Roy Teranishi

Precursors of sulfur‐containing flavor compounds

Sulfur‐containing volatiles contribute to the flavor of many food products because of their high volatility and their strong odor. Understanding of their formation from natural precursors is not only of scientific value, but also of practical use in the flavoring of processed foods and in the prevention of off‐flavor formation.

VOLATILES FROM STRAWBERRIES. II. COMBINED MASS SPECTROMETRY AND GAS CHROMATOGRAPHY ON COMPLEX MIXTURES.

Abstract The technique of combined mass spectrometry and gas chromatography has been applied to the analysis of a complex oil of strawberry volatiles. Capillary gas chromatography indicated over 150 components. Most of the major components have been identified. These include alcohols, esters, acetals, aldehydes, furfural, methyl furfural, aromatic aldehydes, ketones, and esters, a few terpenes, and a few aromatic hydrocarbons. The strength of this technique is shown by the determination of several compounds in one sharp chromatographic peak. On the other hand certain prominent species could not bbe identified by the low resolution (resolution about 200) mass spectral data obtained.

The identification of volatile compounds in human urine

Abstract Since we are using the gas chromatography of volatile urine constituents in a procedure to diagnose diseases, we wished to identify the components of our sample. Forty-two compounds were identified by gas chromatography—mass spectroscopy, using a modified head-space collection technique. A co-injection procedure was used to place these components on a chromatogram from our disease diagnosis instrument.

ODOR QUALITY AND CHEMICAL STRUCTURE IN FRUIT AND VEGETABLE FLAVORS

Since the last New York Academy of Sciences Conference on Odor, some progress has been made in correlating chemical structure to certain quantitative odor characteristics. As more quantitative data are obtained, the better we will be able to understand olfaction; therefore, odor thresholds of carbonyls, pyrazines, and thiazoles will be discussed. Additionally some elegant chemistry that answers the old classical question whether enantiomers have different odors or not will be discussed briefly.

An apparatus for the quantitative analysis of volatile compounds in urine

Abstract A completely automated apparatus for the quantitative analysis of volatile compounds in urine vapor and breath is described in detail. More than two-hundred compounds are shown to be routinely measured in urine vapor, and the application of the apparatus to orthomolecular diagnosis is discussed.

Effect of storage and ripening on fresh tomato quality, Part I

Abstract Four varieties of fresh tomato were grown, stored and treated under commercial conditions to assess the effects of storage and ripening conditions on tomato taste and flavor. The qualitative and quantitative changes in values for volatiles, non-volatiles and physical characteristics were determined. The results are reported in two parts. This report discusses the effects of storage temperature and ethylene treatment on changes in the concentrations of 32 tomato volatiles with results expressed in terms of Odor Units (Uo) in order to best approximate human aroma effect. A second report discusses all other parameters along with general statistical analysis. The average Odor Unit value for each of the tracked analytes showed that only half the tracked volatiles were present in concentrations great enough to contribute to over-all aroma. Statistical analysis by Anova showed that the levels of all significant volatiles, except methyl salicylate, can be correlated to changes in storage conditions. The generation of volatiles decreases significantly with storage and ripening temperatures below 10° but the final ripening temperature is the most significant factor in determining levels of volatiles produced. If final ripening temperatures are raised to 20° for tomatoes initially stored at 10° or less, volatiles are produced at a level comparable to tomatoes stored above 10°. When final ripening takes place at temperatures below 10° volatile production is curtailed.

Composition of oxygenated monoterpenoids and sesquiterpenoid hydrocarbons from the cortical oleoresin of Abies magnifica A. Murr.

Abstract Turpentine from cortical oleoresin of Abies magnifica A. Murr. was analyzed by a combination of gas-liquid and column chromatography, and the individual materials separated were identified by u.v., i.r., Raman, nuclear magnetic resonance (NMR), and mass spectral (MS) data as well as by the GLC retention data. Nineteen monoterpenoids and twenty-six sesquiterpene hydrocarbons were identified (Tables 1 and 2) including two new compounds, γ-humulene and cyclosativene, whose structures were determined.

COYOTE ESTROUS URINE VOLATILES

Samples of female coyote urine were taken once or twice each week during the winter and spring for two years. Headspace analysis was employed with Tenax GC trapping and GC-MS. Tenax trapping was started in less than 1 hr after sampling, and mild conditions were used to minimize losses of highly volatile and labile compounds. Thirty-four compounds were identified. They include sulfur compounds, aldehydes and ketones, hydrocarbons, and one alcohol. The principal constituent is methyl 3-methylbut-3-enyl sulfide, which usually comprised 50% or more of the total volatiles observed. The concentration of many constituents varied widely. This appeared to be quasiperiodic for five of the constituents, with a period of a few weeks, and with pronounced maxima at the peak of estrus. Apparently these compounds are 3-methyltetrahydrothiophene, methyl 3-methylbutyl sulfide, octanal, dodecanal, and bis(3-methylbut-3-enyl) disulfide. One or more of these compounds may have pheromonal activity in coyote relationships.

Microcell for Nuclear Magnetic Resonance Analyses

The use of a commercially available all-glass spherical sample-chamber microcell in combination with a time-averaging computer for nuclear magnetic resonance (NMR) analyses of microsamples has recently been reported. Brame has described a technique for trapping small gas-chromatographically isolated samples directly in such an all-glass NMR microcell. A somewhat different, easily fabricated microcell has been constructed and tested in our laboratories with excellent results. The design is a modification of a cell first described by Frei and Niklaus.

DIRECT VAPOR ANALYSES WITH GAS CHROMATOGRAPHY.

The need for an easy, quick, quantitative and objective measure of aroma quality is apparent to all involved with food research. Although the final judging must be with human senses, a permanent record of a simple instrumental analysis is desirable. The obvious approach is the application of gas-liquid chromatography (GLC), especially since the advent of the very sensitive ionization detectors. The problem is as difficult as the need is easy to define; for, although the human olfactory senses are not as acute as those possessed by some animals, the thresholds of detection for 5ome compounds are far beyond any present GLC instrument. Also, very few of the constituents responsible for certain aromas of food have been identified with much certainty. Therefore, detection and recording volatile constituents are only part of the problem. Identification and correlation to organoleptic characteristics constitute the other part, and an arduous part, indeed. In this paper, we wish to discuss some of the problems encountered in detecting and recording food volatiles, the parameters which must be considered in order to utilize the sensitivity possible with the ionization detectors, and some examples of direct vapor sampling analyses.