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.     

Rheological Properties of Chymosin-Induced Skim Milk Gels as Affected by Milk Storage Time and Temperature

Fundamental dynamic rheological tests were used to measure the rigidity (|G*|) and viscoelasticity (tan δ) of gels made from skim milk samples that were (1) never cooled, (2) stored at 4°C, or 3) stored at 4°C and then rewarmed to 25°C. Milk cooled and held at 4°C prior to gel formation produced gels with lower |G*| and higher tan(δ) than fresh milk gels. Chilled milk samples that were rewarmed to 25°C for 16h prior to gel formation produced gels with rheological properties similar to fresh milk gels. The solubilization of β-casein during cold storage was hypothesized to be the cause of observed differences in gel rheology.     

燕麦β-葡聚糖流变特性的测定

以燕麦麸皮为原料提取β-葡聚糖，并通过ARl000流变仪和毛细管粘度计对其流变特性进行了研究。实验结果表明：β-葡聚糖溶液是一种非触变的假塑性流体体系，且假塑性随着浓度的升高而增强。一定条件下溶液同时表现出粘弹性质，但无屈服应力的存在。较之于其它几种常用的食品胶体，β-葡聚糖能产生更大的粘度及良好的口感。此外β-葡聚糖还具有较好的热稳定性，这些性质决定了它在用作食品增稠剂和稳定剂等方面有着巨大的前景。     

Effect of Temperature on Rheological Properties of Different Jams

The rheological behavior of selected jams was analyzed at different temperatures, from 20 to 40°C in a rotational viscosimeter (HAAKE VT550). The rheograms were fitted with Power-Law, Carreau, Herschel-Bulkley, and Cross models. It was observed that the jams presented a pseudoplastic behavior, and the suspended solids influenced the consistency index.     

Rheological and Structural Properties of Egg White/Oat Globulin Co-Gels

Co-gels of egg white (EW) and oat globulin (native and deamidated) were prepared by heating mixtures of the two proteins at different ratios. Rheological properties of the co-gels were assessed by small amplitude oscillatory tests. Storage (G′) and loss (G″) moduli of the co-gels increased with increases in EW content in the mixtures. At comparable EW/non-EW ratios, EW formed much stronger co-gels with deamidated oat globulin (DOG) than with native globulin (OG) or several other non-EW proteins. Microscopic examination of mixed gels revealed structural differences between EW/OG and EW/DOG co-gels. The former exhibited a two gel system with OG distributed discontinuously throughout the supporting EW matrix. DOG and EW formed a homogenous gel network, demonstrating compatibility between the two proteins.     

Effect of Break Temperature on Rheological Properties and Microstructure of Tomato Juices and Pastes

The rheological properties and microstructure of canned juices and pastes made from four tomato cultivars at three breaking temperatures of 85°, 96° and 107°C were studied. The apparent viscosities of tomato juices and pastes at a constant shear rate vary with cultivars and processing conditions. The hot break process produced a high viscosity product. The microstructure of tomato pastes and juices were related to their rheology. The microstructure of tomato juice and paste also vary with processing conditions.     

Rheological Properties of Renneted Reconstituted Milk Gels by Piezoelectric Viscoprocess: Effects of Temperature and Calcium Phosphate

Scanning electron microscopy (SEM) and rheology and permeability were used to evaluate effects of clotting temperature and calcium phosphate on reneted reconstituted milk gels, especially microstructure and permeability. Dynamic measurements with a piezoelectric Viscoprocess determined rheological properties of curd after various times of renneting. An increase in clotting temperature accelerated specific rennet action and gel formation; maximum stiffness was reached faster but its value was weaker. Addition of calcium phosphate increased rate of gel formation. Maximum stiffness was reached faster but its value was not changed. Gel microstructure was not very different but its permeability coefficient decreased.     

Effects of Constituent Concentration on Rheological Properties of Corn Oil-In-Water Emulsions

Rheological properties were studied with a tube viscometer. Emulsifying agents were soy lecithin and Tween 20. The volume concentration of dispersed phase, φ, ranged from 0.32-0.62. The emulsions behaved as pseudoplastic fluids. The flow behavior index, n, of the lecithin emulsions increased slightly with increasing φ and concentration of emulsifying agent, C_e. However, the n values of Tween 20 emulsions were nearly constant. Apparent viscosity of the emulsions increased with increase of φ and C_e. With φ constant the apparent viscosity was still strongly affected by C_e.     

The Effect of Fermentation Temperature on the Microstructure,Physicochemical and Rheological Properties of Probiotic Buffalo Yoghurt

The properties of buffalo and bovine milk differ and the procedures developed to make bovine yoghurt may require optimisation for the production of buffalo yoghurt. This study aimed to apply cryo-scanning electron microscopy and confocal laser scanning microscopy to determine the optimal temperature for processing buffalo yoghurt. Milk was fermented at three different temperatures (37, 40 and 43 °C), stored for 28 days and the yoghurt microstructure, physicochemical and rheological properties assessed. Yoghurt fermented at 37 °C had a compact microstructure and the probiotic Lactobacillus acidophilus La-5 was more viable on storage. In contrast, yoghurt produced from a faster fermentation at 43 °C was firmer with a more porous microstructure that exhibited a higher degree of syneresis. The rheological properties during storage including the thixotropy, consistency coefficient and flow behaviour index were not significantly affected by temperature nor were the concentration of lactose, ionic calcium or titratable acidity. This study shows how changes to processing can be used to alter the microstructure of buffalo products and suggests that a decrease in fermentation temperature could be used to improve the quality of buffalo yoghurt.     

Blanch Temperature/Time Effects on Rheological Properties of Applesauce

Peeled and cored ‘Idared’ and ‘Rome’ apples were blanched in water for 20, 40, and 60 min at 35°. 47°. 59°. 71°. and 83°C minor to making into applesauce by a conventional process each month from Nov. through March. USDA Consist meter values decreased as blanch temperature increased from 35° to 59°C and increased again from 71° to 83°C. There was little variation in flow behavior index (“n” values). Yield stress increased as blanch temperature increased from 35° to 59°C and decreased from 71° to 83°C. The consistency index (K) and serum viscosity were almost unchanged by blanching temperature but both decreased with increasing storage time of fresh fruit. Blanching apples at 59° to 71°C before making into applesauce gave substantially thicker sauces than unbalanced apples.     

水苏糖对面团流变学特性影响的研究

用布拉班德粉质仪和拉伸仪研究分析了水苏糖对面团流变学性质的影响.结果表明:水苏糖能降低小麦粉的吸水率,增加面团的形成时间、稳定时间和评价值,增大面团的拉伸阻力、最大拉伸阻力和拉伸能量,能显著改善面团的弹性,并且水苏糖对小麦粉的影响顺序依次为:低筋粉＞中筋粉＞强筋粉.     

Flow Properties of Low-Pulp Concentrated Orange Juice: Effect of Temperature and Concentration

Three 65° Brix low-pulp concentrated orange juice (COJ) samples, between −19 and 30°C were shear-thinning (pseudoplastic) fluids with negligible magnitudes of yield stress. The simple power law model fit welt the shear rate-shear stress data. For one sample, the Powell-Eyring model also described the data well. The Arrhenius model described the effect of temperature on the apparent viscosity and the consistency index of the power law model. The activation energy of flow (E_a) was 10.7 ± 0.2 kcal/g mole. The models of Harper and El Sahrigi and Christiansen and Craig were suitable for describing the combined effect of temperature and shear rate. The magnitude of E_a decreased with decrease in concentration. Apparent viscosity and K increased exponeitially with concentration.     

单一胶粘剂对涂料流变性的影响

对常用的氧化淀粉、羧基丁苯胶乳和聚乙烯醇在不同的添加量情况下配成的涂料进行了系统的研究,结果表明涂料都呈剪切稀化特性,通过对实验结果进行多次分析,认为用修改的幂律方程表达很理想。     

Effect of Malonaldehyde on the Rheological Properties of Wheat Flour

The addition of malonaldehyde (MA) results in significant changes in the visco-elastic behaviour of wheat flour dough. Incorporation of MA in wheat flour also enhances its rate of maturation during subsequent storage. After storage, MA treated wheat flour had lesser extensibility and higher resistance, dough development time and stability than the untreated sample. Altered visco-elastic behaviour of wheat flour has been explained by the reaction of MA with sulphohydryl and amino groups.     

Effect of Karnal Bunt Disease on the Milling, Rheological and Nutritional Properties of Wheat: Effect on the Quality & Rheological Properties of Wheat

The effect of Karnal bunt disease at 1, 3, 5, and 10% infection of wheat on milling and rheological properties was studied. Both the yield and quality of flour were adversely affected by the disease. The quality and quantity of gluten as well as farinographic quality of flour were found to deteriorate with progressive degree of infection.     

Effect of Milk Fat on the Stability of Vitamin A in Ultra-High Temperature Milk

The stability of vitamin A in ultra-high temperature milks with .15, 2.92, 6.16, and 9.7% fat during storage at 26°C was studied over 3 wk. Milks were fortified with synthetic retinyl palmitate to a final concentration of approximately 120 μg retinol equivalent/I 00 ml milk. The four milk samples were ultra-high temperature processed and packaged in 100 ml sterile milk dilution bottles and stored in the dark at 26°C for 3 wk. Vitamin A concentrations decreased rapidly during the first 2 wk of storage then stabilized. Degradation rates during the first 2 wk were linear and varied inversely with the fat content in the milk (the more fat, the slower the rate of degradation). Final vitamin A concentrations at the end of 3 wk of storage were higher in milk with high fat and closely corresponded to the native vitamin A concentrations present in milk prior to fortification. The results indicate a possible protective effect due to fat or a difference in stability between native and synthetic vitamin A.     

超高压处理对豆浆感官状态和流变特性的影响

超高压处理使豆浆中蛋白质颗粒和脂肪球的存在状态发生明显地变化,蛋白质颗粒变小,而脂肪球增大。豆浆在≤２００ＭＰａ的压力处理１５ｍｉｎ后,浊度略有上升;当压力＞２００ＭＰａ时,浊度又下降,但豆浆的沉降稳定性随处理压力的增大而提高,豆浆的粘度也开始有所增大,３００～４００ＭＰａ范围内粘度的增加最为明显。豆浆的热稳定性在不同压力处理后均有所提高。豆浆的浓度在１．５％～２．５％蛋白质（ｗ／ｖ）时,压力处理后豆浆沉降稳定性的提高更为明显,粘度的增加也最多。豆浆的贮藏模量Ｇ′在≤２００ＭＰａ压力处理后增加,而压力＞２００ＭＰａ时又下降;压力处理后的损耗模量Ｇ″有所增加,且在４００ＭＰａ处理后增加的较多;相对粘弹性ｔｇδ在０～３００ＭＰａ处理后有所下降,而在４００ＭＰａ后又增加。     

Effect of Modified Starches on Rheological Properties of Ketchup

The aim of this work was to study the effect of commercial modified starches of different origin on rheological properties of ketchup. The following starches were used to produce the ketchup samples: chemically modified potato (acetylated distarch adipate from potato starch), waxy maize (acetylated distarch adipate from waxy maize starch and hydroxypropyl distarch phosphate from waxy maize starch), and cassava (acetylated distarch adipate from cassava starch) starches and physically modified cassava and waxy maize starches (physically modified cassava starch and physically modified waxy maize starch). The SEM microphotographs revealed that swollen or disrupted starch granules were present in the ketchup samples. As was evaluated by particle size distribution analysis, two peaks characteristic for different starch granule sizes were observed, the first peak at about 100 μm for ketchup thickened with potato starch and the second one at about 50 μm for the rest of the samples. Ketchups showed non-Newtonian, shear-thinning flow with tendency to yield stress. Values of the rheological parameters describing the flow curves significantly correlated with Bostwick consistency. Ketchup samples exhibited different susceptibility for temperature changes, while values of flow activation energy were from 4.18 to 9.00 kJ/mol. On the basis of mechanical spectra, it is noted that values of G′ were higher than these of G″ showing that elastic properties dominated over the viscous ones. Ketchup samples exhibited properties of weak gels which were estimated from the values of G′ and G″ moduli and their relation and from values of tangent of phase angle (tan δ = 0.14???0.37). Principal component analysis revealed both similarities and differences in rheological behavior of the examined ketchup samples thickened with different modified starches.     

基于亲水胶体的流变学性能研究及其在黑糖奶茶中的应用

黑糖作为当下流行、时尚、具有健康概念的食品原料,广泛地应用在饮料、烘焙食品等中,但是黑糖奶茶作为一种时尚街饮,在商业化饮品生产中需要解决体系的稳定性问题.本文研究不同复配比例微晶纤维素和卡拉胶的流变性以及其在黑糖奶茶中的应用情况,结果表明:卡拉胶用量0.25g/L,微晶纤维素用量2.1g/L时体系较稳定,此时黑糖奶茶的...