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.     

Influence of quinoa roasting on sensory and physicochemical properties of allergen‐free,gluten‐free cakes

The objectives of this study were to determine pasting properties of non‐roasted (NR) and roasted quinoa (RQ) and to investigate the effect of RQ on consumer acceptance and physicochemical properties of an allergen‐free, gluten‐free cake formulation. Quinoa seeds were roasted at 177 °C for 15 (R15), 30 (R30) and 45 min (R45), and flours were analysed for pasting properties. Five cakes including a commercial chocolate cake (CCC) and cakes made with NR and RQ flours were evaluated for preference by fifty panelists. Quality parameters included colour, water activity, moisture content, firmness, weight and height. Peak and final viscosity increased with roasting time. The NR cake had the highest sensory scores for appearance, colour and texture. On flavour and overall acceptability, CCC was the highest. Regarding quality data, CCC, NR and R15 cakes had similar L* values, while CCC had the lowest a*, b*, a_w, moisture content and firmness values.     

In vitro availability of minerals from oat products

The content of macroelements P, Mg and Ca and microelements Mn, Fe, Zn and Cu was determined in 10 commercially sold oat products made by different technological processes (dehulling, instantinising, extrusion, flaking). Phosphorus was the most prevalent of the macroelements (from 240.8 ± 2.2 to 845.5 ± 8.1 mg per 100 g), followed by magnesium (from 73.2 ± 0.7 to 271.9 ± 2.7 mg per 100 g) and calcium (from 30.69 ± 0.01 to 112.7 ± 0.3 mg per 100 g). The Ca/P ratio ranged from 1:5.3 in crushed oat to 1:8.2 in oat flakes. Regarding the microelements, manganese was present at the highest concentrations (from 2.62 ± 0.02 to 8.69 ± 0.01 mg per 100 g). The content of iron was similar and that of zinc not much lower, whereas the amount of copper was considerably smaller (from 0.23 ± 0.002 to 0.59 ± 0.002 mg per 100 g). The highest concentrations of mineral elements were found in instant oat bran flakes and the lowest in extruded oat and corn crisps containing 50% corn grouts. Samples of the products analysed were subjected to in vitro enzymatic digestion, simulating the digestive process occurring in the human alimentary tract. The supernatants thus obtained were analysed for their content of the previously determined mineral components; the percentage of minerals released from the products was calculated. The following sequence of mineral components released was observed: Cu (57.2–95.6%) > P (39.7–60.9%) > Ca (18.2–39.5%) > Mg (16.4–39.8%) > Mn (6.4–24.7%) > Fe (6.5–29%) > Zn (11–17.2%). The Ca/P ratio in the supernatant worsened from 1:8.2 in crushed oat to 1:23.3 in extruded oat and corn crisps. Crushed oat released the highest amounts of mineral elements during enzymatic hydrolysis, with oat grouts coming second. As regards the other products, it is difficult to establish their relative sequence in the release of minerals. © 2002 Society of Chemical Industry     

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.     

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     

Effects of quinoa and amaranth on zinc,magnesium and calcium content in beer wort

Pseudocereals such as quinoa and amaranth can be used as partial replacements for malt in the production of new beers. Quinoa and amaranth are of interest due to their high levels of nutrients and micronutrients, including minerals which can significantly improve the performance of brewing yeast and the fermentation rate. In this study, we investigated whether the use of quinoa or amaranth as partial replacements for malt affected the concentration of ions such as zinc and magnesium in beer wort. The use of amaranth, and in particular quinoa, increased the content of both zinc and magnesium ions substantially, even when only 10% of the barley malt was replaced. With 10% quinoa, Zn²⁺ and Mg²⁺ content increased by 41% and 49%, respectively, while the ratio of Mg²⁺ to Ca²⁺ rose from 1.4:1 to 1.9:1. Use of unmalted quinoa and amaranth appears a good way of enriching wort with essential metal ions.     

Effect of processing on in vitro digestibility of protein and starch in quinoa seeds

The in vitro digestibility of protein in raw quinoa assessed by an enzymic method was 78%, significantly ( P > 0.01 ) lower than that of casein, 91%, and also somewhat lower ( P > 0.01) than that of the raw washed quinoa sample, 83%. the process used to remove the outer layers of the seeds containing saponins increased the protein digestibility significantly ( P > 0.01), by 7%. Heat treatments increased protein digestibility over that of raw quinoa samples. Only the cooked sample treated for 60 min presented a slightly lower protein digestibility, 77%, than those obtained for other heat-treated samples.
The temperature, time and moisture used in cooking and autoclaving of whole seeds of quinoa did not improve starch digestibility significantly. the digestibility of the starch in the raw and precooked samples was 72 and 77%, respectively, after drum drying and about 64% after extrusion in both cases. Precooking at 60°C for 20 min does not improve the digestibility of the quinoa starch.     

Effects of roasting and boiling on the chemical composition,amino acids and oil stability of safflower seeds

The objective of this study was to determine the effects of roasting and boiling on compositional and oil stability of safflower seeds. The moisture, carbohydrate and fibre contents decreased because of roasting and boiling treatments while fat and protein contents increased. The fatty acid compositions of treated samples changed slightly compared with control. The total amount of amino acids in control sample was 151.29, and this amount increased to 158.8 and 186.9 mg g^?1 N by roasting and boiling, respectively. The peroxide value of the oil increased because of roasting and boiling, and it reaches above the accepted value to consumer. Concentrations of major elements such as Na, K and Cu in raw safflower seeds were significantly (P < 0.05) higher than roasted and boiled seeds. The effects of roasting and boiling with regard to loss and retention of the nutrients differed significantly (P > 0.05), with only the roasting retaining more of the nutrients than boiling. The peak intensities of control oil using FTIR spectroscopy were changed in comparison with treated oils.     

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。     

The effect of dairy products on iron availability.

Many researchers report substantial reductions in iron availability when dairy products are consumed with solutions of iron. Yet other studies indicate that dairy products have little effect on iron availability when added to complex meals. The conflicting data may be due to differences in the technique used to measure availability, species of animal used, form of iron in the diet, and meal composition. Human studies show superior bioavailability of iron in human milk when compared with cow's milk. Definitive causes for the differences between human and cow's milk have not been identified. Human milk contains lower amounts of casein, phosphate, and calcium, components thought to inhibit iron absorption. More work is needed to identify the factors that influence iron-dairy interactions. The nutritional benefits provided by dairy products outweigh the slight inhibitory effect they may have on iron availability.     

不同菌种发酵对藜麦蛋白质特性及脂质构成的影响

藜麦被认为是一种伪谷物,联合国粮农组织推荐其为最适宜人类食用的“全营养食品”。随着大健康产业的迅速发展,市场对藜麦产品需求也不断增加。据FAO标准,藜麦蛋白有均衡的氨基酸组成,含有人体必需的9种氨基酸,相较于其他谷物和豆类含有高水平的赖氨酸和蛋氨酸。因此,越来越多的研究关注藜麦蛋白的营养价值和功能特性。本文主要综述了有关藜麦蛋白的组成、营养价值、提取方法及乳化性、起泡性、凝胶性、消化性等功能特性的研究进展。除此之外,由于藜麦蛋白改性之后的功能特性增强,本文也概述了藜麦蛋白的物理和生物改性对藜麦蛋白功能特性的影响。藜麦蛋白作为优质蛋白,可以在植物蛋白加工领域被更多的挖掘和使用,推动藜麦蛋白的产业化。

     

The effect of probiotics (Lactobacillus rhamnosus HN001, Lactobacillus paracasei LPC-37, and Lactobacillus acidophilus NCFM) on the availability of minerals from Dutch-type cheese

The use of probiotic cultures in the production of Dutch-type cheeses did not lead to significant changes in their chemical composition but it lowered their acidity. The availability of calcium and magnesium analyzed by in vitro enzymatic hydrolysis was 19 and 35%, respectively; the availability of phosphorus was significantly higher, at >90%. The use of probiotic cultures significantly increased the availability of calcium (~2.5%), phosphorus (~6%), and magnesium (~18%). The in vitro method supports accurate determination of the effect of the Lactobacillus spp. cultures on the availability of mineral compounds ingested with Dutch-type cheese.     

世界藜麦研究的计量分析与展望

采用计量分析的研究方法,对国内外有关藜麦研究公开发表的文献(中文1984~2016年4月、英文2002~2016年4月)进行数据统计与定量、定性分析。从文献年代、国家/地区、研究机构、来源出版物、研究方向、著者及引文等角度,分析国际藜麦研究分布和发展态势,对藜麦研究领域各国、各科研机构、核心作者的发文情况及研究热点与中国藜麦研究领域的文献进行对比分析,帮助我国学者了解世界藜麦学术领域的研究进展,为推动中国藜麦的深入研究和发展提供借鉴与参考。      

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.     

Flavonoids and other phenolic compounds in Andean indigenous grains: Quinoa (Chenopodium quinoa), kañiwa (Chenopodium pallidicaule) and kiwicha (Amaranthus caudatus)

The amount of phenolic acids, flavonoids and betalains in Andean indigenous grains, quinoa (Chenopodium quinoa), kañiwa (Chenopodium pallidicaule) and kiwicha (Amaranthus caudatus), was determined. The total amount of phenolic acids varied from 16.8 to 59.7 mg/100 g and the proportion of soluble phenolic acids varied from 7% to 61%. The phenolic acid content in Andean crops was low compared with common cereals like wheat and rye, but was similar to levels found in oat, barley, corn and rice. The flavonoid content of quinoa and kañiwa was exceptionally high, varying from 36.2 to 144.3 mg/100 g. Kiwicha did not contain quantifiable amounts of these compounds. Only one variety of kiwicha contained low amounts of betalains. These compounds were not detected in kañiwa or quinoa. Our study demonstrates that Andean indigenous crops have excellent potential as sources of health-promoting bioactive compounds such as flavonoids.     

不同色型藜麦对高脂膳食小鼠脂代谢的影响及机制

为了探索同一产地、不同色型藜麦对高脂膳食小鼠脂代谢的影响。将50 只SPF级雄性健康小鼠适应性喂养7 d后,根据体质量随机分为空白对照组、模型组、白藜麦组、黑藜麦组和红藜麦组,干预时间为8 周。实验结束后,测定其Lee’s指数、腰围、腹部脂肪质量,血清和肝脏组织的总胆固醇（total cholesterol,TC）、甘油三酯（triglyceride,TG）、低密度脂蛋白胆固醇（low-density lipoprotein cholesterol,LDL-C）、高密度脂蛋白胆固醇（low-density lipoprotein cholesterol,HDL-C）等脂代谢相关生理生化指标;并采用实时荧光定量聚合酶链式反应（quantitative real-time polymerase chain reaction,qPCR）和蛋白质免疫印迹检测肝脏胆固醇和脂质代谢关键基因mRNA和蛋白相对表达量。结果表明：与模型组相比,白、黑、红藜麦可降低小鼠Lee’s指数、腰围、腹部脂肪质量;显著下调小鼠血清、肝脏组织的TC和TG水平（P＜0.05）,显著上调小鼠肝脏组织的HDL-C水平（P＜0.05）;显著下调小鼠肝脏3-羟基-3甲基戊二酸单酰辅酶A还原酶（3-hydroxy-3-methylglutaryl CoA reductase,HMG-CoAr）和固醇调节元件结合蛋白（sterol regulatory element binding protein,SREBP）-1c的mRNA及蛋白相对表达量（P＜0.05）,其中白、黑、红藜麦的HMG-CoAr mRNA相对表达量分别下调了56.22%、72.55%和27.77%,蛋白相对表达量分别下降了53.02%、29.72%、29.80%;SREBP-1c mRNA相对表达量分别下调了62.96%、45.50%和21.27%,蛋白相对表达量分别下降了20.79%、23.97%、20.26%;明显提高AMP活化蛋白激酶α（AMP-activated protein kinase alpha,AMPKα）、低密度脂蛋白受体（low density lipoprotein receptor,LDL-R）、肝X受体（liver X receptor,LXR）、过氧化物酶体增殖物激活受体α（peroxisome proliferators-activated receptor-α,PPARα）和胆固醇7α-羟化酶（cytochrome P450 family 7 subfamily A member 1,CYP7A1）的mRNA相对表达量和LDL-R、PPARα的蛋白相对表达量,其中白、黑、红藜麦的LDL-R mRNA相对表达量分别升高了243.86%、273.04%和121.93%,蛋白相对表达量分别上调了18.02%、17.16%、22.45%;PPARα mRNA相对表达量分别升高了62.45%、87.54%和126.91%,蛋白相对表达量分别上调了54.26%、51.10%、33.82%。结论：不同色型藜麦均可改善高脂膳食小鼠脂代谢紊乱,其中白藜麦和黑藜麦效果优于红藜麦,其机制可能与降低胆固醇合成和减少脂肪酸从头合成有关。