The effect of extraction solvents and temperatures on extraction yields of monosaccharides, sucrose, and raffinose oligosaccharides from plant materials was investigated. Toasted soybean meal, cotton seed meal, field peas, and a feed mixture were extracted in either water, 50% (v/v), or 80% (v/v) aqueous methanol or ethanol at 20 or 50 °C or at the boiling point of the solvent. Extraction in 80% (v/v) alcohol was strongly influenced by the extraction temperature and maximum extraction was only achieved at the boiling point. Extraction in water and 50% (v/v) methanol or ethanol was less heat sensitive and gave comparable results. Aqueous ethanol (50%, v/v) was as effective as 50% (v/v) methanol, whereas lower yields were seen at higher alcohol strength. There was no consistent difference in the extraction yield when comparing reflux with constant stirring and water bath with occasional mixing for any of the extraction solvents used. Keywords: Oligosaccharides; α-galactosides; HPLC; extraction solvent; extraction temperature

Four pigs fitted with a gastric cannula were fed on a wheat-flour-based diet (WF) and three oat-based diets, consisting mainly of oat flour (OF), rolled oats (RO) or oat bran (OB), for 1 week each. The stomach contents were collected quantitatively daily at 0 5 , 1, 2, 3 or 5 h after feeding. The viscosity (mPa . s) of the liquid fraction of stomach contents 1 h after feeding was 1.7 with diet WF, 15 with diet OF, 30 with diet RO and approximately 400 with diet OB. The viscosity and the concentration of /?-glucan in the liquid phase was to some extent determined by the dietary level of /?-glucan in the diet. However, there was a trend towards a lower viscosity after longer exposure to the gastric juices. The correlation between logarithmic values for viscosity and concentration of jl-glucan in the liquid phase of digesta was r 0-45. On centrifugation of digesta there was a higher proportion present in the sediment phase when the pigs were fed on diets with a higher content of soluble dietary fibre (DF), suggesting that the digesta was more coherent. This possibility was supported by the higher water-holding capacity (WHC) of the sediment. Feeding diets with oats containing a higher soluble DF content led to lower recoveries of digesta, PEG 4ooo (liquid-phase marker), and the DF components /?-glucan and arabinoxylan in the first hour after feeding. No effect related to the DF content of the diet was seen in the gastric emptying of starch and Cr,O, (solid-phase marker). In conclusion, soluble DF from oats increased the viscosity of stomach contents and increased the ability of the dry matter to retain water. Higher levels of soluble DF led to higher recoveries of digesta, the liquid phase and DF itself in the initial stage of gastric emptying, whereas no effect was seen on the gastric emptying of starch. jl-Glucan: Oats: Viscosity: Gastric emptying

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Pigs were fed three diets containing different mill fractions from oats-oat flour, rolled oats, and oat bran. The molecular weight of the (l-*3)(l-*-4)-3-D-glucan (3-glucan) in diets and from the jejunal contents of the pigs was determined by size exclusion chromatography. There was no significant difference in the molecular weight (MW) of the 3-glucan in the diet, regardless of origin. MW was reduced 7-35-fold after passage through the stomach and the proximal small intestine of pigs, oat bran being least affected. Depolymerization toward a specific MW range of about 100 000 was seen in some digesta samples, indicating cleavage at randomly distributed susceptible bonds. The oat fractions themselves had some capacity to degrade 3-glucan, but this was insufficient to account for the MW loss during digestion. Degradation also took place when isolated 3-glucan was incubated with jejunal digesta from pigs fed an oat-free diet. Fractionation of the digesta by ultracentrifugation showed that the degrading activity was mostly associated with the supernatant. Since autoclaved digesta were without effect, the activity was presumably enzymatic, originating from microbes present in the gut. Neither isolated 3-glucan nor crude extracts from oat bran were sensitive to trypsin, indicating that cleavage of peptide bonds was not responsible for the reduction in molecular weight and loss of viscosity in digesta from pigs.