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1.
不同灭酶处理对燕麦气味和品质的影响 总被引：2，自引：0，他引：2
为选择合适的灭酶处理方法,通过电子鼻、感官评价和快速黏度分析等方法,对5种灭酶处理（焙炒、常压蒸煮、高压蒸煮、远红外处理和微波加热）对燕麦粉的气味、色泽和糊化特性的影响进行了研究。研究表明：燕麦粉的电子鼻主成分分析（PCA）二维和三维指纹图谱均可将不同灭酶处理的样品明显区分开来;样品的感官评价气味值由高到低依次为：焙炒组,红外组,高压蒸煮组,常压蒸煮组,微波组;样品白度检测结果由高到低依次为：红外组,微波组,焙炒组,蒸煮组,与色泽的感官评价结果基本一致,微波组和红外组的色泽明显优于其他3组的色泽。样品的糊化特性指标中,除糊化温度外,其他6项快速黏度分析（RVA）特征值均差异显著。由此说明,不同灭酶处理对燕麦粉的气味、色泽和糊化特性均有不同影响,应结合燕麦粉的不同用途选用不同的灭酶处理。 相似文献
2.
《农业工程学报》编辑部 《农业工程学报》2010,26(12):383-384
近年来,面对能源需求与资源环境保护的突出矛盾,发展可再生、清洁、环保的新能源已经成为我国节能减排、实现可持续发展的重要战略任务。农业和农村作为我国清洁能源生产与消费的重要领域,对国家节能减排目标的实现举足轻重。开发利用太阳能、生物质能、水能、风能、地热能以及低碳节能技术等,已经成为农业工程领域的研究热点。为了加强学术交流,提升我国清洁能源及低碳节能技术的开发和利用水平,展示相关科研成果,推动技术进步和产业发展,由中国农业工程学会主办,河南农业大学、中国农业工程学会农村能源工程专业委员会、《农业工程学报》编辑部和河南省农业工程学会共同承办的“全国农村清洁能源与低碳技术学术研讨会”,定于2010年4月22－24日在河南省郑州市召开。会期3天,会后组织技术参观。会议拟邀请国内各大专院校、科研院所、企业等单位从事清洁能源与低碳节能研究的专家、学者进行深入交流、成果推广,并为企业、厂商提供科技合作的平台。会议征集论文并出版论文集,通过评审优秀的论文拟安排在《农业工程学报》（正刊）发表,基本通过审核的将在《农业工程学报》（增刊）上发表,正刊和增刊均送EI收录。欢迎相关专家、学者、企业家、研究生参加此次大会,并踊跃投稿、展示、交流。 相似文献
3.
Hydrothermal treatments, which are routine in oat processing, have profound effects on oat flour dough rheological properties. The influence of roasting and steam treatments of oat grain on dough mixing and breadbaking properties was investigated when hydrothermally treated oat flour was blended with wheat flour. Roasting of oat grain (105°C, 2 hr) resulted in oat flours that were highly detrimental to wheat flour dough mixing properties and breadbaking quality. Steaming (105°C, 20 min) or a combination of roasting and steaming of oat grain significantly improved the breadbaking potential of the oat flours. The addition of oat flours increased water absorption and mixing requirements of the wheat flour dough and also decreased bread loaf volume. However, at the 10% substitution level, steamed oat flours exhibited only a gluten dilution effect on bread loaf volume when wheat starch was used as a reference. Oat flour in the breadbaking system decreased the retrogradation rate of bread crumb starch. The results indicate that adequate hydrothermal treatments of oat grain are necessary for oat flour breadbaking applications. Steamed oat flours used at a 10% level retarded bread staling without adversely affecting the loaf volume. 相似文献
4.
Oxygenated fatty acids were identified in oat grain by gas chromatography‐mass spectrometry. We hypothesized that most of these were the results of lipoxygenase activity. This hypothesis was tested by measuring concentrations of these compounds after hydrothermal treatments and storage of oat groats or oat flour for 22 weeks at 37°C and 65% relative humidity. Steam treatments inactivated lipases, whereas roasting at 106°C did not. Free fatty acids accumulated quickly in untreated or roasted flour, but not in steamed flour or groats. A total of six hydroxy and epoxy fatty acids were identified. Oxidized fatty acids were found in both esterified lipids and free fatty acids, indicating that lipase action was not necessary for lipid oxidation. More oxidation products were found in flour than in groats, and less were found in the steamed treatments. Lipoperoxygenase appeared to be involved in the formation of oxidation products, although nonenzymatic mechanisms may also operate. Hydroxy‐fatty acids are associated with strongly bitter flavors and are undesirable. Results indicate the importance of enzyme inactivation before storage of processed oat products. 相似文献
5.
Several food regulatory agencies around the world have approved health claims for oat‐derived β‐glucan for cholesterol lowering and glycemic control. The biological efficacy of β‐glucan appears to depend both on daily intake and on physicochemical properties, such as molecular weight and viscosity. The objective of this study was to determine the effects of oat processing, genotype, and growing location on the physicochemical properties of β‐glucan. Five oat genotypes (HiFi, Leggett, CDC Dancer, Marion, and CDC Morrison) grown in two locations (Saskatoon and Kernen) were dehulled (untreated) and processed in a pilot facility through kilning (kilned, not flaked) and subsequent steaming and flaking (kilned, flaked). Untreated groats gave a relatively low Rapid Visco Analyzer (RVA) apparent viscosity (164 cP) and a low extractable β‐glucan molecular weight (332,440) but exhibited high β‐glucan solubility (90.49%). Compared with untreated groats, the kilned (not flaked) samples had significantly increased RVA apparent viscosity (314 cP) and extractable β‐glucan molecular weight (604,710). Additional processing into kilned and flaked products further increased RVA apparent viscosity (931 cP) and β‐glucan molecular weight (1,221,760), but β‐glucan solubility (63.83%) was significantly reduced. Genotype and growing environment also significantly affected β‐glucan viscosity and molecular weight, but no significant interaction effects between processing, genotype, and environment were found. Results indicate that there is potential for processors to improve the physicochemical and nutritional properties of oat end products through processing of specific oat genotypes from selected growing locations. 相似文献
6.
Van der Plancken I Van Loey A Hendrickx M 《Journal of agricultural and food chemistry》2007,55(1):127-135
This article addresses the effect of moisture content (0.8-9.9%) during dry-heating (80 degrees C) on selected physicochemical (solubility, turbidity, residual denaturation enthalpy, aggregation, surface hydrophobicity, and sulfhydryl content) and functional (foaming ability, foam density, and stability) properties of freeze-dried egg white (FDEW). Moisture content during dry-heating proved to be a parameter determining the functionality of the resulting egg white powder. The degree of conformational changes induced in the egg white proteins by dry-heating was strongly dependent on the amount of water present. Preferentially, dry-heating at 80 degrees C should be performed on egg white powder with a moisture content below 6.8%, as the loss of protein solubility above this value is extensive. In addition to insoluble aggregates, soluble, strongly stabilized aggregates were also formed, especially at higher moisture contents. The decrease in denaturation enthalpy, increase in surface hydrophobicity, and exposure of SH groups previously hidden in the protein core and their subsequent oxidation were more pronounced at prolonged dry-heating times and at higher moisture contents. These conformational changes resulted in improved foaming ability and foams with lower density. No effect of dry-heating on the foam stability was observed. 相似文献
7.
燕麦麸分离蛋白的酶解对其功能性质的影响 总被引：4，自引：3，他引：4
为了改善燕麦蛋白的功能性质以扩大其在食品工业中的应用，该文以燕麦麸为原料制备了燕麦麸分离蛋白(OBPI)，并利用胰蛋白酶对其进行水解，得到了3种不同水解度(4.1%、6.4%、8.3%)的酶解产物。SDS-PAGE分析结果表明OBPI中的主要蛋白成分是球蛋白，其经过胰蛋白酶处理后，球蛋白酸性亚基被部分水解而碱性亚基相对保持完整。胰蛋白酶水解显著改变了OBPI的功能性质。在所考察的水解度范围内，随着水解度的升高，酶解产物的溶解性、持水性、乳化活性及起泡能力等方面均逐渐增加；但持油性、乳化及泡沫稳定性有不同程度的降低。 相似文献
8.
不同干燥方法对栗粉的理化性质与功能特性的影响 总被引：7，自引：1，他引：7
以毛板红板栗品种为原料，研究了4种不同干燥方法加工所得栗粉的理化与功能特性，结果表明自然干燥与热风干燥加工成的栗粉在理化和功能特性上差异较小，但自然干燥粉比热风干燥粉具有更好的起泡能力和泡沫稳定性；微波干燥粉比热风干燥有较多的淀粉发生糊化，表现在具有较低的峰粘度、崩解值和回复值，其吸水能力较热风干燥粉大，但起泡能力、泡沫稳定性和复水成泥后的一些质地特征值较热风干燥粉低。高温蒸后热风干燥粉的理化与功能特性与微波干燥粉类似，但有较高的崩解值和较低的回复值。从色泽来看，自然干燥和热风干燥粉比微波干燥和高温蒸后热风干燥的要白，而且有光泽。 相似文献
9.
为提升大豆分离蛋白（soy protein isolate,SPI）的功能性质,该文引入大豆可溶性多糖（soybean soluble polysaccharides,SSPS）,构建大豆分离蛋白-大豆可溶性多糖体系（SPI-SSPS）,研究动态高压微射流（dynamic high-pressure microfluidization,DHPM）处理对SPI-SSPS功能特性的影响。分别采用0,60,100,140和180 MPa的 DHPM压力处理SPI-SSPS,探究不同压力对SPI-SSPS起泡特性、乳化特性、溶解性、粒度分布和表面疏水性的影响。结果表明,DHPM处理能提高SPI的溶解性和起泡特性,且SSPS的存在能显著提高DHPM对SPI功能性质的改善效果（P<0.05）。100和60 MPa的DHPM处理能使SPI-SSPS呈现较高的起泡能力和起泡稳定性,分别为未处理样品的1.2和2.4倍。140 MPa的DHPM处理使SPI-SSPS溶解性较强,为未处理样品的1.8倍。然而,DHPM处理会显著降低SPI-SSPS的乳化特性、粒径和表面疏水性（P<0.05）。随着处理压力的增加,SPI-SSPS的粒度和表面疏水性逐渐降低,在180MPa的DHPM处理下SPI-SSPS具有较小的粒径和较低的荧光强度。综上所述,DHPM结合SSPS改性技术可用于改善SPI的功能性质（如溶解性、起泡性）,促进SPI在食品工业的应用。该文的研究结果可为SPI的功能性质改性提供参考。 相似文献
10.
Structural and functional properties of two amaranth protein isolates as a function of pH were studied. Isolates, A9 and A11, were obtained by alkaline extraction at pH 9 and 11, respectively. Gel filtration chromatograms of A9 and A11 showed similar profiles. The A11 isolate contained mainly albumins and globulins, and a small proportion of globulin‐P aggregates, suggesting the presence of species with a higher degree of denaturation compared to A9. Differential scanning calorimetry (DSC) showed that A9 was characterized by two thermal transitions (65.8 and 98°C); A11 exhibited only a small endotherm (66.6°C) and a second, less defined one. DSC analysis of A9 at pH 2–4 did not show endotherms, but at pH 5, some protein structures were observed. A11 showed a greater degree of denaturation. FPLC results showed that the proteins in A9 are more folded and their conformation is closer to the native state than those in A11, which are more unfolded due to pH‐mediated denaturation, mainly in acid media. The surface hydrophobicity of the isolates in acid media was lower than in alkaline media. The fluorescence emission spectra of the isolates showed differences in acidic pH conditions. As expected, the highest solubility was at alkaline pH. The water‐holding capacity was similar for both isolates. The water‐imbibing capacity and speed of foaming was higher for A11 than for A9. In summary, intense pH treatment of amaranth isolates generated partial or total protein denaturation and differences in the functional properties. 相似文献
11.
Starch and protein separated from oat were chemically modified using cross‐linking and acetylation protocols for starch, and deamidation and succinylation for protein isolate. Cross‐linking decreased swelling power of starch, whereas syneresis increased, but cross‐linking does not have a significant effect on gelatinization temperature. Acetylation increased swelling power, but gelatinization temperature and syneresis diminished. Deamidation and succinylation increased nitrogen solubility index, emulsion activity, foaming capacity, and water and oil binding capacity. Emulsion stability did not change with deamidation and it diminished with succinylation, while foaming stability decreased with both treatments. Acetylated starch and two types of modified proteins were substituted for 5, 10, 15, and 20% of oat flour to bake cake samples and then physical properties of the cakes were measured. Acetylated starch increased batter viscosity, cake volume, and whiteness of cake crust. Increased level of deamidated protein produced cakes with lower batter viscosity, higher volume, and darker color (increase in redness). Application of higher levels of succinylated protein led to higher batter viscosity and lightness, and lower cake volume. Therefore, substitution of deamidated protein and acetylated starch can improve cake properties. 相似文献
12.
Effects of hydrothermal treatments (steaming, roasting) of oat grain on β-glucan extractability and rheological properties were tested on oat cultivars with low (Robert) and high (Marion) β-glucan content. Steaming of grain reduced the amount of β-glucan that could be extracted, compared with raw or roasted grain, but the extracts from steamed grain had much greater viscosity. Increased extraction temperatures increased the amount and the average relative molecular mass (M r) value of β-glucan extracted. In boiling water extractions, the average M r values among raw, roasted and steamed oat samples were equivalent, but extracts from steamed oat grain had significantly higher intrinsic viscosity than the extracts from roasted or raw oat grains. β-glucan solutions purified from steamed grain extracts were very viscous and highly pseudoplastic, as described by the power law equation. Oat β-glucan from steamed samples were more viscoelastic than β-glucan from roasted or raw oat samples. Because viscous properties of β-glucan from boiling water extracts are influencedhydrothermal treatments without affecting polymer molecular weight, polymer interaction with the solvent must be affected. Steaming may disrupt intramolecular cross-linkings in native β-glucan, allowing a linear chain configuration to generate greater viscosity. 相似文献
13.
The seed of cowpea (Vigna unguiculata L.) is rich in protein and the amino acid profiles of the meal are suitable for human dietary products, but little is known about the structure and chemical properties of the protein extracted from this legume. This study determined the functional properties of two selected cowpea cultivars and their solubility, emulsifying capacity, surface hydrophobicity, and thermal stability. Seeds of red and black cowpea were surface sterilized and the 7s globulin was isolated and purified using column chromatography with Sephacryl S‐300 (Hi‐Prep 26/60) gel column. Also, SDS‐PAGE and protein structure were analyzed using biochemical procedures. At high ionic strength (μ = 0.5), cowpea 7s globulin fraction exhibited better solubility for a wide range of pH levels, higher emulsifying capacities, and greater thermal stability than those obtained at low ionic strength (μ = 0.08). The lowest solubility was observed at pH 5.3–6.4 at the low ionic strength. Emulsifying capacities at high protein concentration were greater when compared with low protein concentration. Tm values of black cowpea globulin fraction were higher than those of red cowpea globulin fraction, whereas the surface hydrophobicity of the globulin fraction in red cowpea was larger than that in black cowpea. 相似文献
14.
Ilankovan Paraman N. S. Hettiarachchy Christian Schaefer Markus I. Beck 《Cereal Chemistry》2007,84(4):343-349
Rice endosperm protein was modified to enhance solubility and emulsifying properties by controlled enzymatic hydrolysis. The optimum degree of hydrolysis (DH) was determined for acid, neutral, and alkaline type proteases. Solubility and emulsifying properties of the hydrolysates were compared and correlated with DH and surface hydrophobicity. DH was positively associated with solubility of resulting protein hydrolysate regardless of the hydrolyzing enzyme, but enzyme specificity and DH interactively determined the emulsifying properties of the protein hydrolysate. The optimum DH was 6–10% for good emulsifying properties of rice protein, depending on enzyme specificity. High hydrophobic and sulfhydryl disulfide (SH-SS) interactions contributed to protein insolubility even at high DH. The exposure of buried hydrophobic regions of protein that accompanied high-temperature enzyme inactivation promoted aggregation and cross-linking of partially hydrolyzed proteins, thus decreasing the solubility and emulsifying properties of the resulting hydrolysate. Due to the highly insoluble nature of rice protein, surface hydrophobicity was not a reliable indicator for predicting protein solubility and emulsifying properties. Solubility and molecular flexibility are the essential factors in achieving good emulsifying properties of rice endosperm protein isolates. 相似文献
15.
16.
Helianthinin, the main storage protein of sunflowers, has low water solubility and does not form a gel when heated; this behavior is different from other 11S globulins and limits its food applications. To understand this particular behavior, changes on helianthinin association-dissociation state induced by modifications in pH and ionic strength were analyzed. The influence of these different medium conditions on its thermal stability and tendency to form aggregates was also studied. Helianthinin behavior at different pH values and ionic strengths is similar to other 11S globulins except that it remains in a trimeric form at pH 11. Helianthinin thermal stability is higher than other 11S globulins but is lower than oat 11S globulin. Alkaline pH produces a 10 degrees C decrease of its denaturation temperature and also of the cooperativity of denaturation process, but it does not affect the denaturation activation energy. The decrease in thermal stability with the pH increase is also manifested by its tendency to form aggregates by SH/SS interchange reactions. When thermal treatments at alkaline pH are performed, all helianthinin subunits form aggregates, characterized by a higher proportion of beta-polypeptides than alpha-polypeptides, which is an indication that aggregation is accompanied by dissociation. Treatments at 80 degrees C are sufficient to induce aggregation but not to produce denaturation, and in these conditions hexameric forms remain after the treatment. 相似文献
17.
During the germination of oats, the major seed storage proteins (globulins) are hydrolyzed by endoproteinases. We have used two methods to characterize these endoproteinases. A qualitative PAGE method that used oat globulins as gel‐incorporated substrates was used to determine which enzymes hydrolyzed the globulins. The proteolytic hydrolysis products were studied by hydrolyzing the globulins in vitro with the endoproteinases and analyzing the products by SDS‐PAGE. Class‐specific proteinase inhibitors were used to show that the globulin hydrolyzing enzymes were cysteine‐class proteinases. The proteinases were active at pH 3.8. Using the gel analysis method, a little activity was present at the beginning of seed germination, but the major activity only appeared on the sixth day of germination. Extracts from four‐day germinated oats contained cysteine proteinases that hydrolyzed the globulins in vitro to form a polypeptide of intermediate size (MW ≈34,500). Cysteine proteases from an eight‐day germinated sample totally hydrolyzed the globulins in <1 hr. Very little hydrolysis occurred at pH 6.2, the pH of germinated oats endosperm tissue. The fact that hydrolysis occurred quickly at pH 3.8 implies that there is probably pH compartmentalization within the endosperm, with some areas of the seed having a low pH value where the globulins can be degraded. 相似文献
18.
Kimura A Fukuda T Zhang M Motoyama S Maruyama N Utsumi S 《Journal of agricultural and food chemistry》2008,56(21):10273-10279
Legume seeds contain 7S and/or 11S globulins as major storage proteins. The amino acid sequences of them from many legumes are similar to each other in the species but different from each other, meaning that some of these proteins from some crops exhibit excellent functional properties. To demonstrate this, we compared protein chemical and functional properties (thermal stability, surface hydrophobicity, solubility as a function of pH, and emulsifying properties) of these proteins from pea, fava bean, cowpea, and French bean with those of soybean as a control at the same conditions. The comparison clearly indicated that the 7S globulin of French bean exhibited excellent solubility (100%) at pH 4.2-7.0 even at a low ionic strength condition (mu = 0.08) and excellent emulsion stability (a little phase separation after 3 days) at pH 7.6 and mu = 0.08, although the emulsions from most of the other proteins separated in 1 h. These results indicate that our assumption is correct. 相似文献
19.
O. Kaukonen T. Sontag‐Strohm H. Salovaara A.‐M. Lampi J. Sibakov J. Loponen 《Cereal Chemistry》2011,88(3):239-244
The baking properties of oats are poor, mainly due to the lack of gluten matrix and hence the surface properties of the aqueous phase are crucial for the gas retention in oat dough. Our aim was to study the composition and foaming properties of the water‐soluble fraction from differently processed oats. A water extract from kilned oats contained nonpolar triglycerides and had poor foaming properties, whereas removing lipids with hexane extraction improved the foaming capacity and foam stability. A water extract from supercritical carbon dioxide extracted oats (CO2‐oats) was free from nonpolar lipids and had good foam stability and excellent foaming capacity. Moreover, oat lipid‐binding proteins, tryptophanins, were highly concentrated in the CO2‐oats‐derived foam and apparently played an important role in the foam structure. Supplementing CO2‐oats extract with small quantities (<0.05%) of nonpolar lipids of oats destructed its foaming properties. In a preliminary baking trial, the addition of the nonpolar lipids to CO2‐oats and wheat‐starch‐based baking recipes resulted in baked goods with reduced volume. The study showed that nonpolar triglycerides were present in the aqueous phase of oat in a quantity that impaired foaming. Moreover, this was the first study showing that tryptophanins, lipid‐binding proteins of oats, were highly concentrated in foams prepared of oats free of water‐extractable nonpolar lipids. In conclusion, tryptophanins can be considered as the foam‐active proteins of oats that prevent the lipid‐induced destabilization of foam structures which could improve the baking properties of oats. 相似文献
20.
Ilankovan Paraman N. S. Hettiarachchy Christian Schaefer Markus I. Beck 《Cereal Chemistry》2006,83(6):663-667
Rice proteins are nutritional, hypoallergenic, and healthy for human consumption. Efficient extraction with approved food‐grade enzymes and chemicals are essential for commercial production and application of rice protein as a functional ingredient. Rice endosperm proteins were isolated by alkali, salt, and enzymatic methods and evaluated for extractability and physicochemical properties. Alkali (RPA) and salt (RPS) methods extracted 86.9 and 87.3% of proteins with 65.9 and 58.9% yield, respectively. The enzymatic methods with Termamyl (RPET) and amylase S (RPEA) extracted 85.8 and 81.0% proteins with 85.2 and 86.2% yield, respectively. Enthalpy values of RPA (1.79 J/g), RPS (1.22 J/g), RPET (nondetectable), and RPEA (0.17 J/g), determined by differential scanning calorimetry, demonstrated that the varying level of denaturation of proteins depends on the method of extraction. Surface hydrophobicity data supported this observation. Alkali‐ and salt‐extracted proteins had higher solubility and emulsifying properties than those of enzyme‐extracted proteins. Comparatively, more favorable protein composition, lower surface hydrophobicity, higher solubility, and a lower degree of thermal denaturation of alkali‐ and salt‐extracted proteins contributed to higher emulsifying and foaming properties than those of enzyme‐extracted proteins; therefore, alkali‐ and salt‐extracted proteins can have enhanced functional use and a potential starting material for preparing tailored rice protein isolates. 相似文献