Odor and flavor responses to additives in edible oils

Abstract

The odor threshold was determined for a series of unsaturated ketones, secondary alcohols, hydrocarbons and substituted furans added to bland edible oil. Odor thresholds were taken as the point where 50% of a 15-to 18-member taste panel could detect an odor difference from the control oil. These additives are oxidative products of fats, but the concentrations investigated were far below any level associated with an identifying odor or taste of the additive per se. Odor, rather than flavor, was selected as the starting basis because of greater acuity and ease of handling a large number of samples with less taster fatigue. Oil samples containing additive concentrations near the odor threshold levels were evaluated by flavor score and flavor descriptions. Taste panel members were experienced oil tasters and were allowed free choice in selecting terms to describe the flavor quality of the oil samples. The propyl and butyl members of the homologous series of vinyl ketones had the lowest odor thresholds, whereas the difference in odor threshold was small between homologs in the unsaturated alcohols and in the 2 substituted furans. Vinyl propyl ketone, vinyl propyl carbinol (1-hexen-3-ol) and 2-propyl furan had odor thresholds of 0.005, 0.5 and 6 ppm, respectively. Odor thresholds of the unsaturated hydrocarbons are markedly lower than those of the saturated isologs. The odor of nonane can be detected at 650 ppm. However, at 1000 ppm it cannot be tasted and oils containing it were scored equal to the control oil. 1-Nonene, 1-nonyne and other tested C-9 unsaturated hydrocarbons, including a number of dienes, have odor thresholds of about 10 ppm. The hydrocarbons 1-hexyne, 1-nonyne and 1-decyne had odor thresholds of 0.2, 5 and 4 ppm, respectively. INTRODUCTI ONWhen it comes to taste and odor sensations, we are all distinct individualists. Only through experience with food and our environment do we gain and acquire a knowledge of taste and smell. The classification of flavor is strictly a descriptive terminology based on an individual's perception and memory. Most individuals have acute odor perception, as well as the ability to identify different aromas. Offflavors in bland foods, for example, are often described in terms of distinctive odors rather than distinctive tastes. Descriptive terminology characterizing off-flavored fats as cardboardy, trainy, painty, skunky and rubbery illustrates the reliance on odor memory. Although odor perception has generally been regarded as being more sensitive than taste, we and others (1,2) found that when simple odorous compounds are added to fats, the taste threshold is equal to or greater than the individual's odor perception.The contribution of saturated and unsaturated aldehydes to off-flavor characteristics of fats has been well established by many investigators (3-6). Badings (7) in his review in 1960 states that ketones are unimportant in their contribution to oxidation off-flavors. Later, Evans (8), discussing autoxidation of fats, indicated that many volatile corn-1presented ...

Oxidative pathways to the formation of off-flavours

“…The low flavour threshold vinyl alcohol, l-octen-3-01, has been reported to be responsible for the mushroom note in deteriorated milk fat and dairy products (Downey, 1969). Many workers (Hoffmann, 1962;Badings, 1970;Stark and Forss, 1964;Frankel, 1983) have identified the presence of l-octen-3-01 from oxidised methyllinoleate, Kellard et al (1985); d Badings (1970); < Evans et al (1971) deteriorated butter and soyabean oil. The reaction scheme for the formation of this vinyl alcohol from arachidonate 12-hydroperoxide has already been described in Figure 6.14.…”

“…The reaction scheme for the formation of this vinyl alcohol from arachidonate 12-hydroperoxide has already been described in Figure 6.14. Evans et al (1971) have reported the odour threshold of l-octen-3-ol in cottonseed oil to be 0.9 mglkg, and that of I-hexen-3-01 to be 0.5 mglkg. When present at a concentration of 2 mglkg, l-octen-3-ol produced musty/foreign odour, while the latter gave a rubbery/rancid flavour.…”

The quantification of carbonyl compounds in oxidized fat by gas chromatography of the trichlorophenylhydrazones

“…Threshold values found for each were very low, with oct-l-en-3-one being detected at approximately 10 ppb (Hammond and Hill, 1964;Hill and Hammond, 1965). Compounds found to contribute to oxidized flavor in soybean oil included 1-decyne and pentyl furan, with threshold values reported at 0.1 ppm and 1 ppm, respectively (Evans et al, 1974). Other hydrocarbons and alcohols were tested for flavor responses and the threshold of oct-l-en-3-ol measured at 0.1 ppm.…”

“…Several classes of compounds have been implicated in off-flavor development of deteriorating oils. Flavor descriptions and thresholds were studied for many of these (Evans et al, 1974;Badings, 1960;Keppler, 1977;Selke et al, 1975). Duin (1960) identified the following classes of carbonyls as contributing to offflavor in butter; saturated aldehydes (C^ -C^g), 2-enals (C^ ~^ll^ ' 2,4-dienals (C^ -C^^^), enals with the double bond not in the 2-position (Cg -C^g), and dienals with a double bond in non-conjugated position to the 2-enal configuration (Cg -C^g).…”

“…Oct-l-en-3-one (vinyl amyl ketone), pent-l-en-3-one (vinyl ethyl ketone), and 2-trans-6-cis-nonadienal were isolated from autoxidized milk fat and shown to contribute to undesirable flavor components (Hammond and Hill, 1964;Evans et al, 1974). Threshold values found for each were very low, with oct-l-en-3-one being detected at approximately 10 ppb (Hammond and Hill, 1964;Hill and Hammond, 1965).…”