Application of aged egg in enabling increased substitution of sucrose by litesse (polydextrose) in high-ratio cakes

Previous reports show that replacing sucrose by polydextrose in cakes leads to an elevation of the starch gelatinisation temperature such that it no longer coincides with the egg protein denaturation transition. It is known that as eggs age, the ovalbumin transforms to S-ovalbumin with a higher denaturation temperature. Linking these observations led to the hypothesis that baking reduced-sugar cakes with aged eggs might bring the starch gelatinisation into proximity of the protein denaturation thereby improving the final texture. Baking trials and instrumental texture evaluations of the resulting high-ratio cakes were carried out with fresh egg and egg that had been aged at 37°C for 3, 7 and 14 days. Texture changes that do exist are principally related to differences in the cake crumb density and crumb springiness.     

鱼肉蛋白的热变性研究进展

为探究盐浓度对欧洲鳗肌原纤维蛋白热诱导凝胶形成性能的影响,测定了蛋白的浊度、表面疏水性和活性巯基的变化,考察了0.1、0.3、0.5 mol/L的NaCl浓度下的肌原纤维蛋白热诱导凝胶的性质。结果表明,欧洲鳗肌原纤维蛋白的浊度、表面疏水性和活性巯基分别在30、35和40 ℃开始增加。随着NaCl浓度的增加,肌原纤维蛋白的热吸收峰温度降低,而储能模量和损耗模量增加。0.5 mol/L NaCl溶解的欧洲鳗肌原纤维蛋白热诱导凝胶破断强度为98.81 g,高于低浓度NaCl溶解的蛋白热诱导凝胶。电泳结果表明,增加NaCl浓度会促进肌球蛋白重链和肌动蛋白的相互作用。根据傅里叶变换红外光谱和扫描电镜结果,发现0.5 mol/L NaCl溶解的肌原纤维蛋白热诱导凝胶具有最高的酰胺II/酰胺I强度比和最致密的网络结构。研究结果表明欧洲鳗肌原纤维蛋白在35 ℃时开始变性,提高NaCl浓度可以增强热诱导蛋白凝胶的强度和网络结构致密度,将为利用盐浓度和温度调控鳗鱼加热调理产品提供理论指导。     

芡实分离蛋白的凝胶特性及流变特性

以芡实分离蛋白为原料,研究芡实分离蛋白溶液的凝胶特性和流变特性。确定芡实分离蛋白溶液的最低凝胶点蛋白质量浓度为5g/100mL,考察分离蛋白质量浓度和pH值对凝胶形成的影响;测定放置时间和蔗糖添加量对芡实分离蛋白溶液流变特性的影响。结果表明：分离蛋白质质量浓度和pH值对凝胶硬度、稠度和脆度影响较大,对黏着性和黏聚性影响比较小;随着溶液放置时间的增加,蛋白分子水合作用减弱,其蛋白-蛋白分子间作用力增强,芡实分离蛋白溶液表观黏度上升;蔗糖的添加能明显增加蛋白溶液的表观黏度,降低溶液的流动性,增加溶液的稳定性。     

A nutritional, chemical and sensory evaluation of lupin (L. angustifolius) tempe

Tempe, a traditional Indonesian food, is usually made by the fermentation of soybeans. the substitution of soybeans with lupin seed kernels at levels of 50, 75 and 100% was investigated. Organoleptic evaluation using Australian (n = 17–22) and Indonesian panellists (n = 5–8) showed no significant difference ( P > 0.05) for taste, texture and overall acceptability between the samples. the process of soaking, boiling and fermenting the soybeans reduced the content of phytate (17%), protease inhibitors (98%) and oligosaccharides (77%). For lupin seed kernels the reductions were 60%, negligible and 86%, respectively, and for alkaloids 71%. the protease inhibitor content of lupin tempe was only one-fifth that of soy tempe.
Negligible changes in the protein quality of soybeans and lupins were observed. the Protein Efficiency Ratio (PER) was 2.30 for the boiled soybeans and 2.19 for soybean tempe. Cooked (boiled) lupins had a lower protein quality (PER = 0.84) which was not significantly altered by processing into tempe (PER = 0.91). the apparent digestibility of the cooked lupin (88.1%) and lupin tempe (88.4%) were similar to that of cooked soy (87.3%) and soy tempe (88.5%).
These results suggest good prospects for substituting lupin seed for soybeans in tempe production in cases where protein is not limiting and where the lower levels of antinutrients would be of nutritional benefit.     

Rheological Characterization of a Gel Formed During Extensive Enzymatic Hydrolysis

ABSTRACT Extensive hydrolysis of whey protein isolate (WPI) by Alcalase 2.4L® caused a dramatic increase in turbidity and viscosity. A gel was formed after the degree of hydrolysis was ≥ 18%, coinciding with < 16%β-lactoglobulin and < 4%α-lactalbumin remaining unhydrolyzed. Heat-induced and enzyme-induced WPI gels were compared. Frequency and strain dependence indicated that both gels could be considered as strong, physical gels.     

Rheological,texture and sensory properties of kefir with high performance and native inulin

Rheological, textural, and sensory properties of kefirs with inulin were analysed. Besides, the effect of skim milk powder (SMP) and milk fat substitution was examined by high performance (HP) and native inulin. One-third of SMP was substituted by native (IQ) or HP (TEX!, HPX) inulin. Hardness of kefir with IQ inulin was lower than that with HP inulins or pure SMP. Analysis of cohesiveness and adhesiveness showed that kefir with inulin had higher firmness. Rheological analysis revealed that all manufactured kefirs had higher storage than loss modulus, and exhibited thixotropic and shear thinning behaviour. There were no significant differences in odour and consistency between kefirs with and without inulin. Only in case of whole milk powder (WMP) kefir, panellists noticed the difference in flavour, although kefirs based on SMP had the same scores. Substitution of SMP by inulin allowed for reducing 15% and 37% of caloric value in comparison with SMP and WMP kefir, respectively.     

Potential effects of ultrafiltration process and date powder on textural,sensory, bacterial viability,antioxidant properties and phenolic profile of dromedary Greek yogurt

The aim of this study was to improve textural and antioxidant capacity of dromedary yogurt using ultrafiltration process and date powder. Ultrafiltration increased total solids content of dromedary milk within the range considered optimal to develop yogurt. Texture profile of Greek yogurt fortified with date powder (GYD) improved considerably compared to control. Sample of GYD are more appealing to consumer than control. LC-ESI-MS analysis of GYD extracts allowed the identification of fifteen phenolic compounds, among which quinic acid and cirsiliol were found to be the major phenolic acid and flavonol, respectively. GYD exhibited the highest DPPH•-radical scavenging activity, Fe²⁺ chelating capacity and Fe³⁺ reducing power. The follow-up of physical and microbiological stability of GYD and control during cold storage showed that date powder significantly increased bacterial counts and decreased syneresis. Therefore, ultrafiltration and date powder could be valued as effective tool to solve the poor consistency of dromedary milk products.     

Rheological, texture and sensory properties of low-fat mayonnaise with different fat mimetics

Application of whey protein isolate and low-methoxy pectin-based fat mimetics in mayonnaise was studied. Fat was partially substituted by different fat mimetics at levels of 50%, respectively, which the fat mimetics were referred to as PFM1 (microparticulate pectin gel), PFM2 (pectin weak-gel), and PFM3 (microparticulated combination of WPI and pectin). The full fat (Ff) (100% oil) mayonnaise without fat mimetic was used as a control experiment. Physicochemical, rheological, texture analysis, and sensory evaluation of the Ff and low fat (Lf) mayonnaises were performed. The results indicated that all Lf mayonnaises had significantly lower energy content, but higher water content than their Ff counterpart. In terms of texture, the formulation with pectin weak-gel as fat mimetic showed similar texture values as those of the Ff sample. Both Ff and Lf mayonnaises exhibited thixothopic shear thinning behaviour under steady shear tests and were rheologically classified as weak gels under small amplitude oscillatory shear tests. Sensory evaluation demonstrated that mayonnaises substituted with low-methoxy pectin were acceptable. This study shows good potential for pectin weak-gel and microparticulated pectin gel to be used as a fat mimetic in mayonnaise.     

Effect of whey and pea protein blends on the rheological and sensory properties of protein-based systems flavoured with cocoa

Whey and pea protein combined in different proportions (100W:0P, 75W:25P, 50W:50P, 25W:75P, 0W:100P) were used to prepare protein-based systems flavoured with cocoa and containing κ-carrageenan or κ-carrageenan/xanthan gum as thickeners. Steady and dynamic shear rheological properties of samples were measured at 10 °C and sensory differences were evaluated. Protein-based systems exhibited a shear-thinning flow behaviour that was fitted to the simplified Carreau model. Samples showed different viscoelastic properties, ranging from fluid-like to weak gel behaviour. For both types of system (with and without xanthan gum) viscosity, pseudoplasticity and elasticity rose on increasing the pea protein proportion in the blend. The sample with only whey protein obeyed the Cox-Merz rule, while in the rest of the samples complex viscosity was higher than apparent viscosity. Regarding sensory properties, the protein blend ratio mainly affected sample thickness, which rose as pea protein proportion increased. However, at the same time, the chocolate flavour and sweetness decreased and the off-flavour increased.     

Developing a prebiotic yogurt: Rheological,physico-chemical and microbiological aspects and adequacy of survival analysis methodology

The addition of prebiotics such as oligofructose to yogurt can result in a product with consumer benefits, since they stimulate growth of benefic bacteria present in the intestine and also provide a low calorie product, since one can add less sugar to the formulation due to their sweetening power. This work aimed to evaluate the effect of increasing concentrations of oligofructose addition on physicochemical, rheological and microbiological characteristics of non-flavored yogurt. Furthermore, it was investigated the reaction of consumers with the use of the survival analysis methodology. The addition of oligofructose showed no influence on the pH, proteolysis or the viability of Streptococcus thermophilus or Lactobacillus bulgaricus during 28 days of refrigerated storage (p > 0.05). According to rheological measurements the yogurt supplemented with oligofructose was characterized as a weak gel, showing thixotropic and pseudoplastic behavior. Survival analysis was used to investigate consumer responses with respect to different levels of supplementation of plain yogurt with oligofructose (0%, 2%, 4%, 6% and 8% wt. v⁻¹). Using the survival analysis and considering a rejection by 25% of the consumers, the level of oligofructose that can be added to the yogurt was shown to be 2.58% wt. v⁻¹.     

葡萄糖、氯化钠、磷酸盐及卡拉胶对大豆分离蛋白凝胶特性的影响

肉制品生产需要添加多种辅料成分,包括调味类、发色类、品质改良类、抗氧化类等等,辅料的作用并非单纯叠加,而是存在交互作用,共同影响制品状态。本文选择了肉制品中普遍添加的葡萄糖、氯化钠、复合磷酸盐、卡拉胶,以大豆分离蛋白凝胶特性和感官状态为指标,考察了四种成分对大豆分离蛋白的影响,为肉制品辅料的应用提供一些基础数据。      

Flavour evaluation of three black mulberry (Morus nigra) cultivars using GC/MS,chemical and sensory data

The flavour characteristics of three black mulberry (Morus nigra) cultivars from the Aegean region of Turkey were investigated using GC/MS and sensory analysis techniques. A total of 18 flavour compounds were identified by GC/MS in the three cultivars. Total sugar content varied between 11.3 and 16.2%, pH between 3.60 and 3.80 and total acidity between 1.51 and 1.79%. The sensory assessment indicated that black mulberry has fruity, sweet, sour, musky and woody flavour notes and fruity, acid, musky, leafy and woody‐fresh aroma characteristics. The evaluation of GC/MS and sensory data revealed that ethyl linolenate was the most effective compound contributing to the unique flavour of black mulberry. © 2002 Society of Chemical Industry     

Heat Induced Gelation of Pea (Pisum sativum) Mixed Globulins, Vicilin and Legumin

Mixed globulins (MG) were extracted from ground dry peas (Pisum sativum, B-160) with 0.5M NaCl, 50 mM potassium phosphate, pH 7.2, and isolated by precipitation at pH 4.5. Crude vicilin and legumin were fractionated from the MG by dialysis against 0.2M NaCl, pH 4.8, and centrifugation, then further purified using DEAE-cellulose chromatography. Conditions for maximum gel hardness of heat induced MG gel, as determined with an Instron Universal Testing Machine, were heating for 20 min at pH 7.1 at 87°C. Purified vicilin, but not legumin, formed heat induced gels. The relationship was linear between protein (globulin) concentration and log gel hardness. At all protein concentrations studied, as proportion of legumin decreased, gel hardness increased.     

Bioavailability,rheology, and sensory evaluation of mayonnaise fortified with vitamin D encapsulated in protein-based carriers

Vitamin D lost its functionality during processing and storage, thus, encapsulation with proteins is desirable to preserve bioactivity. The aim of the current study was to develop encapsulated vitamin D fortified mayonnaise (VDFM) using whey protein isolates (WPI) and soy protein isolates (SPI) as encapsulating materials in three different formulations, that is, 10% WPI, 10% SPI, and 5/5% WPI/SPI. Increased shear stress decreased the apparent viscosity along with significant effects on the loss modulus of VDFM. WPI encapsulates showed better results as compared to SPI. WPI based VDFM (M₁) depicted the best results in terms of size and dispersion uniformity of oil droplets. Hue angle and total change differed significantly among treatments. The highest value for overall acceptability was acquired by M₃ (5:5%WPI:SPI-encapsulates) thus proceed for in vivo trials. Serum vitamin D level was significantly higher in the encapsulated VDFM rat group (58.14 ± 6.29 nmol/L) than the control (37.80 ± 4.98 nmol/L). Conclusively, WPI and SPI encapsulates have the potential to improve the stability and bioavailability of vitamin D.     

Factors Affecting Rheological Characteristics of Fibril Gels: The Case of β-Lactoglobulin and α-Lactalbumin

ABSTRACT:  Some of the factors that affect the rheological characteristics of fibril gels are discussed. Fibrils with nanoscale diameters from β-lactoglobulin (β-lg) and α-lactalbumin (α-la) have been used to create gels with different rheological characteristics. Values of the gelation time, t_c , the critical gel concentration, c ₀, and the equilibrium value of the storage modulus, G , such as     at long gelation times, derived from experimental rheological data, are discussed. Fibrils created from β-lg using solvent incubation and heating result in gels with different rheological properties, probably because of different microstructures and fibril densities. Partial hydrolysis of α-la with a serine proteinase from Bacillus licheniformis results in fibrils that are tubes about 20 nm in diameter. Such a fibril gel from a 10% (w/v) α-la solution has a higher modulus than a heat-set gel from a 10% (w/w) β-lg, pH 2.5 solution; it is suggested that one reason for the higher modulus might be the greater stiffness of α-la fibrils. However, the gelation times of α-la fibrils are longer than those of β-lg fibrils.     

Effect of polymorphisms in the leptin, leptin receptor, and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes and genetic polymorphism of milk proteins on cheese characteristics

Cheese production has increased worldwide during the last decade and is expected to increase within the coming decade as well. Despite this, the relations between cow genetics and cheese characteristics are not fully known. The aim of this study was to determine if polymorphisms in the leptin (LEP), leptin receptor (LEPR), and acyl-coenzyme A:diacylglycerol acyltransferase 1 (DGAT1) genes as well as genetic variants of β-casein (β-CN), κ-CN, and β-lactoglobulin (β-LG) affect technological properties important for cheese production and, hence, could act as genetic makers for cheese quality. Individual milk samples from the Swedish Red and the Swedish Holstein breeds were analyzed for sizes of CN micelles and fat globules as well as rennet-induced gel strength, gelation time, and yield stress. Model cheeses were produced to study yield, hardness, and pH of the cheeses. The A1457G, A252T, A59V, and C963T single nucleotide polymorphisms (SNP) were analyzed on the LEP gene, the T945M SNP on the LEPR gene, and the Nt984+8(A-G) SNP on the DGAT1 gene. In addition, genetic variants of β-CN, κ-CN, and β-LG were determined. The results indicate that technological properties were influenced by the LEPR_T945M polymorphism, which had an association with gel strength, yield stress, and cheese hardness (T > C). However, also LEP_A252T was shown to affect gel strength (T > A), whereas the LEP_A59V had an effect on fat globule size (T > C). For the milk protein genes, favorable effects were found for the A and B variants of β-LG and κ-CN, respectively, on gel strength, gelation time, and yield stress. In addition, the B variant of κ-CN was shown to be associated with smaller CN micelles than the A variant. Thus, the results demonstrate potential genetic markers for cheese characteristics. However, milk composition traits also affected the obtained results, thus making it necessary to thoroughly assess the different aspects regarding the influence of gene effects on cheese characteristics before directly selecting for certain alleles or genetic variants to improve the processing and quality of cheese.     

Interrelations among physical characteristics,sensory perception and oral processing of protein-based soft-solid structures

Oral processing is essential in breaking down the physicochemical structure of the food and thus important to the sensory perception of food in the mouth. To have an understanding of protein-based, soft-solid texture perception, a multidisciplinary approach was applied that combined studies of food microstructure with mechanical properties, sensory evaluation, and oral physiology. Model foods were developed by combining ion-induced micro-phase separation and protein-polysaccharide phase separation and inversion. Activities of masseter, anterior temporalis and anterior digastric muscles during oral processing were recorded by electromyography (EMG), while jaw movement amplitudes, durations, and velocities were simultaneously collected by a three-dimensional jaw tracking system (JT-3D). Changes in the microstructure of mixed gels significantly altered the characteristics of the chewing sequence, including the muscle activities, number of chews, chewing duration and chewing frequency. Mechanical attributes related to structural breakdown and sensory perception of firmness were highly correlated with the amount of muscle activity required to transform the initial structure into a bolus ready for swallowing. Chewing frequency was linked to mechanical properties such as recoverable energy, fracture strain and water holding capacity of the gels. Increased adhesiveness and moisture release also resulted in slower chewing frequency. Evaluation of oral processing parameters at various stages (i.e., first cycle, first 5 cycles, and last 3 cycles) was found to be a useful method to investigate the dynamic nature of sensory perception at first bite, during chewing and after swallowing. The study showed that muscle activity and jaw movement can be used to understand the links between physical properties of foods and sensory texture.     

Rheological behavior and organoleptic effects of ovalbumin addition in yogurt mousse production

Yogurt mousse is a novel, high added-value dairy product that has been well received by the market. This paper presents a study of the effect of the addition of ovalbumin to the product on its rheological and organoleptic qualities. The ovalbumin was previously separated from egg white with a high grade of purity using an ion exchange resin synthesized by the authors. Diverse rheological tests at different temperatures and corresponding sensorial assessments were conducted to compare samples without and with added ovalbumin.The obtained results confirm that the product is viscoelastic and combines the properties of foams and emulsions; the elastic component is greater than the viscous component. Moreover, at temperatures ranging from 5 to 15°C, a usual interval of consumption, the product behaves rheologically in a similar way. Conversely, the addition of ovalbumin under the assayed conditions also makes the elastic character of the product increase at a given temperature. Finally, the sensorial assessment tests and determinations of stability and volume yield enabled us to verify that the addition of ovalbumin at an amount of 1.3% hardly alters the stability, resistance to shear stress, or the texture and improves the degree of foaming. Therefore, the product with additive is of good commercial quality.