The objective of this study was to investigate the effects of barley-rich diets in the intestinal tract of rats. Four test groups (A-D) of 10 young male Wistar rats were fed diets containing 50 g/100 g barley extrudates (A, B and D) or mixtures (C) for 6 wk; the control diet contained no barley. The barley-containing supplements in the test diets were: A = cultivar "HiAmi"; B = "HiAmi" and "Prowashonupana" (50:50); C = "Prowashonupana" and Novelose (50:50); D = "Prowashonupana" and amylose from maize (60:40). These supplements contained 7-12 g/100 g beta-glucan and 7-24 g/100 g resistant starch. Additionally, 5 g microcrystalline cellulose/100 g was present in all diets. Carbohydrate utilization (indirect calorimetry) was lower (P < 0.05) in rats fed the barley-containing diets C or D than in the controls. In the test groups, the following differences from the controls were found: greater food intake in the last 2 wk (P < 0.05); increased weight gain in wk 6 (P < 0.05); greater mass of the ceca (groups B-D; P < 0.05) and colons (P < 0.001) as well as masses of cecal (groups C and D; P < 0.01) and colon contents (P < 0.001); greater concentrations of resistant starch in cecal and most of the colon contents (P < 0.05); and more beta-glucan in the small intestine, cecum and colon (P < 0.05). The numbers of coliforms and Bacteroides were lower than in the controls in groups B-D and those of Lactobacillus were greater in all test groups (P < 0.05). Short-chain fatty acids (SCFA) were higher in the cecal contents of the test groups (> or = 800 micro mol/g DM; P < 0.001) compared with the controls ( approximately 200 micro mol/g DM). Similarly, SCFA were higher in colon and feces of the test groups. The concentrations of excreted bile acids increased up to 30% during the feeding period. The proportions of secondary bile acids were lower and the amounts of neutral sterols (P < 0.001) were greater in feces of rats fed the barley-containing diets for 6 wk than in the controls. Diets containing more soluble macromolecular dietary fibers such as beta-glucans affected the excretion of bile acids and neutral sterols the most, whereas the fermentation of dietary fiber, including resistant starch, influenced the steroids in feces. These results suggest that dietary fiber-rich barley-containing diets have beneficial physiologic effects.

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Anthocyanins gain more and more importance as natural colourants. Besides many other plant species, coloured potatoes could serve as a potential source. Therefore, 27 potato cultivars and four breeding clones of different origin were analysed for their anthocyanin contents in fresh weight (fw). On average the highest amounts of anthocyanins were found in the skin (0.65 g kg À1 fw) of potatoes. The corresponding values of samples taken from whole tubers (0.31 kg À1 fw) and flesh (0.22 kg À1 fw) were significantly lower (p<0.03). The analysis revealed considerable differences in the amounts of anthocyanins between the 31 cultivars/ breeding clones. Among them 'Peru Purple' revealed the highest anthocyanin content in the skin with 2.96 g kg À1 fw. A similar high value was reached by 'Violettfleischige' and clone 1.81.202-92 N. Also for the other two types of samples, flesh and whole tubers, these three genotypes exhibited the highest level of anthocyanins. Interestingly, different rates of nitrogen fertilization at 100 and 200 kg ha À1 had no significant effect on the pigment content of potatoes. The same was observed with respect to the year or the location of plant growth. There were also no significant changes in the anthocyanin contents of tubers during storage for 135 days. In dry matter, starch and protein contents the coloured potato cultivars/ breeding clones were comparable with traditional cultivars. Further tests have shown that the glycoalkaloids were mainly localized in the skin of coloured potatoes.

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