Fructose has recently received much attention due to renewed interest in natural sweeteners. In addition, fructose has some advantages to sucrose in sweetness, solubility, viscosity, and dental health characteristics. Fructose is deposited as storage fructans of the inulin (beta-1,2) type in tubers and rhizomes of the Compositae family. The utilization of the Jerusalem artichoke (Helianthus tuberosus) tuber as a source of fructose syrup is discussed. This plant has the potential to produce more sugar per acre than corn or sugar beets. In addition, the artichoke has higher frost resistance and lower heat unit requirements than corn and is somewhat more tolerant to low moisture conditions than sugar beets. A high quality fructose syrup can be produced from artichoke tubers. The extraction step was found to be particularly important since development of adverse colors and flavors must be prevented. The fructans may be acid or enzyme hydrolyzed but the latter method gave a higher quality syrup. Ion-exchange resins and activated charcoal were effective in removing coloring and flavoring materials, and also reduced other noncarbohydrate constituents. Since the enzymatic hydrolysis of the fructans is an attractive alternative to acid hydrolysis, a process was developed for producing and purifying a special beta-fructofuranosidase (inulase) from Saccharomyces fragilis. Inulase has a much higher specificity for fructans than commerically available beta-fructofuranosidase (invertase).

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Inulase production by Kluyveromyces fragilis on various fermentable and non-fermentable carbon sources was examined in carbon-limited continuous culture. Fructose and sucrose supported superior inulase yields [above 24 pmol sucrose hydrolysed min-l (mg cell dry wt)-l at pH 5.0, 50 "C], while some other carbon sources, including lactose, galactose, ethanol and lactate, did not stimulate inulase formation beyond basal levels. Thus fructose was identified as the primary physiological inducer. Isolation of a constitutive mutant also provided genetic evidence for the inducible nature of inulase in the wild-type. The mutant was generated spontaneously and selected in continuous culture. It produced high inulase activities in continuous culture irrespective of the carbon source. Inulase formation in the wild-type and mutant strain was further controlled by general carbon catabolite repression as suggested by enzyme yield patterns in batch and continuous culture.

J. 1992. The effect of organic acids and enzyme supplementation on the performance of pigs fed barley-based diets. Can. J. Anim. Sci. 72: 395-402. Two factorial design experiments (sex X treatment) were conducted to determine the efficacy of enzyme and organic acid supplementation on improving the nutritive value ofbarley-based diets for both starter and finisher pigs. for exp. 1, 48 crossbred growing pigs (25.1 + 2.8 kg) were fed either a barleybased controi diet or a similar diet supplemented wtth0.25% enzyme (AspergiLlus nlger; 750 units g I beta-glucanase),2.5% propionic acid or a combination of these additives during a 77-d feeding irial. Forixp. 2, 120 cross6red weaner pigs (8.1 + 1.3 kg) were fed a hulless barley-based control diet or a similar diet supplemented with 0.25% enzyme (Aspergillus niger; 150 units g ' betaglucanase), 2.0% fumar\c icid or both additives in combination for a 35-d feeding period. In exp. 1, iupplementation with either enzyme or propionic acid alone, significantly (P<0.05) increased dry matter digestibility. However, when ihe additives were fed in combination, the digestibility coefficient for dr-y matter was not significantly different from the control. Digestibility coefficients for crude protein und .n.rgy were not;ffected by any treatment. Growth rate, feed intake, feed efficiency and carcass traits weie also not improved by supplementation with enzyme or propionic acid, either when fed alone or in combinarion. ln exp. 2. digesribiliry coefficients for dry matter. crude protein antJ energy were not affected by enzyme or acid treatment. In addition, there were no differences in growth, feed intake or feed efficiency is a result of any treatment. Supplementation with organic acids would therefbre appear to be ineffective in potentiating the response to dietary beta-glucanase in pigs fed barley-based diets.