藜麦发芽过程中蛋白质与皂苷及淀粉消化特性的变化规律

发芽是改善谷物质构及其营养价值的一种高效的加工方式。本文研究了藜麦发芽过程中蛋白质与皂苷及淀粉消化特性的变化规律。结果显示,发芽显著地提高了藜麦中粗蛋白和可溶性蛋白含量,分别增加了5.38%和17.55%。随着发芽时间不断增加,藜麦总淀粉、直链淀粉及支链淀粉含量分别减少25.95%、4.86%和29.53%,而还原糖含量增加了26.60%。发芽处理显著改善了藜麦种子的淀粉消化性能。发芽前藜麦种子中快消化淀粉、慢消化淀粉及抗性淀粉的百分含量分别为38.45%、43.64%和17.90%。发芽48h后,快消化淀粉的百分含量显著地增加至53.46%,而慢消化淀粉及抗性淀粉的百分含量分别下降至40.42%和6.11%。此外,发芽后藜麦种子中总皂苷含量显著增加了16.46%。研究表明,发芽的藜麦种子含有更好的营养价值和消化性能,可以用于加工功能性食品,促进人体健康。     

Digestibility of common native starches with reference to starch granule size,shape and surface features towards guidelines for starch-containing food products

Influence of diverse botanical sources (wheat, maize, waxy maize, cassava, potato, rice or waxy rice) on in vitro native starch digestibility has been investigated. Physicochemical properties (chemical composition, particles size and shape, surface features) of starch granules were determined with a view to explaining digestibility differences between samples. Rapidly digestible starch (RDS), slowly digestible starch (SDS) and resistant starch (RS) contents were measured according to Englyst method. Potato starch was shown to be composed of large rounded granules having smooth surfaces, which explains its slow enzymatic breakdown. Potato starch displayed the highest RS (86%) content and the lowest RDS content (9.9%). Since RS positively influences health and SDS may result in cell, tissue and/or organ damages, potato starch is an ideal starch nutrient. Conversely, waxy rice starch was rich in amylopectin and displayed small diameters and angular shapes, which are both known to facilitate enzymatic starch hydrolysis. It exhibited a near-zero RS content (0.9%) and a high RDS fraction (60%). According to this study, potato starch exhibited the best nutrient profile, followed up in this order by cassava, waxy maize, wheat, maize and waxy rice starches.     

Pregelatinised amaranth flour as an ingredient for low-fat gluten-free cakes

This work explored the use of pregelatinised amaranth flour (PAF) as an oil substitute in the preparation of amaranth cakes. Amaranth flour was extruded to achieve approximately 50% gelatinisation, ground and sieved. The PAF was used to replace the oil in the cake preparation at levels 33, 66% and 100%. FTIR analysis of the cake formulations showed that PAF modified the molecular organisation of starch and proteins. The starch showed more hydrated structures, although less ordered. The proteins exhibited a significant reduction in the β structures and a marked increase of the side chains, probably caused by the interaction with amaranth starch. The in vitro digestibility of starch showed a slight increase with the addition of PAF. The slowly digesting starch fraction showed a visible decrease, reflecting the presence of starch chains more accessible to amylolysis. Instrumental texture revealed an increase (P < 0.05) in cake hardness with the addition of PAF, particularly for medium (66%) and high (100%) oil replacements. Sensory analysis showed that the perceived texture, flavour and colour were negatively affected by the addition of the pregelatinised flour. Overall, the sensory analysis indicated that cakes with low levels of PAF oil replacement may be acceptable to consumers.     

青稞及其制品的体内外淀粉消化特性研究

淀粉是青稞中的主要成分,其消化速率及程度直接影响餐后血糖反应。通过探究青稞及其制品体外淀粉消化特性,同时参照国际标准办法,招募12名健康志愿者,测定4种青稞制品的体内血糖生成指数(GI)。结果表明:青稞熟粉的淀粉消化速率显著低于小麦熟粉,蒸煮和挤压处理均可显著增加青稞及小麦中快消化淀粉(RDS)质量分数,降低抗性淀粉质量分数。青稞制品的GI值从大到小依次为青稞馒头(70±11)、青稞鲜湿面(60±13)、青稞挂面(51±11)、青稞炒面(33±14)。相关性分析结果表明,GI值与RDS呈极显著正相关(R=0.733,P=0.007)。体内外实验均表明:不同加工方式可显著影响青稞制品的消化特性,消费者有必要根据自身的健康状况选择合适的产品。青稞挂面及青稞炒面属于低GI食品,有利于血糖控制人群或糖尿病病人食用。     

Properties of extruded whole grain cereals and pseudocereals flours

Common cereals such as wheat are widely used worldwide in extruded products. Nevertheless, other locally available grains would be beneficial for local consumers regarding taste preference, nutritional needs and sustainability. Locally available cereals, that is millet, teff, sorghum and pseudocereals, that is quinoa and amaranth flours were extruded at the same processing conditions, and the resulting properties were compared to those of extruded refined wheat flour. Amaranth flour contained the highest protein content (16%). Sorghum was the highest in calories because of its high lipid content (10%). The extrusion process greatly increased a water solubility index (WSI) of amaranth from 11% to 61%, while the WSI level of quinoa was almost not affected (WSI of 4%). The expansion properties varied differently among grain types. These grains had a sectional expansion index (SEI) ranging between 11 and 13, which could not achieve the performance of the refined wheat (SEI of 22). The lowest expansion was observed for amaranth flour which contained the lowest starch content. Sorghum extrudates, interestingly, provided comparable stress at rupture value to that of wheat. For the mechanical properties, none of these local grains could fully replace refined wheat at the employed extrusion conditions.     

Effects of Processing on Dextrin, Total Starch, Dietary Fiber and Starch Digestibility in Infant Cereals

ABSTRACT: :
This study was conducted to determinate the effect of industrial processing on the carbohydrates composition and in vitro starch digestibility in 4 varieties of infant cereals, 2 gluten-free ( Growth , and Rice and carrots ) and 2 with gluten ( Mixed cereals , and Wheat ). Samples were obtained at 4 processing stages (raw, roasted, film and commercial product) and total starch (TS), free glucose (FG), dextrin, amylose, and total dietary fiber (TDF) contents were evaluated. Industrial processing caused a significant decreased in TS and amylose and a significant increase in dextrin. Infant cereals showed a higher in vitro starch digestibility index than white bread (used as a reference), being fully hydrolyzed in-between 60 to 90 min of assay. It can be concluded that regarding the source of cereal used for the manufacture, the enzymatic processing ensure a complete digestion of starch and so the glucose availability for infant nutrition, while TDF may influence colonic events without affecting glucose absorption.     

淀粉凝胶储藏过程中消化特性和质构特性的变化

采用酶解法和全质构分析分别测定了红薯、绿豆和马铃薯淀粉凝胶在储藏过程中的消化特性和质构特性,并对消化特性与质构特性指标之间进行简单相关和逐步回归分析。结果表明:在25℃储藏10 d内,绿豆淀粉凝胶的老化性能强于红薯淀粉和马铃薯淀粉。淀粉凝胶的消化率降低,慢消化淀粉和抗性淀粉含量增加,快消化淀粉含量降低;淀粉凝胶的硬度随储藏时间的延长逐渐增加,回复值则逐渐减小。快消化淀粉含量、硬度和回复值可作为淀粉凝胶类食品的老化评价指标。     

挤压膨化对山药全粉理化性质、加工特性和淀粉体外消化性的影响

以山药全粉为原料,分析比较了其挤压膨化前后理化性质、加工特性和淀粉体外消化特性的变化.结果 表明,山药全粉经挤压膨化后,总淀粉、总脂肪含量分别从(67.80±0.01)％、(14.5±0.06)％下降到(65.47±0.01)％和(8.23±0.02)％,多酚和多糖含量分别增加了4.20％和38.38％,而可溶性蛋白、...     

Effect of seed treatments on the chemical composition and properties of two amaranth species: starch and protein

The seeds of two Amaranth species were studied. The starch contents were 543 and 623 g kg^?1 while crude protein contents were 154 and 169 g kg^?1 for Amaranthus caudatus and Amaranthus cruentus seeds, respectively. The effect of several treatments, including cooking, popping and germination and flour air classification on the protein and starch properties were studied. Air classification decreased the starch content and increased the protein content, while heating increased the protein but did not affect the starch content. Germination decreased both starch and protein contents. Amylose content was increased by air classification and heating, but was not affected by germination. It was found that all treatments increased the starch swelling power and reduced the falling number. The resistant starch content was increased in the high protein flour (HPF) fraction and germinated flour compared with the raw flour, while its content decreased in the heat treated seed flours. These processes also affected the starch gelatinization temperature and peak viscosity. The thermal properties of the starch flour were not affected by air classification while gelatinization energy was decreased significantly (by 52.0 and 90.0% and by 70.0 and 95.0%) in cooked and popped A caudatus and A cruentus seed flours, respectively. The gelatinization energy was highest in germinated seeds dried at 90 °C with values of 2.67 and 3.87 J g^?1. Air classification reduced the level of all protein fractions. Thermal treatment decreased the water‐soluble fraction (albumins + globulins) and alcohol‐soluble fraction (prolamins) in both species. The levels of all fractions except the water‐soluble fraction (albumins + globulins) were reduced significantly in both species by germination, which mainly increased the amount of aspartic acid, serine and alanine, while the amounts of threonine, arginine and tyrosine decreased in both species. The polypeptide bands of the HPF in both species were unchanged compared with the raw seed flours, but more intensive coloured bands were observed. Thermal treatments eliminated major and minor bands above 35.0 KDa in both species. Copyright © 2004 Society of Chemical Industry     

Determination of nutritionally important starch fractions of some Turkish breads

By using an in vitro technique that measures the rate and extent of starch digestion, the starch in a food can be classified as rapidly-digestible starch (RDS), slowly-digestible starch (SDS) and resistant starch (RS). The amount of these fractions in rye bread, wheat bran bread and corn flour bread were calculated from the experimentally determined values obtained by controlled enzymatic hydrolysis and measurement of released glucose by colorimetry, using a glucose oxidase kit. Free glucose and total starch analysis were also carried out to calculate rapidly-available glucose (RAG) content and starch digestibility rate index (SDRI) of breads. RDS content of the rye bread was higher than the wheat-bran bread and corn flour bread (P<0.05). SDS contents of all breads were not significantly different from each other. Wheat bran bread was found to have a significant amount of RS (6.6%; on dry matter basis) when compared to the other breads (P<0.05). A significant negative correlation (r=−0.95, P<0.05) was also found between RS content and SDRI value of breads.     

螺杆挤压对马铃薯淀粉消化性及血糖指数的影响

目的研究螺杆挤压对马铃薯淀粉消化特性的影响。方法马铃薯淀粉经过螺杆挤压后(过程中淀粉未膨化),采用酶重量法测定挤压后抗性淀粉的含量变化情况,并通过模拟体外消化和动物实验评价挤压后淀粉的消化性能和餐后血糖上升速率。结果螺杆挤压后马铃薯淀粉中抗性淀粉的含量增加了1.08%,酶解时间为0~1.5 h时,马铃薯淀粉快速消化淀粉的含量减少,酶解时间为1.5~6.5 h时,抗性淀粉和慢消化淀粉的含量增加。挤压后的马铃薯淀粉在一定程度上可以降低小鼠的餐后血糖指数。结论螺杆挤压技术可以提高抗性淀粉和慢消化淀粉的含量,减缓餐后血糖上升速率,为马铃薯食品的深度开发提供一定的参考。     

Nutritional study of raw and popped seed proteins of Amaranthus caudatus L and Amaranthuscruentus L

The nutritional value of raw and popped (similar to popcorn preparation) seed proteins of two amaranth species, Amaranthus caudatus L and A cruentus L, was investigated. After popping, the true protein content in A caudatus and A cruentus decreased by 9 and 13% respectively. Among the amino acids, the loss of tyrosine due to the popping effect was the highest, followed by phenylalanine and methionine. Leucine was the first limiting amino acid in the raw samples, followed by lysine, while the reverse order was observed in the popped samples. The in vivo protein quality of raw and popped seeds was tested with male weanling rats and compared with wheat flour and casein samples. There was no difference between the in vivo digestibility of the raw and the popped seeds, although the in vitro digestibility was slightly higher for the popped samples. The protein efficiency ratio (PER) for all the amaranth seed samples was higher than that for the wheat sample, while the PER for the raw amaranth seed samples was close to that for the casein reference protein. The rat blood serum levels of total cholesterol, triglycerides and high‐density lipoprotein cholesterol for all the amaranth samples were lower than those for the reference protein, while the wheat flour sample showed the lowest values. Copyright © 2004 Society of Chemical Industry     

Chemical composition and in vitro starch digestibility of corn tortillas with added amaranth flour

Background: Corn tortillas containing 20% (w/w) amaranth flour (AF) were kept in cold storage and analysed after various times for chemical composition and in vitro starch digestibility, including predicted glycemic index. Comparison was made with traditional nixtamalised corn flour (NCF) tortillas. Results: Lipid and protein contents were higher in mixed NCF/AF tortilla than in NCF tortilla. Available starch (AS) content was lower in NCF/AF tortilla and decreased during cold storage. However, this decrease was greater in NCF tortilla, suggesting slower starch retrogradation in NCF/AF tortilla. After 96 h of storage, total resistant starch (RS) content was higher in NCF tortilla than in NCF/AF tortilla. However, no differences were detected thereafter, indicating similar retrogradation after long storage times. Retrograded resistant starch contents indicated that only part of the total RS in tortilla is due to retrogradation, which agrees with the tendency recorded for AS and RS in both types of tortilla. α‐Amylolysis rates were similar in NCF/AF and NCF tortillas, decreasing with storage. The predicted glycemic index was always higher in NCF/AF tortilla, a pattern that might be due to the waxy‐type starch present in AF. Conclusion: NCF/AF tortilla might be suitable as a product with higher protein content and higher glycemic index than conventional NCF tortilla. Copyright © 2007 Society of Chemical Industry     

Amaranth Flour Blends and Fractions for Baking Applications

Selected Amaranthus eruentus ecotypes from different places of origin were used to prepare baking products. Amylograph, alveograph and farinograph data of mixtures of white wheat flour with whole amaranth grain flour from raw, toasted and popped amaranth seeds, as well as with higher protein fractions obtained by air classification, presented clear differences with respect to wheat flour. Six selected amaranth lines displayed different behaviors according to their origin and the seeds, previous treatment. Results indicate the opportunity of employing wheat-amaranth mixtures in programs developed to improve the diet of the population's marginal sectors. Enriched cookies and "bolillos" (French bread) with NPR values of 3.63 and 4.35, respectively, slightly higher than casein (3.0 and 4.0). are especially recommended for this purpose.     

Influence of xanthan gum and gluten on in vitro digestibility and textural properties of rice bread

Starch digestibility of gluten-free bread has been expected to be suppressed for the purpose of decreasing glycemic response. The objective of this study was to investigate the effects of adding xanthan gum and gluten on starch and protein digestibility of rice bread prepared using the developed recipe involving pickering stabilization of foams and emulsions. The extent of starch digestion of gluten-free bread was suppressed by adding 2% xanthan gum from 79.8% to 57.3%. This suppressive effect was diminished by using gluten and that of rice bread containing 2% xanthan gum and 20% gluten was 75.5%. The extent of starch digestion of gluten-free bread was similar or less than that of bread containing gluten. The gluten-free bread with 2% xanthan gum had significantly lower loaf volume, porosity, and sticker structure of breadcrumb than the control. The suppressive effects of xanthan gum on starch and protein digestion were mainly dependent on reducing accessibility of the enzyme into the inner structure.     

Chemical composition and in vitro starch digestibility of pigmented corn tortilla

BACKGROUND: Tortillas were prepared from two (blue and regular white) maize varieties and compared with regard to chemical composition and in vitro starch digestibility, i.e., available starch (AS), total (RS) and retrograde (RRS) resistant starch contents, amylolysis rate and predicted glycemic index (pGI). The impact of cold storage (4 °C) on digestibility was also investigated. RESULTS: Despite its higher protein and lipid contents, pigmented tortilla exhibited lower AS content than the white product. AS in both types of tortilla decreased during the first 2 days of storage, and remained stable thereafter. Blue tortilla had lower RS content (21 g kg^?1 dry matter basis) than the white tortilla (30 g kg^?1 dry matter basis). RS values were slightly higher in 2 day‐stored tortillas than in their fresh counterparts. Although the RRS content in recently made white tortillas was greater than in the colored preparation, stored blue tortillas exhibited double RRS values compared with freshly baked samples. α‐Amylolysis of blue tortilla was slower than in the white sample. Consequently, blue tortilla exhibited a lower pGI value. pGI for the white tortilla decreased upon cold storage, a change that was not be observed for the colored preparation. CONCLUSION: Starch digestibility characteristics of blue tortilla make it suitable for people with special nutritional or metabolic requirements. Copyright © 2007 Society of Chemical Industry     

Chemical composition and starch digestibility in flours from Polish processed legume seeds

The study was undertaken to determine the effect of various treatments, i.e. cooking after soaking, freezing after cooking and storage at a low temperature (-18°C, 21days), and autoclaving, of Polish cultivars of bean, pea and lentil seeds on the chemical composition and starch digestibility of the resultant flours. The cooking of seeds caused a significant decrease in contents of ash (by 11-48%), polyphenols (by 10-70%) and protein (to 19%) in flours made of bean. In addition, analyses demonstrated significantly decreased contents of resistant starch, RS (by 61-71%) and slowly digestible starch, SDS (by 56-84%). Storage of frozen seeds resulted in insignificant changes in the chemical composition, and in increased contents of both RS and SDS. The flours produced upon the autoclaving process were characterized by similar changes in the contents of ash and protein as in cooked seeds, yet losses of polyphenols were lower and, simultaneously, contents of RS and SDS were higher. All the analyzed flours were shown to be characterized by a reduced content of amylose in starch, which might have affected its digestibility. This was indicated by a strict negative correlation reported between the value of the starch digestion index (SDRI) and amylose content of starch (r=0.84, p>0.05).     

双螺杆挤压对菠萝蜜种子淀粉消化特性及血糖指数的影响

为探究双螺杆挤压对菠萝蜜种子淀粉(JFSS)的消化特性及血糖指数的影响,采用体外消化试验,考察了JFSS经挤压处理前后的消化性与消化动力学变化,并通过水解指数(HI)、血糖指数(GI),预测了菠萝蜜种子淀粉的餐后血糖水平(PPBS)。结果表明,双螺杆挤压增加了快速消化淀粉(RDS)与慢消化淀粉(SDS)含量,提高了平衡浓度(C_∞)、酶解速率(k)、水解指数(HI)、血糖指数(GI)和淀粉消化率,显著降低了抗性淀粉含量(RS)(P<0.05)。在低水分含量下,增加螺杆转速与机筒温度,RDS含量由47.85%增加到58.91%,且k、C_∞、HI、GI值也均呈现增加趋势,而SDS含量、RS含量呈降低趋势。螺杆挤压使菠萝蜜种子淀粉由致密结构转变为疏松多孔的多面体结构。     

非晶颗粒态玉米淀粉理化性质及消化性能的研究

非晶颗粒态淀粉是一种特殊的淀粉物态形式,具有颗粒性,但不具有结晶性。为了实现对原淀粉颗粒的改性,本文以玉米淀粉为原料,采用乙醇溶液处理法制备非晶颗粒态淀粉。在此基础上,研究了这种非晶化处理方法对玉米淀粉的颗粒形貌、结晶性质、溶解度与膨胀力及体外消化性能的影响。结果表明,原淀粉经非晶化处理后颗粒性仍保持完整,但颗粒表面有较大爆裂孔生成,并出现明显褶皱;非晶颗粒态玉米淀粉呈现V-型衍射结构,其结晶性基本消失,颗粒由多晶颗粒态结构转变为非晶颗粒态结构;与玉米原淀粉相比,其溶解度和膨胀度在相同的测定温度下均明显增加。原淀粉经乙醇溶液处理后,其快消化淀粉含量由92.83%下降到81.64%。而慢消化淀粉和抗性淀粉总含量由7.17%上升到18.36%。因此,采用乙醇溶液处理法对淀粉颗粒进行改性将有助于开发低热量和慢血糖应答的产品。     

超微粉碎处理对木薯淀粉结构及消化特性的影响

为研究超微粉碎改性木薯淀粉及其对消化性的影响,以粒度分析、扫描电子显微镜(SEM)、X射线衍射(XRD)、傅里叶红外分析(FT-IR)以及Englyst法为分析手段,研究木薯淀粉经过不同时间(0、15、30、45、60 min)超微粉碎处理后的粒度、微观结构及消化特性的变化。结果表明:木薯淀粉经超微粉碎处理60 min后,颗粒结构被严重破坏,淀粉颗粒之间发生团聚,淀粉粒径由13.50 μm增加至36.17 μm;超微粉碎处理对木薯淀粉的晶型没有影响,仍为A型,但其相对结晶度由21.33%下降至1.14%;木薯淀粉在3000~2800 cm-1与1080 cm-1处的吸收峰强度减弱,表明超微粉碎处理使木薯淀粉的结构遭到破坏,氢键相互作用减弱;天然木薯淀粉的快消化淀粉(RDS)、慢消化淀粉(SDS)、抗性淀粉(RS)的含量分别为3.91%、44.71%、51.38%,经过超微粉碎处理60 min以后,RDS与SDS的含量分别增加至6.87%和45.91%,RS的含量下降至47.21%,说明超微粉碎处理能够在一定程度上改变木薯淀粉的消化性。