The effectiveness of guar gum in reducing post-prandial blood glucose and plasma insulin levels in human subjects seems to depend mainly on its ability to increase the viscosity of digesta in the small intestine. However, the precise relationship between the rheological properties of guar gum (either in vitro or in vivo) and the changes in blood metabolites and hormones is unknown. The aim of the present study, therefore, was to investigate the effects of wheat breads containing guar gum samples varying in molecular weight (M,) and particle size (characteristics that strongly influence the rheological properties of guar gum) on post-prandial blood glucose and plasma insulin levels in healthy subjects. The sensory qualities of breads containing guar-gum flours of different M, were also evaluated using a hedonic scoring technique. No significant differences in the post-prandial blood glucose responses were found between the control and guar breads. However, all the guar breads elicited significant (P < 0.05) decreases in the post-prandial rise in plasma insulin, an effect that did not appear to be influenced by large variations in M, or particle size of guar gum. Moreover, the sensory qualities of guar bread were markedly improved by using low M, grades of guar gum.

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Invertase from Saccharomyces cerevisiae was immobilized on celite and on polyacrylamide by an absorption procedure. The properties of the immobilized invertase were characterized and compared with those of soluble invertase. The activity yield for immobilized invertase on celite and on polyacrylamide was 92% and 81% respectively. The optimum pH and temperature for both soluble and immobilized invertase activity were 4.6 and 60 • C respectively. The activity of immobilized invertase is stable in the range pH 4.0-6.5. The immobilized invertase was thermostable when incubated at temperatures ranging from 40 to 60 • C. Immobilized invertase had a high stability when stored at room temperature for 90 days and had an excellent operational stability when used 20 times repeatedly. The invertase immobilized on celite was more stable than invertase immobilized on polyacrylamide. The invertase preparations immobilised by absorption procedures exhibited marked stability towards temperature, pH changes and had high storage and operational stability, suggesting their excellent potential for use as supports.

Fish protein concentrate (FPC) from river Nile bolti fish (Tilapia nilotica) was prepared and compared with commercial FPC and fresh bolti fish flesh. Fish meal (FM) from bolti fish offals was prepared and compared with commercial FM and also fresh bolti fish flesh. FPC from bolti fish showed a higher crude protein content but less fat, ash, calcium and sand than the commercial sample, while FM from bolti fish showed a higher content of ash and phosphorus than commercial FM but was nearly similar in crude protein, fat, calcium and sodium chloride. FPC from bolti fish had a higher content of lysine, arginine, aspartic acid, glycine and glutamic acid and a lower content of the other free amino acids. The bolti fish FM had a lower content of total amino acids and the contents of the free amino acids cysteine, glycine, aspartic acid, serine, alanine, valine, and methionine increased slightly. The yield was 12% for FPC and 19.5% for FM. Coliform bacteria were not present in both FPC and FM from bolti fish. Low moisture contents of FPC and FM were essential for preventing microbiol growth and to attain a good keeping quality. The FPC and FM from bolti fish reached moisture equilibrium and stopped increasing in weight within 144 to 192 h.

Fish protein concentrate (FPC) from river Nile bolti fish (Tilapiu nilofica) was prepared by two extractions with isopropyl alcohol. This FPC was used as a supplement to manufacture salt biscuit (mixed with cumin) for raising its nutritional quality. The supplementation at level of 4, 5, and 6 % increased the protein content by about 2.6, 3.5, and 4.57; respectively. Increase was high in some amino acids such as glycine, serine, and threonine while cysteine, lysine, alanine, glutamic acid, arginine, isoleucine, and phenylalanine increased in a low rate. Consumer acceptability was the best at 67; level. The increasing of the supplementation to more than 67;, e.g. 7, and 8% levels caused a drop in the overall quality. There were significant differences in colour and highly significant ones in taste, flavour and texture due to differences in the supplementation level. The presence of all essential amino acids in significant quantities suggests an importance of supplementation of salt biscuit in human nutrition.