Home About us Contact
|
Home About us Contact | ||
|
|
||
Marginal Reduction (marginal + reduction)
Selected AbstractsEffect of glutenin subfractions on bread-making quality of wheatINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2001Sudesh Jood Five glutenin subfractions (R2,R6) were extracted by sequential centrifugation and addition of sodium chloride, from defatted flours of three wheat cultivars viz. Aubaine (extra-strong), Hereward (strong) and Riband (weak). Seven minutes mixing time was used to carry out fractionation on the basis of depolymerization of glutenin macropolymers (GMP) by using a 2-g Mixograph traces. Depolymerization of GMP occurred at much higher rates in dough of weak cultivars compared with strong and extra-strong cultivars. Protein content was also estimated in GMP (SDS-unextractable) and supernatant (SDS-extractable). Extra-strong cv. Aubaine contained maximum amount of all the glutenin fractions (R2,R6) followed by strong cv. Hereward and weak cv. Riband. Polypeptide compositions of different glutenin fractions were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS,PAGE) under reduced and unreduced conditions, followed by densitometric scanning of stained patterns. The pattern areas of reduced fractions were divided into subareas representative of three main protein classes: high molecular weight (HMW) glutenin subunits; ,-gliadins and a mixture of low molecular (LMW) glutenin subunits and ,, , and ,-gliadins. The amounts of various subunits were proportionate according to the molecular weight of the fractions in each cultivar. The ratio of HMW-glutenin subunits to the LMW-glutenin subunits in each cultivar were found to decrease with the fractionation from R2 to R6. Bread-making quality of three cultivars was also assessed by adding various fractions to a base flour and measuring mixograph peak development time and loaf volume in an optimized baking test. The quality of bread prepared from flour of weak cv. Riband was improved significantly by the addition of HMW fraction (R2) when measured in terms of loaf volume. However, the addition of LMW fraction (R5 + R6) did not cause any appreciable improvement in bread quality over control. On the other hand, addition of HMW fraction (R2) in the flour of good bread wheat cv. Hereward caused adverse effects on the bread-making quality by disturbing the viscoelastic properties. Supplementation of R2 fractions in extra strong wheat cv. Aubaine caused marginal reduction in loaf volume over control. Therefore, the precise proportion present of the two classes of subunit is essential to achieving a proper balance between elastic and viscous properties. [source] Effects of Grain-Boundary Structure on the Strength, Toughness, and Cyclic-Fatigue Properties of a Monolithic Silicon CarbideJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 8 2000Da Chen An in situ -toughened silicon carbide (ABC-SiC) has been examined in the as-processed condition, where the grain-boundary films are predominantly amorphous, and following thermal exposure at a temperature of 1300°C, where the films become fully crystalline. Previous work has shown that, at elevated temperatures (up to 1300°C), after the grain-boundary films crystallize in situ, only a marginal reduction in strength, fracture toughness, and cyclic-fatigue crack-growth properties is observed, in comparison with those of the as-processed microstructure at 25°C. In the present study, the effect of such crystallization on the subsequent strength, toughness, and fatigue properties at 25°C is examined. Little or no degradation is observed in the room-temperature properties with the crystallized grain-boundary films/phase; in fact, although the strength shows a small reduction (,3%), the fracture toughness and fatigue-crack-growth threshold both increase by ,20%, compared with that of the as-processed structure with amorphous grain-boundary films. [source] Dystrophia Helsinglandica: a new type of hereditary corneal recurrent erosions with late subepithelial fibrosisACTA OPHTHALMOLOGICA, Issue 6 2009Björn Hammar Abstract. Purpose:, To describe the phenotype of an autosomal-dominant corneal dystrophy with an early onset of recurrent corneal erosions and development of subepithelial fibrosis in the cornea, and also to exclude genetic linkage to known corneal dystrophies with autosomal-dominant inheritance and clinical resemblance. Methods:, We describe the medical history and clinical findings in individuals from a seven-generation family with recurrent corneal erosions. A total of 43 individuals were evaluated by ophthalmological examination. Genomic DNA was prepared from peripheral blood and polymorphic microsatellite markers were analysed to study haplotypes surrounding genes causing corneal dystrophies with similar phenotypes. Results:, Erosive symptoms usually lasted for between 1 and 10 days. By the age of 7 almost all of the affected individuals suffered from recurrent corneal erosions. The attacks generally declined in frequency and intensity from the late 20s, but all examined individuals had developed subepithelial fibrosis by the age of 37. The fibrosis generally started in the mid periphery and was followed in some family members by central fibrosis and the development of gelatinous superficial elevations. Only a marginal reduction of visual acuity was seen in a few individuals. The affected individuals did not share haplotypes for genetic microsatellite markers surrounding genes that are known to cause autosomal-dominant corneal dystrophies. Conclusion:, We describe a new type of autosomal-dominant corneal disorder with recurrent corneal erosions and subepithelial fibrosis not significantly affecting visual acuity. [source] Acrylamide: An Update on Current Knowledge in Analysis, Levels in Food, Mechanisms of Formation, and Potential Strategies of ControlNUTRITION REVIEWS, Issue 12 2004Richard H. Stadler PhD This review summarizes the research to date on acrylamide levels in food, analytical methods, main sources of dietary exposure, mechanisms of formation, and mitigation research in the major food categories. Significant progress in the research has been made over the past 18 months, as reflected by the numerous publications and national and international workshops on the subject. This rapid pace of developments is mainly attributable to the coordinated and collaborative efforts of all of those concerned: the food industry, academia, private/enforcement laboratories, and national authorities. Most of the information gaps identified since the findings in early 2002 on the occurrence of acrylamide in foods and exposure assessments have been addressed, and public databases have been established by several authorities. Today, the performance of analytical methods, particularly for "difficult" food matrices, is adequate, and any modifications made over the past 12 to 18 months in analytical procedures did not significantly impact the initial exposure calculations. Several avenues into mitigation have been explored in the different food categories, with much emphasis being placed on potato-based products, and empirical trials (mostly pilot studies) have provided better knowledge of the key parameters that influence acrylamide formation. However, despite these intensive efforts, only marginal reductions have been achieved by the food industry, and any further progress will entail long-term studies at the primary production level. Any measures devised to reduce exposure to acrylamide in commercial foods must be carefully assessed in terms of food safety and quality. A hitherto poorly addressed concern is the formation of acrylamide in foods prepared by consumers in the home, and more guidance on this by national authorities is warranted. [source] | ||||||||||