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...     

Afrosimetric estimation of threshold saponin concentration for bitterness in quinoa (Chenopodium quinoa Willd)

Taste testings and saponin estimation by a simple afrosimetric method showed that quinoa containing 0·11% saponins or less (corresponding to foam heights of 1·0 cm or less) can be considered sweet. A variation of the standard afrosimetric method is described which reduces total analysis time from 73 to 7 min. Used with the proper precautions, this rapid method, in which quinoa producing foam heights of 1·3 cm or less is considered sweet, is suitable for selecting promising low-saponin varieties in field trials and for monitoring the efficacy of abrasive dehulling (polishing) as a debittering process.     

Cell wall phenolics and polysaccharides in different tissues of quinoa (Chenopodium quinoa Willd)

Quinoa (Chenopodium quinoa Willd) is an Andean pseudo-cereal, of the Chenopodiaceae family, which is currently being studied for introduction in Northern Europe as an alternative to industrial crops. The aim of this work was to verify existence in quinoa of the distinctive cell wall features identified in other Chenopodiaceae, ie presence of pectin-bound ferulic acid and dehydrodiferulic acids. Alcohol-insoluble solids (AIS) were prepared from leaves, stems and roots of mature quinoa plants, representing 0.10, 0.20 and 0.47 g g⁻¹ respectively of the fresh weight. Ferulic acid and dehydrodiferulic acid derivatives were present in all the organs, with the highest concentrations in the leaves with 2.1 and 0.5 mg g⁻¹ AIS respectively. The ratio of dehydrodiferulic acid to ferulic acid was highest in the roots. Pectins extracted by hot HCl from AIS of leaves were rich in ferulic acid (3.4 mg g⁻¹), but also highly acetylated (DAc 20), and rich in rhamnose, two characteristics encountered in other Chenopodiaceae. © 1999 Society of Chemical Industry     

Interrelationships among seed yield, total protein and amino acid composition of ten quinoa (Chenopodium quinoa) cultivars from two different agroecological regions

BACKGROUND: Quinoa is a good source of protein and can be used as a nutritional ingredient in food products. This study analyses how much growing region and/or seasonal climate might affect grain yield and nutritional quality of quinoa seeds. RESULTS: Seeds of ten quinoa cultivars from the Andean highlands (Bolivia/Argentina site) and Argentinean Northwest (Encalilla site) were analysed for seed yield, protein content and amino acid composition. Grain yields of five cultivars growing at Encalilla were higher, and four were lower, compared with data from the Bolivia/Argentina site. Protein contents ranged from 91.5 to 155.3 and from 96.2 to 154.6 g kg^?1 dry mass for Encalilla and Bolivia/Argentina seeds respectively, while essential amino acid concentrations ranged from 179.9 to 357.2 and from 233.7 to 374.5 g kg^?1 protein respectively. Significant positive correlations were found between the content of essential amino acids and protein percentage. CONCLUSION: It appears that there are clear variations in seed yield, total protein content and amino acid composition among cultivars from the two sites. Essential amino acid composition was more affected than grain yield and protein level. The study revealed that both environmental and climatic factors influence the nutritional composition of quinoa cultivars growing in different agroecological regions. Copyright © 2011 Society of Chemical Industry     

藜麦皂苷研究进展

藜麦(Chenopodium quinoa Willd.)是南美洲特有的一种植物,其叶片、花、果实、籽实和种皮中富含皂苷,藜麦皂苷是一种苦味物质和抗营养因子。目前常用的皂苷提取方法主要有溶剂提取法、酸碱水解法、沉淀法、超临界CO_2法及超声波萃取法等。近年来的研究表明,藜麦皂苷具有抗氧化、抗肿瘤、抑菌、免疫调节等药理活性,这些特性都使藜麦皂苷成为医学、保健品、食品等行业的重点研究对象。本文主要对藜麦皂苷的研究现状、结构组成、提取方法、分离纯化、分析测定、生物活性、以及环境对藜麦皂苷的影响进行了概述,以期为藜麦的进一步研究开发提供参考。     

Antioxidant activities and functional properties of soy protein isolate hydrolysates obtained using microbial proteases

Soy protein isolate (SPI) hydrolysates were prepared using microbial proteases to produce peptides with antioxidant activity. The process parameters (substrate and enzyme concentrations), hydrolysis time, functional properties and the effects of ultrafiltration were further investigated. The results showed that the soy protein isolate exhibited a 7.0‐fold increase in antioxidant activity after hydrolysis. The hydrolysis parameters, defined by the experimental design, were a substrate concentration of 90 mg mL^?1 and the addition of 70.0 U of protease per mL of reaction. The maximum antioxidant activities were observed between 120 and 180 min of hydrolysis, where the degree of hydrolysis was approximately 20.0%. The hydrolysis increased solubility of the soy protein isolate; however, the hydrolysates exhibited a tendency to decrease in the interfacial activities and the heat stability. The SPI hydrolysates fractions obtained by ultrafiltration showed that the enzymatic hydrolysis resulted in samples with homogenous size and strong antioxidant activity.     

藜麦营养功能成分及生物活性研究进展

藜麦是适宜人类食用的全营养食品,不仅含有丰富的蛋白质、淀粉、VB1、叶酸、矿物质（Ca、Zn、Fe）等营养物质,还含有多酚、黄酮、芦丁、槲皮素、异槲皮素、皂苷等功能成分,具有抗氧化、抗炎、降血糖、减肥等生理活性。本文综述藜麦的营养功能成分及其生物活性的国内外研究进展,并对其发展应用前景进行展望。     

藜麦皂苷的提取及其酪氨酸酶抑制活性

探究藜麦"陇藜1号"籽粒中皂苷的最佳提取条件并验证其酪氨酸酶抑制活性。设计三因素三水平正交实验,探索料液比,乙醇浓度及超声时间对藜麦皂苷提取得率的影响。构建L-多巴诱导的B16细胞模型,测定藜麦皂苷对细胞活性及酪氨酸酶活性的影响,最终通过免疫印迹法(Westernblot)探索藜麦皂苷影响酪氨酸酶活性的作用通路。结果显示:藜麦皂苷最佳提取条件为料液比1:40,70%浓度的乙醇下超声60 min,得率为17.85 mg/g。当藜麦皂苷的浓度低于200μg/m L时,其对B16细胞无显著抑制作用,但能显著抑制酪氨酸酶的活性和黑色素的形成,200μg/m L藜麦皂苷处理B16细胞72 h,黑色素相对含量降至73.85%,酪氨酸酶活性降至53.31%。藜麦皂苷通过抑制小眼畸型相关转录因子(MITF)及酪氨酸酶(TYR)蛋白表达来抑制黑色素形成。藜麦皂苷可以作为一种具有美白活性的组分在化妆品或药品中应用。     

Occurrence of sapogenins in leaves and seeds of quinoa (Chenopodium quinoa Willd)

Seeds of the Andean seed crop quinoa usually contain saponins in the seed coat. Saponins give a bitter taste sensation and are a serious antinutritional factor. Therefore selection of sweet genotypes with a very low saponin content in the seeds is a main breeding goal. However, selection for sweet genotypes is retarded by cross‐pollination. Early identification of sweet and bitter quinoa genotypes before anthesis would speed up breeding considerably. The ability to distinguish sweet and bitter genotypes was investigated in a glasshouse and in a field experiment. In the glasshouse experiment the content of sapogenins was determined in leaves of sweet and bitter quinoa genotypes at successive stages of plant development and finally in the seeds. Detectable amounts of sapogenins were found earliest 82 days after sowing in leaves of both sweet and bitter quinoa genotypes. The total sapogenin content in leaves of sweet and bitter genotypes increased during plant development but remained lower than the content found in the seeds. The sapogenin content in seeds of sweet genotypes varied from 0.2 to 0.4 g kg⁻¹ dry matter and in seeds of bitter genotypes from 4.7 to 11.3 g kg⁻¹ dry matter. The difference in sapogenin content between leaves and seeds was much higher in bitter genotypes than in sweet genotypes. Hederagenin was the major sapogenin found in leaves, and oleanolic acid in seeds. In the field experiment it was found that the content of sapogenins in the leaves of F2 plants of crosses between both quinoa types did not differ between sweet and bitter genotypes. The obtained results demonstrated that sweet genotypes could not be selected before anthesis on the basis of the sapogenin content in the leaves. © 2000 Society of Chemical Industry     

响应面法优化藜麦种皮过氧化物酶固定化条件

以从藜麦种皮中提取的过氧化物酶为原材料,利用0.2%聚乙烯醇-3%海藻酸钠（PVA-CA）为载体,Ca Cl2溶液作固定剂,采用包埋法对藜麦种皮过氧化物酶进行固定。在单因素实验的基础上,利用响应面分析法对藜麦种皮过氧化酶固定化的影响因素进行了优化。优化后得到的最佳固定化条件如下:氯化钙浓度为7%,固定化时间为26 min,载体与酶液的比例为1.25∶1（m L/m L）,在此条件下实际测得固定化酶的活性为416.5 U。实测值与理论值（417.4U）相差较小,充分验证了所建模型的可靠性。      

Nutrition facts and functional potential of quinoa (Chenopodium quinoa willd.), an ancient Andean grain: a review

Quinoa, Chenopodium quinoa Willd., is an Amaranthacean, stress‐tolerant plant cultivated along the Andes for the last 7000 years, challenging highly different environmental conditions ranging from Bolivia, up to 4.500 m of altitude, to sea level, in Chile. Its grains have higher nutritive value than traditional cereals and it is a promising worldwide cultivar for human consumption and nutrition. The quinoa has been called a pseudo‐cereal for botanical reasons but also because of its unusual composition and exceptional balance between oil, protein and fat. The quinoa is an excellent example of ‘functional food’ that aims at lowering the risk of various diseases. Functional properties are given also by minerals, vitamins, fatty acids and antioxidants that can make a strong contribution to human nutrition, particularly to protect cell membranes, with proven good results in brain neuronal functions. Its minerals work as cofactors in antioxidant enzymes, adding higher value to its rich proteins. Quinoa also contains phytohormones, which offer an advantage over other plant foods for human nutrition. Copyright © 2010 Society of Chemical Industry     

响应面法优化藜麦麸皮皂苷酸水解工艺

为了提高藜麦麸皮皂苷的抗氧化性,以DPPH·清除率为指标,对其酸水解工艺条件进行了响应面法优化。结果表明:影响藜麦麸皮皂苷酸水解的因素大小顺序为:水解时间水解温度盐酸浓度液液比,优化的最佳工艺条件为:盐酸浓度4.8 mol/L、液液比1∶2(mL/mL)、水解温度80℃、水解时间2.5 h。此工艺条件下,藜麦麸皮皂苷水解产物对DPPH·的清除率为68.84%,较水解前清除率提高了2倍多。酸水解可有效提高藜麦麸皮皂苷清除自由基及抗氧化活性。     

Saponins of quinoa (Chenopodium quinoa): Effects of processing on their abundance in quinoa products and their biological effects on intestinal mucosal tissue

Quinoa (Chenopodium quinoa) is a valuable source of protein in some parts of South America, and it is likely to be exploited further in both developing and industrialised countries. However, quinoa seeds contain significant levels of saponins which are potential antinutrients. In the present study, the effects of processing on the quantity and composition of saponins in quinoa products were determined, and the biological effects of quinoa grain and cereal products containing high or low levels of saponins were investigated both in vitro and in vivo in the rat. Quinoa saponins were shown to be membranolytic against cells of the small intestine and to cause an increase in mucosal permeability in vitro. Unwashed bitter quinoa caused a significant food aversion and poor food conversion efficiency in rats. However, processing quinoa, during the manufacture of an infant cereal, reduced the concentration and membranolytic activity of saponins, and increased the palatability and nutritional quality of the cereal product to a level similar to that of a wheat-based cereal product.     

Physicochemical and rheological properties of purees based on Mafafa (Xanthosoma robustum) and quinoa (Chenopodium quinoa Willd.) with the addition of cryoprotectants

Growing interest in processed frozen products with similar characteristics to natural products has generated the study of new products in the food industry field. The characteristics of each matrix, the process of elaboration, composition, and structure of the additives and the interactions amongst these modify the food's texture, structure, physical and sensory properties and, hence, interfere directly with consumer acceptance. This research studied the effect of adding cryoprotectors during frozen storage on the rheological, physicochemical, structural, and microbiological properties in a Mafafa‐quinoa‐olive oil puree. To carry out the study, the rheological properties were determined through dynamic oscillatory tests and in steady state; likewise, the physicochemical properties (humidity, color, pH, and syneresis) were analyzed. Regarding physicochemical properties, the humidity content in the purees formulated varied between 57 and 74%, without important variation (p > .05) with respect to the formulation, however, in the storage during the freezing/thawing process, this parameter diminished in greater proportion in those purees containing carrageenan as cryoconservant. Both the addition of cryoconservants and the storage time affected significantly (p < .05) the puree's syneresis, with the degree of exudation being lower in the formulation containing xanthan gum at 1% w/w. During the freezing/thawing process, decreased apparent viscosity was noted. Additionally, the analysis of the viscoelastic properties of the purees evidences that already described, given that a significant effect (p < .05) was observed of the formulation of purees in the elastic component G′, in contrast with a notable decrease in the viscous component G″.     

Effects of microwave heating,steaming, boiling and baking on the structure and functional properties of quinoa (Chenopodium quinoa Willd.) protein isolates

The effects of microwave heating (MW), steaming (SM), boiling (BL) and baking (BK) on the structure and functional properties of quinoa protein isolates (QPI) were investigated. SDS-PAGE showed the 20–30 kDa band strength of QPI-BL was enhanced, which indicated the disulphide bond was broken and protein molecules dissociated. Due to the recombination of subunits, some large molecular weight or insoluble polymer components of QPI-SM and QPI-BK did not pass through the gel. Microwave heating and boiling showed negative effects for α-helix and positive effects for β-sheet, which implied the molecular structure was transformed from ordered to disordered, the secondary structure became loose. The reduction of free SH (sulfhydryl) and surface hydrophobicity implied that aggregation and cross-linking of protein molecules for QPI-SM and QPI-BK. QPI, QPI-MW and QPI-BL exhibited better solubility, which was related to the water holding capacity (WHC) and emulsification. For QPI-SM and QPI-BK, functional properties (including solubility, WHC and gel-forming ability) decreased due to molecular aggregation. Heat treatments significantly affect the structure and functional properties of QPI, the current research showed that microwave heating and boiling might be better heat treatment methods for QPI and would help the development of quinoa protein products.     

藜麦芽多肽制备及其应用研究

该研究以白藜麦为原料,通过人工调控藜麦萌芽的培养条件,促进藜麦萌发过程中蛋白质向多肽的转变,制备富含多肽的藜麦芽(多肽藜麦芽)。考察浸泡温度、浸泡时间、培养时间3个因素对藜麦芽中多肽富集的影响,在单因素的基础上采用正交试验方法对藜麦芽培养条件进行优化,得出最佳培养条件为浸泡温度25℃,浸泡时间4 h,培养时间48 h,在此条件下,藜麦芽中多肽含量为(12.4±1.13)mg/g。将培养得到的多肽藜麦芽进行低温打浆处理,以冷冻干燥技术得到多肽藜麦芽粉,所得多肽藜麦芽粉呈乳白色,易溶解,在饮料等食品当中可作为营养型添加剂加入使用。     

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).     

藜麦的营养价值及其应用前景

藜麦是一种营养价值极高的\