RHEOLOGICAL PROPERTIES AND APPLICATIONS OF MESQUITE TREE (PROSOPIS JULIFLORA) GUM 2. RHEOLOGICAL PROPERTIES AND STABILITY OF O/W EMULSIONS CONTAINING MESQUITE GUM

Oil-in-Water emulsions stabilised by mesquite gum have been examined by their creep compliance-time response at a constant low shear stress and by shear stress-shear rate studies. The Theological data were influenced by pH, electrolyte (NaCl, CaCl₂) and aging time. Both pH and electrolyte altered the degree of compactness of the mesquite molecules adsorbed on the oil drops. Aging produced changes in the rheological properties, the general trend depending on the rate of drop coalescence and the ability of adsorbed mesquite layers on adjacent flocculated drops to interpenetrate and form new linkages. The drop coalescence rate was highest at pH 7.0, but this was offset by greater interpenetration so that the rheological parameters increased substantially during aging.     

大米交联淀粉的制备及其冻融稳定性的研究

以大米淀粉为原料。三偏磷酸钠为交联剂，以不同的PH值、温度、时间为条件，采用正交实验设计，确定出制备大米交联淀粉的最佳工艺条件为：三偏磷酸钠2．2％、PH值10、50℃、35min。另外对交联淀粉以及在其中加入不同添加剂后的冻融稳定性进行了初步研究，结果表明：大米交联淀粉的冻融稳定性明显优于原淀粉，加入氯化钠和柠檬酸降低了交联淀粉的冻融稳定性，而加入蔗糖则增加了交联淀粉的冻融稳定性。     

MICROSTRUCTURE AND TEXTURE OF CHEESE ANALOGS CONTAINING DIFFERENT TYPES OF FAT

The texture of cheese analogs, whose fat fraction was composed of butterfat, soybean oil or soybean fat and their blends was measured by instrumental Texture Profile Analysis (TPA), and sensorially by a trained panel and the results were subjected to Response Surface Methodology (RSM). The microstructure was examined by Scanning Electron Microscopy (SEM). The models showed that the diverse fat types differently influenced the instrumental characteristics of hardness and springiness, and the sensory characteristics of firmness, elasticity, shear resistance, mouthfeel and creaminess of the cheese analogs. Scanning electron micrographs indicated that the morphology, size and distribution of fat droplets also varied with the fat type.     

QUALITY CHARACTERISTICS OF CORN NOODLES CONTAINING GELATINIZED STARCH, TRANSGLUTAMINASE AND GUM

ABSTRACT

Effects of gelatinized corn flour addition level (40, 60 and 80%), gum (locust bean gum or xanthan gum, 3%) and/or transglutaminase (TG, 0.5%) on quality characteristics of corn noodle were investigated. Gelatinized corn flour was used as a binder for remaining untreated corn flour (60, 40 and 20%). Corn noodles were evaluated in terms of cooking properties (cooking loss, total organic matter (TOM), water absorption, swelling volume and maximum force), color, sensory and pasting properties. Noodle sample containing gelatinized corn flour at level of 80% exhibited best cooking and sensory properties. Gum and/or TG were added to this noodle formula. Gum improved noodle quality in terms of some cooking properties. Improving effect of xanthan gum was more obvious. Covalent crosslinks catalyzed by TG caused significantly lower cooking loss and TOM values. Gums generally caused increases in Rapid ViscoAnalyzer viscosity values of noodles. Gum and/or TG show great promise in processing of gluten‐free corn noodle.

PRACTICAL APPLICATIONS

Celiac disease occurs in about one in 300 people in Europe. Lack of gluten in cereals that are safe for gluten‐free food causes major problems in dough processing and product quality. Technological difficulties in production and lack of awareness of number of celiac patients in need of gluten‐free products might restrict researches related to gluten‐free food. In recent years, various approaches to overcome the technological problems are arising. Searching for ingredients that have ability to mimic properties of gluten in production of gluten‐free food is the most common approach. We report herein beneficial effects of gelatinization, gum (locust bean gum, xanthan gum) and/or transglutaminase (TG) in gluten‐free corn noodle production. They have major improving effects in noodle quality and show great promise as a processing aid in bulk manufacture of gluten‐free corn noodle. To the best of our knowledge, there is no study investigating utilization of TG in gluten‐free corn noodles.     

EFFECTS OF GELLAN GUM, CITRIC ACID AND SWEETENER ON THE TEXTURE OF LEMON JELLY

Effects of various ingredients on the texture of lemon jellies prepared from gellan gum, citric acid and sweetener were investigated by rheological measurement and sensory evaluation. The data were analyzed by use of the modification of Scheffé's mixture experiment method in converse triangle experiment area. The contours of the response surface were drawn using the best model whose terms were searched by AIC statistic, and the approximate model was calculated to consider the contours. "Hardness" estimated by both methods was large in jellies with high content of gellan gum and low content of citric acid. The content of citric acid significantly influenced "smoothness" estimated by a subjective method. The influence of citric acid varied with the content of gellan gum. The correlation coefficients of evaluation between "hardness" and "lemon flavor" or "sourness" were negative.     

多重乳状液的稳定性及其在食品工业中的应用

综述了影响多重乳状液稳定性的各种因素，如乳化剂、油水相比、粘度、渗透压、电解质和乳化工艺等。介绍了多重乳状液在食品工业中的应用，主要包括脂肪替代品、乳化液膜、香精香料的缓释和微胶囊技术方面，并指出了其发展前景。     

RHEOLOGICAL STUDY OF O/W EMULSIONS CONTAINING DRIED WHOLE EGG AND LOCUST BEAN GUM

The influence of sucrose addition and type of salt (NaCl; Morton Lite salt: 50% NaCl and 50% KCl, and Mineral salt: 65% NaCl, 25% KCl and 10% MgSO₄) on the rheological properties of O/W emulsions containing locust bean gum was analyzed. Flow curves over the range 0.1 to 100 s⁻¹ and transient flow curves at 0.2 s⁻¹, at 20 and 30C were obtained for 12 different emulsions, containing 30% (w/w) of sunflower oil. The K and n power law parameters and the hysteresis loop area (HL) were evaluated from the flow curve. So were the Hahn parameters from time-dependent stress decay fitting. Rheological behaviour of emulsions was affected by the type of salt and the presence of sucrose. Changes in solvent properties of the continuous phase in the emulsions on the macromolecules present could be responsible for the different behaviour. The ageing effect on flow behaviour parameters and on the hysteresis loop area was also studied. Evolution of rheological parameters during emulsion storage suggests that increase of ionic strength and polar solutes concentration decrease the stabilizing properties of locust bean gum.     

STABILITY OF CAPSICUM ANNUUM OLEORESIN-IN-WATER EMULSIONS CONTAINING PROSOPIS AND ACACIA GUMS

Chilli oleoresin-in-water emulsions were stabilized with very low concentrations of mesquite ( Prosopis juliflora ), arabic ( Acacia Senegal ) and acacia ( Acacia spp.) gums at different pH values in order to establish which polysaccharide had the best emulsifying capacity and provided the best stability against droplet coalescence and pigment degradation. Mesquite gum was the best emulsifying and stabilizing agent, followed by gum arabic and acacia gum. In all cases, pH had a dramatic effect on the emulsion stability against droplet coalescence and color degradation. The stabilizing mechanisms governing these two deteriorative processes were opposite. While coalescence kinetics was hindered at high pH values, color degradation kinetics took place at a higher rate, while the opposite effect occurred at lower pH values. A number of factors were important in determining the emulsifying capacity, the droplet coalescence stability and the color degradation stability of the gums among them, the protein content, the molecular weight, the surface charge and the steric configuration adopted at different pH values.     

OXIDATIVE STABILITY, COOKING YIELD AND TEXTURE OF PORK TREATED WITH A LOW-SODIUM SALT

The effect of a low-sodium salt mixture (LSSM) on the characteristics of cooked ground pork was investigated. LSSM, similar to NaCl, exhibited a minor but definite prooxidative effect in the system examined. The cooking yield of meat containing 1% LSSM was 69.8% compared to 74.3% for 1% NaCl. The cooking yields of samples with 2 and 3% LSSM were similar to those containing 2 and 3% of NaCl, respectively (p > 0.05). Maximum shear force values of samples containing 1% LSSM and 1% NaCl were similar. However, the maximum shear force values of meats treated with LSSM at 2 and 3% LSSM (19.1 and 24.8 kg) were lower (P < 0.05) than those containing 2 and 3% NaCl (21.9 and 27.0 kg). Addition of LSSM or NaCl to ground pork also enhanced the cooking yield and firmness over those containing no salt. The color characteristics of cooked pork remained generally unaffected by LSSM.     

甘油和木糖醇复合增塑剂对大豆蛋白塑料性能的影响

研究了甘油和木糖醇复合增塑剂对大豆蛋白塑料特性的影响。将甘油与木糖醇以不同比例添加到大豆蛋白中，经压制成型制成大豆蛋白塑料。结果表明，采用复合增塑剂，大豆蛋白塑料的拉伸强度，杨氏模量均增加。复合增塑剂塑化大豆蛋白塑料存在2个玻璃化温度，分别产生在富集复合增塑剂区域和富集大豆蛋白区域。除甘油和木糖醇比率4：6外，其他比率复合增塑剂塑化塑料2个玻璃化温度之差均低于纯甘油增塑蛋白塑料的。复合增塑剂塑化塑料的吸水率增加。     

EFFECT OF SALT ON THE STABILITY OF PROPYLENE GLYCOL ALGINATE/XANTHAN GUM/POLYSORBATE-60 STABILIZED OIL-IN-WATER EMULSIONS

Stabilization mechanism of salt, as a dissolved electrolyte, in oil-in-water emulsions in the presence of stabilizers and/or emulsifiers, propylene glycol alginate, xanthan gum and/or polysorbate-60 has been studied using rheological techniques, particle size analysis and surface tension measurements. Salt affected the stability of the ternary system, propylene glycol alginate/xanthan gum/polysorbate-60, depending on the emulsifier/stabilizer ratio. Creep measurements indicated that low salt concentrations were particularly effective when PGA:X ratios were used in the presence of PS-60. In both PGA:X and PGA:X/PS-60 systems salt did not affect the particle size distribution during aging. Surface tension measurements were in agreement both with particle size distribution and high shear rate experiments.     

CONTENT AND STABILITY OF HEXANE EXTRACTABLE LIPID AT VARIOUS STEPS OF PRODUCING MACARONI CONTAINING GROUND FLAXSEED

Research was conducted to determine changes in content and stability of hexane extractable lipid during processing of macaroni containing 15% (w/w) ground whole flaxseed and ground flaxseed hull. Dry mixture, hydrated mixture, extruded macaroni, dried macaroni and cooked macaroni were evaluated. Results were similar for macaroni containing ground whole flaxseed or ground flaxseed hull. Hydration decreased extractable lipid. Hydration decreased the amount of α-linolenic acid (ALA) and free fatty acid (FFA) and increased the amount of conjugated diene in the extracted lipid. Little or no conjugated triene was detected in lipid extracted from samples containing flaxseed, regardless of the processing step. Extruding, drying and cooking had little or no effect on the stability of lipids in macaroni containing flaxseed. The low levels of FFA, conjugated diene and conjugated triene indicate that lipid remained relatively stable during processing and cooking of macaroni containing ground flaxseed.