Effect of storage at 0 °C on mantle proteins and functional properties of jumbo squid

Effect of iced storage of jumbo squid mantle with fin on gelling capacity and changes in protein fractions and functional properties of jumbo squid mantle protein during storage at 0 °C were assessed. Most values of texture variables in gels did not significantly change during storage. On average, they were: strength 65.07 ± 4.71 N; elasticity 68.14 ± 5.3%, fracturability 52.97 ± 1.28 N and cohesiveness 36.6 ± 0.1%. Protein solubility increased more than 40%. Whippability increased during storage for 16 days at 0 °C (81–162%), as did foam stability (73–94%). Results suggest that iced squid mantle protein is a suitable ingredient for food products where these functional properties are desirable. Muscle fibres of squid mantle undergo various changes during storage. At 0 °C, they are disrupted, whereas at −20 °C, they aggregate and develop empty spaces in the tissue.     

PROTEIN SOLUBILITY AND PRODUCTION OF GELS FROM JUMBO SQUID

Solubility at several ionic strengths (0 to 1.0 M), pH (2 to 13) and gelling capacity of jumbo squid Dosidicus gigas muscle proteins were evaluated. Protein recovery was > 90% at pH 9 – 12. Autohydrolysis was evaluated and affected only sarcoplasmic proteins. Folding score was 5 on all gels. Strength was higher for thermal gels prepared from squid fin (50.2  ±  1.2 N) than that prepared from the mantle (23.4  ±  2.5 N). There was no significant difference in gel strengths from previously frozen (46.4  ±  7.5 N) and never-frozen samples (43  ±  5.5 N). Moisture, water drip and water-holding capacity were evaluated on thermal gels. There were significant differences between frozen and never-frozen samples. Results on solubility and gel forming capacity of the proteins from mantle and fin of jumbo squid suggest that these properties can provide additional value to this resource.

PRACTICAL APPLICATIONS

Jumbo squid is a rich source of high-quality protein. Obtaining sophisticated products would be an easy way to take advantage of the high-quality proteins in jumbo squid muscle. Knowledge of the functional properties of those proteins is needed to achieve this. The use of such properties, such as gel-forming capacity, which are similar to other proteins used in the food industry, will give jumbo squid added value. The results described here indicate that jumbo squid proteins may be useful as a food ingredient because of their solubility and gel-forming capacity.     

EFFECT OF ENZYMATIC HYDROLYSIS ON SOME FUNCTIONAL PROPERTIES OF WHEY PROTEIN

A study was undertaken to further elucidate the functional properties of whey protein with respect to foaming and emulsifying capacities and to observe the effect of enzymatic hydrolysis on these properties. Emulsion capacity decreased as proteolysis continued suggesting there is an optimum mean molecular size of the proteins involved which is lower than that of casein. Heat treatment of the reconstituted protein concentrate was necessary for foam stability; specific volume and foam stability increased directly with temperature of heating. Re effect of pH on whippability, data indicate that the greater the net charge the greater the tendency to foam. A limited amount of hydrolysis appears desirable to increase foaming but greatly decreases foam stability.     

Enzymatic Hydrolysis of Recovered Protein from Frozen Small Croaker and Functional Properties of Its Hydrolysates

ABSTRACT:  Fish protein isolate were recovered from frozen small croaker using pH shift. The partial enzymatic hydrolysates were fractionated as soluble and insoluble parts. They were dried using the drum dryer and their functional properties were examined. The total nitrogen content of the enzymatic hydrolysates ranged from 12.9% to 13.7%. The degree of hydrolysis of precipitates was 18.2% and 12.2% for croaker hydrolysates treated with Protamex 1.5 MG ( Bacilllus  protease complex) and Flavourzyme 500 MG (endoproteases and exoproteases, Aspergillus oryzae ), respectively. The TCA supernatant, after centrifugation of hydrolysates, contained numerous peptides ranging from 100 to 4000 daltons. The solubility of the supernatants was higher than that of the precipitates at 0% to 3% NaCl and pH 2 to 10. The precipitate of Flavourzyme- and Protamex-treated hydrolysates showed a high emulsion activity index value compared to egg white and bovine plasma protein. In addition, the highest emulsion stability was observed for Protamex-treated precipitate hydrolysates. Emulsion stability of Protamex-treated precipitate hydrolysates was comparable to those of protein additives (egg white, bovine plasma protein, and soy protein concentrate). Water and fat binding capacity of precipitates were higher than those of supernatant. The results indicate that precipitate hydrolysate from undersized croaker can be used in processed muscle foods as a functional and nutritional ingredient.     

Functional properties of hydrolysates from Phaseolus lunatus seeds

Use of low degree of hydrolysis (DH < 10%) with enzymatic treatment can produce protein hydrolysates with functional properties superior to the raw material. Suspensions of Phaseolus lunatus protein isolate (PPI) were treated with one of two commercial enzymes (Alcalase or Flavourzyme) at 50 °C and pH 8.0. DH with Alcalase was greater than Flavourzyme at 5 or 15 min of reaction. Alcalase-prepared hydrolysates had more peptides than those prepared with Flavourzyme. All the hydrolysates had higher solubility than the PPI, the highest being for the Alcalase-prepared hydrolysate at 15 min reaction time. Overall, the Alcalase-prepared hydrolysates had better solubility characteristics, whereas the Flavourzyme-prepared hydrolysates had better film properties (maximum emulsifying capacity and the highest foam formation values). This is probably because of the greater ease of movement toward the interface as shown by their high surface hydrophobicity values. The Alcalase-prepared hydrolysates had generally low or nonexistent film properties.     

Protein hydrolysates from meriga (Cirrhinus mrigala) egg and evaluation of their functional properties

Protein hydrolysates from underutilised meriga (Cirrhinus mrigala) fish egg were prepared by using commercial Alcalase and papain enzymes. The degree of hydrolysis was 62% for Alcalase and 17.1% for papain, after 90 min digestion at 50–55 and 60–65 °C, respectively. The protein content of Alcalase-produced hydrolysate was higher (85%) than that of papain hydrolysate (70%) (p < 0.05). Hydrolysis by both enzymes increased protein solubility of fish egg protein hydrolysates to above 72.4% over a wide pH range (2–12). Results showed that the hydrolysates had good fat absorption capacity (0.9 and 1.0 g/g sample), foam capacity (70% and 25%) and emulsifying capacity (4.25 and 5.98 ml/g hydrolysate), respectively for Alcalase and papain protein hydrolysates. Gel filtration chromatograms and SDS–PAGE analysis indicated the distribution of smaller peptides. These results suggested that fish egg protein hydrolysates could be useful in the food industry.     

Antioxidant and functional properties of gelatin hydrolysates obtained from skin of sole and squid

Antioxidant and functional properties were evaluated for gelatin hydrolysates obtained from sole and squid skin gelatin by Alcalase, with a degree of hydrolysis of ∼35% and ∼50%, respectively. Both hydrolysates mainly consisted of peptides below 6.5 kDa, together with peptidic material from around 16 to 6.5 kDa. Moreover, the squid hydrolysate showed a peptide band of around 26 kDa. Antioxidant properties of both gelatins were highly increased by hydrolysis, especially ABTS and metal chelating abilities. The squid hydrolysate showed the highest antioxidant capacity by FRAP, ABTS and metal chelating assays in spite of the lower content in hydrophobic amino acids. Both gelatin hydrolysates had a good solubility (over 95%). The emulsifying activity index (EAI) decreased with increasing concentration. Conversely, the foam expansion increased with increasing concentration. However, both foam and emulsion stabilities were not apparently affected by the concentration of hydrolysate. In the case of the sole hydrolysate, which showed a lower degree Pro and Lys hydroxylation, foam stability was very poor, and 50% of foam expansion was lost after 5 min at all concentrations.     

Assessment of functionality of sesame meal and sesame protein isolate from Indian cultivar

Plant proteins are cheaper source of proteins as compared to animal proteins. So they have great potential as functional food ingredient and could be supplemented in human diets. The use of isolated proteins depends on their ability to impart properties in processed foods. So for effective utilization of particular protein, it is necessary to study its all types of properties and characteristics which is necessary for development of methodology for their use. Sesame protein isolate (SPI) was extracted from sesame meal. The physicochemical and functional properties of both sesame meal and SPI were evaluated. The solubility was maximum (94.13 %) at pH 12. Foaming capacity and foam stability of SPI was pH dependent. SPI showed increase in emulsion stability (ES) with increase in pH. Gelling ability of SPI increased with alkaline pH.     

鳄鱼皮酶解产物功能特性及抗氧化活性

为了解鳄鱼皮酶解产物功能特性和抗氧化活性,采用2种商业蛋白酶(木瓜蛋白酶、碱性蛋白酶)在各自最适反应条件下分别酶解鳄鱼皮,研究水解度(DH)、酶种类及pH值对酶解产物功能特性及抗氧化活性的影响.结果显示:随着酶解时间延长,鳄鱼皮水解度逐渐增加,鳄鱼皮在碱性蛋白酶酶解作用下水解度较高,水解4h时可达12％;木瓜蛋白酶酶解产物与碱性蛋白酶酶解产物的溶解性差异不显著(P＞0.05).相同水解度下,碱性蛋白酶酶解产物的热稳定性在pH4时优于木瓜蛋白酶酶解产物.酶解时间在1h之内,木瓜蛋白酶酶解物亚铁离子螯合力明显增强;随着时间延长,酶解产物亚铁离子螯合能力变化不显著(P＞0.05).酶解3h后碱性蛋白酶酶解产物亚铁离子螯合能力高于木瓜蛋白酶酶解产物,但木瓜蛋白酶酶解产物具有较强的清除DPPH自由基能力.综上表明,碱性蛋白酶水解作用的鳄鱼皮水解度较高,其酶解产物乳化活性和热稳定性优于木瓜蛋白酶酶解产物;鳄鱼皮酶解产物抗氧化能力较强,有较高的开发利用价值.     

Functional Characteristics of Protein Flaxseed Concentrate Obtained Applying a Response Surface Methodology

ABSTRACT:  Food preferences by human beings are based on sensory attributes such as texture, flavor, color, and appearance that depend mainly on the interactions between minor and major components of the food. Some functional properties depend directly on the proteins, such as oil and water absorptions, foam and emulsion activities, and viscosity. The objective of this work was to obtain and evaluate the functional properties of flaxseed protein concentrate. Flaxseed was ground, defatted, and sieved to eliminate hull fiber. Surface response methodology with 5 central points and 4 axial points was used to determine how to obtain the highest protein concentrate. The independent variables used were solubilization pH (which varied from 9 to 11) and precipitation pH (which varied from 4.2 to 4.8). Treatment with a solubilization pH of 11 and a pH extraction of 4.8 gave 66.03% protein content. The flaxseed protein concentrate contained 2.56% fat, 6.62% ash, 2.44% insoluble fiber, 15.79% soluble fiber, and 6.59% sugars. The product had oil and water absorption capacities of 150.25% and 253.5%, respectively. Better foam stability (83.33%), emulsifying capacity (84.76 mL/g), and emulsifying activity (88.37%) of the flaxseed protein concentrate were observed at a pH 6. In light of its functional properties as indicated by this study, flaxseed protein concentrate may be recommended for use as an ingredient in products such as meat batters, hamburgers, and ice cream.     

抗坏血酸对大豆分离蛋白酶解产物功能特性影响研究

采用木瓜蛋白酶水解不同浓度的大豆分离蛋白,研究了抗坏血酸对较低水解度（DH为3.7%）和较高水解度（DH为8.9%）酶解产物黏度、发泡性、发泡稳定性、乳化性和乳化稳定性的影响.结果表明：在水解度为3.7%的、浓度为7%的大豆分离蛋白酶解液中添加0.3%抗坏血酸,体系的黏度最大、乳化性最强、乳化稳定性最高;在水解度为8.9%的、浓度为3%的大豆分离蛋白酶解液中添加0.3%抗坏血酸,体系的发泡性最大;在水解度为3.7%的、浓度为7%的大豆分离蛋白酶解液中添加0.5%抗坏血酸,体系的泡沫体积比最大.     

Foaming properties of barley protein isolates and hydrolysates

Foaming properties of the barley protein isolates (BPI) and barley protein hydrolysates (BPH) were investigated by using gas sparging method. BPIs were produced from hulled (BPI-1) and hull-less (BPI-2) barley flours by extracting with 70% (v/v) ethyl alcohol. BPI-2 was hydrolyzed with Subtilisin enzyme using pH-stat technique in order to produce hydrolysates at 3% (BPH-1) and 6% (BPH-2) degree of hydrolysis. Barley flour, BPI-1 and the pellets and supernatants obtained from centrifugation of BPI-1 were examined by SDS-PAGE. The foaming properties of BPIs and BPHs were determined as a function of pH and protein concentration. The results showed that foaming properties were affected by the changes in pH of the medium in isolates and hydrolysates. Foaming properties of isolates were improved below and above the isoelectric pH. The lowest values were observed at pH 6, which is close to the isoelectric pH of BPIs. The protein hydrolysates displayed improved foam stability at basic pH values, while stability was very low at acidic pH values. Generally, at all pH values in both isolates, the highest foam volumes and stability were observed for 1% (w/v) protein concentrations.     

Modified Soy Proteins with Improved Foaming and Water Hydration Properties

Soy proteins were modified by alkali treatment at pH 10.0, followed by papain hydrolysis. Solubility, water hydration capacity (WHC), surface hydrophobicity, foaming and emulsifying properties of unmodified, alkali-treated, and papain-modified soy protein (PMSP) were compared. PMSP exhibited higher solubility (100% at pH > 7.0), WHC (3.13) and hydrophobicity (40.8) than unmodified soy protein which had solubility 68.5%, WHC 0.21, and hydrophobicity 8.1. The PMSP had foaming capacity (22.0 mL) similar to egg white (21.2 mL) at pH 7.0; and enhanced foam stability (36.4) compared to the unmodified control (32.9). In general, alkali-treated soy had lower functional properties. Emulsifying properties of PMSP and alkali treated soy were unchanged by the modification. PMSP could be used as an egg white substitute in foaming applications at neutral pH.     

Functional properties of proteins isolated from phorbol ester-free physic nut (Jatropha curcas L.) seed cake

Phorbol ester-free physic nut (Jatropha curcas L.) seed cake is a nutritious protein source. Functional properties of the protein isolates obtained from various protein precipitation methods were investigated. Proteins isolated from the seed cake by ammonium sulfate gave the highest yield. The solubility of all proteins increased with increasing pH with their maximum and minimum solubility at pH of 12.0 and 4.0, respectively. The protein prepared by ethanol provided the maximum water holding capacity (3.34 mL water/g protein). The oil binding capacities of all proteins were 1.96–2.03 mL oil/g protein. The protein precipitated by ethanol showed higher emulsion activity and stability than that precipitated by acetone and ammonium sulfate. The protein obtained from ammonium sulfate gave the highest foam capacity, while the protein from acetone had the highest foam stability. Different functional properties of the proteins were achieved by various protein precipitation methods. The protein isolate obtained from each method could serve as a food ingredient applied to food products requiring a specific functional property.     

鲤鱼鱼肉蛋白酶水解物抗氧化性及功能特性

采用碱性蛋白酶对鲤鱼鱼肉蛋白进行酶解,制备不同水解度的水解物。测定水解物的抗氧化活性以及不同pH值条件下水解物的功能特性。结果表明:随着水解度的逐渐升高,水解物的抑制脂质氧化能力、D PP H自由基清除能力、还原能力以及金属离子(Cu2+和Fe2+)螯合能力逐渐增加(P<0.05);同时,水解物的溶解性、乳化性和起泡性都在pH值为4.0(等电点)时达到最低,而后溶解性和乳化性随着pH值升高而增大(P<0.05),而起泡性随着pH值的升高先上升后又下降。因此,鲤鱼鱼肉蛋白碱性蛋白酶水解物可以提高蛋白质的抗氧化活性和溶解性,但是较高的水解度会在一定程度上降低其乳化性和起泡性。     

碱性蛋白酶限制性酶解对蓝圆鲹分离蛋白功能特性的影响

以蓝圆鲹(Decapterus maruadsi)分离蛋白为原料,采用碱性蛋白酶对其进行限制性酶解,研究水解度(degree of hydrolysis,DH)对分离蛋白酶解产物溶解性、持油力、乳化性与起泡性等功能特性的影响.结果表明,碱性蛋白酶酶解产物的相对分子质量显著下降.酶解可有效提高分离蛋白的溶解性,其溶解度随...     

小麦面筋蛋白质酶解产物用作啤酒发泡蛋白的研究

为改善啤酒的泡沫性能,作者分别采用木瓜蛋白酶、胃蛋白酶以及碱性蛋白酶对小麦面筋蛋白进行适度酶解改性,并对其产物用作啤酒发泡蛋白的可行性进行了研究.结果表明,经适度酶解作用后,小麦面筋蛋白在pH 4.5条件下溶解性和泡沫性能得到显著改善(P<0.05),且小麦面筋蛋白酶解产物在啤酒环境中热稳定性较好,经30 min的热处理,含100 mg/L小麦面筋蛋白酶解产物的啤酒浊度与加热前相比增加不显著(p>0.05).小麦面筋蛋白胃蛋白酶酶解产物和碱性蛋白酶酶解产物对啤酒初始泡持性的改善效果都较好,但胃蛋白酶酶解产物对酵母蛋白酶A作用较敏感,对纯生啤酒货架期内泡持性的改善效果不太理想,而碱性蛋白酶酶解产物可明显改善纯生啤酒货架期内的泡沫稳定性.     

Composition and functional properties of hemp seed protein isolates from various hemp cultivars

Hemp seed protein isolates (HPI) were extracted from seven commercial hemp cultivars, a Cornell breeding line, and a commercial hemp heart product, and their composition and functional properties were investigated. HPI contained different ratios of edestin, vicilin, and albumin proteins, which affected protein solubility and functionality. Higher protein solubility was associated with cultivars that contained more vicilin and albumin, which influenced the subsequent functional properties of HPI. Significant differences in water holding capacity (0.83–1.05 g water/g protein isolate), oil holding capacity (1.28–1.81 g oil/g protein isolate), foam capacity (52.9%–84.9%), and foam stability (68.1%–89.4%) were observed across HPI. The Cornell hemp breeding line exhibited the highest protein solubility at pH 7.0 and was uniquely capable of forming an emulsion. The relationship identified between hemp seed protein composition and functionality, in conjunction with the demonstration of an on-going hemp breeding line, suggest that continued, targeted development of hemp cultivars can improve its seed protein functional properties for ingredient utilization in plant-based foods.     

鸡蛋清蛋白水解物的物化及功能性质的研究

蛋清蛋白质溶解性欠佳且容易起泡,使其应用受限。本文利用Alcalase酶解鸡蛋蛋清蛋白制取水解度为5~15%的酶解物并对酶解物的理化性质和功能性质进行了表征。测定性质包括乳化性、起泡性及稳定性以及溶解性、表面疏水性。所有酶解产物具有较低的表面疏水性,水解大大提高了溶解度,当水解度15%时最大值为89%,但乳化性有所降低,起泡性及稳定性也大约下降了40%。     

金华火腿副产品蛋白酶解物的功能特性与抗氧化活性研究

目的:研究以金华火腿副产品为原料制备的蛋白酶解物的功能特性与抗氧化活性.方法:分析金华火腿副产品蛋白酶解物在不同pH值条件下的乳化活性、乳化稳定性、起泡力以及泡沫稳定性;通过体外试验考察不同浓度的酶解物的自由基清除能力、还原力以及抑制脂质过氧化能力.结果:在体系pH9.0时,金华火腿副产品蛋白酶解物显示出较好的乳化与起泡性能.酶解物的抗氧化活性与其浓度有一定的相关性,当酶解物质量浓度为7.5 mg/mL时,超氧阴离子的清除效果最理想;当酶解物质量浓度为10 mg/mL时,DPPH自由基清除率为32%,还原力为0.79.与空白对照组相比,不同浓度的蛋白酶解物均能够抑制亚油酸的自氧化,且随着浓度的增加,抑制效果明显.结论:在碱性条件下,金华火腿副产品蛋白酶解物具有较好的功能特性.金华火腿副产品蛋白酶解物具有一定的体外抗氧化活性.