不同热处理对藜麦蛋白质营养品质的影响

本研究分别采用微波、蒸制、煮制和烘焙对藜麦分离蛋白（QPI）进行热处理,并评价处理前后QPI氨基酸组成、体外消化特性和生理活性变化。结果表明：蒸制、煮制和烘焙处理分别使QPI中必需氨基酸总量降低了2.93%、8.68%和1.91%（p<0.05）,同时改变了QPI中氨基酸的组成及评分;微波和煮制处理后QPI最终消化率分别提高至77.10%和82.86%（p<0.05）;在测定浓度范围内,各组QPI消化产物均展现出体外抗氧化活性,其中微波处理组样品DPPH自由基清除能力（42.71%）及氧自由基吸收能力最强（34.90%）; QPI消化产物能够促进3T3-L1脂肪细胞胰岛素抵抗模型对葡萄糖的摄取,蒸制、煮制和烘焙能够进一步提高该效果（p<0.05）。该研究为藜麦蛋白质的加工和功能性应用提供理论指导,旨在促进藜麦产业的进一步发展。     

Stability of quinoa flour proteins (Chenopodium quinoa Willd.) during storage

The amino acid composition and the physicochemical and functional properties of quinoa flour proteins (QFP) were evaluated during storage (at 20, 30 and 40 °C). Quinoa flour showed a protein content of 14.2 ± 0.1 g 100 g⁻¹ and high levels of essential amino acids as lysine. SDS–PAGE of the QFP presented ten major band, and native-PAGE of the QFP showed similar banding; there was a little variation due to time-temperature. TCA-protein solubility variation (%) was small and the values of water activity were low, a non-significant endogenous hydrolysis was observed. Differential scanning calorimetry flour analysis allowed determining two endotherms, starch and protein. Important structural changes of protein soluble fractions were not detected by UV and fluorescence spectroscopy due to temperature and time of storage. It was found during storage time loss of protein solubility and water absorption. These changes could be to influence in the manufacture of quinoa flour based products. For avoid changes in these functional properties (solubility and water holding capacity), quinoa flour can be stored at ambient temperature (between 20 and 30 °C) and packed in double kraft paper bags (2 months).     

Nutritional and functional characterisation of hydrolysates from quinoa flour (Chenopodium quinoa) using two proteases

The objective was to study the nutritional and functional properties of hydrolysates from quinoa (Chenopodium quinoa) obtained by enzymatic hydrolysis of defatted quinoa flour (DQF). The commercial enzymes alcalase and flavourzyme were used to obtain the hydrolysates defatted quinoa flour hydrolysate with alcalase (DQFA) and defatted quinoa flour hydrolysate with flavourzyme (DQFF), respectively, after 3 h of digestion at 50°C and pH 8. The degree of hydrolysis (47.32%), yield (31.05%) and protein recovery (88.80%) values were higher in DQFA; however, its protein content (48.34%) was lower compared to that of DQFF (55.06%). Also, DQFA had a solubility greater than 57% over a wide pH range (2–10) and good foam stability (70–90%). On the other hand, DQFF presented adequate emulsifying activity (61.30 m²/g), emulsifying stability (158.62 min) and foaming capacity (131%). Due to the high content of macro- and micronutrients and adequate emulsifying and foaming properties, DQFA and DQFF could be used as ingredients in various processed food products and protein supplements.     

超高压及三聚磷酸钠质量分数对肌球蛋白凝胶保水性及热胶凝过程的影响

为探究超高压处理及三聚磷酸钠质量分数对肌球蛋白凝胶保水性及热胶凝过程的影响,在不同压力条件（100、200、300 MPa）下对添加不同质量分数（0%、0.15%、0.30%、0.45%）三聚磷酸钠的兔骨骼肌肌球蛋白进行25 ℃、9 min超高压处理后再经程序升温（1 ℃/min）制备凝胶,以未经超高压处理的含质量分数0.30%三聚磷酸钠的肌球蛋白为对照组,测定凝胶的保水性,并筛选出对其有显著影响的参数组合。在该条件下对蛋白的溶解度、ATP酶活力和升温过程中的蛋白二级结构含量、表面疏水性、活性巯基含量、静态流变性以及凝胶微观结构等指标进行测定。结果显示：含质量分数0.15%三聚磷酸钠的肌球蛋白经不高于200 MPa的超高压处理后,其溶解度显著下降,ATP酶活力显著上升（P＜0.05）;质量分数0.15%三聚磷酸钠对超高压处理诱导的肌球蛋白功能特性变化存在拮抗作用,且蛋白在升温过程中的变性、聚集受抑制,随着三聚磷酸钠质量分数升高到0.30%,拮抗作用消失,蛋白在热胶凝过程中结构充分展开,疏水基团与所包埋的巯基快速暴露,形成的凝胶结构富有弹性且致密有序,保水性显著提高（P＜0.05）;而300 MPa超高压处理使蛋白的ATP酶活力丧失,溶解度及热变性程度降低,分子间交联弱化,最终使凝胶保水性显著下降（P＜0.05）。三聚磷酸钠通过影响蛋白的结构与理化特性,改变其热凝胶形成过程中的变性速率与交联方式,导致最终凝胶保水性发生变化。     

Physical,chemical and nutritional characteristics of puffed quinoa

Puffed quinoa can be used as ready-to-eat breakfast food or as an ingredient in snack formulations. In this study, puffed quinoa products with and without starch–chitosan coating were developed by gun, extrusion and microwave puffing at different process conditions (pressure, power, moisture content and energy consumption). Size, bulk density, colour, expansion index, water absorption and solubility, microstructure, mechanical and thermal properties, chemical composition and in vitro digestibility of organic matter and proteins of popped quinoa were assessed. Optimal process conditions for gun puffing were maximum 1.31 MPa after 780 s, 500 r.p.m. and 180 s for extrusion puffing and 1200 W for 60 s applying microwave puffing at 18–20% moisture contents. Gun and extrusion puffing yielded high-quality popped quinoa with a biological availability of organic matter between 84–88% and 79–90% for proteins. Extrusion and gun puffing are the most promising processes to prepare quinoa snacks.     

不同加工方式对藜麦蛋白质结构与功能特性的影响

为探究藜麦加工方式对其蛋白质的影响,采用蒸煮、萌发和挤压膨化处理藜麦并提取蛋白质,对蛋白质结构与功能特性进行分析。结果表明：与对照组（藜麦45 ℃烘干后粉碎过100 目筛）藜麦蛋白相比,pH 7.0时萌发组蛋白溶解度提高了14.12%,而蒸煮和挤压膨化组在不同pH值下溶解度均明显降低;3 种处理使蛋白乳化性降低7.09%～21.28%,但乳化稳定性提高至对照组的1.08～2.03 倍;萌发组蛋白起泡性（69.58%）和泡沫稳定性（67.86%）最高,而热处理（蒸煮和挤压膨化）组大体上显著降低（P＜0.05）;差示扫描量热分析结果显示3 种处理后蛋白质变性温度略有升高;萌发组蛋白游离巯基含量变化不显著（P＞0.05）,蒸煮组存在氧化损失,而挤压膨化组游离巯基含量增加至33.20 μmol/L;光谱分析显示,处理后藜麦蛋白质发生了变性,萌发组无规卷曲相对含量减少1.96%,而蒸煮和挤压膨化组β-折叠相对含量分别由对照组的58.17%增加至89.42%和100.00%。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳结果表明藜麦蛋白主要分子质量为48～63 kDa及＜15 kDa组分,且各组分通过二硫键连接,萌发组亚基增多,而热处理组有聚合物形成。3 种加工方式对藜麦蛋白质结构影响不同,因而蛋白质表现出的功能特性也存在差异。     

Denaturation Kinetics and Aggregation Mechanism of the Sarcoplasmic and Myofibril Proteins from Grass Carp During Microwave Processing

Optimizing the physicochemical properties of microwave-cooked meat needs a better understanding of the mechanisms responsible for protein changes. This paper explored the causes of aggregation of the denatured fish protein in ready-to-eat food by determining the changes in sarcoplasmic and myofibril proteins, which includes the effects of different microwave power levels (300, 600, and 900 W) and heating times (0–60 s) on the aggregation kinetics and physiochemical properties. The determination of aggregation kinetics that accurately describes microwave cooking characteristics is crucial for the optimization of operating parameters, performance improvement of the cooked food system, and product quality. The aggregation rate and turbidity of proteins increased with increasing microwave power and time. A negative correlation was observed between the protein solubility and microwave power and time. Protein aggregation induced by microwave showed a reliable and reproducible characterization of particle size distributions. At longer microwave heating time or higher microwave power, these protein particles formed larger aggregates.     

不同蒸煮方式对藜麦营养特性及风味的影响

研究常压蒸煮、高压蒸煮、微波蒸煮三种不同蒸煮方式对藜麦的营养特性(VB1、VB2的损失;酚类物质含量和组成;淀粉水解率)的影响,并采用固相微萃取联用气相色谱-质谱技术对样品的风味物质进行分析。结果表明:与其他两种蒸煮方式相比,常压蒸煮藜麦可保留较多的VB1、VB2,有较低的淀粉水解指数,可产生更多的风味物质。但在酚类物质的保留上,常压蒸煮不及高压蒸煮。因此,常压蒸煮可能是一种较适于藜麦的烹调方式。     

不同热处理方式对玉米醇溶蛋白特性的影响

研究了不同热处理方式（水浴、微波、射频）和处理终点温度（70、80、90 ℃）对玉米醇溶蛋白功能性 质与结构的影响。结果表明：多种热处理均会提高玉米醇溶蛋白溶解度、乳化能力和巯基含量,且这3 项指标随着 处理终点温度的升高而升高,射频处理至90 ℃使玉米醇溶蛋白溶解度、乳化能力和巯基含量分别提高了74.65%、 171.7%和53.94%。应用差示扫描量热法测定玉米醇溶蛋白变性温度,发现微波处理后蛋白质变性温度略有升高。 此外,紫外光谱分析提示,玉米醇溶蛋白经微波和射频加热处理后,蛋白质分子结构舒展、基团暴露,这使得蛋 白质的溶解性和乳化能力有所改善。傅里叶变换红外光谱分析发现热处理改变了玉米醇溶蛋白的二级结构,其中 微波和射频处理效果更明显。     

Effects of processing on the nutraceutical profile of quinoa

Quinoa flour was subjected to a variety of thermal processes. Both unprocessed and processed quinoa samples were subjected to successive extractions in methanol and ethyl acetate solvents. Effects of processing were gauged via comparison of HPLC chromatograms of the quinoa extracts. Quinoa flour subjected to processing via roasting and extrusion resulted in a significant impact on the chemical profile when compared to unprocessed quinoa flour. Steam pre-conditioning had minimal effects on the chemical profile of quinoa flour. Process-enhanced isolate from roasted and extruded quinoa possessed a molecular weight of 480 D, was dissolved in methanol and ethyl acetate, and possessed a NMR spectra reminiscent of a terpenoid compound. This research suggests that thermal processing of quinoa flour can result in degradation of saponin molecules. Saponin decomposition may influence sensory or pharmacological properties.     

微波钝化藜麦脂肪酶及改善藜麦风味研究（网络首发、推荐阅读）

采用不同微波条件对藜麦进行处理,并对比微波和传统传导加热模式（水浴和烘烤）对藜麦中脂肪酶和风味物质的影响。结果表明：随着微波功率的提高和处理时间的延长,脂肪酶的活性均出现明显下降的趋势,在功率达到600 W、处理时间4 min后脂肪酶活性趋于稳定;通过对藜麦中风味物质含量的分析,发现微波处理显著降低了甲基酮、1-辛烯-3-醇、反式-2-壬烯醛的含量;而且随着储藏时间的延长,微波抑制了藜麦中油脂氧化,藜麦中过氧化值和酸价均降低。与传统的加热模式相比,藜麦乳微波处理能够明显降低藜麦中脂肪酶的活性,在改善其风味的同时提高了感官特性。     

脱皮处理对藜麦粉物化特性及结构的影响

为探究脱皮工艺对藜麦粉物化特性及结构的影响,采用差示扫描量热仪、扫描电镜和傅里叶红外光谱等对比脱皮处理前后和传统制粉工艺对藜麦粉的理化性质的变化;结果表明:脱皮处理工艺可以保留藜麦粉中的营养成分,降低其非营养成分含量;藜麦粉热糊稳定性升高;藜麦颗粒脱皮处理后保持完整的粒形;无新特征峰出现;说明脱皮处理对于改善藜麦粉的加工特性效果明显,为藜麦的营养成分、物化特性及结构提供参考。     

微波-超声波协同影响菜籽蛋白糖基化改性

采用微波-超声波协同作用强化菜籽蛋白的糖基化改性,并对所得糖基化产物进行了功能性质和分子结构的对比分析。结果表明,当改性条件为微波功率500 W、超声波功率300 W、协同作用时间7 min时,菜籽蛋白的接枝度可达67.1%,显著高于湿热法和微波法制备的糖基化产物,有效提高了蛋白质糖基化反应的效率;协同作用可显著改善所得糖基化产物的溶解性、乳化活性、起泡能力、泡沫稳定性,分别提高至55.7%、13.9 m~2/g、50.0%和80.0%;糖基化产物的表面疏水性和圆二色谱结果分析表明,微波和超声波处理使得菜籽蛋白的分子展开,表面疏水性和分子柔性增加,从而促进了糖基化反应的进行,改善了蛋白质糖基化产物的功能特性。     

Protein deterioration and longevity of quinoa seeds during long-term storage

Seed protein stability and seed deterioration during storage were studied in seeds of two different quinoa (Chenopodium quinoa Willd.) cultivars, i.e., cv. Ollagüe and cv. Baer II. Germination and viability tests proved that cv. Baer II was more longevous than cv. Ollagüe. Protein insolubilisation was detected during storage and correlated with longevity. However, protein solubility was restored by priming in both cultivars, disregarding their germination capability. Extremely high contents of advanced glycation end-products (AGEs), assessed by carboxymethyllysine (CML) quantification, were obtained from stored seeds as viability was reduced; primed seeds showed slightly lower AGE content, indicating a strong association between quinoa seed ageing and Maillard products accumulation. High intensity fluorescence values were observed in seeds stored in the gene bank bearing 100% germination values, which indicate that the detection of fluorescence is not by itself an appropriate indicator of protein damage by Maillard-type product accumulation in quinoa seeds. This work establishes for the first time a direct association between seed viability and AGE accumulation, due to Maillard reaction, in quinoa seeds.     

比较不同方法提取藜麦蛋白

目的比较不同方法提取藜麦蛋白的效果。方法以藜麦为原料,采用碱溶酸沉法、盐析法、酸提法、水提法4种方法制备藜麦蛋白,分析其蛋白提取率、蛋白纯度、抗氧化活性和氨基酸成分,并通过扫描电镜观察蛋白质的超微结构。结果碱溶酸沉法的提取率最高(47.36±0.41)%,盐析法的提取率最低(12.82±0.46)%,但盐析法制备的蛋白纯度最高(77.75±1.16)%。酸提法制备的蛋白质外观最好,碱溶酸沉法制备的蛋白质颜色微黄且更容易发生褐变。碱溶蛋白包含7个主条带,酸溶蛋白和水溶蛋白的亚基组成相近,包含5条条带,盐溶蛋白含一个条带。藜麦蛋白质氨基酸组成平衡,必需氨基酸含量丰富,且藜麦蛋白具有一定的抗氧化活性。通过扫描电镜观察4种藜麦蛋白的表面结构,碱溶酸沉法和酸提法制备的藜麦蛋白整体结构完整,表面光滑,结构紧密,呈连续的聚集块状结构;水溶法制备的藜麦蛋白,其空间结构较为连续,呈不规则块状,其块状表面有些许蜂窝与孔洞;盐析法制备的藜麦蛋白,结构疏松,颗粒表面粗糙,不规则,有小颗粒组成的微结构,说明盐析法制备的藜麦蛋白对蛋白质的表面结构有一定程度的破坏。结论碱溶酸沉法快速、易操作,可为大批量制备藜麦蛋白的最佳方法。     

微波加热及NaCl添加量对牦牛肉糜凝胶特性和保水性的影响

微波加热是食品加工的一种新型技术,为探讨微波加热对牦肉糜凝胶特性的影响,采用单因素试验设计,研究微波加热的时间、功率以及NaCl添加量对牦牛肉糜凝胶质构特性和保水率的影响。以水浴为对照组,利用质构仪测定牦牛肉糜凝胶硬度、咀嚼性、弹性和回复性。结果表明：随着对牦牛肉糜微波加热时间的延长,其凝胶硬度、咀嚼性、弹性逐渐下降（P＜0.05）,回复性逐渐增加（P＜0.05）,保水率显著下降（P＜0.05）;而随着微波功率增大,牦牛肉糜凝胶的硬度、咀嚼性降低（P＜0.05）,弹性变化不大（P＞0.05）,蒸煮损失率明显增加（P＜0.05）;同时,随着NaCl添加量增加,牦牛肉糜凝胶保水率显著增加（P＜0.05）。本研究为微波技术在肉制品加工中应用提供了理论依据。     

藜麦蛋白的提取及功能性质与生物活性概述

藜麦被认为是一种营养均衡且全面的假谷物,与传统谷物相比,藜麦蛋白质含量丰富,氨基酸比例均衡,在蛋白质功效比、生物学价值和营养指数等方面都饱具优势。本文主要综述了藜麦蛋白的提取方法和功能性质的研究进展,并对其营养价值和生物活性作了简要概述,目的是为藜麦蛋白的深入研究和相关产品开发提供参考。     

不同蛋白酶制备藜麦麸皮多肽及其活性研究

以藜麦麸皮为原料,利用高浓度乙醇粗提藜麦麸皮蛋白,并用4种蛋白酶(碱性、中性、复合、风味蛋白酶)酶解蛋白得到多肽。测定醇沉蛋白的分子质量分布、氨基酸组成以及4种蛋白酶的酶解能力和所得多肽的活性。结果表明,藜麦麸皮蛋白分子质量主要条带分布在22.8 k、39.1 k和52.7 kDa,其含有17种氨基酸,必需氨基酸/总氨基酸为35.17%,疏水性氨基酸/总氨基酸为28.48%。碱性蛋白酶对藜麦麸皮蛋白具有较高的水解能力,在120 min时达到13%,肽得率高达88.88%。风味蛋白酶酶解的多肽具有较好的α-葡萄糖苷酶抑制活性和Fe^2+螯合能力,分别为81.67%和89.03%;碱性蛋白酶酶解的多肽对酪氨酸酶的抑制率达到73.17%;中性蛋白酶酶解的多肽对DPPH自由基清除能力较强,为84.91%。研究结果表明藜麦多肽具有良好的生物活性,为藜麦麸皮进一步开发利用提供了一定的理论依据。     

藜麦蛋白对低钠盐体系中猪肉肌原纤维蛋白凝胶特性的影响

分别将3%、6%、9%和12%藜麦蛋白添加到低钠盐（0.40 mol/L NaCl、0.10 mol/L KCl和0.05 mol/L CaCl2）猪肉肌原纤维蛋白（myofibrillar protein,MP）体系中,考察藜麦蛋白添加量对复合蛋白溶液/凝胶的理化性质、蛋白二级结构、化学作用力和微观结构的影响。结果表明：藜麦蛋白的添加提高了MP的凝胶强度、保水性和动态流变特性,这是因为藜麦蛋白提高了复合蛋白溶液的蛋白溶解度和ζ-电位绝对值,降低了蛋白粒径;复合蛋白体系中的化学作用力以二硫键和疏水作用为主,但是藜麦蛋白的添加提高了离子键和氢键含量;藜麦蛋白促进了无规则卷曲向β-折叠和α-螺旋转化,增加了凝胶的稳定性;扫描电镜显示,藜麦蛋白提高了复合凝胶的致密程度。综上,藜麦蛋白作为一种优质植物蛋白,可以增强MP的凝胶特性,特别是当藜麦蛋白添加量为6%～9%时,对低钠盐体系中MP凝胶特性的改善效果较好。     

Gluten-free quinoa noodles: effects of intermediate moisture extrusion and soy protein isolates supplement on cooking quality and in vitro digestibility

Quinoa is considered as a superior gluten-free material due to its balanced composition of amino acids in protein and abundant nutrients. However, the processing behaviour of quinoa flour is limited by protein functional properties. In this study, twin-screw extrusion was used for the production of gluten-free quinoa noodles (GFQNs). Moisture was found to be closely related to the cooking quality and texture characteristics of extruded noodles by regulating the formation of starch gel. With this in concern, the moisture dose was optimised as 30%. Then, soy protein isolate (SPI) was supplemented into quinoa flour to improve the texture and cooking quality of GFQNs while decrease its in vitro starch digestibility. It was found that SPI could significantly reduce the cooking loss of GFQNs from 16.65% to 11.82% while increase the hardness of the noodles from 6.35 N to 7.99 N, and form a more porous structure as observed by SEM. Furthermore, the addition of SPI also delayed the in vitro hydrolysis rate of quinoa-based noodles, as shown by the significant decrease in rapid digestible starch around 8%. Therefore, quinoa–SPI mixture flour with the intermediate moisture extrusion showed prospective to develop low glycaemic index GFQNs.