A method was devised and tested for rapid and quantitative identification of microbial flora in fresh seafoods. The rapid identification of large numbers of isolates was made possible by (1) a simplified identification scheme established by reference culture studies and from the known reactions of microorganisms reported in the literature, (2) the multiple transfer of large numbers of isolates by means of replica-plating, and (3) the use of an electronic computer to analyze data. For the identification of microbial isolates, colonies developing on initial isolation plates were picked by sterile toothpicks and inoculated on a master-plate in prearranged spacing and order. Growth on the master-plate was replicated on a series of solid agar plates containing differential or selective agents. Identifying characteristics consisted of growth responses of the isolates on media containing penicillin, tylosin, vancomycin, streptomycin, chloramphenicol, neomycin and colistin; growth responses on Bacto-SS, Bacto-S-110, Bacto-potato dextrose agar; and culture pigmentation, cell morphology and the Gram-reaction. Information was processed by an IBM 1410 digital computer which sorted and grouped each isolate into one of ten microbial genera or groups, according to a programmed identification key. The identification system was tested by analyzing the microbial flora of dover sole fillets (Microstomas pacificus) and ground beef. This rapid identification method was employed in an investigation designed to determine the nature of the microbial flora shifts in dover sole resulting from irradiation and storage at 6°C. The relationship between the microorganisms which initially survive irradiation, and those making up the final spoilage flora, was determined. A total of 2,723 isolates were examined in this study. The spoilage of unirradiated control samples during storage at 6°C was almost entirely due to the growth of Pseudomonas. This group, which occupied 25 percent of the fresh flora, grew up to nearly 100 percent in two days storage. In contrast, irradiation doses of 0.1, 0.2, 0.3, and 0.4 megarad favored the growth of Achromobacter and yeasts. Micrococcus species, which survived radiation, did not grow at 6°C. At 0.5 megarad, spoilage of fish samples at 6°C was due entirely to yeasts. / Graduation date: 1966

Numerous investigations have been made on the contribution of butter cultures to the flavor of cultured cream butter, but production of uniform cultured cream butter has not been possible in industry. Therefore, it was desirable to investigate in detail the qualitative and quantitative chemistry of the flavor of high quality butter cultures, and to examine more closely some of the aspects of flavor production by butter culture organisms. Volatile flavor components of high quality butter culture and control heated milk were isolated from intact samples by means of a specially designed low-temperature, reduced-pressure steam distillation apparatus. Most of the flavor compounds present in the resulting distillate fractions were tentatively identified by gas chromatographic relative retention time data. Flavor concentrates obtained by ethyl ether extractions of aqueous distillates were also separated by temperature-programmed, capillary column gas chromatography, and the effluent from the capillary column was analyzed by a fast- scan mass spectrometer. Many of the flavor compounds in the flavor concentrates were positively identified by correlation of mass spectral and gas chromatographic data. In addition, supporting evidence for the identification of some flavor components was obtained through the use of qualitative functional group reagents, derivatives and headspace gas chromatography. Compounds that were positively identified in butter culture include ethanol, acetone, ethyl formate, methyl acetate, acetaldehyde, diacetyl, ethyl acetate, dimethyl sulfide, butanone, 2-butanol, methyl butyrate, ethyl butyrate, methane, methyl chloride, carbon dioxide and methanol; also included were 2-pentanone, 2-heptanone, acetoin, formic acid, acetic acid, lactic acid, 2-furfural, 2-furfurol, methyl hexanoate, ethyl hexanoate, 2-nonanone, 2-undecanone, methyl octanoate and ethyl octanoate. Compounds that were tentatively identified in butter culture include hydrogen sulfide, methyl mercaptan, n-butanal, n-butanol, 2-hexanone, n-pentanal, n-pentanol, 2-mercaptoethanol, n-butyl formate, n-butyl acetate, 2-methylbutanal, 3-methylbutanal, methylpropanal, methyl heptanoate, n-octanal, 2-tridecanone, methyl benzoate, methyl nonanoate, ethyl nonanoate, ethyl decanoate, methyl dodecanoate, ethyl dodecanoate, delta-octalactone and delta-decalactone. Compounds that were positively identified in control heated milk include acetaldehyde, ethyl formate, ethyl acetate, 2-heptanone, 2-furfural, 2-furfurol, 2-nonanone, 2-undecanone, ethyl octanoate and methyl decanoate. Compounds that were tentatively identified in control heated milk include dimethyl sulfide, hydrogen sulfide, ammonia, methyl mercaptan, methyl acetate, acetone, methanol, butanone, butanal, n-butanol, methyl butyrate, ethyl butyrate, 2-pentanone, 2-hexanone, 2-mercaptoethanol, 2-furfuryl acetate, ethyl hexanoate, methyl heptanoate, 2-tridecanone, ethyl decanoate, ethyl dodecanoate, delta-octalactone and delta-decalactone. The data indicated that the qualitative flavor composition of control heated milk and butter culture were very similar. Diacetyl, ethanol, 2-butanol and acetic acid were noted to be consistently absent in the data for the control heated milk. Other compounds were not observed in the heated milk fractions, but were also absent from some of the culture fractions. This was attributed to their presence in low concentrations, chemical instability or inefficient recovery. A modified 3-methyl-2-benzothiazolone hydrazone spectrophotometric procedure was adapted for the determination of acetaldehyde produced in lactic starter cultures. The procedure was applied in conjunction with diacetyl measurements in studying single- and mixed-strain lactic cultures. The diacetyl to acetaldehyde ratio was found to be approximately 4:1 in desirably flavored mixed-strain butter cultures. When the ratio of the two compounds was lower than 3:1 a green flavor was observed. Acetaldehyde utilization at 21°C by Leuconostoc citrovorum 91404 was very rapid in both acidified (pH 4.5) and non-acidified (pH 6.5) milk cultures. The addition of five p.p.m. of acetaldehyde to non-acidified milk media prior to inoculation greatly enhanced growth of L. citrovorum 91404 during incubation at 21°C. Combinations of single-strain organisms demonstrated that the green flavor defect can result from excess numbers of Streptococcus lactis or Streptococcus diacetilactis in relation to the L. citrovorum population. Diacetyl, dimethyl sulfide, acetaldehyde, acetic acid and carbon dioxide were found to be "key" compounds in natural butter culture flavor. Optimum levels of these compounds in butter culture were ascertained by chemical or flavor panel evaluations. On the basis of these determinations, a synthetic butter culture prepared with heated whole milk and delta-gluconolactone (final pH 4.65) was flavored with 2.0 p.p.m. of diacetyl, 0.5 p.p.m. of acetaldehyde, 1250 p.p.m. of acetic acid, 25.0 p.p.b. of dimethyl sulfide and a small amount of sodium bicarbonate for production of carbon dioxide. The resulting synthetic butter culture exhibited the typical aroma, flavor and body characteristics found in natural high quality butter cultures, except that the delta-gluconolactone was found to contribute an astringent flavor. / Graduation date: 1965

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No description available.

Jojoba, Simmondsia chinesis, a shrub native to the Sonoran Desert, has seeds with a high percentage of oil. The oil, which has properties similar to sperm whale oil, is expressed with heat and pressure, leaving behind a pressed meal rich in protein and carbohydrate. High concentration of a cyanoglycoside, simmondsin, and polyphenolic compounds in the meal make it unusable for animal or human consumption. Commercial means of protein extraction were improved by washing the protein concentrate with methanol, acetone, and acidic methanol to remove sugars, polyphenolic components and simmondsin. A concentrate with 85% protein, less than 0.3% polyphenolic compounds, and less than 1% simmondsin resulted. The foamability, water absorption, oil absorption, gelation, emulsification and nitrogen solubility were comparable to other plant protein concentrates. Fewer than 15 proteins in the pressed meal and concentrates were detected using PAGE (12.5% T, 2.4% C) in a Laemmli discontinuous system. The proteins were deficient in the sulfur amino acids, and marginal in threonine and lysine. The amino acid imbalance might be partially responsible for poor weight gain and other toxicity symptoms reported previously.

In this work, glucose isomerase (GI) activity was measured with several sugar substrates. Lactase was also used with several carbohydrate substrates to observe its hydrolytic action. In order to observe the enzymes' action, a small batch reactor was designed and used in the entire project. Paper partition chromatography, was the analytical method of choice to measure the reaction end products. It proved to be a valuable technique in combination with other analytical methods for determination of various carbohydrates. GI showed positive activity with glucose, fructose, xylose and L-sorbose but none with mannose, galactose, lactose, maltose, melibiose and cellobiose. Lactase was active on maltose, cellobiose, raffinose, lactose and sucrose but not with maltiol, melibiose or melezitose. Whey proteins were removed either by ultrafiltration or heat precipitation. This deproteinized whey was treated with the two enzymes to produce a syrup composed mainly of galactose, glucose, fructose and small amounts of oligosaccharides. The syrup had a predominantly sweet taste with a slight salty attribute. The proper utilization of whey lactose has potentially valuable features in the production of a sweetening ingredient for foods. This is especially true after the lactose has been hydrolyzed by lactase and then the glucose in the hydrolyzate isomerized to fructose with glucose isomerase.

No description available.

No description available.

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No description available.