Improving effect of xanthan and locust bean gums on the freeze-thaw stability of white sauces made with different native starches

The effect of adding xanthan gum and locust bean gum at low concentrations (0.15% w/w) on the freeze/thaw stability of white sauces prepared with native starches from four different sources (corn, waxy corn, potato, and rice) was investigated. Linear viscoelastic properties were taken as structural indicators and these and syneresis as indicators of the freeze/thaw stability of the sauces. The pasting properties of the starch in the sauce system were also studied. Both hydrocolloids reduced the structural changes occurring after thawing, xanthan gum being more effective than locust bean gum. In corn and potato sauces, the most affected by the freeze/thaw cycle, the appearance of syneresis and the increase in viscoelastic functions were significantly reduced by both hydrocolloids. In general, the addition of hydrocolloids affected peak, hot peak and cold peak viscosities and reduced relative total setback. The results regarding the possible effects of hydrocolloid addition to white sauce systems are discussed in molecular terms.     

Comparing microwave- and water bath-thawed starch-based sauces: Infrared thermography,rheology and microstructure

The purpose of this study was to compare the effects of microwave thawing and water bath thawing on white sauces prepared with two different native starches (potato and corn) and a modified waxy maize starch. The linear viscoelasticity, microstructure and thermographic characteristics of the thawed sauces were analysed and compared with those of freshly prepared sauces. Due to starch retrogradation, the quality characteristics of the native starch-based sauces were strongly affected by freezing and thawing, but these effects were smaller for microwave heating than for heating in a water bath. The water accumulated during freezing tended to diffuse more uniformly in the microwave-thawed sauces, providing a more homogeneous structure than that of the water bath-thawed sauces. It is hypothesized that the shorter heating time in microwave reduces the extent of starch retrogradation during thawing and that local high temperature zones in the microwave may be more effective in the melting of retrograded starch.     

Effect of cooking time and ingredients on the performance of different starches in white sauces

The effect of white sauce ingredients and increased cooking time at 90 °C on the degree of gelatinization of corn, waxy corn, rice, potato and modified waxy corn starches was studied. The changes in pasting properties, linear viscoelastic properties, and microstructure were determined. In all the native starches in water, a longer cooking time at 90 °C caused greater starch granule swelling and more leaching of solubilized starch polymers into the intergranular space. These effects were more noticeable in the waxy corn and potato starches. The potato starch was the most affected, with complete disruption of the starch granules after 300 s at 90 °C. The microstructural changes which transformed a system characterized by starch granules dispersed in a continuous phase (amylose/amylopectin matrix) into a system with an increase in the continuous phase and a decrease in starch granules were associated with a decrease in system viscoelasticity. The elastic moduli were higher in the sauce than in the starch in water system. However, with the exception of potato starch, the white sauce showed lower viscoelasticity than the starch in water system. The white sauce ingredients decreased the effect of cooking time on the starch gelatinization process, particularly in potato starch.     

Clean label starches as thickeners in white sauces. Shearing, heating and freeze/thaw stability

The linear viscoelastic properties and syneresis of freshly prepared and freeze/thawed white sauces prepared with different native starches (corn, waxy corn, potato and rice) at different shearing speeds were studied. Viscosity changes during processing were also measured using a starch pasting cell attached to a rheometer. The freeze/thaw cycle produced a significant increase in the viscous and elastic modulus and the appearance of syneresis in the corn and potato starch sauces, while the waxy corn and rice starch sauces were only slightly affected. Syneresis was significantly reduced upon subsequent heating. Greater shearing speed produced a significant decrease in viscoelasticity. Viscosity profiles revealed that the increase in shearing speed decreased the starch gelatinization temperature and swelling capacity and increased starch breakdown.     

MODEL PREDICTION FOR SENSORY ATTRIBUTES OF NONGLUTEN PASTA

Response surface methodology was used to predict sensory attributes of a nongluten pasta and develop response surface plots to help visualize the optimum region. Optimum regions of xanthan gum, modified starch, and locust bean gum were selected by overlapping the contour plots of sensory properties of nongluten pasta as compared with the control pasta. The formula of nongluten pasta that possessed the most desirable properties was xanthan gum at 40 g, modified starch at 35 g, locust bean gum at 40 g, tapioca starch at 113 g, potato starch at 57 g, corn flour at 250 g, and rice flour at 50 g. The quality of nongluten pasta could be improved by using different levels of nongluten starches and flours, and nonstarch polysaccharides.     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

Microstructural, physical, and sensory impact of starch, inulin, and soy protein in low-fat gluten and lactose free white sauces

The microstructural, physical, and sensory properties of low-fat sauces made with different starches, soy protein, and inulin as a fat replacer were analyzed. Gluten-free waxy starches-rice and corn-were selected as well as soy protein to obtain sauces suitable for celiac and lactose intolerant consumers. Light microscopy was used to visualize the swollen starch granules dispersed in a protein-amylopectin-inulin phase. Inulin seemed to limit protein network development, which was related with a higher dispersion of starch granules within the sauce matrix. Therefore, the sauces made with inulin had a lower apparent viscosity (η(app) ) values (P < 0.05) in comparison with oil sauces. The sauces made with rice starches also exhibited a lower viscosity (P < 0.05) since these granules did not swell as corn granules do. All the sauces had a remarkable physical stability since there were no syneresis phenomena and color did not change significantly (P < 0.05) after 15 d of refrigeration storage (4 °C). Finally, the sensory test suggests that oil could be substituted by inulin in the preparation of low-fat sauces since no significant differences (P < 0.05) in texture and flavor were found. These results encourage further research to optimize the formulations of these types of alternative white sauces. Practical Application: Nowadays there is a great demand of ready-to-eat products due to new consumptions habits. In this context, it would be interesting to develop low-fat sauces with inulin that could be used in this type of products improving their nutritional profile. The requirement of processed food for specific groups of population, such as celiac and lactose intolerant consumers, makes it necessary to use gluten free starches and soy protein in the formulation of sauces. The characterization of structural, physical and sensory properties is required to understand the product acceptability and its behavior during its shelf life.     

Amylopectin structure of heat–moisture treated starches

The effects of heat–moisture treatment (HMT; moisture content of 25%, at 100°C for 24 h) on starch chain distribution and unit chain distribution of amylopectin in normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starches were investigated. After HMT, starch chain distribution (amylose and amylopectin responses) of waxy corn and potato starches were identical to those of untreated starches, whereas the chromatographic response of waxy rice starch showed a slight decrease, but with a slight increase in peak tailing. This result indicated that HMT had no (or very limited) effect on the degradation of amylopectins. Analysis of unit chain distribution of amylopectins revealed that waxy characteristics affected the molecular structure of amylopectin in untreated starches, i.e., the CL of normal‐type starches was greater than that of waxy‐type starches. After HMT, the CL and unit chain distribution of all starches were no different than those of untreated starches. The results implied that changes in the physico‐chemical properties of HMT starches would be due to other phenomena rather than the degradation of amylopectin molecular structure. However, the thermal degradation of amylopectin molecules of waxy starches could occur by HMT at higher treatment temperatures (120 and 140°C).     

变性淀粉对卡仕达酱性能的影响及复配配方

本文在比较羟丙基二淀粉磷酸酯（HWMDP）、乙酰化二淀粉磷酸酯（AWMDP）、乙酰化双淀粉己二酸酯（AWMDA）糊化特性的基础上，将三种变性淀粉应用于卡仕达酱中，通过对比卡仕达酱的质构特性、耐烘烤度、流变特性及感官品质，筛选了合适的变性淀粉，并考察了变性淀粉、玉米淀粉、卡拉胶和刺槐豆胶添加量对卡仕达酱品质的影响。结果表明:HWMDP应用在卡仕达酱后，较添加AWMDP和AWMDA的卡仕达酱硬度大、黏度高，感官特性和耐烘烤性较佳。卡仕达酱增稠剂的适宜添加量为:HWMDP 4%（m/m）、玉米淀粉3%（m/m）、卡拉胶0.45%（m/m）、刺槐豆胶0.45%（m/m）。由该配方制得的卡仕达酱各指标接近对照样。     

Retrogradation Kinetics of Eight Starches

Retrogradation rate and extent were determined by differential scanning calorimetry and rheology measurements on 40% dry matter gels made from pea, modified waxy maize, rice, waxy rice, wheat, manioc, potato and microwaved irradiated potato starches. As a result, each starch retrogrades differently, depending also on the measurement technique. Nevertheless, potato and pea starches seem to be the most sensitive and the waxy and modified waxy types are the least sensitive to retrogradation.     

Rheological,Textural and Flavour Properties of Yellow Mustard Sauce as Affected by Modified Starch,Xanthan and Guar Gum

Influence of a modified starch-gum thickening system on the rheological, textural and flavour properties of yellow mustard sauce was studied. The rheological measurements indicated that the sauces exhibited a weak gel-like, strong shear thinning behaviour. Dynamic viscoelasticity measurements showed that the sauces with modified starch (MS) and xanthan gum (XG) presented superior viscoelastic properties to those with MS and guar gum (GG) samples. All tested sauces showed non-Newtonian, pseudoplastic and thixotropic fluids characteristics. Parameters such as hardness, springiness, cohesiveness, gumminess and spreadability were used to evaluate the textural properties, and the results indicated that MS/XG was more influential than MS/GG on the textural properties. Sensory analysis suggested that 0.4 % MS/0.3 % XG, 0.4 % MS/0.4 % XG and 0.4 % MS/0.4 % GG were superior thickeners for the yellow mustard sauces. The flavours of these three sample groups with the highest sensory scores and a sample with only MS were analysed by an electronic nose, which showed that the electronic nose was able to distinguish their differences.     

Effects of xanthan and galactomannan on the freeze/thaw properties of starch gels

Three starches (maize, rice and wheat), and the two non-starch polysaccharides xanthan and locust bean gum galactomannan (LBG) were examined in gel and dough systems for texture and stability properties during freezing and low temperature storage. Xanthan and LBG were found to confer increased resistance to freeze/thaw cycling on rice starch gels but the non-starch polysaccharides had little effect on the performance of maize and wheat starch gels or on wheat dough.     

不同来源的淀粉制备淀粉磷酸单酯的性能及应用

本文比较了马铃薯淀粉、蜡质玉米淀粉、木薯淀粉、小麦淀粉及经磷酸化后产品的物理性能，着重研究了其粘度及糖、盐对其粘度的影响并比较了磷酸化对糊的透明度、冻融稳定性及其对发泡体系的影响，结果表明不同淀粉制得的淀粉磷酸单酯的性能有很大差别。在蛋糕中的应用试验表明，在蛋糕中添加淀粉磷酸单酯可以增加比容并延长其货架寿命。     

辛烯基琥珀酸淀粉酯在速冻水饺中的应用

采用黏度速测仪和分光光度计测定糯玉米淀粉和大米淀粉辛烯基琥珀酸酐改性前后糊的性质,并将其按照不同比例分别添加到面粉中,研究其对速冻水饺品质的影响。结果表明：辛烯基琥珀酸酐改性使糯玉米淀粉和大米淀粉糊的透明度提高、凝沉性降低、冻融稳定性得到改善。添加不同比例的糯玉米辛烯基琥珀酸淀粉酯和大米辛烯基琥珀酸淀粉酯可增大面粉的黏度,提高饺子皮的硬度、弹性和咀嚼性(P ＜ 0.05);其中添加5% 预糊化糯玉米辛烯基琥珀酸淀粉酯的饺子冻裂率最低,并且饺子的色泽、透明度、韧性和细腻度最好。     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.     

Rheologische Untersuchungen zum Einfluß von Hydrokolloiden auf die Gefrier-Tau-Stabilität von Stärkekleistern

Rheological Examination of the influence of Hydrocolloids on the Freeze-thaw-stability of Starch Gels. On thawing, frozen food containing starch often exhibits synaeresis, which is clearly related to structural changes. In order to determine the extent of synaeresis generated by freeze-thaw-cycles (FTC), rheological measurements were conducted with potato starch, waxy rice starch and 4 different maize starches. The relative growth of the storage modulus due to an FTC was defined as a measure of the freeze-thaw-stability (FTS). A value of less than 1 indicates an adequate FTS. Comparison of different maize and waxy maize starches revealed no correlation between FTS and amylose content. Potato starch, which exhibits very poor FTS, was chosen as a medium to examine the influence of hydrocolloid addition on the freeze-thaw-properties. First no or only little improvement of FTS was detected when examining tara gum, l-carrageenan and locust bean gum. Maximum FTS was achieved with mixtures of 5%-gels containing 10% of hydrocolloids as either l-carrageenan or locust bean gum. On the basis of the viscoelastic data, the mechanism by which hydrocolloids improve the FTS was deduced as a combination of network coupling and exclusion effect.     

几种不同品种淀粉及羟丙基产物糊液性质比较研究

以薯类淀粉(木薯,马铃薯)及禾谷类淀粉(普通玉米、蜡质玉米、高直链玉米及糯米)为原料,以环氧丙烷为醚化剂。制备了羟丙基变性淀粉。反应条件:淀粉乳质量分数40%、反应温度40℃、无水Na_2SO_4添加量12%(以淀粉干基计)、NaOH添加量1.2%、环氧丙烷添加量12%、反应时间18h。分别对原淀粉及在相同的反应条件下制备的羟丙基变性淀粉糊性质做了对比研究。不同品种淀粉糊性质存在很大差别。经过羟丙基改性。淀粉糊液粘度性质、冻融稳定性、透光率、都有不同程度的改善,但凝沉性质不能准确反映羟丙基化对蜡质玉米淀粉和糯米淀粉糊液性质的改善。     

Assessment of some parameters involved in the gelatinization and retrogration of starch

Factors influencing the formation of resistant starch (RS) during gelatinization and retrogradation were studied in starches and flours from cereals (wheat, corn, rice) and potato. RS obtained using a high-pressure autoclave system varied between 3.94 and 21.21% (rice and potato starches, respectively) similar to the values obtained after gelatinization in a boiling water bath. Except for rice, RS was higher in pure starches than in flours. Stirring during gelatinization yielded more homogeneous products than non-stirred samples. Apparently, gelatinization was unaffected by pH values between 3.5 and 10.5. To obtain optimum RS yields during retrogradation, it was necessary to cool down starch gels prior to freezing, followed by thawing at room temperature and drying at 60°C. These conditions ensure good yields in the formation of RS with potential industrial applications. ©     

直链淀粉含量对玉米淀粉/瓜尔胶复配体系糊化和流变特性的影响

为考察直链淀粉含量对淀粉/瓜尔胶复配体系性质的影响,以不同直链淀粉含量的玉米淀粉(蜡质玉米淀粉、普通玉米淀粉和高直链玉米淀粉)为原料,加入瓜尔胶,研究复配体系的糊化、流变及凝胶特性。结果表明:瓜尔胶与直链淀粉之间的相互作用是引起淀粉复配体系黏度和稠度系数增加、成糊温度和流体指数降低的主要原因。动态流变实验结果表明淀粉中直链淀粉含量不同对复配体系的动态模量的影响也不同。在糊化过程中,随着直链淀粉含量增加,直链淀粉分子与瓜尔胶间的相互作用增强,阻碍了直链淀粉分子间的聚集重排,使得复配体系硬度值减小,3种玉米淀粉形成了质地更为柔软的凝胶。     

酯化蜡质玉米淀粉对糯米粉团冷冻特性的影响

目的评价酯化蜡质玉米淀粉和预糊化酯化蜡质玉米淀粉对糯米粉团冷冻特性的影响。方法测定酯化蜡质玉米淀粉与预糊化酯化蜡质玉米淀粉的冻融稳定性;分别往糯米粉中添加1%、2%、3%、4%(m:m)4个比例的酯化蜡质玉米淀粉和预糊化酯化蜡质玉米淀粉制作速冻糯米粉团,检测速冻糯米粉团的失水率、裂口率、煮熟时间、糊汤率、感官评价等指标。结果预糊化酯化蜡质玉米淀粉与酯化蜡质玉米淀粉均具有良好的冻融稳定性,能有效降低速冻糯米粉团的失水率和裂口率,同时改善速冻糯米粉团的蒸煮和食味品质;预糊化酯化蜡质玉米淀粉在改善糯米粉团冷冻特性斱面效果更优,但两者差距不大,当预糊化酯化蜡质玉米淀粉的添加量为1%时,速冻糯米粉团的失水率为11.8%,裂口率为22.5%,煮熟时间为229 s,吸光度为0.823,感官及外观评分分别为79.3分、23.1分。结论添加1%预糊化酯化蜡质玉米淀粉制成的糯米粉团冷冻特性最好。