Corn Masa and Tortillas from Extruded Instant Corn Flour Containing Hydrocolloids and Lime

Extruded instant corn flour (EICF) samples with hydrocolloids (gums), such as gum arabic, carboxymethylcellulose (CMC), guar and xanthan and with different concentrations of lime (0.1, 0.2 and 0.3% w/w) were prepared by extrusion. The gums were added before or after thermal processing. The dehydration process followed through the weight loss (WL) in masa, the physicochemical (water absorption capacity (WAC) and WL during cooking) characteristics of masa were optimized to give longer dehydration times and tortillas with good textural (rollability, tensile strength and cutting force) properties. The lowest effective moisture diffusion coefficient (D*) was found in masa samples containing 0.2% (w/w) of lime and 0.5% (w/w) of the xanthan gum added before extrusion. These masas produce tortillas with optimum textural characteristics and highest yields.     

Effect of hydrocolloids on the rheological, microscopic, mass transfer characteristics during frying and quality characteristics of puri

Effect of hydrocolloids such as guar gum (GG), arabic gum (AG), carrageenan (CG), locust bean gum (LBG), xanthan gum (XN), hydroxypropyl methylcellulose (HPMC) and carboxymethylcellulose (CMC) at 0.5% w/w level on rheological and quality parameters of puri from whole wheat flour was studied. Hydrocolloids like CMC, XN and HPMC increased the water absorption of puri dough, while it decreased in all other samples. The dough development time and mixing tolerance index values increased, while dough stability did not get affected. On addition of hydrocolloid, there was a reduction in the pasting temperature, while the peak viscosity, hot paste viscosity and cold paste viscosity values increased. Hardness, cohesiveness and adhesiveness properties of the puri dough increased with the addition of hydrocolloids. All the hydrocolloids used in general helped in retention of moisture in the puri and hence remained softer and pliable, while there was a significant reduction in the oil content of puri samples containing hydrocolloids. Among the different hydrocolloids used, addition of guar gum at 0.5% w/w level led to puris having improved quality characteristics to a greater extent with respect to moisture retention, lowering of oil content upon frying with softer and pliable texture and better keeping quality. The mass transfer studies confirmed that the mass transfer co-efficient values for moisture loss and oil uptake were lower in puris with guar gum than control.     

Textural and Physicochemical Properties of Low-Fat, Precooked Ground Beef Patties Containing Carrageenan and Sodium Alginate

Textural and physicochemical characteristics of selected hydrocolloids incorporated into low-fat, precooked, beef patties were investigated. Patties with an alginate/carrageenan combination had higher yields and percent moisture but lower shear force values than those of alginate or carrageenan treatments within the same fat level. Alginate appeared to improve texture slightly more than carrageenan, but carrageenan tended to release more free water after cooking and reheating. Patties with 10% fat were generally lower in shear value, cooking yield and percentage free water released as compared to their 5% fat counterparts with the same added ingredient. Low-fat, precooked, ground beef patties containing alginate/carrageenan combinations were comparable to regular beef patties (20% fat control) regarding yields and textural properties.     

基于主成分分析构建混合多糖凝胶品质综合评价模型

为了构建混合多糖凝胶的综合评价预测模型,该研究采用全质构分析法（TPA）和感官评价法对5种亲水胶体复配得到的25种混合多糖凝胶进行测定。结果表明,混合凝胶质构硬度与感官硬度、脆性呈极显著正相关;质构内聚性、咀嚼性与感官硬度、脆性、咀嚼性、弹性、总体可接受度呈极显著正相关;质构弹性与感官弹性、咀嚼性呈极显著正相关,而感官气味与质构指标均不相关。利用主成分分析法从混合凝胶的11个评价指标中提取出3个主成分,累计方差贡献率达到82.45%,建立了混合多糖凝胶的综合评价模型。根据综合评分结果知,当混合凝胶配方为k-卡拉胶0.8%、魔芋胶1.2%、低酰结冷胶0.4%、刺槐豆胶0.6%、海藻酸钠0.4%时,混合多糖凝胶的得分最高为1 476.17;而当混合凝胶中不添加k-卡拉胶时,综合评分最低为424.56。基于主成分分析得到的综合评价模型对混合多糖凝胶品质进行评价,可以客观的反映出混合多糖凝胶的品质。     

Role of maltodextrins in the staling of starch gels

The possible role of maltodextrins with a low degree of polymerisation (DP) as agents that retard bread staling was studied by following the staling process on a model system consisting of starch gels by means of textural and calorimetric assays. Maltodextrins of DP 2 to 7 were added at concentrations of 0.5% (starch base) to 15% (w/w) starch gels. Textural and calorimetric results were analysed by the Avrami equation. The addition of maltodextrins promoted a slight decrease in the initial firmness of the starch gels. All the samples with maltodextrins showed a lower rate of firming. The same effect was observed on the rate of amylopectin retrogradation, except for the maltose sample under short and intermediate storage times. It was concluded that low DP maltodextrins might be responsible for the anti-staling effect obtained by using α-amylase addition in the breadmaking process.     

Effect of some hydrocolloids on the rheological properties of different formulated ketchups

Five different hydrocolloids (tragacanth gum, guar gum, carboxy methyl cellulose, xanthan gum and locust bean gum) were added, at levels of 0, 0.5, and 1 g/100 g (w/w), respectively, to three different formulated ketchups which were processed from cold-break tomato paste dilutions, having total soluble solid (TSS) contents of 7.5, 10, and 12.5 g/100 g (w/w), in sequence, and the effect of these hydrocolloids on the rheological properties of tomato ketchups was investigated using a viscometer with smooth surface wide-gap coaxial cylinders. All hydrocolloids increased the consistency of the tested samples; however, guar gum and locust bean gum caused the maximum increase, followed by xanthan gum, tragacanth gum and carboxy methyl cellulose (CMC). Both the ketchup formulation and the hydrocolloid concentration were found to affect the consistency of ketchups. The highest consistency index was obtained by processing dilutions with a TSS content of 12.5%, and the addition of hydrocolloids at the level of 1%. The fluidity of the ketchups decreased with both the addition of all hydrocolloids and the increase in hydrocolloids concentration. Furthermore, the fluidity of the ketchups was also affected by ketchup formulation, and it was found to be the lowest for the samples prepared from the tomato paste dilutions having a TSS content of 12.5%.     

EFFECT OF ADDED SALT ON TEXTURAL PROPERTIES OF HEAT-INDUCED GELS MADE FROM GUM–PROTEIN MIXTURES

Large deformation rheological tests were employed to determine the textural differences in heat‐induced gel systems. Three different large deformation rheological methods (viscosity index and apparent elasticity, texture profile analysis (TPA) and torsional fracture) were employed to study the dependence of the ion type on the textural properties of heat‐induced mixed protein–gum gels. Protein–gum mixed solutions were prepared with bovine serum albumin (BSA) or egg white albumin (EWA) (20% w/v) with κ‐carrageenan (KCG), gellan (GLN) or xanthan gums (XNT) (0.5% w/v) at 0.1 M sodium chloride (NaCl), potassium chloride (KCl) or no added salt. Despite inherent differences in protein type, the main effect on the textural properties evaluated was for the kind of salt added, since potassium ions, with a strong influence on KCG and GLN gelation, affected the parameters related to the structure or hardness of the samples. There was no significant effect on parameters associated with sample ductility or elasticity. GLN formed stronger gels than KCG, whereas XNT did not perform as well in gel formation since it does not contribute to protein matrix formation. The results indicated that potassium may be substituted for sodium ions at low ionic strengths in foods where the incorporation of KCG or GLN helps to improve texture and related features.     

Long-term storage stability of selected potato starch – Non-starchy hydrocolloid binary gels

All 3, 4 and 5% potato starch gels containing either κ-carrageenan, guar gum or xanthan gum were prepared and their stability in terms of rheological and textural properties was checked on 30 day storage. It was shown that rheology of these binary potato starch – non-starchy hydrocolloid mixtures could be controlled by anionic character of the admixed hydrocolloid. Depending on the hydrocolloid added, gels made of the tuber starch can either retain their pattern typical for tuber starches or turn into that typical for gels of cereal starches. Hydrocolloids added plasticity to the binary gels but it was lost to a significant extent within the first day of storage. Resulting gels with dominating elastic character are rheologically and texturally fairly stable for subsequent 30 days of storage. Generally, hydrocolloids stabilized potato starch gel on long-time storage to the extent dependent on the gel concentration.     

The use of microbial transglutaminase and soy protein isolate to enhance retention of capsaicin in capsaicin-enriched layered noodles

Specialty layered noodles (LN) were prepared by sandwiching a capsaicin-enriched dough (CED) between two gastro-resistant dough layers made up of wheat flour, soy protein isolate (SPI) and microbial transglutaminase (MTG) at 0.5 (0.5MTG LN), 1.0 (1.0MTG LN) and 1.5 (1.5MYG LN) g/100 g of wheat-SPI flour. The textural, tensile and structural breakdown properties, capsaicin retention, microstructures and the sensory characteristics of cooked LN were evaluated. Compared to other LN, 1.5MTG LN exhibited the highest textural and tensile parameters, highest capsaicin retention, densest structure and was the most difficult to breakdown. The sensory quality of all LN was acceptable, even though it was the Control LN (prepared without SPI and MTG) that scored the highest acceptability. In general, increasing the level of MTG in the sandwiching dough layers of MTG LN reduced the release of capsaicin in simulated mouth, gastric and intestinal conditions, and these results could be due to increased protein cross-linking.     

LINEAR AND NONLINEAR VISCOELASTIC BEHAVIOR OF OIL-IN-WATER EMULSIONS STABILIZED WITH POLYSACCHARIDES

The rheological behavior and stability of oil-in-water emulsions stabilized by different thickening agents were analyzed. Food emulsions were prepared with commercial sunflower oil (40% w/w oil-in-water) and stabilized with 1% emulsifier. The tested thickeners were: (1) 1% w/w xanthan gum (XG), (2) 5% w/w potato starch (PS), (3) 5% PS + 0.5% XG, (4) 1% w/w guar gum (GG), and (5) 0.5% XG + 0.5% GG. Mean droplet size and droplet size distribution (DSD) of emulsions were determined by static light scattering. Steady flow (viscosity versus shear rate), transient flow (viscosity versus time) and oscillatory shear tests (linear viscoelasticity) were performed. The addition of thickening agents improved the stability of the emulsions, the effect was less marked in systems containing only GG. DSD was not significantly modified in emulsions containing starch or hydrocolloids. Microscopic observations showed that all the tested emulsions were flocculated due to the presence of hydrocolloids. The observed shear thinning behavior was attributed to the molecular structure of the polysaccharides and to the flocculation/deflocculation process; viscosity data were satisfactorily fitted to the Cross model. Frequency sweeps showed that emulsions with PS or XG have a weak gel structural network (G' > G); those with GG correspond to a polymeric solution where G' and G" curves intersect within the range of tested frequencies. The viscoelastic linear behavior was described according to the Maxwell generalized model. The discrete relaxation spectrum and relaxation times were estimated from the experimental values of G' and G" for emulsions with PS, PS + XG, and XG. Nonlinear viscoelasticity was also studied from stress relaxation curves at different shear strains. The damping function was calculated and the Soskey-Winter parameters were determined. Transient flow viscosities at different shear rates were comparable to the values estimated from stress relaxation measurements.     

Textural and viscoelastic properties of pork frankfurters containing canola-olive oils, rice bran, and walnut

Textural, rheological and microstructural properties of frankfurters made with 20% pork backfat, 20% canola or 20% canola-olive (3:1) oils, including rice bran (RB) and walnut extract (WE) as macronutrients (2.5%) were investigated. Textural parameters, including hardness, gumminess and rupture-force, were highly (P<0.05) influenced by the fat-oil composition. Addition of RB or WE in vegetable oil emulsions improved textural consistency (P<0.05). However, RB addition reduced gelling capacity, suggesting antagonistic interactions between fiber and oil droplets. Vegetable oil addition favored gel network formation, and, when combined with WE, showed the highest improvement of gel elasticity. These textural and gelling properties were corroborated by frankfurter micrographs, which revealed interactions between vegetable oils, RB, or WE with protein matrix and fat globules affecting these parameters. The results suggest that functional plant-derived ingredients can be valuable to the modification of frankfurter formulations for improved nutrition and as well as textural quality.     

亲水性胶体对广式腊肠水分迁移及质构的影响

本文研究了卡拉胶、魔芋胶、瓜尔豆胶及其复配对广式腊肠烘烤过程中水分迁移、产品质构、感官等质量品质的影响。结果表明,广式腊肠添加亲水性胶体后,可略有提高产品的水分含量,尤其是瓜尔豆胶组(19.94%),比对照提高4.02%;在烘烤中期,亲水性胶体可降低广式腊肠的干燥速率,整体而言,亲水性胶体对烘烤过程中水分散失影响较小。胶体添加组感官得分除D3组,均高于对照组,其中添加复配卡拉胶与魔芋胶的感官综合得分最高,达到87.5;除瓜尔豆胶外,单独胶体和复配胶均能一定程度上改善广式腊肠的质构特性,尤其是复配胶体组。广式腊肠添加亲水性胶体后,复水率显著提高(p0.05),尤其是瓜尔豆胶及其复配组,达到3.79%。复配胶的加入可改善广式腊肠的感官品质、质构特性及复水性,不同亲水性胶体有不同的作用特点。     

Production and Textural Properties of Soy-Cheese Whey Curd

Soy-cheese whey curd was prepared by mixing soymilk and cheese whey with the addition of glucono-delta-lactone (GDL) to coagulate the proteins. Three soymilk concentrations, 6:1, 8:1 and 10:1 (water:bean, v/w), and four cheese whey levels, 3%, 4.5%, 5.25% and 6% (w/v), were used. Heating the GDL treated soy-cheese whey milk in a hot water bath at 85°C for 25 min consistently produced a smooth and compact. curd without syneresis. Textural properties of the curd were tested by an Instron machine. Five parameters-stiffness, bioyield point, firmness, relaxation and plasticity—were determined. Among these, only stiffness and firmness could be used as the textural parameters for the curd.     

Optimization of Gluten-Free Formulations for French-Style Breads

ABSTRACT:  The formulation of gluten-free bread, which will be suitable for patients with coeliac disease, was optimized to provide bread similar to French bread. The effects of the presence of hydrocolloids and the substitution of the flour basis by flour or proteins from different sources were studied. The added ingredients were (1) hydrocolloids (carboxymethylcellulose [CMC], guar gum, hydroxypropylmethylcellulose [HPMC], and xanthan gum), and (2) substitutes (buckwheat flour, whole egg powder, and whey proteins). The bread quality parameters measured were specific volume, dry matter of bread, crust color, crumb hardness, and gas cell size distribution. Specific volume was increased by guar gum and HPMC. Breads with guar gum had color characteristics similar to French bread. Hardness decreased with the addition of hydrocolloids, especially HPMC and guar. Breads with guar gum had the most heterogeneous cell size distribution, and guar gum was therefore selected for further formulations. Bread prepared with buckwheat flour had improved quality: an increased specific volume, a softer texture, color characteristics, and gas-cell size distribution similar to French bread. Bread with 1.9% guar gum (w/w, total flour basis) and 5% buckwheat flour (of all flours and substitutes) mimicked French bread quality attributes.     

Trehalose improves flavour retention in dehydrated apricot puree

The influence of the addition of two sugars (trehalose and sucrose) on the retention of volatiles responsible for the characteristic aroma in dehydrated apricot puree was studied. Aroma compounds of fresh and both freeze‐dried and foam‐mat‐dried apricot puree were analysed by manual headspace solid‐phase microextraction coupled with gas chromatography (GC‐FID and GC‐MS). The best retention of aroma compounds in dehydrated apricot puree was obtained when trehalose was added, regardless of the dehydration process used (freeze drying or foam‐mat drying), although, generally, a much higher retention of flavour volatiles was obtained in freeze‐dried purees. Principal Component Analysis and Cluster Analysis were applied to all the apricot purees studied to obtain a simplified view of the relationship among the aroma compounds in dehydrated apricot purees. This study gives further insights into the mechanisms that occur when trehalose is applied as an additive and will enable the development of new processes to maximize this effect and to produce superior dried products.     

两种海藻酸钠基凝胶的溶胀和质构性能

壳聚糖、果胶和海藻酸钠是天然多糖,具有良好的生物相容性和生物可降解性等优点。以CaCl_2为交联剂制备壳聚糖-海藻酸钠水凝胶和果胶-海藻酸钠水凝胶,研究Ca Cl2浓度、多糖质量比(壳聚糖与海藻酸钠、果胶与海藻酸钠)和交联温度对水凝胶在模拟人体胃肠道环境(pH 1.2胃、pH 6.8小肠、pH 7.4结肠缓冲溶液)中溶胀性能的影响。当壳聚糖或果胶和海藻酸钠质量比为1.25∶1、CaCl_2浓度为0.09 mol/L、温度为60℃时,制备的水凝胶在pH 1.2溶液中溶胀率最小,在pH 6.8和pH 7.4溶液中溶胀率较大;结果表明所制备水凝胶具有pH值敏感性。此外,在优化条件下水凝胶具有较好的质构性能。     

Aroma of dehydrated pear products

Pear purees and cubes were dehydrated with sugars (sucrose and trehalose) addition. Freeze drying and foam-mat drying were used. Manual solid-phase microextraction (SPME) coupled with gas chromatography (GC-flame ionization detector (FID) and GC-MS) was applied to determine the changes in retention of aroma compounds in dehydrated pear purees and cubes. The best retention of aroma compounds in dehydrated pear purees was noticed in the case when freeze drying and trehalose addition were combined. In dehydrated pear cubes, previously dipped in trehalose solution, the highest aroma retention was also determined. This study showed possible application of trehalose as potentially beneficial food ingredient, with the aim to improve the quality of dehydrated fruit products, especially their aroma, and to produce superior dried fruit products or ingredients, which are widely used in food formulation.     

Compressive textural attributes, opacity and syneresis of gels prepared from gellan, agar and their mixtures

Gellan, agar and their mixed gels at an equal proportion of both were subjected to uniaxial compression to determine the textural attributes including fracture characteristics, opacity and syneresis. An increase in concentration of hydrocolloids increased opacity but decreased syneresis. Highly transparent gellan gels with opacity less than 8% were obtained; opacity of agar gels was highest, and was between 5% and 30% for their mixed gels. Syneresis as low as 1.5% was observed with the mixed gel containing 2% each of agar and gellan. The maximum stress and energy for compression increased with the level of gelling agents while instantaneous relaxation in height decreased. Binary combinations or mixed gels containing agar and gellan can provide unique textural and physical characteristics like syneresis and opacity.     

Effect of Hydrocolloids on Quality of Frozen-Thawed Vegetable Curry

Effect of addition of various hydrocolloids in gravy was studied to improve the quality of frozen-thawed vegetable curry. Hydrocolloids such as pectin, sodium alginate, carboxymethyl cellulose, and gellan gum were added (0–0.2%) in the gravy prepared from dry and green spice mix. Frozen-thawed gravy samples showed significantly (P < 0.05) lower drip loss (in percent) with the addition of hydrocolloids by centrifugal and screen (100 meshes) tube test which resulted in increasing concentration of the curry. Pectin (0.2%) reduced the drip losses up to 36% while gellan gum (0.2%) showed about 55% retention of liquid separation over control. Maltodextrin pretreatment at the level of 20% was found to have maximum retention of firmness (6.7 N) in potato cubes as compared to untreated samples.