Rheological properties of modified lupin proteins.

The properties of acetylated, succinylated and phosphorylated protein isolates extracted from the flour of yellow lupins (L. luteus) were studied by means of oscillatory rheology. The flow behaviour of protein dispersions (15% w/w) and the properties of thermotropic gels were distinctly influenced by the modification. Succinylation increased the viscosity of the dispersions of unmodified protein isolate (LPI) from 99 mPas to 515 mPas and results in the lowest gel point (T = 30.5 degrees C). Acetylation and phosphorylation enhance the pseudoplastic flow behaviour of the dispersions. Acylated lupin samples formed the strongest gels with a small visco-elastic range while phosphorylation leads to weak and "rubber-like" gels.     

Some functional properties of lupin proteins modified by lactic fermentation and extrusion

The aim of this work was to determine modifying effects of lactic fermentation and extrusion processes on functionality of lupin proteins. Protein content, surface hydrophobicity, water absorption capacity (WAC), water solubility index (WSI) and emulsifying properties (EAI, ESI) of protein preparations obtained from lupin seeds (Lupinus luteus, Lupinus albus, Lupinus angustifolius), with various contents of hull, were analyzed. Changes of protein properties were affected by lupin cultivar, hull content and applied processing method. An increase of soluble protein content after controlled lactic fermentation of lupin seeds, and changes of surface protein hydrophobicity, WAC and WSI values after each treatment and significant worsening of protein emulsifying properties were observed. Correlations were found between parameters examined in this study.     

Cross-reactivity between peanut and lupin proteins

Peanut-allergic individuals may also react to lupin, which, for this reason, has been included in the EU list of food allergens. Since there is not yet any general consensus on the major allergen/s in lupin, the objective of this investigation was to compare the reactivity of the main lupin proteins towards the IgE of the sera of allergic patients. Both Lupinus albus and Lupinus angustifolius were investigated. ELISA’s, Western blotting and mass spectrometry, including also de novo sequencing of the unknown lupin proteins, were used for identifying the IgE-binding proteins. Significant differences in the protein reactivities were observed. In particular, there was a direct relationship between the level of peanut-specific IgE’s and the cross-reactivity to lupin proteins; also the reactivity of each serum appeared to be unique. Although numerous lupin proteins bind IgE’s, our data suggest a predominant contribution of α-conglutin in the reactivity of both L. albus and L. angustifolius.     

Technological strategies to improve gelation properties of legume proteins with the focus on lupin

There is a growing demand for plant protein due to the increasing number of consumers looking for healthier food options. Protein from the legume seed lupin is a viable plant protein source due its high protein content and agricultural sustainability of lupin production. Lupin protein is however underutilised in food manufacturing due to its poor gelling and thickening properties. This review uncovers the link between lupin protein structural properties and its poor gelling functionality. It will compare lupin with other legume proteins in terms of protein structure and gel quality. Current knowledge of legume protein gelation processes, factors controlling gelation mechanisms and methods for evaluating gel quality will be presented. Finally, green and efficient protein modification technologies to improve gelation will be detailed. This review also reveals the scarcity of information on approaches to improve the poor gelation properties of lupin protein, highlighting the need for research in this area.     

Rheological properties of emulsions containing milk proteins mixed with xanthan gum

Oil in water emulsions (30% w/w) containing mixtures of milk proteins with xanthan gum were rheologically characterized at ambient temperature and the evolution of their properties was measured during a month under cold storage. The milk proteins used were sodium caseinate and whey concentrate at 2% mixed with xanthan gum at 0.3% or 0.5%. Emulsions properties were compared to those of respective aqueous systems and in general showed same rheological behaviour as their respective aqueous system, however, emulsions presented higher consistency index, due to oil droplets concentration. The flow behaviour index showed a small variation, increasing its value slightly. The consistency of emulsions with xanthan was similar, independently of the milk protein used, confirming that xanthan rheology predominates on emulsion rheology.     

Rheological properties of rice pasta dough supplemented with proteins and gums

Rheological properties of rice pasta dough were studied by creep-recovery tests for various formulations containing guar gum (0.5%), casein (1%), and egg white (1%) mixtures. Non-gelatinized rice semolina (RS) was also mixed with gelatinized RS in different ratios (0, 25, 50, 75 and 100%) for each formulation. The effects of gelatinization, gum and proteins on pasta dough rheology were determined by a control stress rheometer (Haake Rheostress 1). From the creep-recovery data it was obvious that as the amount of gelatinized fraction increased there was an increase in the elasticity of the samples. However, the samples that were produced with 75 and 100% gelatinized RS in the formulation were not smooth in texture, but lumpy. From the creep-recovery and dynamic oscillation measurements it was found that guar gum and protein mixture can be used as a stabilizer together with 50% pre-gelatinized rice semolina. This will result in an improvement in dough properties during gluten free pasta processing from rice.     

Rheological and equilibrium properties of milk proteins and tara gum mixtures

The stability of aqueous purified tara gum (TG) mixtures with sodium caseinate (NaCas) and whey protein concentrate (WPC) was investigated. Phase diagram of TG–milk proteins mixtures was obtained by measuring the sedimented fraction or the rheological parameters. The rheological behaviour was also evaluated as function of NaCas and WPC concentration, considering the zero-shear rate viscosity and the relaxation time as response variables. The rheological parameters were determined by rotational rheometry. The studied solutions presented a meta-stable condition provided by the increase in viscosity, while mixtures with NaCas at low TG concentrations sedimentation by volume exclusion occurred. The rheological behaviour of NaCas and WPC aqueous solutions approached the Newtonian and shear-thickening model, respectively. The mixtures with TG showed a pseudoplastic behaviour, approaching the Cross model. The results indicated interaction between TG and the studied proteins, expressed by an increase of zero-shear viscosity and the relaxation time at higher gum concentration.     

Differential scanning calorimetry of lupin and soy proteins

Differential scanning calorimetry (DSC) was used to study the 7S and 11S globulin fractions extracted from lupin seed (Lupinus luteus) flour. In agreement with previous work on other lupin species, the isolate showed three denaturation peaks compared to the two observed with soy. By comparison with the isolated globulin fractions, the denaturation peaks at the two higher temperatures in the lupin isolate were assigned to the 11S and 7S globulins. The denaturation temperature of the lupin 7S globulin was about 10 K higher than that for the corresponding soy globulin, whereas the values for the 11S globulin were similar. All globulins displayed increasing thermal stability with decreasing moisture contents. Possible reasons for the differences in behaviour of soy and lupin protein isolates are discussed.     

Functional properties of plant proteins Part IV. Foaming properties of modified proteins from faba beans

The foaming ability (foam capacity and stability) of protein isolates from faba beans (Vicia faba L.) depends closely on the manner of isolation and treatment of the isolates. Unmodified isolates possess a moderate foaming ability with a maximum foam capacity of 210 % in alkaline solution (pH 10.0) at concentrations of about 3 %. The foam capacity and stability can be improved by treatment with isopropanol or moderate temperature, as well as by denaturing by alkali or by specially heating at 80 °C. Thereby modified preparations are formed possessing a foam capacity of more than 400 % and a foam stability of 80-100%. High concentrations of protein favour the formation of stable foams. Succinylation improves the foam formation properties of proteins. Maximum values of foam capacity (≈ 400%) are produced at a high degree of succinylation, that is after blocking more than 80% of protein amino groups, in neutral solution, while the foam stability under these conditions decreases. Heating at 80 °C, high'protein concentrations (10 %) and a weak acidic milieu (pH 5.5) favour the formation of stable foams from succinylated proteins.     

Functional properties of plant proteins. Part IV. Foaming properties of modified proteins from faba beans

The foaming ability (foam capacity and stability) of protein isolates from faba beans (Vicia faba L.) depends closely on the manner of isolation and treatment of the isolates. Unmodified isolates possess a moderate foaming ability with a maximum foam capacity of 210% in alkaline solution (pH 10.0) at concentrations of about 3%. The foam capacity and stability can be improved by treatment with isopropanol or moderate temperature, as well as by denaturing by alkali or by specially heating at 80 degrees C. Thereby modified preparations are formed possessing a foam capacity of more than 400% and a foam stability of 80-100%. High concentrations of protein favour the formation of stable foams. Succinylation improves the foam formation properties of proteins. Maximum values of foam capacity (approximately equal to 400%) are produced at a high degree of succinylation, that is after blocking more than 80% of protein amino groups, in neutral solution, while the foam stability under these conditions decreases. Heating at 80 degrees C, high protein concentrations (10%) and a weak acidic milieu (pH 5.5) favour the formation of stable foams from succinylated proteins.     

Alcalase改性豌豆蛋白功能性研究

该研究以生产淀粉的副产物豌豆蛋白粉为原料,采用Alcalase对豌豆蛋白在加酶量0.16%、水解时间32.5 min、pH 8.0、温度55.4℃、底物浓度8%的水解条件下进行限制性水解,对酶改性豌豆蛋白的溶解性和泡沫特性进行研究,并对其相对分子质量分布进行分析。结果表明:水解产物的泡沫特性和溶解性在不同pH和NaCl浓度时均高于未水解样品,和大豆蛋白相当。同时,改性之后产物的分子量分布也有较大改变,小于10 000部分所占比例由未水解时的22.22%提高到79.39%,而相对分子质量小于2 000的比例提高了11.55%。     

金钱菇多糖的流变学性质研究

从金钱菇子实体水提残渣中纯化获得了一个多糖组分JQPs,采用DHR-3型旋转流变仪研究了JQPs溶液流变学性质,为其在食品工业中的应用提供理论支持。静态流变学实验结果表明,JQPs溶液流动指数n1,为假塑性流体,浓度越高其假塑性越明显。通过对溶液流动曲线的拟合,发现幂律方程可以作为描述JQPs溶液流动曲线的模型;动态粘弹性实验表明JQPs溶液的G'和G″在1~100rad/s扫描频率下与测试浓度和测试温度均具有一定的相关性。一定温度下,随着浓度的增加,G'的增加速率超过G″,当浓度达到2.0%时曲线重合,开始形成弱凝胶。浓度为2.5%的JQPs溶液的G'和G″随着温度的升高而逐渐减小,在15℃时基本重合,开始形成弱凝胶。     

大麦醇溶蛋白的流变特性

以大麦粉为原料制备了纯度为92.63%的大麦醇溶蛋白,并对其流变特性进行了深入研究。实验结果表明:大麦醇溶蛋白在溶剂——体积分数55%异丙醇溶液中呈现典型假塑性流体特性,且蛋白浓度、剪切速率、溶液温度对其流变性质均有显著影响。大麦醇溶蛋白溶液的表观黏度随蛋白浓度的增大而升高,随剪切速率增加而减小。25℃下,100 mg/m L与150 mg/m L的大麦醇溶蛋白溶液损耗模量G″大于弹性模量G',表明蛋白溶液不能形成凝胶;当蛋白的质量浓度为200 mg/m L时,随着剪切速率的增大,出现凝胶点,黏性溶液转变为黏弹性流体。升温过程(25℃升至90℃)可促进高浓度(200 mg/m L)大麦醇溶蛋白溶液产生凝胶,凝胶温度为43℃。     

Rheological properties of myosin-gelatin mixtures

ABSTRACT:  This study was designed to investigate changes of dynamic rheological properties of myosin and gelatin mixtures during heating and cooling. The rheological and calorimetric attributes (G', G", tan δ, and heat flow) of myosin and gelatin mixtures were measured during heating and cooling. The results indicated that gelatin could increase the G' and G" values and decrease the denaturation temperature of myosin. The G' and G" values of myosin and gelatin mixtures decreased with pH over 5.5 to 7.5 and ionic strength over 0.3 to 0.6. Therefore, it is advisable to add gelatin into chicken meat comminuted products in that it could improve the rheological attributes of myosin.     

New processing of lupin protein isolates and functional properties

A growing demand for functional plant proteins could be identified, which properties are customized for specific applications and formulations as food ingredients. Native lupin proteins (α, β, γ) conglutin have a good solubility at appropriately chosen conditions. A novel procedure has been proposed to maintain the native protein properties. Lupin proteins are extracted from hexane deoiled lupin. The protein product type E comprises high molecular weight proteins (α, β‐conglutin( which are separated using alkaline extraction and acid precipitation procedures. The protein product type F is enriched in the γ‐conglutin fraction and is separated from the acid pre‐extract applying cross flow filtration at pH 7–8. For the zirconium oxide membrane the filtration rate can be increased by appropriately chosen pH conditions up to 70 l/m²h. Lupin protein fraction (type E and F) are highly soluble protein isolates with outstanding emulsification, salt tolerance and foaming properties. These new lupin proteins (type E and F) offer extremely interesting properties for application in food systems and are available from pilot plant fractionation.     

Effect of lupin seed proteins on quality characteristics of fermented sausages

Lupin seed flours (LSF) and lupin seed protein isolates (LSPI) from a sweet (S) variety of Lupinus albus and a bitter (B) variety of Lupinus albus ssp. Graecus were used in the manufacture of fermented sausages at 2% level, based on the weight of meat and pork back fat, and hydrated to a protein/water ratio 1/4, to replace beef and pork meat on a protein to protein basis. LSF and LSPI had no effect (p>0.05) on the microbial counts, the pH, the moisture content and weight losses, the instrumentally measured colour numbers (L*, a*, b*), the firmness, the appearance and the sensory evaluated colour of fermented sausages. Fermented sausages produced with LSPI from the bitter variety had similar (p>0.05) sensory attributes to the control and lower (p<0.05) TBA values after the 28th day of storage. Fermented sausages produced with LSPI from the sweet variety had acceptable sensory attributes but TBA values higher than 1 mg of malonaldehyde/kg. LSF from both varieties had a high pro-oxidant effect and affected negatively the odour and taste of fermented sausages.     

Functional effects of lupin proteins in comminuted meat and emulsion gels

The mechanical and textural properties of gel network resulting by heating at 90 °C of comminuted meat systems, containing lupin seed protein isolate at a relatively low concentration (2%), were studied in an attempt to establish the role of the lupin proteins in the gel structure network development. These results are supported with data from SDS–PAGE analysis of the adsorbed protein at the fat particle surface of the system. The findings are considered in terms of lupin protein involvement in interactions, either at the fat particle surface, or within isolated pockets of high lupin protein content.     

Rheological and textural properties of sorghum-based formulations modified with variable amounts of native or pregelatinised cassava starch

Sorghum bread was made from native or pregelatinised cassava starch and sorghum flour in the ratio 10:90, 20:80, 30:70, 40:60 and 50:50. The other ingredients, measured on flour-weight-basis, were water (100%), sugar (6.7%), egg white (6%), fat (2%), salt (1.7%) and yeast (1.5%). The dynamic oscillatory behaviours of the batters were affected by the amount and type of starch. In the amplitude sweep measurements, increasing concentration of native starch decreased storage modulus, whereas increasing concentration of pregelatinised starch increased the linear viscoelastic range of the batters. In the frequency sweep measurements, the loss factor of batters treated with native starch declined with increasing frequency. Batters treated with 10 or 20% pregelatinised starch showed declining loss factors, whereas batters treated with 40 or 50% pregelatinised starch showed increasing loss factors with increasing frequency. Sorghum-based batters containing native starch gave bread with better crumb properties than batters containing pregelatinised starch. Crumb firmness and chewiness declined with increasing native or pregelatinised starch concentration. Crumb adhesiveness of breads containing pregelatinised starch increased with increasing starch content but was not affected by native starch. Cohesiveness, springiness and resilience increased with increasing native starch content, but were minimally affected by increasing pregelatinised starch content.