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The relation of protein solubility to the degree of denaturation and to the extent and the mechanism of enzymatic hydrolysis is discussed, and a model based on Linderstrom-Lang's theory for the initial enzyme attack on the protein molecule is presented. In the practical use of protein hydrolysates in foods, the formation of bitter peptides is the most serious problem. According to the literature reviewed, the bitterness seems to be related to the content of hydrophobic amino acids in the protein rather than to the enzyme applied. Consequently, the majority of reports describes ways of attacking the bitterness problem, such as the application of a reverse osmosis cell or the extended hydrolysis by peptidases. The literature on the engineering aspects of protein hydrolysis comprises important work on continuous hydrolysis of fish protein concentrate and soy protein isolate.

Production of specific-structured lipids (SSL) by lipase-catalyzed interesterification has been attracting more and more attention recently. However, it was found that acyl migration occurs during the reaction and causes the production of byproducts. In this paper, the elucidation of acyl migration by response surface design was carried out in the Lipozyme IM (Rhizomucor miehei)-catalyzed interesterification between rapeseed oil and capric acid in solvent-free media. A five-factor response surface design was used to evaluate the influence of five major factors and their relationships. The five factors, water content, reaction temperature, enzyme load, reaction time and substrate ratio, were varied at three levels together with two star points. All parameters besides substrate ratio had strong positive influences on acyl migration, and reaction temperature was most significant. The contour plots clearly show the interactions between the parameters. The migration rates of different fatty acids were also compared from three different sets of experiments during the lipase-catalyzed reaction. The best-fitting quadratic response surface model was determined by regression and backward elimination. The coefficients of determination (R 2 ) of the model were 0.996 and 0.981 for Q 2 value. The results show that the fitted quadratic model satisfactorily expresses acyl migration for the enzymatic interesterification in the batch reactor used.

detergents were determined in laboratory wash experiments. Four test strains-Staphylococcus epidermidis, S. aureus, Escherichia coli, and Pseudomonas aeruginosa-were evaluated on cotton textile. A significant survival and transfer between textiles were found for all four test strains washed in E.U. and U.S. color detergents (without bleach), whereas no survival was observed in bleach-containing detergents. Gram-negative strains generally survived in greater numbers than Gram-positive strains. A greater survival was observed in U.S. detergents at U.S. conditions (30°C, 12 min) than in E.U. detergents at E.U. conditions (40°C, 30 min). The adhesion of odorants to cotton and polyester textiles during washing and drying was studied using six previously identified odorants in laundry [ethylbutanoate, (Z)-4-heptenal, (E)-2-nonenal, 3-methylbutanoic acid, 2-methoxyphenol (guaiacol) and 4-methyloctanoic acid]. All odorants were effectively removed from cotton during wash, whereas the odorants were more strongly associated with polyester fibers. During wash, hydrophobic odorants [(Z)-4-heptenal, (E)-2-nonenal, and guaiacol] adhered more strongly to polyester than the acids. The odor formed by surviving skin microflora attached to textiles soiled with human sebum and sweat after laundering at 30°C was studied by sensory evaluation and aroma extract dilution analysis. Intensive odor was formed in both cotton and polyester textiles during prolonged drying. Generally, the odor formation in cotton swatches and the bacterial count of the wash liquor from cotton swatches were greater than the odor formation and bacterial count from polyester swatches. Odorants with animal notes (branched fatty acids) dominated the odor profile after prolonged drying. Polyester swatches possessed a more complex odor profile than cotton; in particular, aldehydes were more dominating in polyester than in cotton. A high-impact and malodorous component, 3-methylindole, was formed during prolonged drying in cotton. The study demonstrates that microbial odor formation is a dominating factor determining the odor impression of laundered cotton and polyester textiles dried under slow drying conditions. The initial soiling with aromatic components has an additional impact on the odor profile of polyester textiles after wash, due to strong adherence of odorants during the wash cycle. a RI, retention index; FD, flavor dilution; ND, not determined, but a tentative identification is suggested by means of results with two different capillary GC columns, DB-FFAP and DB-5 (see Experimental Procedures section). b Identification based on comparison with the reference compound using the following criteria: 1 RI on the FFAP and DB-5 capillaries, mass spectra in the electron impact mode, and odor quality at the sniffing port (identified in Ref. 14). 2 Criteria described under footnote b,1 but not identified previously in Reference 14. 3 RI on two capillaries, mass spectra in the chemical ionization mode, and odor quality at the sniffing port (identified in Ref. 14). 4...

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