Measurement of the colour and transparency of gels: application to fruit gels

Colour measurement was studied in peach gels prepared with different amounts of peach pulp, using carrageenan or a mixture of carrageenan and locust bean gum as gelling agent. The colour was measured conventionally, in CIELAB terms, applying Kubelka—Munk criteria. The K/S parameter values in relation to lightness are a good representation of the sensory lightness of the samples, whereas the L^* values are not. In the case of colour intensity, both the Kubelka—Munk and CIELAB parameters are a good representation of the sensory colour intensity. The use of carrageenan on its own or in a mixture of carrageenan and locust bean gum does not produce differences in the visual appearance of these two types of gels. Finally, mathematical equations were developed that relate K/S to the fruit and sugar concentrations. It was found that fruit concentration has a greater effect than sugar concentration on the K/S values of these equations, which agrees with the sensory valuation of the appearance of these gels.     

EFFECT OF OTHER HYDROCOLLOIDS ON THE TEXTURE OF KAPPA CARRAGEENAN GELS1

The effect of different hydrocolloids on the breaking strength, cohesiveness and rigidity of kappa carrageenan gels was studied using comression tests with the Instron. Instrumental measurements were supplemented with benchtop sensory evaluation of texture by mouth, gel clarity and syneresis. The evaluated hydrocolloids included locust bean gum, iota carrageenan, amidated low methoxyl pectin, xanthan gum, and their selected combinations. Best gels were obtained by using 0.15% kappa carrageenan and 0.85% iota carrageenan, or 0.2% kappa carrageenan, 0.2% locust bean gum and 0.6% amidated LM pectin. Although none duplicated the textural quality of gelatine gels, they represented a wide range of interesting and potentially useful textures.     

Rheological behavior of functional sugar-free guava preserves: Effect of the addition of salts

The addition of salts to carrageenan and locust bean gum gels functions to improve the characteristics of texture, thereby increasing gel strength. This effect is widely studied in gels of model systems but is studied to a lesser extent in complex systems, such as fruit preserves. The objective of this study was to evaluate the effect of adding salts on the rheological behavior of functional sugar-free guava preserves, as well as to correlate the rheological parameters. To this end, three types of texture properties were analyzed (texture profile, stress relaxation and uniaxial compression) in functional sugar-free guava preserves prepared with different concentrations of KCl and CaCl₂ salt. The analyses were performed with a texturometer (Stable Micro Systems, Model TA - XT2i), and the parameters were analyzed using a Scott-Knott test at 5% probability, principal components analysis and Pearson correlation. CaCl₂ was more effective for improving the characteristics of texture, especially gel strength (concentration near the F3: 0.33%), whereas KCl addition degraded gel strength. In the analysis of test relaxation, the Maxwell model parameters provided better discrimination between samples than the Peleg model parameters. Positive and negative correlations were observed, and the parameters of hardness, adhesiveness and elastic modulus ideal (E₁) were the most correlated with other rheological parameters.     

Effect of Gums on Low-Fat Meat Batters

The effects of adding Iota-carrageenan, kappa-carrageenan, guar gum, locust bean gum, xanthan gum, methylcellulose, and a locust bean gum/kappa carrageenan mixture to low-fat, high moisture meat batters were investigated. The methylcellulose treatment showed an increase in weight losses between 60° and 70°C, while other treatments remained similar throughout heating. Xanthan gum and guar gum at 0.2% altered textural parameters as determined by texture profile analysis. Increasing the concentration of xanthan gum decreased batter hardness without affecting batter stability. Sensory evaluation indicated that low-fat frankfurters (11–12% fat) were as acceptable as control frankfurters (27% fat).     

A Modified Maxwell and a Nonexponential Model for Characterization of the Stress Relaxation of Agar and Alginate Gels

Compressive stress relaxation curves of agar and alginate gels of different gum concentration (1–3% and 0.5–2%, respectively) were fitted by a two parameter nonexponential empirical model and a three term modified Maxwell model with two fixed relaxation times (10 and 100s). The asymptotic portion of the residual (unrelaxed) stress calculated by the two models for each gel had a similar magnitude, and therefore could serve as an objective measure of the gels degree of solidity. The coefficients of the modified Maxwell model provided a simple but meaningful means to compare, in quantitative terms, the differences in the relaxation time spectra that were associated with the gels' stiffness and strength.     

Relaxation Time Spectrum of Hydrogels by CONTIN Analysis

CONTIN is a general-purpose program for inverting noisy linear algebraic and integral equations by means of inverse Laplace transform. This study explored the application of CONTIN analysis to determine the relaxation time distribution spectra for food gels, including gellan, carrageenan, whey protein, and gelatin gels, based on stress-relaxation data. CONTIN results represent the continuous relaxation time spectra when the number of the terms in the discrete Maxwell stress-relaxation model approached infinity. The CONTIN results for gellan gels were correlated to the texture properties of gels from compression tests with respect to the effects of calcium concentrations. CONTIN analysis may be a very effective tool in elucidating the microstructural properties of a hydrogel from mechanical testing.     

响应面法优化复合果味柿子果冻工艺研究

该研究以柿子为主要原料,与椰浆粉、百香果果粉、金桔果粉按质量比2∶2∶1复配制成的混合果粉汁(浓度2%)进行混合,采用卡拉胶、魔芋胶复配作为凝胶剂,以感官评分作为评价指标,对柿浆与复合果粉汁比例、胶的复配比例及添加量、白砂糖添加量等因素及水平进行探究。通过单因素试验和响应面法分析,得出复合柿子果冻的最佳配方:柿浆与复合果粉汁比例为质量比6∶4,卡拉胶与魔芋胶的配比为质量比3∶1,复配胶添加总量为1.4%,混合果汁添加量为25%,白砂糖添加量为14%,柠檬酸添加量为0.13%。采用此配方制得的复合柿子果冻具有协调的宜人果香,酸甜适中,质地均匀有弹性。     

食用胶对虾蛄中磷酸化肌原纤维蛋白凝胶特性的影响

将魔芋胶、卡拉胶、黄原胶分别添加到虾蛄磷酸化肌原纤维蛋白中,在不同食用胶、三聚磷酸钠添加量及不同温度下形成凝胶,研究食用胶对磷酸化蛋白凝胶特性的影响。结果表明：随着三聚磷酸钠添加量的增加,3 种食用胶形成的蛋白凝胶强度和保水性均提高;随着食用胶添加量的增加,卡拉胶与黄原胶形成的蛋白凝胶强度和保水性提高,魔芋胶添加量为0.1%时,其蛋白凝胶强度最高;随着温度的升高,魔芋胶与卡拉胶均对蛋白凝胶强度和保水性有显著性影响（P＜0.05）,但黄原胶对凝胶强度和保水性无显著影响（P＞0.05）。     

Effect of addition of sucrose and aspartame on the compression resistance of hydrocolloids gels

The effect of adding sucrose (5–25% w/w) and aspartame (0.04–0.16% w/w) on the compression resistance of three hydrocolloid gelled systems: κ‐carrageenan, gellan gum and κ‐carrageenan/locust bean gum at three different concentrations (0.3, 0.75 and 1.2% w/w) was studied. Sucrose addition increased true rupture stress in the three‐gelled systems, this effect being stronger in gellan gels. The deformability modulus increased with sucrose concentration in gellan gels, but not in the other systems. Rupture stress and deformability modulus increased with the addition of sucrose only in the harder gels (0.75 and 1.2% w/w). The effect of sucrose addition on the true rupture strain was significant but, in general, not important, mainly for lower gum concentrations. Aspartame addition did not affect the compression parameters.     

Effect of polysaccharides with different ionic charge on the rheological,microstructural and textural properties of acid milk gels

The effects of addition of polysaccharides with different ionic charge on rheology, microstructure, texture and water holding capacity (WHC) of acid milk gels were studied and compared to that of gelatin addition. Similar to gelatin, starch (neutral) and xanthan gum (anionic) did not prevent milk gelation in the first 30 min of the acidification stage, even at high concentrations, and the typical casein network in acid milk gels could still be seen from electron micrographs; gelling and melting of these hydrocolloids were observed during the cooling and heating stages at specific concentrations. On the other hand, two neutral polysaccharides, guar gum (≥ 0.05%) and locust bean gum [LBG] (≥ 0.1%) inhibited milk gelation from the beginning of the acidification stage; the microstructure of the gel was modified greatly and no gelling/melting was observed during the cooling or heating stages. Another anionic polysaccharide, carrageenan, induced earlier milk gelation at low concentration (≤ 0.05%), but inhibited gelation entirely at high concentration (0.2%); inflections at ~ 27 °C and 21 °C were also observed during the cooling and heating stages at 0.05% concentration. The gel microstructure was not changed greatly, but showed smaller particle size at a carrageenan concentration of 0.05% than control sample. None of the polysaccharides showed as much improvement in WHC of the milk gels as gelatin did. Hence, xanthan and starch were found to be closer to gelatin in their effect on acid milk gels compared to guar gum, LBG and carrageenan.     

Lightness and gloss of peach gels: effect of fruit and sugar content

 Lightness and gloss were studied in peach gels prepared with different quantities of sugar and peach pulp, using a mixture of xanthan and locust bean gum as gelling agents. Colour was described in terms of the colour coordinates established by the Commission Internationale de l'Eclairage and gloss was determined as a percentage. The values of lightness determined optically (L^*), when ranked, corresponded well with those determined by eye, but there was less similarity between the ranked values of gloss determined optically and by eye. There was a clear relationship between the sensory evaluation of lightness and gloss and the fruit and sugar content of these gels. Mathematical equations were developed to relate both L^* and gloss values determined optically with fruit and sugar concentrations. It was found that fruit had a greater effect than sugar on the L^* values and that gloss depended only on the sugar content. Finally, the gloss of gels prepared with different gelling agents were compared and it was found that lightness can affect the sensory evaluation of gloss. Received: 15 July 1997 / Revised version: 3 February 1998     

Lightness and gloss of peach gels: effect of fruit and sugar content

 Lightness and gloss were studied in peach gels prepared with different quantities of sugar and peach pulp, using a mixture of xanthan and locust bean gum as gelling agents. Colour was described in terms of the colour coordinates established by the Commission Internationale de l'Eclairage and gloss was determined as a percentage. The values of lightness determined optically (L^*), when ranked, corresponded well with those determined by eye, but there was less similarity between the ranked values of gloss determined optically and by eye. There was a clear relationship between the sensory evaluation of lightness and gloss and the fruit and sugar content of these gels. Mathematical equations were developed to relate both L^* and gloss values determined optically with fruit and sugar concentrations. It was found that fruit had a greater effect than sugar on the L^* values and that gloss depended only on the sugar content. Finally, the gloss of gels prepared with different gelling agents were compared and it was found that lightness can affect the sensory evaluation of gloss. Received: 15 July 1997 / Revised version: 3 February 1998     

卡拉胶/刺槐豆胶对猪肉糜品质的影响研究

亲水性胶体是用于改善肉制品品质的常用添加剂之一。本文通过在猪肉糜中添加卡拉胶和刺槐豆胶,研究两种胶体及其复配对猪肉糜色差、质构、水分活度的影响。研究结果表明,适宜比例的卡拉胶与刺槐豆胶的复配胶对猪肉糜品质的改善起到了一定的作用。卡拉胶/刺槐豆胶添加量为0.16%/0.24%时,猪肉糜品质较佳,硬度达到521.20±15.40,咀嚼性达到27.00±10.40,失水率降低至0.040±0.002。     

蓝靛果红枣果冻的生产工艺研究

以蓝靛果果汁、红枣果肉为主要原料,魔芋精粉、卡拉胶和白砂糖等为辅料采用正交试验确定蓝靛果红枣果肉果冻的最佳工艺配方。结果表明：最佳配方为蓝靛果汁8%、红枣果肉12%、魔芋精粉与卡拉胶的混合胶0.6%和白砂糖12%。采用该配方制备的果冻呈紫红色,果香浓郁、口感爽滑。     

五彩果蔬水晶素香肠的研究

研发了一种果蔬风味的素香肠,以玉米、胡萝卜、青豆、椰果、红椒5种果蔬组成的复合果蔬颗粒为主要原料,以卡拉胶、魔芋胶、黄原胶组成的复配胶体为载体,开发具有果蔬风味的五彩水晶素香肠.首先通过正交试验对复配胶体配方进行优化,确定复配胶体中卡拉胶:魔芋胶:黄原胶的复配比例;然后通过单因素试验和正交试验对五彩果蔬水晶素香肠的制作...     

Na+ Binding as Measured by 23Na Nuclear Magnetic Resonance Spectroscopy Influences the Perception of Saltiness in Gum Solutions

Binding of Na⁺ in aqueous gum systems as determined by ²³Na nuclear magnetic resonance (NMR) spectroscopy and its relations to perceived saltiness were examined. Two levels of NaCl (0.1% and 0.2%) were added to two concentrations (0.1% and 0.3%) of two ionic (xanthan and kappa carrageenan) and two non-ionic (locust bean and guar) gum solutions. Saltiness perception was affected by the ionic properties of the gums. NMR transverse relaxation rates (R₂, see^?l) indicated Na⁺ was less mobile in ionic than nonionic systems. Ionic gums correspondingly suppressed saltiness perception- compared to nonionic gums. As Na⁺ increased in both ionic and nonionic systems, R₂ values converged and perceived saltiness equalized. Food components that bind Na⁺ may suppress saltiness perception, which may be important in low-sodium foods.     

卡拉胶凝胶特性及其在巧克力牛奶中的应用

针对卡拉胶水凝胶的两个主要指标凝胶强度和胶体黏度,研究了卡拉胶含量、钾离子浓度和pH值三个主要因素对卡拉胶水凝胶特性的影响,结果表明:凝胶强度随胶体含量的增加线性增大后渐趋平稳、受钾离子的影响出现峰值、在pH值8.0和10处出现两个拐点;胶液黏度随卡拉胶含量增加迅速增大、随钾离子浓度提高而减小、中性时的黏度最大.通过正交实验确定了影响卡拉胶凝胶因素的主次顺序为卡拉胶浓度、钾离子浓度和溶液的pH值,最佳条件组合为卡拉胶浓度1.2%,钾离子浓度1.2%,pH值9.0;通过考察单独使用卡拉胶以及卡拉胶与魔芋胶、刺槐豆胶及结冷胶等几种食品胶在巧克力牛奶中形成凝胶时的结构状态,判定卡拉胶与刺槐豆胶的协同作用效果最佳.     

Comparison of effects of prickly pear (Opuntia ficus indica sp) fruit,arabic gum,carrageenan, alginic acid,locust bean gum and citrus pectin on viscosity and in vitro digestibility of casein

The consumption of high levels of fibres can induce a decrease in both food digestibility and nutrient availability. Prickly pear is a pectin‐rich fruit and it is possible to use it to decrease plasma cholesterol levels. Its effect on food digestibility deserves attention. This effect was determined by using a mixture of a constant quantity of casein and an increasing quantity (10, 20, 25% of the casein) of prickly pear pulp, skin and seed. In parallel, the effect of similar mixtures of carrageenan, gum arabic, locust bean gum, alginic acid and citrus pectin with casein was also studied. The flow behaviour of the different mixtures was determined and their digestibilities were measured using an in vitro digestion cell device. The apparent viscosities of the mixtures with prickly pear components and gum arabic were similar. The nature and level of fibres in the diet modified nitrogen release in the in vitro digestion cell model. The pulp of the prickly pear decreased the digestibility of the casein‐based diet to a greater extent than the other soluble fibres, whatever the percentage used. The results suggest that the decrease in N release in the digestion cell model is due to the interaction of the fibres with the enzymes or casein rather than to the apparent viscosity of the mixtures. © 2000 Society of Chemical Industry     

SIMULATING VISCOELASTIC PROPERTIES OF SELECTED FOOD GUMS AND GUM MIXTURES USING A FRACTIONAL DERIVATIVE MODEL

A four parameter semi-empirical model has been developed using the fractional derivative (FD) theory, which consists of applying a mathematical operator to a constitutive equation. The Fourier transform approach is used to obtain the analytical function of the derived model. Since a single four parameter model can predict both storage modulus (G') and dynamic viscosity (η'), the developed FD model was appropriate in describing the viscoelastic properties of selected food gum dispersions, food gum mixtures and gellan gel. This fractional derivative model shows good simulation capability for selected food gum dispersions (0.5% xanthan gum, 0.5 and 0.75% locust bean gum, and 0.5, 0.75, and 1.0% guar gum), 0.6% gellan gel, and binary mixtures of carrageenan and guar gum, car-rageenan and xanthan, as well as guar and xanthan gum.     

基于亲水胶体改性和混料设计优化传统粘豆包的配方

目的 用亲水胶体改性和混料设计来优化传统粘豆包的配方, 改善其食用品质。方法 选用3种食品工业中常用的亲水胶体, 卡拉胶、黄原胶和瓜尔豆胶, 对糯玉米与糯大黄米淀粉进行改性, 通过快速粘度分析仪和质构仪比较回生值和硬度的变化, 筛选出复配糯玉米粉和复配大黄米粉作为粘豆包的制作原料, 然后利用混料设计优化粘豆包配方。结果 卡拉胶、黄原胶、瓜尔豆胶对糯性谷物淀粉有着良好的抗老化作用, 回生值都明显变小, 尤其瓜尔豆胶效果最明显; 通过混料设计发现当糯大黄米为33%, 糯玉米粉为24%, 红豆馅为43%时感官评分最高。结论 利用混料设计优化传统粘豆包的生产配方, 感官评分高, 传统粘豆包品质得到改善。