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.

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.

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

Acidulants can contribute considerably to the flavor of food. However, limited research on differences in acid flavor exists. While numerous researchers have studied acids, most have focused on sourness exclusively. Acids have been shown previously to differ in non-sour components, such as bitterness and astringency. A series of experiments were conducted to determine flavor characteristics of selected acids in different systems. First, selected acids (lactic, malic, citric, acetic) and 2 acid blends (lactic/acetic 1:1 and 2:1) in a model (water) system were evaluated on an equivalent weight (0.2% w/v) and on an equivalent pH basis. Three pH levels were explored: 3.5, 4.5 and 6.5. The technique of free-choice profiling was applied to characterize the flavor profile. Results analyzed by generalized procrustes analysis showed two significant findings: (1) acids differ in sensory character, and (2) the flavor of an acid changes with pH. Second, selected acids (lactic, malic, citric, tartaric) were evaluated in sweetened, flavored drinks on an equivalent weight basis at two concentrations (0.4 and 0.6% w/v). Four flavors were evaluated: orange, cherry, cola and strawberry. Descriptive analysis was used, and the data was analyzed by principal component analysis. Significant differences were found on among acids and concentrations. For the orange flavor system, citric acid enhanced the orange flavor of the drink. Third, selected acids (lactic, citric, acetic) and 2 acid blends (acetic/lactic 1:1 and 2:1) were evaluated in emulsions on an equivalent pH basis. Three pH levels were explored: 3.5, 4.5 and 5.5. These findings support the first study as differences were found among acids, and flavor changes existed when pH changed. / Graduation date: 1995

Graduation date: 1962

The effect of refluxing on the aromas of Valencia aqueous orange essences was determined through analysis by GC, MS, Osme, and by a descriptive panel. The strengths and descriptions of volatiles were investigated to determine if differences in essence aroma character and intensity existed. During production, 1 sample was subjected to reflux conditions and contained 16.2% ethanol. The other sample had not been refluxed and contained 6% ethanol. The aroma activity of volatiles was measured by Osme, a method of gas chromatography / olfactometry developed at Oregon State University. The majority of aroma active peaks were found to be present in the reflux and no reflux aqueous orange essence samples. Octanal, linalool, ethyl butanoate and 2 unknowns were the components with strongest aroma activities in both samples. Descriptive analysis was conducted with 7 trained panelists from the Food Science and Technology Department at Oregon State University. Following 12 training sessions, initial testing indicated overall intensity was the major separating attribute of essences. After 6 additional training sessions and adjustment of concentrations to yield essences of approximate equal strength, testing indicated there were no significant differences between samples. Osmegrams, GC FID chromatograms, and descriptive analysis indicated the effect of reflux produced an essence that was more concentrated. Although refluxing concentrated individual volatiles to different levels, character differences other than those associated with concentration were minimal. / Graduation date: 1996

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 126-137). Also available on the Internet.