Direct in-vitro assay of resistant starch in phosphorylated cross-linked starch

Direct assay of resistant starch (RS) in food and feed is accomplished by (i) removal of lipid, protein, and digestible starch to obtain insoluble dietary fiber, and (ii) dissolution of the resistant starch in the insoluble fiber followed by its quantification with specific enzymes. Phosphorylated cross-linked (CL) RS resists dissolution and therefore has not been assayed directly. The objective of this study was to develop a method to solubilize the RS fraction in phosphorylated (0.4% phosphorus) CL wheat starch (RS4) after its incubation with α-amylase and amyloglucosidase for 16 h at 37 °C as directed by the RS assay AOAC Method 2002.02. The residue was hydrolyzed and solubilized by conducting two back-to-back incubations with thermostable α-amylase for 30 min at 100 °C and pH 5.0, cooling to 50 °C, then incubating quickly with amyloglucosidase at 50 °C for 1 h at pH 5.0. Importantly, the cooling process after α-amylase incubation was done by placing the mixture in a water bath at 50 °C. The degree of hydrolysis of the CL phosphorylated wheat starch was determined as d-glucose using high-performance anion-exchange chromatography with pulsed amperometric detection (99.0%), glucose-oxidase/peroxidase (95.3%), and phenol-sulfuric acid determination of total carbohydrate (105.2%). Based on those findings, we propose a direct determination of RS in foods containing phosphorylated CL wheat starch

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Transcriptional Profiling of Serogroup B Neisseria meningitidis Growing in Human Blood: An Approach to Vaccine Antigen Discovery

Neisseria meningitidis is a nasopharyngeal commensal of humans which occasionally invades the blood to cause septicaemia. The transcriptome of N. meningitidis strain MC58 grown in human blood for up to 4 hours was determined and around 10% of the genome was found to be differentially regulated. The nuo, pet and atp operons, involved in energy metabolism, were up-regulated, while many house-keeping genes were down-regulated. Genes encoding protein chaperones and proteases, involved in the stress response; complement resistant genes encoding enzymes for LOS sialylation and biosynthesis; and fHbp (NMB1870) and nspA (NMB0663), encoding vaccine candidates, were all up-regulated. Genes for glutamate uptake and metabolism, and biosynthesis of purine and pyrimidine were also up-regulated. Blood grown meningococci are under stress and undergo a metabolic adaptation and energy conservation strategy. The localisation of four putative outer membrane proteins encoded by genes found to be up-regulated in blood was assessed by FACS using polyclonal mouse antisera, and one (NMB0390) showed evidence of surface expression, supporting its vaccine candidacy

NEW SYNTHESES OF THIOLEVOGLUCOSAN AND POLYMERIZATION OF MONOACETONE AND DIACETONE GLUCOSE

Abstract not availabl

Consumption of cross-linked resistant starch (RS4XL) on glucose and insulin responses in humans

Objective: The objective was to compare the postprandial glycemic and insulinemic responses to nutrition bars containing either cross-linked RS type 4 (RS4XL) or standard wheat starch in normoglycemic adults (n=13; age= 27±5 yr; BMI=25±3 kg/m2). Methods: Volunteers completed three trials during which they consumed a glucose beverage (GLU), a puffed wheat control bar (PWB), and a bar containing cross-linked RS4 (RS4XL) matched for available carbohydrate content. Serial blood samples were collected over two hours and glucose and insulin concentrations were determined and the incremental area under the curve (iAUC) was calculated. Results: The RS4 XL peak glucose and insulin concentrations were lower than the GLU and PWB (p<0.05). The iAUC for glucose and insulin were lower following ingestion of RS4 compared with the GLU and PWB trials. Conclusions: These data illustrate, for the first time, that directly substituting standard starch with RS4XL, while matched for available carbohydrates, attenuated postprandial glucose and insulin levels in humans. It remains to be determined whether this response was due to the dietary fiber and/or resistant starch aspects of the RS4XL bar

Volume, texture, and molecular mechanism behind the collapse of bread made with different levels of hard waxy wheat flours

Physico-chemical properties of bread baked by partially replacing normal wheat (Triticum aestivum L.) flour (15, 30, and 45%) with two hard waxy wheat flours were investigated. Substitution with waxy wheat flour resulted in higher loaf volume and softer loaves. However, substitution at \u3e30% resulted in excessive post-bake shrinkage and a ‘key-hole’ shape with an open crumb structure. Bread crumb microstructure indicated a loss of starch granule rigidity and fusing of starch granules. The cells in the interior of the bread did not become gas-continuous and as a result, shrunk as the loaf cooled. Soluble starch content was significantly higher in bread crumb containing waxy wheat flour than in control bread. Debranching studies indicated that the soluble starch in bread made with 30e45% hard waxy wheat flour was mostly amylopectin. Incorporation of waxy wheat flour resulted in softer bread immediately after baking but did not retard staling upon storage

Properties of Starch and Vital Gluten Isolated from Wheat Flour by Three Different Wet-Milling Methods

Wheat is extensively used for food, feed, seed and wet-milling. Wheat starch and vital wheat gluten isolated by wet-milling of wheat flour are utilized in numerous food and nonfood applications. Five commercial wet-milling processes, namely Martin, Batter, Alfa-Laval/Raisio, Hydrocyclone and High-Pressure Disintegration (HD), have been employed to co-produce wheat starch and vital gluten. Martin and Batter are the traditional processes, whereas Alfa-Laval/Raisio, Hydrocyclone and HD are the modern-day processes. In the traditional processes, separation of starch and gluten starts with a stiff dough or batter with optimally developed gluten and proceeds with kneading and/or screening to separate starch granules from gluten mass. In the modern-day processes, however, separation starts with a sheared flour-water or dough-water dispersion with partially developed gluten and proceeds with centrifugation to separate starch granules from gluten network. The purpose of this study was to compare the pasting properties of starches and breadmaking qualities of vital glutens isolated from RBS-98 wheat flour by three different laboratory wet-milling methods, namely highly sheared flour-water dispersion (HS-FWD), moderately sheared dough-water dispersion (MS-DWD) and dough-washing (Martin), which respectively represent the commercial wet-milling processes of HD, Hydrocyclone and Martin. Three wet-milling methods were found to be somewhat comparable in many respects, yet they differed in certain wet-milling parameters. Damaged starch levels and RVA pasting properties of A-starch fractions isolated by all three wet-milling methods were quite similar, indicating that starch was neither mechanically damaged nor physico-chemically altered during shear treatment of HS-FWD or MS-DWD methods. Similarly, breadmaking qualities of vital glutens isolated by all wet-milling methods did not fluctuate extensively, suggesting that gluten proteins were not damaged nor altered during shear treatment of HS-FWD or MS-DWD methods. In other words, wet-milling methods used for the isolation of starch and vital gluten are of almost no or limited influence on the properties of starch and vital gluten

A bench-scale high-shear wet-milling test for wheat flour

Bench-scale wet-milling tests for wheat flour are available for the traditional processes of Martin and Batter, but tests for the high-shear processes of Alfa-Laval/Raisio, Hydrocyclone, and High-Pressure Disintegration are few in number. In this study, critical processing parameters of a high-shear wet-milling process, namely high-shear mixing, gluten-aging, and gluten-washing steps, were investigated using response surface methodology, and those parameters led to a bench-scale wet-milling test starting with a ‘‘highly sheared flour–water dispersion’’ (HS-FWD). Optimum conditions for the test were: a water– flour ratio (db) of 1.7, water temperature of 35 C, and homogenizer speed of 6000 rpm for 2.0 min in the high-shear mixing step, a temperature of 40 C for 20 min in the gluten-aging step, and glutenwashing of 2.0 min in the Glutomatic system. The HS-FWD wet-milling test with high level of repeatability was capable of discriminating wet-milling qualities of several hard, soft, and coarsely ground wheat flours

Different Types of Resistant Starch Elicit Different Glucose Reponses in Humans

The purpose of this study was to determine whether different types of resistant starch (RS) elicited different glycemic responses. Eleven healthy subjects consumed solutions containing 30 g of either dextrose (DEX), resistant starch type 2 (RS2), or cross-linked resistant wheat starch type 4 (RS4XL) on three separate occasions, which were assigned randomly. Finger stick blood samples were collected before and over the following two hours and measured for glucose. The incremental area under the curve (iAUC) for the glucose response was calculated for all trials. The two types of resistant starch significantly (P < .05) decreased iAUC compared withDEX.The response with RS4XL was significantly decreased compared with the RS2 trial. These data demonstrate that different types of resistant starch elicit significantly different glycemic responses