The extractability and molecular weight of β‐glucan in oat bran, oat bran muffins, and oat porridge and the changes taking place during processing and storage were studied. The β‐glucan was extracted using hot water and a thermostable α‐amylase and by an in vitro system that simulated human digestion. Molecular weight (MW) of the extracted β‐glucan was determined using high‐performance size‐exclusion chromatography. Hot‐water treatment extracted 50–70% of total β‐glucan in oat bran samples and rolled oats. The chromatographic peak MW of extracted β‐glucan was in the 1.4–1.8 × 106 range. Using the in vitro digestion system, 12–33% of total β‐glucan in bran and rolled oats was solubilized, and peak MW was in the same range as β‐glucan extracted by hot‐water treatment. In muffins, 30–85% of total β‐glucan was solubilized by in vitro digestion, with a major difference in extractability among muffins from different recipes. Peak MW of extracted β‐glucan was lower in all muffins when compared to original bran. During frozen storage, extractable β‐glucan decreased by >50% in all muffins, but no change in peak MW of extracted β‐glucan was detected.

Data from clinical studies established that there was an inverse linear relationship between measures of postprandial blood glucose and insulin responses to an oral glucose load, consumed in a drink, and the logarithm of viscosity of the drink. These data have been re-analysed using concentration and molecular weight as the dependent variables. Molecular weight (M) of the β-glucans used was determined using high-performance size exclusion chromatography equipped with a triple detector system of right angle light scattering, viscometry and refractive index. A significant relationship between changes in peak blood glucose and a combination of logarithm of the concentration and logarithm of M was found.

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All activated sludge systems for removing phosphate microbiologically are configured so the biomass is cycled continuously through alternating anaerobic and aerobic zones. This paper describes a novel aerobic process capable of decreasing the amount of phosphate from 10 to 12 mg P liter ؊1 to less than 0.1 mg P liter ؊1(when expressed as phosphorus) over an extended period from two wastewaters with low chemical oxygen demand. One wastewater was synthetic, and the other was a clarified effluent from a conventional activated sludge system. Unlike anaerobic/aerobic enhanced biological phosphate removal (EBPR) processes where the organic substrates and the phosphate are supplied simultaneously to the biomass under anaerobic conditions, in this aerobic process, the addition of acetate, which begins the feed stage, is temporally separated from the addition of phosphate, which begins the famine stage. Conditions for establishing this process in a sequencing batch reactor are detailed, together with a description of the changes in poly-␤-hydroxyalkanoate (PHA) and poly(P) levels in the biomass occurring under the feed and famine regimes, which closely resemble those reported in anaerobic/aerobic EBPR processes. Profiles obtained with denaturing gradient gel electrophoresis were very similar for communities fed both wastewaters, and once established, these communities remained stable over prolonged periods of time. 16S rRNA-based clone libraries generated from the two communities were also very similar. Fluorescence in situ hybridization (FISH)/microautoradiography and histochemical staining revealed that "Candidatus Accumulibacter phosphatis" bacteria were the dominant poly(P)-accumulating organisms (PAO) in both communities, with the phenotype expected for PAO. FISH also identified large numbers of betaproteobacterial Dechloromonas and alphaproteobacterial tetrad-forming organisms related to Defluviicoccus in both communities, but while these organisms assimilated acetate and contained intracellular PHA during the feed stages, they never accumulated poly(P) during the cycles, consistent with the phenotype of glycogen-accumulating organisms.High levels of phosphate in effluents from activated sludge systems not designed to remove it can lead to toxic cyanobacterial blooms in receiving bodies of water. Consequently, efforts have been directed towards removing phosphate during treatment by microbiological means with a process called enhanced biological phosphorus removal (EBPR), where phosphate is removed from the wasted biomass as intracellular poly(P) (5, 37, 45). Such treatment processes are based on the underlying principle that the biomass needs to be recycled repeatedly through alternating anaerobic and aerobic stages (37), a requirement regarded as crucial for successful EBPR operation. Only after repeated recycling are poly(P)-accumulating organisms (PAO) thought to have a selective advantage over other populations, eventually allowing them to become dominant (5,37,45). In the anaerobic (feed) stage, PAO are belie...

The content and molecular weight (MW) of β‐glucan in extracts from a selection of oat and barley cultivars were compared using flow‐injection analysis and high‐performance size‐exclusion chromatography. From 60 to 75% of the β‐glucan was extracted from oat and waxy barley by hot water (90°C) containing heat‐stable α‐amylase, whereas just 50–55% was extracted from nonwaxy barley. Consecutive extractions with hot water and dimethylsulfoxide (DMSO) extracted 65% (nonwaxy barley) or 75–80% (oat and waxy barley) of the total β‐glucan. An extraction with sodium hydroxide and sodium borohydride (NaOH/NaBH4) increased the percentage of β‐glucan extracted to 86–100% but decreased the MW. The MW of β‐glucan in the oat cultivars selected was significantly higher than those in the barley cultivars. The β‐glucan extracted from the nonwaxy barley cultivars showed significantly higher peak MW than that from the waxy barley cultivars.

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Fluorescence in situ hybridization (FISH) was used to analyse the community composition of a sequencing batch reactor (SBR) operating with aerobic-anaerobic cycling and fed acetate as its sole carbon source. Phosphorus was removed from the SBR microbiologically. Marked shifts in the community structure occurred as the phosphorus/carbon (P/C) ratio in the feed was changed. When the P/C ratio was shifted from 1 :10 to 1 :50, FISH analysis showed that the percentage of β-Proteobacteria fell from ca 77 % of the total bacteria to ca 38 %. This decrease in the β-Proteobacteria coincided with a reduction in both the proportions of the β-proteobacterial Rhodocyclus-related phosphorus-accumulating bacteria and the biomass phosphorus content. Both the α-and β-proteobacterial ' G-bacterial ' populations assimilated acetate and synthesized PHA anaerobically. The α-Proteobacteria are considered responsible for glycogen production in these SBR systems.

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