High‐molecular‐weight glutenin subunit composition of Pakistani hard white spring wheats grown at three locations for 2 years and its relationship with end‐use quality characteristics

Eleven Pakistani hard white spring wheat cultivars, along with one durum wheat and two hard white American‐grown wheat cultivars, were evaluated for their high‐molecular‐weight (HMW) glutenin subunit composition via sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS‐PAGE). The relationships among different quality characteristics and between these characteristics and HMW glutenin subunits were computed. Three to six HMW glutenin subunits were observed in Pakistani bread wheat cultivars. The presence of HMW glutenin subunits was not affected by growth locations or crop years. However, variations in intensities were observed. Correlations were noticed between certain HMW glutenin subunits and some quality attributes, such as protein, farinograph dough development time, farinograph water absorption, loaf volume and mixograph peak height. The presence of HMW glutenin subunit 20 in the older wheat cultivars C591 and C273, known for excellent chapati quality, indicated a possible relationship between this band and chapati quality. This observation will need to be confirmed by testing a larger number of wheat samples known to have characteristics for both good and poor chapati quality. © 2000 Society of Chemical Industry     

USE OF A MODIFIED UREA GEL ISOELECTRIC FOCUSING METHOD FOR SPECIES IDENTIFICATION OF RAW OR BOILED WHITE,PINK, AND ROCK SHRIMP1

Isoelectric focusing (IEF) polyacrylamide gel containing an 80% pH 4–6.5 and 20% pH 3–10 ampholyte mixture greatly improved protein banding pattern for species identification of water extracts of raw pink, white and rock shrimp compared with the system using only the pH 3–10 range ampholyte. Identification of a specific species in mixture samples was achieved by the detection of water-extractable shrimp specific protein bands present in the gel. Sodium dodecyl sulfate (SDS) was a better protein extractant than water for cooked shrimp. Both water and SDS extracts of cooked shrimp showed specific protein banding patterns and improved resolution for species identification.     

Physicochemical,Pasting, and Functional Properties of Amaranth Seed Flours: Effects of Lipids Removal

The present work was carried out to evaluate physicochemical (composition, hunter color, and sodium dodecyl sulfate–polyacrylamide gel electrophoresis [SDS‐PAGE]), pasting, and functional properties (foaming, emulsification, water, and fat absorption capacity) of amaranth full‐fat flours from 6 lines/cultivars (AFs), and to see the effects of lipid removal/defatting on these properties. Protein, ash, and lipid content of AFs ranged between 12.5% to 15.2%, 3.0% to 3.5%, and 7.1% to 8.0%, respectively. The flours showed a number of bands between 97 and 7 kDa, with main subunits of approximately 58, 37, 33, 31, 23, and 16 kDa in the SDS‐PAGE profiles. The protein content and L* value increased, while b* values decreased following defatting for most of the lines/cultivars. The defatted flours (DAFs) had higher final viscosity and stability (lower breakdown viscosity) as compared to counterpart AFs. The protein profiling of the flours was not affected with the lipid removal/defatting. However, water absorption capacity and foam stability of the flours improved upon defatting. Principal component analysis revealed that pasting temperature was positively related to lipid content, while breakdown viscosity was negatively related to protein content. Foaming properties (capacity and stability) showed negative relationship with lipid content, and positive with protein content, ash content, water, and fat absorption capacity.     

Differences in accumulation of storage proteins between wheat cultivars during development

The concentration and composition of storage proteins in the developing kernels of five different wheat cultivars were investigated. The plants were grown in solution culture under strictly controlled conditions in climatic chambers and with long-term limitation of external nitrogen availability. Thus, by growing these cultivars under the same defined treatments, reliable differences in the storage protein development could be determined. The total protein concentration was assayed using an automatic nitrogen analyser. The storage protein composition was examined by acidic polyacrylamide gel electrophoresis and sodium dodecyl sulphate polyacrylamide gel electrophoresis from 6 to 58 days after anthesis. The results showed that, in all stages of plant development, the ranking of the cultivars as to the storage protein concentration was the same as for mature field-grown kernels. The differences in the storage protein concentration between the cultivars could not be explained by differences in protein composition. The start of storage protein formation during plant development did not differ between the tested cultivars, as determined by the electrophoresis pattern. The differences in the storage protein concentration between cultivars most likely depends on the relative balance between starch and nitrogen deposition in the grain, during the whole grain filling period.     

Electrophoretic Identification of Raw and Cooked Shrimp using Various Protein Extraction Systems

Proteins were extracted from raw or cooked pink (Penaeus duorarum), white (Penaeus setiferus) or rock shrimp (Sicyonia brevirostris) with five different solutions: water, water homogenate adjusted to pH 8.0, 0.1M NaCl, 1% SDS, or 8M urea. Each extract from each species was analyzed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Water extraction showed highly species-specific banding patterns for raw shrimp, while patterns for SDS extracts were not as species-specific. However, SDS extracts provided the greatest information on species variation of cooked shrimp. SDS-PAGE was useful in distinguishing shrimp of different genus. This technique was tested and proven in a blind study to be useful for species identification and detection (within 10% of actual amount) of fabricated products.     

Elektrophoretische Differenzierung hitzedenaturierter und eisgelagerter Fischproteine

Zusammenfassung Eine Natrium-dodecylsulfat(SDS)-Lösung mit Mercapto-ethanol in Tris-Borat-Puffer pH 8.9 löst bei Raumtemperatur alle Fischproteine, auch die von gekochten Proben. Die Trennung durch Polyacrylamidgel(PAG)-Elektrophorese in Gegenwart von SDS ergibt trotz verschiedener Vorbehandlung artencharakteristische Pherogramme, vor allem im Bereich der sarkoplasmatischen Proteine. Die PAG-Focussierung der SDS-extrahierten Proteine gelingt nach Fällung von überschüssigem SDS und Trennung in PAG unter Zugabe von Harnstoff und Tetramethylharnstoff im pH-Bereich von 2–11. Dabei wird das artenspezifische Muster überlagert von einer Veränderung, die z. T. die fortschreitende Autolyse etc. während der Lagerung widerspiegelt.

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Evaluation of fish proteins by electrophoretic methods after boiling and after storage on ice

Summary All proteins from fish including boiled samples can be dissolved at room temperature in Tris-borate-buffer pH 8.9 containing 2% Sodiumdodecylsulfate (SDS) and 1% mercapto-ethanol. The separation is carried out in polyacrylamidegels (PAG) by SDS-electrophoresis, showing a species-specific pattern even for the heated samples. Focussing in PAG after removing SDS by precipitation and separation in the presence of urea and tetramethyl-urea between pH 2 and 11 showed species-specificity and a shift of protein bands which partially mirrored the increasing autolysis and degradation of the samples during storage.

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Verwendete Abkürzungen PAA Polyacrylamid - PAGE Polyacrylamidgelelektrophorese - PAGIF Polyacrylamidgelisoelektrische Focussierung - SDS Natrium(Sodium)-dodecylsulfat - ME 2-Mercapto-ethanol - Tris Tris-(hydroxymethyl)aminomethan - kD Kilo-Dalton (Einheit für scheinbares Molekular-Gewicht)     

Differences in polymeric proteins among grains in spring wheat spikes

A uniform amount and size distribution of polymeric proteins within grains in a spike might determine the stability of wheat quality. Two cultivars were grown to maturity in solution culture in a climate chamber. Nitrogen (N) in the form of nitrate was added daily and replaced with ¹⁵N before harvest. Plants were harvested during grain development. Protein composition and relationships of labelled N in grains from different spikelets within the spike were determined. Higher percentages of large unextractable polymeric proteins (%‐LUPP) and total unextractable polymeric proteins (%‐TUPP) were found in the lower‐ and uppermost spikelets in the spike compared with the middle ones for cv. WL, but not for cv. Sport. Both cultivars showed variations in the percentage of large unextractable monomeric proteins (%‐LUMP) and total SDS‐extractable protein (Tote) in the spikelets within the spike. The amount of total SDS‐unextractable protein (Totu) did not vary for either of the cultivars. The spikelets within the spike showing high and low %‐LUMP and Tote at maturity showed a similar behaviour shortly after flowering in cv. WL, but not in cv. Sport. The N concentration of SDS and sonicated extracts varied along the spikelets of the spike for both cultivars. The atom‐% excess ¹⁵N decreased in cv. Sport SDS‐extractable and ‐unextractable proteins and cv. WL albumins + globulins, gliadins and glutenins from grains at different spikelet positions along the spike. Copyright © 2005 Society of Chemical Industry     

Capillary gel electrophoresis versus SDS PAGE of exudate from fresh pork

This investigation compared electrophoretic profiles of exudate from fresh normal pork in which the protein separation was undertaken by both sodium dodecyl sulphate polyacrylamide gel electrophoresis SDS PAGE and capillary gel electrophoresis. The profiles obtained using the two techniques were similar and in many investigations either method would be suitable. It is suggested that capillary gel electrophoresis offers a number of benefits over the traditional time consuming and labour intensive gel electrophoresis techniques which involves gel preparation, sample application, staining and eventually quantification of the zones by densitometry. For separation of proteins in meat-based systems the advantages of capillary gel electrophoresis include on-capillary detection, instrumental automation, rapid analysis time and low sample volumes while providing similar information to that obtained from SDS PAGE.     

Species Identification of Raw and Boiled Shrimp by a Urea Gel Isoelectric Focusing Technique

Isoelectric focusing (IEF) using 9.2M urea and 6.2% (v/v) ampholytes in a polyacrylamide gel was used to separate protein banding patterns for species identification of pink, white and rock shrimp. A 17-hr focusing time was used. IEF of water extracts of raw shrimp showed excellent banding patterns useful for distinguishing each shrimp species. For cooked shrimp, water and sodium dodecyl sulfate (SDS) were better protein extractants. Detection of shrimp species in a mixture was difficult due to similar banding patterns between closely related species.     

Physiological traits related to terminal drought resistance in common bean (Phaseolus vulgaris L.)

BACKGROUND: A major problem in common bean (Phaseolus vulgaris L.) agriculture is the low yield due to terminal drought. Because common beans are grown over a broad variety of environments, the study of drought‐resistant genotypes might be useful to identify distinctive or common mechanisms needed for survival and seed production under drought. RESULTS: In this study the relationship between terminal drought resistance and some physiological parameters was analysed using cultivars contrasting in their drought response from two different gene pools. Trials were performed in three environments. As expected, drought treatments induced a decrease in leaf relative humidity and an increase in leaf temperature; however, when these parameters were compared between susceptible and resistant cultivars under optimal irrigation and drought, no significant differences were detected. Similar results were obtained for chlorophyll content. In contrast, analysis of relative water content (RWC) and stomatal conductance values showed reproducible significant differences between susceptible and resistant cultivars grown under optimal irrigation and drought across the different environments. CONCLUSIONS: The data indicate that drought‐resistant cultivars maximise carbon uptake and limit water loss upon drought by increasing stomatal closure during the day and attaining a higher RWC during the night as compared with susceptible cultivars, suggesting a water balance fine control to achieve enough yield under drought. Copyright © 2012 Society of Chemical Industry     

Temperature conditions for the frozen storage of representative marine products in Japan

Abstract

Four representative seafoods in Japan were examined for quality changes during frozen storage up to 1 year, and reasonable temperature conditions for their frozen storage were determined.

Tuna meat was stored at ‐20 ～ ‐80°C for 1 year and its quality changes were followed by using parameters such as the metmyoglobin to total myoglobin ratio, water‐holding capacity, and pH. Ikura, a salted product of salmon eggs, was stored frozen. Quality changes were followed by using the following parameters: toughness of the egg membrane, carotenoid content, and TBA value. Surimi, meat paste from Alaska pollack, was kept frozen, and the quality changes were followed by analyzing protein composition, SDS‐gel electrophoretic and ultracentrifugal patterns, and the gel strength of kamaboko processed therefrom. Finally, prawn was stored frozen. At selected time intervals, the meat was analyzed for changes in water‐holding capacity, pH, tyrosine content, protein composition, and SDS‐gel electrophoretic pattern.

From the present experiments, it was concluded that ‐20°C is low enough for frozen storage to keep the quality unchanged for 2–3 months, irrespective of the types of seafood tested. In frozen storage for 1 year, however, lower temperatures are needed to maintain the quality. Temperatures between ‐30 and ‐40°C seemed to be more reasonable from the viewpoint of energy saving.     

Changes in physicochemical properties and microstructure of dried squid during softening treatment

Dried squid were prepared at 4 or 40 °C and softened first in water and then in alkaline solution. The physicochemical and structural changes in the dried squid during the softening treatment were examined. A significantly higher wet weight was observed for the 4 °C‐dried squid during the softening treatment compared with the 40 °C‐dried squid. The rupture stress and rupture energy of the 40 °C‐dried squid were significantly higher than those of the 4 °C‐dried squid during the softening treatment. The sodium dodecyl sulphate polyacrylamide slab gel electrophoresis (SDS‐PAGE) pattern of the 4 °C‐dried squid was almost the same as that of raw squid. The SDS‐PAGE pattern of the 40 °C‐dried squid showed many fragments of lower molecular weight. After soaking in distilled water the SDS‐PAGE pattern of the 40 °C‐dried squid did not change significantly; however, the SDS‐PAGE pattern of the 4 °C‐dried squid became the same as that of the 40 °C‐dried squid. Histological analysis by light microscopy showed the formation of muscle fibre bundles in the 40 °C‐dried squid. A higher water permeation was observed among the muscle fibres of the alkali‐softened 4 °C‐dried squid when compared with the alkali‐softened 40 °C‐dried squid. Copyright © 2003 Society of Chemical Industry     

Determination of Amylose Content in Different Starches Using Modulated Differential Scanning Calorimetry

A simple calorimetric method for determination of amylose content in starch is reported. Starches were heated in the presence of two common surfactants, viz., sodium dodecyl sulphate (SDS) and cetyltrimethylammonium bromide (CTAB), and the enthalpies of melting of the amylose‐surfactant complexes were determined using Modulated Differential Scanning Calorimetry (MDSC). A large number of native starches including cereal, root and pea starches were examined. The results were compared with those obtained by iodimetry and gel permeation chromatography (GPC) for all the starches. There was a good correlation between the values from iodimetry and GPC with those obtained using the surfactants. Both surfactants seemed to work equally well, even for those starches with about 40% amylose content. However, in case of SDS higher standard deviations were usually obtained than for CTAB in the determination of transition enthalpies.     

Milling and physicochemical properties of chickpea (Cicer arietinum L.) varieties

BACKGROUND: Physical characteristics of chickpea (Cicer arietinum L.) seeds such as grain size, weight and hull content are important from a milling and marketing point of view. Chemical characteristics provide the information on nutritional status of grains. Chickpea of Desi (cv. A1) and Kabuli (cv. L550) cultivars were analyzed for their physicochemical, milling and milled flour quality characteristics. RESULTS: Between dry and wet milling, higher yield of dhal was obtained from wet milling, which was found to be true in both cultivars. An extra yield of 2–4% was obtained in wet milling. Between the cultivars, Desi was found to be the higher dhal‐yielding cultivar in both dry and wet milling methods. Fat, ash and protein contents were found to be higher in Kabuli than in Desi and the values were respectively 5.3%, 3.5% and 24.9% for Kabuli and 4.3%, 2.2% and 22.6% for Desi. CONCLUSION: The chickpea cultivars Desi and Kabuli vary significantly in their physical properties such as seed color, size, 100‐seed weight and 100‐seed volume. Between the dry and wet milling, a higher yield (2–4%) of dhal was obtained from wet milling. Between the cultivars, electronic nose analysis of chickpea flour indicated the possibility of differentiating the variations associated with varietal difference and milling. The gel electrophoresis pattern of chickpea showed as many as 15 protein bands in flours from both the cultivars, either in phosphate or SDS buffer. The Rapid Visco Analyzer profile did not show a significant difference between the two cultivars. Copyright © 2008 Society of Chemical Industry     

不同亚基变异类型的大豆分离蛋白凝胶质构特性的研究

以6个蛋白亚基含量变异类型大豆品种制备的分离蛋白为材料,采用SDS-PAGE测定了蛋白亚基的含量以及采用质构仪测定了凝胶的质构特性,并对结果进行了相关性分析.结果表明：不同品种制备的分离蛋白在凝胶的硬度、粘性、内聚性、胶粘性、咀嚼性、回弹性、破裂强度等特性方面存在显著差异,而在凝胶弹性上无显著差异;桂阳紫金豆制备的分离蛋白凝胶具有最高的硬度、弹性、内聚性、胶粘性、咀嚼性、回弹性和破裂强度值,而西峡小粒黄制备的分离蛋白凝胶具有最低的硬度、粘性、胶粘性、咀嚼性、回弹性和破裂强度值;大豆分离蛋白各亚基含量与凝胶各质构特性在相关程度和相关性质上也存在差异,尤以A3和B4亚基对分离蛋白质构特性影响较大;7S、11S组分含量和11S/7S比值与分离蛋白凝胶质构特性无显著相关关系.     

Condensed proanthocyanidins of fababeans

Condensed proanthocyanidins were extracted from fababean hulls with water. The aqueous extract, after deproteinisation by freezing, thawing and acetone precipitation, was purified by chromatography using Sephadex LH20 gel and 95% ethanol developing solvent. Gradient chromatography of the purified condensed proanthocyanidins using 95% ethanol-(50% v/v)acetone-water with a Sephadex LH20 column yielded two peaks when the column effluent was monitored at 400 nm. Chromatographic behaviour before and after oxygen treatment indicated certain structural differences between fractions collected under the major peak. There were also considerable differences between the chromatographic properties of material collected from under the major peak and under the minor peak. Solvolysis experiments on the various fractions yielded differences in delphinidin: cyanidin and delphinidin: phlobaphene ratios. There were also differences in ‘tannin’ contents (determined by acidified vanillin methods) and all these differences confirmed that there were structural dissimilarities between the fractions. Tannin determinations made on the hulls of seven different cultivars of fababeans indicated condensed proanthocyanidin levels between 0–6%.     

Reducing the stiffness of concentrated whey protein isolate (WPI) gels by using WPI microparticles

Concentrated protein gels were prepared using native whey protein isolate (WPI) and WPI based microparticles. WPI microparticles were produced by making gel pieces from a concentrated WPI suspension (40% w/w), which were dried and milled. The protein within the microparticles was denatured and the protein concentration after drying was similar to the native WPI powder. WPI microparticles had irregular shape with an average size of about 70 μm. They absorbed water when dispersed in water, but the dispersion did not gel upon heating. Replacing part of the native WPI powder with WPI microparticles in the protein gel resulted in lower gel stiffness compared with a gel with the same overall protein concentration but without microparticles. However, microparticles also strengthened the continuous phase because they take up water from this phase. This might increase gel stiffness more than would be expected from an inert particle/filler. There was also good bonding between the microparticles and the WPI continuous phase in the gel, which contributed to gel stiffness.     

Effect of Purification Methods on Rice Starch Structure

Various methods for obtaining and purifying rice starch from white rice were examined and compared. Processed starch was then debranched with isoamylase and the molecular weight distribution of the branches analysed by gel‐permeation chromatography (GPC). The distribution of the chain lengths was compared between methods to quantify any damage sustained by the starch during purification. Effectiveness of protein removal was also determined by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE). A combination of defatting and protein removal methods was shown to be useful in the purification of rice flour into starch and presented significant advantages over other reported methods.     

大豆脂肪氧化酶凝胶电泳分析研究

本文介绍利用SDS电泳、簿层等电聚焦电泳技术及激光光密度计扫描分析大豆脂肪氧化酶的方法,其中薄层等电聚焦电泳技术具有准确、快速、分辨率高的特点,并应用于53份大豆资源LOX同功酶缺失体的鉴定以及激光扫描定量测定酶带峰值面积,为在我国开展大豆脂肪氧化酶研究提供了鉴定技术。