The muscle of shellfish, in particular shrimp, is characterized by high amounts of free amino acids especially glycine as well as proline, serine and alanine which all contribute to the overall pleasant and desirable flavour perceived. The two major proteolytic enzymes, chymotrypsin and trypsin, were used at different ratios (E/S, 0.0-0.3%), temperatures (25$ sp circ$C-45$ sp circ$C) and time of hydrolysis (1-3h) for frozen and fresh shrimp. These conditions were optimized in order to generate a product with desirable sensory and chemical characteristics. The thermal stability of chymotrypsin and trypsin were investigated, to determine the suitability of heat to stop the hydrolysis reactions at desired conditions. The results for the frozen shrimp showed that chymotrypsin was found to be inactivated after incubation for 1 min at 80$ sp circ$C while trypsin was found to be relatively heat stable. The commercial soybean trypsin inhibitor was used to inactivate trypsin. The use of both enzymes accelerate the rate of hydrolysis to some extent. Higher free amino acids yield for glycine, serine, and proline were obtained for chymotrypsin-treated hydrolysates. (Abstract shortened by UMI.)

No description available.

No description available.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 135-141). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 135-141). Also available on the Internet.

No description available.

The development of synthetic culture flavors for use in dairy products such as sour cream, cottage cheese, butter, and buttermilk has created the need for a rapid quantitative analysis for the synthetic flavor concentrates. An internal standard gas chromatographic method has been developed which is capable of +10% accuracy for each flavor compound in single sample analyses. The separation of water, acetaldehyde, dimethyl sulfide, acetic acid, diacetyl, propylene glycol, and acetone (the internal standard) was performed with a column consisting of a 1/8 inch OD section of stainless steel tubing 10 feet in length packed with 120-150 mesh Porapak Q plus a stainless steel precolumn 1/8 inch OD and 10 inches in length packed with 120-150 mesh Porapak R. The column was operated isothermally at 155°C with a flow rate of 44 ml per min of nitrogen carrier gas. A flame ionization detector was used. In the course of the investigation, Porapak Q (available from Waters Associates Inc., Framingham, Mass.) was evaluated. The optimum mesh size under the conditions employed was the 120-150 mesh range. The efficiency of Porapak Q columns, as reflected by the number of theoretical plates per foot for n-propanol and the resolution of n-propanol and iso-propanol, was found to increase when the column diameter was increased from 1/16 inch OD to 1/8 inch OD to 1/4 inch OD. / Graduation date: 1967

The malty flavor defect produced by Streptococcus lactis var. maltigenes has been the cause of considerable economic distress to various segments of the dairy industry. This study was conducted in order to develop a more thorough understanding of the chemical nature of this defect, and to formulate a synthetic malty flavor preparation. An 18 hour malty culture and an acidified heated skim milk control were steam distilled using a specially designed, low temperature, reduced pressure glass apparatus fitted with ground glass ball or standard taper joints. After subsequent ethyl ether extractions, the aqueous distillates yielded flavor concentrates which were suitable for gas-liquid chromatographic (GLC) and mass spectrometric analysis. Flavor component identifications were made on both a tentative and positive basis. Tentative identifications were made using the technique of GLC relative retention times. Identifications were considered positive when GLC retention data could be coupled with mass spectral data. Compounds positively identified as being present in the malty culture included acetaldehyde, 3-methylbutanal, phenylacetaldehyde, ethanol, butanol, 2-methylpropanol, 3-methylbutanol, 2-furfurol, phenethyl alcohol, acetone, butanone, 2-pentanone, 2-heptanone, 2-nonanone, ethyl formate, ethyl acetate, ethyl butyrate, ethyl isovalerate, ethyl octanoate, isoamyl acetate and toluene. Compounds tentatively identified included 2-methylpropanal, pentanal, benzaldehyde, 2-furfural, 2-undecanone, 2-tridecanone, ethyl hexanoate, ethyl decanoate, methyl acetate, γ-octalactone, δ-octalactone, formic acid and acetic acid. In the heated skim milk control, acetaldehyde, benzaldehyde, 2-furfural, 2-furfurol, 2-pentanone, 2-heptanone, 2-nonanone, 2-undecanone, 2-tridecanone, ethyl acetate and methyl chloride were positively identified while pentanal, hexanal, octanal, nonanal, 2-hexanone, 2-octanone, ethyl formate, ethyl octanoate, methyl acetate, γ-octalactone and δ-octalactone remained as tentative identifications. Quantitative evaluations of the volatile constituents present in each of four strains of the malty culture were conducted using a gas entrainment, on-column trapping, GLC technique. From the quantitative data obtained from a 24 hour S. lactis var. maltigenes L/M-20 culture, a synthetic malty flavor preparation, suitable for use in baked foods, was developed. This investigation used biscuits as a model system for the baking studies. The biscuits were prepared using the General Mills' Bisquick mix and a malty milk preparation replaced the normal milk requirement. The milk contained 1.70 p.p.m. acetaldehyde, 34.20 p.p.m. 3-methylbutanal, 17.90 p.p.m. 2-methylpropanolr 90.10 p.p.m. 3-methylbutanol and 10.00 p.p.m. diacetyl. / Graduation date: 1968

Graduation date: 1978

Thesis (Ph. D.)--University of Minnesota, 1918. / Biography.