Influence of pH and salt concentration on protein solubility,emulsifying and foaming properties of sesame protein concentrate

The effects of pH and NaCl concentration on protein solubility, emulsification, and foamability of sesame protein concentrate from dehulled seeds were investigated. The protein content of the concentrate was 70.7%. Protein solubility, emulsion, and foaming capacities varied with pH and ionic strength. Protein solubility, which was least at pH 4, (2.1%) ranged from 6.6% at pH 2 to 13.1% at pH 10. The solubility increased with increase in ionic strength, ranging from 9.8% at 0.0 M to 16.1% at 1.0 M concentration. The emulsion capacity ranged from 6.2 mL oil/g sample at pH 2 to 19.4 mL oil/g sample at pH 10. The emulsion capacity increased from 11.5 mL oil/g sample at 0.0 M to 20.9 mL oil/g sample at 1.0 M salt concentration. Stability of the emulsion increased with increase in NaCl concentration, ranging from 42% at 0.0 M concentration to 70% at 1.0 M concentration, but 0.5 M NaCl produced the most stable foam after 120 min of whipping while the least stable was at 1.0 M.     

INFLUENCE OF ENZYMATIC HYDROLYSIS ON THE FUNCTIONAL PROPERTIES OF SESAME CAKE PROTEIN

This study investigated the effect of enzymatic hydrolysis on the functional properties of sesame cake protein. Protein hydrolyzates from sesame cake protein were obtained by enzymatic hydrolysis using Alcalase at 50°C and pH 8.5. Water-holding capacity, oil-holding capacity, foam capacity and stability, and emulsifying activity and stability of the hydrolyzates were determined. All protein hydrolyzates showed better functional properties than the original protein. Foaming and emulsifying stability decreased as the degree of hydrolysis increased. The water-holding capacity, foaming activity, and emulsifying activity of the hydrolyzates increased with the increase in levels of hydrolysis. Enzymatic modification was responsible for the changes in protein functionality. These improved functional properties make sesame cake protein hydrolyzates a useful product in foods such as bread, cake, ice cream, meat products, desserts, and salad dressing.     

Functional properties and protein concentrate of Pigeon pea (Cajanus cajan (I.) Millsp) flour

The objective of this investigation was to study the functional properties of Pigeon pea (Cajanus cajan (L.) Millsp) flour and protein concentrate. The solubility of both samples were superior than 70% at pH above 6.7 and below 3.5. The water and oil absorption were 1.2 and 1.07 ml/g of sample and 0.87 and 1.73 ml/g of flour and protein concentrate samples, respectively. The minimum concentration of flour and protein concentrate needed for gelation was 20% and 12%, respectively. The emulsifying capacity of flour and concentrate was 129.35 g and 191.66 g oil/g of protein and the emulsion stability 87.50 and 97.97%, respectively, after 780 minutes. The foam capacity and stability of flour foam were 36.0% and 18.61, while of the concentrate were 44.70% and 78.97% after 90 minutes. These properties indicate that the flour as well as the concentrate could have application in various food systems.     

Functional properties of pea (Pisum sativum, L.) protein isolates modified with chymosin

In this paper, the effects of limited hydrolysis on functional properties, as well as on protein composition of laboratory-prepared pea protein isolates, were investigated. Pea protein isolates were hydrolyzed for either 15, 30 and 60 min with recombined chymosin (Maxiren). The effect of enzymatic action on solubility, emulsifying and foaming properties at different pH values (3.0; 5.0; 7.0 and 8.0) was monitored. Chymosin can be a very useful agent for improvement of functional properties of isolates. Action of this enzyme caused a low degree of hydrolysis (3.9-4.7%), but improved significantly functional properties of pea protein isolates (PPI), especially at lower pH values (3.0-5.0). At these pH values all hydrolysates had better solubility, emulsifying activity and foaming stability, while longer-treated samples (60 min) formed more stable emulsions at higher pH values (7.0, 8.0) than initial isolates. Also, regardless of pH value, all hydrolysates showed improved foaming ability. A moderate positive correlation between solubility and emulsifying activity index (EAI) (0.74) and negative correlation between solubility and foam stability (-0.60) as well as between foam stability (FS) and EAI (-0.77) were observed. Detected enhancement in functional properties was a result of partial hydrolysis of insoluble protein complexes.     

Functional properties of dehulled sesame (sesamum indicum L.) seed flour

Certain functional properties of sesame seed flour were obtained after oil extraction from dehulled seed meal was investigated. The protein content in the flour was 69.7% and the least gelation concentration was 6.0%. Water and oil absorption capacities at room temperature (31 ± 2°C) were 2.3 g H₂O/g sample and 3.0 g oil/g sample, respectively. The values were higher at 100°C. The emulsification capacity, which was more stable at alkaline conditions, ranged from 25.0 mL oil/g sample at pH 4 to 66.0 mL oil/g sample at pH 10. The foaming capacity was more stable at pH 4 but lower (205.0%). The highest foaming capacity (315.0%) was at pH 2 whereas at pH 10 it was 310.0%. Protein solubility, which was least at pH 4, ranged from 7.9% at pH 2 to 14.2% at pH 10. The viscosity of the flour dispersion ranged from 2.5 cps at 1% concentration to 7.0 cps at 10% concentration. The findings show that sesame flour could impart desirable characteristics when incorporated into products such as ice cream, frozen dessert, sausages, baked food and confections.     

Extraction,Composition and Functional Properties of Pennycress (Thlaspi arvense L.) Press Cake Protein

This study compared two methods for extracting the protein in pennycress (Thlaspi arvense L.) press cake and determined the composition and functional properties of the protein products. Proteins in pennycress press cake were extracted by using the conventional alkali‐solubilization–acid‐precipitation (AP) method or saline‐based (SE) procedure (0.1 M NaCl at 50 °C). The extraction method has a major influence on the purity and functional properties of press cake protein products. AP had a lower protein yield (23 %) but much higher purity (90 % crude protein) compared with SE (45 % yield, 67 % crude protein). AP protein isolate had high foam capacity (120 ml), high foam stability (96 % foam volume retention) and high emulsion stability (24–35 min), and it was resistant to heat denaturation (3 % loss of solubility at pH 2 and pH 10). On the other hand, SE protein concentrate showed remarkably high solubility (>76 %) between pH 2 and 10 and exceptional emulsifying activity (226–412 m²/g protein), but was more susceptible to heat denaturation at pH 7 and pH 10 (65–78 % loss of solubility). These results strongly demonstrate that higher purity pennycress press cake protein can be produced by either saline extraction or acid precipitation and have functional properties that are desirable for non‐food uses.     

Mechanism Study on the Severe Foaming of Rhamnolipid in Fermentation

Although the biosurfactant rhamnolipid has been previously characterized as having low foam ability, its fermentation is largely impeded by severe foaming. Hence, the investigation of this paradox is critically important for improving the mass production of rhamnolipid. Unexpectedly, the hydrophobic cell, instead of rhamnolipid, has been claimed to explain such severe foaming in rhamnolipid fermentation. This study tried to systematically investigate the severe foaming in fermentation, aiming to propose an effective strategy for foam control. The overflowing foam sustained a super high stability in terms of half‐time for over 30 min. The major product of rhamnolipid largely contributed to the severe foaming in the fermentation process whereas other products like cells elicited much more limited effects. Furthermore, the foam stability of the fermentation broth increased with rhamnolipid concentration and noticeably increased with agitation speed. In the classic Bikerman foam test system without stirring, rhamnolipid showed foam stability as low as Tween 20 which is well known for its poor foam stability. However, in a stirring Bikerman system, rhamnolipid exhibited a foam stability almost as high as sodium dodecyl sulfate (SDS) at 10 g/L and even surpassed SDS at a higher concentration of 20 g/L. Hence, the extraordinarily increased foam stability of rhamnolipid with both agitation and concentration could explain the severe foaming at its late‐stage fermentation when rhamnolipid‐rich solution is mechanically agitated.     

Effect of xanthan gum on enhancing the foaming properties of whey protein isolate

The foaming properties of whey protein isolate (WPI) in the presence of xanthan gum (XG) were investigated. XG dispersion did not exhibit any foaming properties. The optimal foaming overrun (FO), or the amount of air incorporated into the dispersion, was obtained from the dispersion of 5% WPI and 0.05% XG at 949%. This WPI-XG dispersion had a significantly higher overrun than that of WPI (868%) or egg white (879%) (P<0.05). Optimal foam stability (FS) of 216 min was obtained at 5% WPI and 0.2% XG; however, the overrun was reduced slightly (844%). XG increased stability to 15 times that of WPI alone. The overrun of 5% WPI plus 0.05% XG was further increased to 1343% when 1 M NaCl was added (P<0.05). However, FS (51 min) was significantly reduced. A significant increase in the FO of 5% WPI plus 0.05% XG (1081%) was observed when pH was adjusted to 5.0 with no significant change in FS (56 min) (P<0.05). The FO (1457%) was significantly increased (P<0.05) when the WPI-XG was heat treated (55°C for 5 min). WPI-XG dispersions at acidic pH and temperatures below 85°C have a variety of potential applications in products such as protein beverages, angel food cake, and unique infant formulas.     

Effect of dehulling methods and desolventizing temperatures on proximate composition and some functional properties of sesame (Sesamum indicum L.) seed flour

Sesame seeds were dehulled mechanically and in 10% sodium chloride solution before oil extraction and drying to obtain the flour. The effect of these dehulling methods on the proximate composition, oil and water absorption, emulsification, and foaming properties of the flour was investigated. The effect of desolventizing temperatures (80, 90, and 100°C) on these properties was also investigated. Protein contents of seeds, dehulled mechanically (MDSF) and in 10% NaCl solution (SDSF), were 58.5 and 52.1%, respectively. Carbohydrate and ash contents of both flours also varied. The oil and water absorption capacities of the flours were 268 and 252% for MDSF and 370 and 410% for SDSF, respectively. The emulsion capacity of the MDSF sample was slightly lower (20.0 mL oil/g sample) but more stable than the SDSF sample, whose value was 20.4 mL oil/g sample. The foam capacity of MDSF was, however, higher (48.5%) but less stable than SDSF (33.7%). An increase in desolventizing temperatures of the meal led to increases in oil and water absorption capacities of the flours. Foam and emulsion capacities, on the other hand, decreased with increase in temperature. Desolventizing temperatures had no effect on the stability of the formed emulsion but had a decreasing effect on the stability of the foam.     

Effect of xanthan gum on enhancing the foaming properties of soy protein isolate

The foaming properties of soy protein isolate (SPI) in the presence of xanthan gum (XG) were investigated. The XG solution alone did not exhibit any foaming ability. The optimal foaming properties were obtained from the SPI-XG dispersion that contained 0.1% SPI and 0.2% XG. This SPI-XG dispersion gave higher foaming capacity than that of SPI or egg white (P<0.05). The foam stability of SPI-XG dispersion was nine times higher than that of SPI and egg white (P<0.05). The SPI-XG foams were stable over wide ranges of ionic strength (0.1 to 1.0 M NaCl) and pH (4.5 to 9.0), and when heated (85°C, 1 h).     

可生物降解的(2-羟基-3-十二烷氧基)丙基-羟丙基壳聚糖的制备及其泡沫性和乳化性的研究

在相同实验条件下 ,先后将羟丙基和 (2 羟基 3 十二烷氧基 )丙基分别引入 3种不同相对分子质量的壳聚糖分子结构中 ,制得一系列可生物降解的两亲性的壳聚糖表面活性剂——— (2 羟基 3 十二烷氧基 )丙基 羟丙基壳聚糖 (HDP HPCHS)。通过红外光谱对其进行了结构表征 ,并在 0 2～ 1 0 0g/L质量浓度范围内测定了其泡沫性能和乳化性能。结果表明 :室温下 ,不同相对分子质量的HDP HPCHS均具有良好的泡沫性和乳化性 ,并且均随其相对分子质量的改变而呈现规律性变化。具体表现为 :HDP HPCHS的相对分子质量越高 ,达到最大起泡能力所需的溶液浓度越小 ,其乳化能力也越强 ;但其最大起泡能力和乳化层的稳定性却随相对分子质量的增大而下降。     

无患子皂素水提液发酵精制联产表面活性剂鼠李糖脂

以无患子皂素水提水解液为底物,发酵生产生物表面活性剂,在精制无患子皂素的同时发酵联产生物表面活性剂鼠李糖脂。经铜绿假单胞菌发酵后发酵完成液中不含葡萄糖,葡萄糖的消耗速率与接种量成正相关,在发酵液中额外添加大豆油可促进表面活性剂亲油基团的生成,溶液表面活性进一步提高。发酵后溶液中表面活性物质浓度达到50.8g/L,比对照组提高了16.1%,溶液表面张力明显降低。接种10%的菌种发酵获得的无患子皂素复合产物干粉其临界胶束浓度由10g/L降低到2.5g/L,临界胶束浓度下的复合产物水溶液表面张力比未接种菌种的低18.67%,复合产物具有很好的起泡性能及更高的泡沫稳定性。     

Profile and Functional Properties of Seed Proteins from Six Pea (Pisum sativum) Genotypes

Extractability, extractable protein compositions, technological-functional properties of pea (Pisum sativum) proteins from six genotypes grown in Serbia were investigated. Also, the relationship between these characteristics was presented. Investigated genotypes showed significant differences in storage protein content, composition and extractability. The ratio of vicilin:legumin concentrations, as well as the ratio of vicilin + convicilin: Legumin concentrations were positively correlated with extractability. Our data suggest that the higher level of vicilin and/or a lower level of legumin have a positive influence on protein extractability. The emulsion activity index (EAI) was strongly and positively correlated with the solubility, while no significant correlation was found between emulsion stability (ESI) and solubility, nor between foaming properties and solubility. No association was evident between ESI and EAI. A moderate positive correlation between emulsion stability and foam capacity was observed. Proteins from the investigated genotypes expressed significantly different emulsifying properties and foam capacity at different pH values, whereas low foam stability was detected. It appears that genotype has considerable influence on content, composition and technological-functional properties of pea bean proteins. This fact can be very useful for food scientists in efforts to improve the quality of peas and pea protein products.     

Effects of ultrasound and microwave pretreatments on the ultrafiltration desalination of salted duck egg white protein

The effects of application of ultrasound and microwave treatments before the ultrafiltration desalination of salted duck egg white protein were investigated in this work. The desalination rate, color, microstructure, foaming capacity, emulsifying index and gelling property were determined. The results showed that ultrasound and microwave pretreatments increased about 10% and 3% desalination rate, respectively, compared to that without any pretreatment sample, beside the product quality was also improved. The effect of ultrasound pretreatment was better than that of microwave in terms of foaming capacity and emulsifying index of the product.     

无机电解质对十二烷基硫酸钠性质影响的研究

选择不同类型的无机电解质(NaCl、Na2SO4、Na3PO4、MgCl2、AlCl3),考察了电解质对十二烷基硫酸钠(SDS)表面张力、临界胶束浓度、润湿力、发泡力、乳化力的影响规律。实验表明,无机电解质对SDS的CMC影响显著,随着无机盐的加入,CMC降低,表面活性增强。当加入的氯化钠浓度达到0.3mol/L时,SDS的CMC降到了原来的十分之一,高价位离子对CMC影响大于低价位离子,同价位不同离子影响差别不大;SDS润湿性、乳化性、泡沫性能较好,加入电解质后,其润湿性增强,乳化性、泡沫高度和稳泡性降低。     

Enzymatic modification of soy protein concentrates by fungal and bacterial proteases

Solubility, foaming capacity and foam stability of denatured soy protein concentrate obtained from toasted flour were improved by proteolysis with fungal or bacterial proteases. Emulsifying capacity was unchanged, but emulsion stability decreased; bacterial protease highly improved oil absorption. Also, the bacterial protease was able to solubilize more protein and gave products which foamed more than those obtained with the fungal enzyme. However, the stabilizing properties of the bacterial modified soy protein concentrate at the air/water or oil/water interface were inferior. By limited hydrolysis up to degree of hydrolysis 10% most functional properties were improved without greatly reducing emulsion stability and water absorption.     

Functional properties of hydrothermally cooked soy protein products

The effects of hydrothermal cooking on the functional properties of defatted soy flour, aqueous alcohol washed soy protein concentrate, and soy protein isolate were determined in samples that were treated at 154°C by infusing steam under pressure for 11, 19, 30, and 42 s, and then spray dried. Hydrothermal cooking increased the nitrogen solubility index (NSI) of the concentrate from 15 to 56% and altered the solubility profile from a flat profile to one more typical of native soy protein. Hydrothermal cooking also improved foaming and emulsifying properties of the concentrate. For isolate, hydrothermal cooking also improved NSI and foaming and emulsifying properties, although the improvements were less dramatic than with concentrate. NSI and emulsifying properties of the flour were improved by some processing conditions, but foaming properties were not improved by hydrothermal cooking. Dramatically increased protein solubility of concentrate and modestly improved protein solubilities of flour and isolate by hydrothermal cooking, which will also inactivate trypsin inhibitors and microorganisms, have considerable practical significance to protein ingredient manufacturers and those who use these ingredients in foods and industrial products.     

基于响应曲面法的三相泡沫灭火剂基础配方优化设计

为得到发泡及稳定性能优异的三相泡沫,响应曲面法优化设计三相泡沫灭火剂基础配方。通过单因素实验确定表面活性剂及固相粉体为SDS、Fc-134、6501、2000目（6.91 μm）合成云母粉,以发泡高度及稳定时间为响应值,研究其交互作用。利用Box-Behnken方法,建立的二次回归模型显著可靠,该模型预测SDS、Fc-134、6501浓度分别为2.64%,0.096%,3%,合成云母添加量为10 g时,为最优组合,预测发泡高度1533.86 ml,稳定时间12.8792 min,实验得到发泡高度为1550 ml,稳定时间为12 min,误差分别为1.05%,6.82%。与未优化三相泡沫比较在发泡高度及稳定时间分别提高14.8%、26.3%。结果表明,经优化设计三相泡沫发泡及稳定性能较未优化三相泡沫有明显提高且响应曲面法建立的预测模型误差较小,因此,该模型可用于提升三相泡沫灭火剂的发泡及稳定性能,为三相泡沫灭火剂配方设计提供参考。     

十二烷基胍盐酸盐的合成与性能

以氰胺和十二烷基伯胺为原料,一步合成了十二烷基胍盐酸盐表面活性剂,经单因素实验确定了较佳工艺条件为:体积分数95%乙醇为溶剂,n(十二胺):n(氰胺):n(盐酸)=1:1.5:1.1,反应时间2 h。产品通过IR、1HNMR和元素分析进行了结构表征,并对其表面活性、泡沫性、乳化性和抑菌性进行了测试。结果表明,十二烷基胍盐酸盐的CMC为5.5 mmol/L,最低表面张力为24.1 mN/m,与DTAC相比,具有较好的泡沫性能,较差的乳化能力,较强的抑菌活性,在25 mg/L质量浓度下对金黄色葡萄球菌和大肠埃希氏菌的抑菌率达100%,在100 mg/L质量浓度下对白色念珠菌的抑菌率达99.5%。     

Functional properties of protein extracted from flaked,defatted, whole corn by ethanol/alkali during sequential extraction processing

Functional properties (solubility, foaming capacity and stability, emulsifying capacity, emulsion stability, heat coagulability, heat gelation and film formation) of protein extracted by 45% ethanol/55% 0.1 M NaOH from flaked, defatted, undergermed corn during the Sequential Extraction Process (SEP) were evaluated and compared with those of a laboratory-prepared soy protein concentrate. SEP is a new approach to corn fractionation that recycles the ethanol produced from the fermentation of cornstarch to unstream steps of protein extraction and the simultaneous extraction of corn oil and dehydration of the ethanol. Freeze-dried corn protein extracts contained at least 80% crude protein (dry basis), which is indicative of protein concentrates. SEP protein concentrates had solubilities in water of greater than 80% at pH values of 7 or above and were significantly more soluble than the soy protein concentrate at pH above 3. SEP corn proteins also showed better heat stabilities and greater emulsifying capacities and emulsion stabilities. Dilute dispersions (0.1%) of corn protein produced substantial but less stable foams. Corn proteins produced films similar to zein and soy protein films but were unable to form heat-induced gels. These results indicate that SEP produces a protein concentrate with functional properties suitable for food and industrial uses. Paper presented at the session on New Processes: Extractions and Purifications II, 83rd Annual Meeting of the AOCS, Toronto, May 10–14, 1992.