势的低分子量化合物的组成上却很相似 .两种橙汁的玻璃化转变温度相近 ,但酶法工艺所制得橙汁的粘度明显高于前者 .添加平均相对分子质量为 3 60 0的麦芽糊精M0 4 0能提高浓缩橙汁的玻璃化转变温度 ,但幅度不大 ,而产品的粘度却能显著上升 . 相似文献
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天然防腐剂柠檬烯在橙汁保鲜中的应用 总被引:4,自引:0,他引:4
对柠檬烯乳化及其在橙汁保鲜中的应用进行研究。乳化实验结果表明,添加20g/L 的蔗糖酯SE-15,乳化效果最好,离心前后吸光变化率为26.70%。橙汁保鲜实验结果表明,添加0.25g/L 的柠檬烯保鲜效果较差,贮存期间细菌总数变化,只有第4 天明显低于空白对照,pH 值和感官品质与空白对照相比,始终无明显差异;而添加大于等于0.50g/L 的柠檬烯,保鲜效果明显,在整个检测过程中,细菌总数、pH 值变化和感官品质都明显优于空白对照。 相似文献
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The non‐Newtonian flow behavior and dynamic viscoelasticity of wheat (Halberd) amylopectin in aqueous solution were investigated. The flow curves of Halberd amylopectin at 25 °C showed shear‐thinning behavior at various concentrations (2.0, 4.0 and 6.0%). The viscosity decreased gradually with increase in temperature at all concentrations investigated. The storage modulus of Halberd amylopectin was rather small and decreased gradually during increase in temperature even in 6.0% solution. The tan δ showed a value of 1.8 at 6.0% even at low temperature (0 °C) and increased slightly with increase in temperature. The storage modulus of Halberd amylopectin (6.0%) increased slightly upon addition of urea (4.0 M) and decreased gradually with increase in temperature. The storage modulus was higher in 0.05 M aqueous NaOH solution (6.0%) than in pure water. However, for tan δ almost the same values were observed in aqueous urea (tan δ = 1.7) and in alkaline (tan δ = 1.6) solution as in pure water (tan δ = 1.8). The storage modulus had a very large value in 85% DMSO. However, the tan δ value in DMSO was almost identical to that in aqueous solution. The results obtained led to the suggestion that in aqueous solution the wheat (Halberd) amylopectin molecules might be involved to a little extent in secondary associations. The structure of wheat (Halberd) amylopectin molecules seems to be different from that of rice amylopectin molecules. 相似文献
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以橙汁中糖、氨基酸、抗坏血酸、柠檬酸为变量构建不同的非酶褐变模拟体系,通过研究体系贮藏期间3-羟基-2-吡喃酮(3-hydroxy-2-pyrone,3OH2P)、5-羟甲基糠醛(5-hydroxymethylfurfural,5-HMF)、糠醛(furfural,2-F)3 种褐变产物的变化,确定褐变产物的可能来源;通过分析比较褐变度(A420 nm)、褐变指数(browning index,BI)、总色差值(ΔE)3 种非酶褐变评价标准的相关性,确定不同评价标准是否有一致性。结果表明:果糖降解是生成5-HMF的主要途径,3OH2P来源于抗坏血酸的降解,糖能促进2-F的生成;在含糖的模拟体系中,A420 nm、BI、ΔE相互之间均呈显著正相关(P<0.05),这3 种评价标准具有一致性;然而在不含糖的体系中,A420 nm与BI、ΔE均无显著相关性(P>0.05),这3 种评价标准存在差异性。 相似文献
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High-Pressure Processing of Orange Juice: Combination Treatments and a Shelf Life Study 总被引:6,自引:0,他引:6
ABSTRACT: Several process alternatives for the stabilization of fresh orange juice at pressures between 500 MPa and 800 MPa and temperatures between 25 and 50 °C were evaluated. Processing at 800 MPa and 25 °C for 1 min and use of thermally pasteurized pulp yielded the lowest level of residual pectinmethylesterase activity (3.9%) and good cloud stability at 4 and 37 °C over a period of more than 2 mo. Ascorbic acid loss was less than 20% after storage for 3 mo at 4 °C or 2 mo at 15 °C. Color values were stable during storage at 4, 15, and 26 °C 相似文献
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Effect of concentration and temperature on thermophysical properties of clarified apple juice was studied. Density, viscosity, specific heat, and thermal conductivity were measured at different conditions, ranging from 20 to 90oC and 12 to 70oBrix. Experimental data were related to the corresponding properties of water and compared with the behavior of sugar solutions. The results obtained were used to derive mathematical models and correlations for predicting these properties as a function of both concentration and temperature. 相似文献
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Elhamalsadat Shekarforoush Bahareh Tabatabaee Amid Hasanah Ghazali Kharidah Muhammad Md Zaidul Islam Sarker 《International Journal of Food Properties》2016,19(3):662-679
Gum karaya is a polysaccharide gum from Sterculia urens tree. It is used as an emulsifier and thickening agent in cosmetics and pharmaceuticals. However, it has very strong swelling properties, high viscosity, and low solubility, providing the restricted applications in the food industry. The main objective of this study was to investigate the effects of different heat treatment and microwave variables (i.e., time: 8, 10, and 12 min; power: 700 and 1000 W) on the functional properties of gum karaya in the aqueous system and oil-in-water emulsion. In this regard, the rheological properties, emulsifying activity, average droplet size, and surface morphology of the native- and microwave-treated gums were analyzed and compared. Dynamic oscillatory test indicated that the microwave-treated gum karaya had more gel-like behavior than viscous-like behavior (G′ > G″) at a relatively high concentration (20% or 20 g/100 g). When gum karaya was treated by microwave for 8–12 min, both elastic (G′) and viscous (G″) moduli were declined. The native- and microwave-treated gum karaya exhibited a shear-thinning (pseudoplastic) behavior in the aqueous system and oil-in-water emulsion. The results showed that the microwave-treated gum karaya had smaller particles than the native gum in the aqueous system. On the other hand, the emulsion containing the microwave-treated gum karaya had finer emulsion droplets than the control containing the native gum karaya. This confirmed that the application of microwave treatment led to significantly (p < 0.05) improve the emulsifying activity of gum karaya. 相似文献
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为了开发柑橘全果产品,降低全果原浆粒径,改善其流变特性,对柑橘全果粗浆进行球磨处理。以赣南脐橙为原料,经粗粉碎后球磨处理不同时间(0、30、60、90、120、150、180 min),得到不同粒径的全果原浆,研究经球磨处理后赣南脐橙全果原浆的粒径和流变特性的变化。结果表明,球磨处理能有效降低全果原浆的粒径,球磨处理180 min后果浆平均粒径由110.00 μm下降到56.53 μm,整体下降了49%。随着球磨处理时间的延长,全果原浆越来越均匀细腻,且无团聚现象。球磨处理的赣南脐橙全果原浆体系随剪切速率的上升,剪切应力增大,而表观黏稠度下降,出现剪切稀化现象,是一种典型的假塑性流体,具有较好的黏弹性。与未经球磨处理的原浆相比,球磨处理60 min得到的赣南脐橙全果原浆黏稠度最高,凝胶状态最为稳定,适合加工为果酱类黏稠度较高的产品;而球磨处理30 min得到的原浆体系黏稠度最低,但流动性最佳,适合加工为果汁类流动性较好的产品。本实验为柑橘全果产品加工提供了参考依据。 相似文献
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Carolina P. Kechinski Andrea B. SchumacherLígia D.F. Marczak Isabel C. TessaroNilo S.M. Cardozo 《Food Hydrocolloids》2011
In the present work the influence of temperature, xanthan gum and fructose addition on rheological behavior in steady state of blueberry puree was evaluated. The blueberry pulp was formulated with addition of xanthan gum (1.6, 2.0, 2.5, 3.0 and 3.3%) and fructose (6.6, 10.0, 15.0, 20.0 and 23.4%). Rheological data were obtained by shear rate scan tests in a rotational rheometer, with geometry of concentric cylinders in temperatures of 27, 40, 60, 80 and 93 °C. The thixotropy analysis was made through the calculation of the difference between the areas under up and down cycles’ flow curves. The analysis of the formulation influence on puree viscosity was carried out in two stages: i) selection of an appropriate rheological model for representation of data obtained in experiments and ii) statistical analysis of formulation and temperature influence on rheological parameters of selected model. Three 2-parameter models (Bingham, Ostwald–de Waele and Casson) and three 3-parameter models (Herschel–Bulkley, Mizrahi–Berk and Sisko) were tested. Based on the values of correlation coefficients and variance of the estimated parameters, Casson model was chosen for fitting of experimental data. The content of xanthan gum appears as a determinant variable of the rheological behavior of the puree, both at short and long times. The correlation among the variables studied was represented through statistical models which could be used for the development of formulations with specified viscosity in the range of additive concentrations studied. 相似文献
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D. S. Sogi D.P.S. Oberoi Saurabh Malik 《International Journal of Food Properties》2013,16(6):1207-1214
Central composite design was used to analyze the effect of particle size (0.075, 0.15, 0.25, 0.355, 0.425 mm), temperature (1.6, 5, 10, 15, 18.4°C) and total soluble solids (14.77, 25, 40, 50, 65.23°Brix) on the rheological properties of watermelon juice. Experimental values of consistency coefficient k, varied from 0.178–0.628 Pa sn and flow behavior index n from 0.281 to 0.949. Regression equation was computed and used to predict the values of k and n. Results revealed that coefficient of determination (R2) and standard error for consistency coefficient k were 0.84 and 0.043 and for flow behavior index n were 0.42 and 0.102 respectively. Surface graphs showed that k value increased with increase in total soluble solids and particle size while decreased with temperature. 相似文献
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The rheological properties of fresh and cooked (15 min in boiling water) potato tissue which had been deformed to a lessor
or greater extent by uniaxial compression, shear, uniaxial tension, successive cycles of stress relaxation, creep compliance
and texture profile analysis were evaluated. Structural failure of fresh tissue under compression always occurred along a
single plane of maximum shear stress, while fresh tensile specimens failed under tension. Tensile tests proved better methods
by which to determine the failure parameters of cooked specimens since it was possible to observe two differents modes of
failure with this technique. Equivalent modes of failure (causing damage to the cell wall or cell separation) and changes
in structural components caused by cooking proved easier to idetify with tensile tests. The six element Burger's model incorporating
two discrete Voigt-Kelvin units was the most suitable for defining tissue creep behaviour. The instantaneous elastic modulus
could be related to the internal cell pressure, and gelatinization of starch and viscoelastic units appeared to reflect the
viscoelastic properties of pectic sustances and hemicelluloses, respectively.
Received: 1 December 1997 相似文献
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Changes on Dough Rheological Characteristics and Bread Quality as a Result of the Addition of Germinated and Non-Germinated Soybean Flour 总被引:1,自引:0,他引:1
Maribel Rosales-Juárez Beatriz González-Mendoza Emigdio C. López-Guel Flora Lozano-Bautista Jorge Chanona-Pérez Gustavo Gutiérrez-López Reynold Farrera-Rebollo Georgina Calderón-Domínguez 《Food and Bioprocess Technology》2008,1(2):152-160
The increasing interest in functional and healthy food products has promoted the use of germinated soybean flour in the manufacture
of foods for human consumption. Considering the beneficial effects of soy and its germination, farinograph and extensograph
were used to study the effect of adding defatted flour of germinated (32 °C, 72 h) or non-germinated soybean—at different
dry protein ratios (0, 0.5, 1.0, 1.5%)—to wheat flour on: water absorption (WA), maximum consistency time (MCT), dough stability
(S), maximum resistance to extension (R
max), and dough extensibility (L). Baking tests (straight-dough procedure) were also performed to evaluate the effect of this addition on bread characteristics:
loaf volume, texture (firmness, compression force, resilience), color (L*, a*, b*), crumb–grain structure (cell density, mean cell area, shape factor), and consumer acceptance (sensory analysis). Addition
of both kinds of soybean flours increased the values of farinographic parameters (WA, MCT, S), although they did not have
significant effects (p > 0.05) on extensographic properties (R
max, L). Loaf volume and crumb color were improved as soy flour addition was increased, whereas crust color was not affected (p > 0.05). Texture analysis showed that the addition of soy flour produced breads similar or better than the control, whereas
the addition of GSF produced a coarser crumb grain. No detectable differences were found among samples during the sensorial
analysis. Germinated soybean flour was better to improve dough breadmaking properties. 相似文献
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Ashok K. Shrestha Tharalinee Ua-arak Benu P. Adhikari Tony Howes Bhesh R. Bhandari 《International Journal of Food Properties》2013,16(3):661-673
Spray drying behavior of orange juice concentrate with various levels of maltodextrin (DE 6) was studied. Five combinations of orange juice concentrate and maltodextrin (25:75, 30:70, 35:65, 40:60, and 50:50) were spray dried at 160 and 65°C inlet and outlet temperatures, respectively. The product recovered with 50% maltodextrin concentration was sticky and only 20% powder was recovered. The recovery of orange juice powder increased as the amount of maltodextrin in powders increased. The particle size and bulk density remained almost the same in all except in 50% maltodextrin powder which was slightly larger and more dense. The moisture content of spray dried powders was high and desiccated before measuring glass transition temperature. The anhydrous spray dried powders showed increased Tg values with increasing maltodextrin concentration, from 66°C in 50% maltodextrin to 97°C in 75% maltodextrin containing powders. The glass rubber transition (Tg-r) values of all the products measured using novel Thermal Mechanical Compression Test (TMCT) were higher than Tg values measured by DSC; the difference in values increased with increase in maltodextrin concentration. 相似文献