Graduate Thesis Or Dissertation

 

Malty flavor components of Streptococcus lactic var. maltigenes Public Deposited

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/jd473097c

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  • 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.
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  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-01-25T20:47:19Z (GMT) No. of bitstreams: 1 SHELDONROSS1968.pdf: 541301 bytes, checksum: 9f12b16ad7788596c95db50af018d155 (MD5)
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2012-01-23T20:26:30Z (GMT) No. of bitstreams: 1 SHELDONROSS1968.pdf: 541301 bytes, checksum: 9f12b16ad7788596c95db50af018d155 (MD5)
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