高压均质对大豆分离蛋白功能特性的影响

研究了高压均质压力(40～160MPa)和均质次数(1次/2次)对大豆分离蛋白(SPI)功能特性的影响。结果表明:均质次数为1次时,40MPa和80MPa可显著提高SPI的溶解性,压力增加至120MPa和160MPa时,溶解性反而明显下降,但持水性提高;1次均质可以显著改善SPI乳化活性,而对其乳化稳定性影响不大;80MPa1次均质和160MPa2次均质能显著提高SPI凝胶性;除160MPa外,均质压力相同时,1次均质比2次均质更有利于改善SPI功能特性(包括溶解性、乳化性、凝胶性和持油性)。     

罗非鱼下脚料分离蛋白的制备及其性质研究

采用酸碱法(pH-shifting)提取罗非鱼下脚料蛋白,主要探讨提取的pH对提取蛋白的得率、分离蛋白的基本成分、溶解性、乳化性和分子量分布的影响。结果表明:在料液比1∶9(g/g)、pH 2.0、pH 3.0以及pH 12.0、pH 13.0条件下溶解,pH 5.5条件下沉淀,提取蛋白得率达52%以上。冷冻干燥制备罗非鱼下脚料分离蛋白粉,其蛋白含量高于85%(干基)。功能特性的研究显示,在pH12.0条件下提取的分离蛋白功能特性最好,其溶解度和乳化活性指数分别为60.80%和42.07 m2/g。SDS-PAGE电泳分析显示,不同pH条件下提取的罗非鱼下脚料蛋白的分子量分布差别不大,主要显示分子量为200 ku和44.3 ku的蛋白条带,分别是肌原纤维蛋白组分中的肌球蛋白和肌动蛋白,另有部分蛋白条带在14.30 ku,属于小分子的肌浆蛋白。     

干燥方式对大豆分离蛋白功能性质的影响

本文以醇洗豆粕为原料制备大豆分离蛋白，着重探讨了冷冻和喷雾干燥两种干燥方式对大豆分离蛋白功能性质，如溶解度、凝胶性能、乳化性能、起泡性能与粘度等的影响。实验表明，冷冻干燥样品具有较低的粘度和溶解度，且凝胶性能和泡沫稳定性明显高于喷雾干燥样品；两种样品的乳化稳定性和起泡能力比较接近，但喷雾干燥样品的乳化活性略高于冷冻干燥样品。     

增塑剂对大豆蛋白可食膜特性的影响

研究了增塑剂对大豆分离蛋白膜(热法成膜和酶法成膜)成膜特性的影响。增塑剂的种类(甘油、山梨醇或甘油山梨醇的等量混合物)对大豆分离蛋白膜的性能有明显影响。无论是否添加谷氨酰胺转移酶(TGase)，以山梨醇为增塑剂的膜都具有最高的抗拉强度、表面疏水性和总可溶性物量，最低的断裂伸长率、水分含量和透光率。TGase处理SPI(4U／g．蛋白)，可显著改善蛋白膜的抗拉强度和表面疏水性，抗拉强度和表面疏水性分别比对照膜增加10％～20％和17％～56％(P≤0.05)；同时也明显降低了(P≤0.05)膜的断裂伸长率、水分含量、总可溶性物量及透光率。     

Reduction of IgE Immunoreactivity of Whole Peanut (Arachis hypogaea L.) After Pulsed Light Illumination

Pulsed light (PL), a novel food processing and preservation technology, has been shown in literature to reduce allergen levels on peanut, soybean, almond and shrimp protein extracts. This study investigated how PL affected the immunoreactivity of whole peanut kernels at two sample-to-lamp distances (7 and 10 cm) and a PL frequency of 3 pulses/s. A combination of different illumination durations and distances were tested to explore the effective conditions for PL roasting of whole peanuts. After the PL treatments, crude protein of the whole peanuts was extracted and compared to that of the raw peanuts (control) in vitro for allergen reactivity using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Western blot, dot blot, and enzyme-linked immunosorbent assay (ELISA) with pooled plasma of allergenic patients. The SDS-PAGE, Western blot, dot blot results all showed that PL was capable of mitigating all major allergens of whole peanut kernels to an undetectable level. Indirect ELISA results showed 80 % signal reduction for the PL-treated peanut as compared to raw peanut. A closer distance (7 cm) between the PL lamp and the sample resulted in stronger reduction of IgE immunoreactivity than 10 cm.     

Proximate,Fatty Acid and Sterol Compositions of Aboriginal Peanut (Arachis hypogaea L) Seeds from Bolivia

Oil, protein, ash, carbohydrate, iodine value, fatty acid and sterol compositions were studied in 46 aboriginal Arachis hypogaea cultivars originating from Bolivia. The oil and protein contents varied between 440 and 547 g kg^-1 and 242 and 547 g kg^-1, respectively. Results showed a lower protein content in the variety hypogaea (264·4 g kg^-1) than in the varieties fastigiata (299·7 g kg^-1) and peruviana (294 g kg^-1). The carbohydrate content ranged between 86 and 216 g kg^-1. The principal fatty acids were oleic (358–536 g kg^-1) and linoleic (250–462 g kg^-1). The variety hypogaea exhibited higher concentrations of oleic acid (449·0 g kg^-1). The sterol composition showed higher concentration of β-sitosterol (554–632 g kg^-1) following by campesterol (139–180 g kg^-1), stigmasterol (82–130 g kg^-1) and Δ⁵-avenasterol (86–138 g kg^-1). © 1997 SCI.     

Functional Properties of Chinese Rapeseed Protein Isolates

A membrane-based protein isolation process developed in our laboratory produced two protein isolates from CH₃OH/NH₃/H₂O-hexane-extracted Chinese rapeseed meal. Both contained ～99% protein (NX6.25), and they were essentially free of glucosinolates or their breakdown products (<2,2 μmol/g). Their functional properties were evaluated and compared with a commercial soybean protein isolate. The precipitated isolate gave high values for all properties except nitrogen solubility index (NSI) while the soluble isolate showed excellent NSI and fat absorption but poor emulsification characteristics. They both had good foaming properties. The two Chinese rapeseed protein isolates complemented each other and were comparable to soybean protein isolate in most functions.     

Solubility and Emulsifying Properties of Soy Protein Isolates Modified by Pancreatin

Soy protein isolates (SPI) with varying degrees of hydrolysis (DH of 7, 11, 15, 17%) were produced using pancreatin. The surface hydrophobicity indices of pancreatin hydrolyzed SPI (PSPI) (34.5, 34.9, 39. 1, and 40.7 for 7, 11, 15, 17% DH, respectively) were higher than that of SPI (10.5) and control SPI (CSPI) (12.5, 11.9, 12.9, and 12.6 for 10, 60, 120, and 180 min incubation, respectively). The solubilities of PSPI at pH 4.5 were 2.7, 9.1, 11.9, and 18.7%, for 7, 11, 15, and 17% DH, respectively, while the solubilities of SPI and CSPI at the same pH were about 1. 6%. Solubilities of PSPI at pH 7. 0 were > 90% for all DHs tested, while those of SPI and CSPI were 85%. The emulsifying activity index (EAI) of PSPI increased with increasing DH. PSPI with 15% DH had highest EAI (1. 122) which was higher (P < 0. 05) than those of SPI (0.550) and CSPI after 120 min incubation without enzyme (0.568). These results suggest that PSPI could be used as an ingredient for emulsified products and where high solubility at low pH is required.     

鹰嘴豆分离蛋白的乳化性及结构关系

研究了蛋白质浓度、加油量、pH及离子强度对鹰嘴豆分离蛋白的乳化活力及乳化稳定性的影响。在蛋白质的等电点pH50时,乳化活力最小,乳化稳定性最高;离子强度增加,乳化活力呈现先降后升,而乳化稳定性表现为先升后降的趋势,当离子强度为02时,乳化活力最低而乳化稳定性最高。为了解释这一现象,研究了pH及离子强度对蛋白质的二级结构及表面疏水性的影响。结果表明,蛋白质的二级结构及表面疏水性随溶液的pH及离子强度的变化而变化,在蛋白质的等电点或离子强度较低(如01)时,蛋白质的二级结构主要以α螺旋形式存在,且当离子强度为01时,蛋白质的表面疏水性最低。     

醇洗豆粕对大豆分离蛋白功能性质的影响(Ⅰ)--凝胶性能

为了探讨醇洗豆粕对大豆分离蛋白凝胶性能的影响。以醇洗豆粕为原料制备的大豆分离蛋白，其凝胶性能得到明显的改善。通过正交试验优化，生产凝胶型大豆分离蛋白的最佳工艺条件为：乙醇浓度85％(V／V)、浸提温度30℃、浸提时间45min、固液比1：4。所得产品的蛋白含量(干基)为96．52％，蛋白质分散指数为94．41％，凝胶硬度为285．4g，凝胶弹性为153．1g。     

花生粉,花生浓缩蛋白制备工艺及功能特性的研究

对花生蛋白，特别是花生浓缩蛋白的制备工艺进行了研究。对浓缩蛋白的三种制备方法进行了分析比较，并将产品的功能特性与大豆浓缩蛋白进行了对照。     

Effect of proteases on groundnut proteins (Arachis hypogaea L.)

The total proteins of Spanish Improved, TMV-2 and DH-3-30 varieties were extracted and hydrolysed with two group specific enzymes alpha-chymotrypsin and trypsin and a less specific enzyme, pepsin. Compared to casein, the proteins were highly resistant to hydrolysis by the group specific enzymes. However, the variety TMV-2 was more susceptible to proteolysis than the other two varieties. While the ratio and extend of hydrolysis for pepsin was same in all the varieties they were different for alpha-chymotrypsin. Nitrogen solubility profile of the meals in water, 1 M NaCl and 2% sodium hexametaphosphate solutions did not show any marked difference. Gel filtration, DEAE-Cellulose chromatography, analytical ultracentrifugation and polyacrylamide gel electrophoretic patterns of the proteins did not indicate any major differences. However, the relative proportions of different fractions differed among the varieties. Gel filtration indicated that Spanish Improved variety contain higher amounts of conarachins (15%). Such quantitative differences of the various fractions may be responsible for the observed difference in the resistance to hydrolysis by the proteolytic enzymes.     

罗非鱼肉分离蛋白的营养成分分析

以罗非鱼鱼肉为原料,采用pH值调节法(pH-shifting),制备鱼分离蛋白,主要探讨提取条件和沉淀条件对提取蛋白得率及其应用特性的影响.结果表明:在极端酸性(pH<3)和极端碱性(pH>10)条件下,鱼肉蛋白的溶解性较好,而在pH值5-6时溶解性较差,由此选择pH值2、3、11和12条件下溶解,pH值5.5条件下沉...     

Phytochemical content and antioxidant capacity of water-soluble isolates from peanuts (Arachis hypogaea L.)

Numerous polyphenolics have been identified in peanuts, but information relating to their storage stability and contributions to total antioxidant capacity are lacking. This study investigated contributors to the antioxidant capacity of six peanut cultivars by means of fractionation from reversed phase C18 cartridges. Five water-soluble peanut isolates were prepared and subsequently stored at 35 °C and evaluated for individual and total polyphenolics, antioxidant capacity, total reducing equivalents, and total amino acids after 0, 2, 4 and 8 weeks. The relative contribution of each isolate to total antioxidant capacity for each cultivar was additive, with the C18 non-retained fraction containing 100% of the p-coumaric acid and 82% of the total amino acids. During storage relatively small changes were observed for antioxidant activity and total reducing equivalents among cultivars and isolates, indicating the lack of oxidative or condensation reactions among the isolated constituents. Results demonstrated the overall stability and diversity of antioxidant polyphenolics found in peanuts, information that advances the marketability of the crop.     

花生蛋白粉功能特性影响因素的研究

研究了花生蛋白粉的功能特性，探讨了不同蛋白浓度、ｐＨ、温度对其溶解性、发泡性、持水性的影响。当ｐＨ在４．２～５．３范围内，为其等电点，此时，花生蛋白粉的溶解性、发泡性、持水性最低，在其两侧随ｐＨ增加或降低，这些特性逐渐增强；当温度超过６０℃时，为花生蛋白溶液大幅度变性的临界温度，其溶解度、持水性下降；随温度升高，发泡性增加，在蛋白浓度为３％时，起泡性最高     

酶法改性对鹰嘴豆分离蛋白功能性的影响

研究了Alcalase及转谷氨酰胺酶(TGase)酶法改性对鹰嘴豆分离蛋白(CPI)的溶解性及乳化性的影响。CPI经A1calase水解60min(DH5.91%),低离子强度对溶解性不再有负面影响;CPI水解30min(DH5.80%),无盐或0.1mol/L NaCl条件下,蛋白质的乳化活力分别是未改性前的1.22和2.78倍。TGase对CPI在0.1mol/L NaCl条件下的溶解性及乳化活力不能起到良好的改善作用。     

大米分离蛋白的酶法提取及其性质

本文研究了以糖渣为原料,用淀粉酶法水解法制备大米分离蛋白(E-RPI)的反应条件,并测定了蛋白质的溶解性、乳化性及其氨基酸组成。结果表明,反应中固液比为1:12.96、加酶量为0.096％、反应时间为2.3h时效果最好,使糖溶出量达到原料重量的25.7％,产物中的蛋白含量为88.6％,回收率为90.5％;E-RPI的乳化活性随pH值的升高而增大,与大豆蛋白相比,乳化活性低而稳定性高。E-RPI中除赖氨酸外,其它必需氨基酸的含量均高于大豆蛋白和酪蛋白。     

Microstructure of Peanut (Arachis hypogaea L. cv. Florigiant) Cotyledons after Oil Cooking

The microstructure of peanut (Arachis hypogaea L. cv. Florigiant) cotyledon before and after oil cooking at 160°C (10 min) was investigated with light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Principal observations included thermal modification of the cytoplasmic network, lipid bodies, protein bodies, starch, and cell-to-cell junctions during oil cooking.     

花生种子中凝集素的凝集活性及性质研究

利用血凝实验及糖抑制实验测定花生种子中凝集素的凝血活性及糖抑制专一性,同时进行热稳定性及pH影响实验。结果显示：花生种子的凝集素粗提液不能凝集人的A、B、O型血细胞,但是可以凝聚唾液酸酶处理后的A、B、O型血细胞。凝集素对红细胞的凝集可被乳糖、蜜二糖、棉籽糖和D-半乳糖四种糖所抑制,在pH为5.0～11.0范围内较稳定,经55℃保温10min后,活性完全消失。在检测的6个不同品种的花生中,河北高油的种子中凝集素活性最强。在花生的生长初期,这种凝集素的存在部位是子叶和根。     

Localisation of thiamine within the cotyledon of dormant groundnut (Arachis hypogaea L.)

Utilising non-aqueous differential centrifugation for isolation of subcellular components from groundnuts, it appears that intracellular thiamine is predominantly non-particulated. A large proportion of the total thiamine of the cotyledon is associated with cell wall material, most likely due to inward migration of the vitamin from the testa during curing.