Monocarbonyl Compounds Research Articles

Effects of Radiation, Heating and Storage on Volatile Carbonyl Compounds in Clam Meats

SUMMARY— The development of volatile carbonyl compounds in clam meats stored at 33–35°F was determined. A gas chromatographic method was used to monitor these compounds.When air‐packed samples were irradiated and/or heated, the concentration of carbonyl compounds increased immediately, except for some low‐boiling compounds that were reduced in concentration when the samples were heated. Storage of nonirradiated, air‐packed samples at 33–35°F caused a gradual increase in the concentration of volatile carbonyls until about the 20th day at which time the trend was reversed.When clam meats were vacuum‐packed, the effects of irradiation, heating, and storage were minimized. The pattern of volatile carbonyls in irradiated fresh clams is similar to that found in nonirradiated clams stored at 33—35°F for 20 days. It is concluded that the volatile monocarbonyl compounds, C2 to C7 and diacetyl detected, do not play a major direct role in the changing quality of stored clam meats.

Autoxidation of tissue lipids. I. Incorporation of dietary fatty acids and formation of monocarbonyl compounds in adipose tissue lipids of the vitamin E‐deficient rat

Male weanling rats were fed vitamin E-deficient and vitamin E-supplemented diets containing 5% corn oil or cod-liver oil for 16 weeks, after which their adipose tissue lipids were extracted and analyzed in a nitrogen atmosphere for carbonyl compounds and fatty acids.The vitamin E-deficient cod-liver oil-fed rats, exhibiting incisor depigmentation and darkened adipose tissue, yielded lipids which had a lower iodine value, contained less polyunsaturated fatty acids, and contained more carbonyl compounds, particularly alkanals and alk-2-enals, than the lipids from the animals fed the vitamin E-supplemented cod-liver oil diet. The tissues of the vitamin E-deficient corn oil-fed rats contained less linoleate and more monocarbonyl compounds than those of the vitamin E-supplemented corn oil-fed animals.The results indicate that vitamin E protection is necessary for the incorporation of C(20) and C(22) fatty acids into the tissues from the diet and that in the deficiency of vitamin E, a low level of autoxidation occurs in the tissues.

Comparitive study of monocarbonyl compounds formed during deep frying in different fats.

AbstractFresh commercial corn oil, fresh commercial lard, and hydrogenated vegetable shortening were analyzed for carbonyl compounds before and after deep frying. The frying was carried out in an apparatus with a capacity for 2000 g of oil designed to quantitatively trap the volatile materials evolved during frying and which would ordinarily escape into the atmosphere. The trapped distillate was also subjected to carbonyl analysis.Analysis of the fats and distillates showed a carbonyl pattern in essential agreement with the classical autoxidation mechanism for the different fats, i.e., the typical alkanals, alk‐2‐enals, and alk‐2,4‐dienals. The pattern correlated generally with the fatty acid composition of the fats. Comparison of the concentrations of the monocarbonyl compounds in the fats before and after frying, and in their distillates, indicated that the deodorization process which accompanies frying is effective in preventing the accumulation of the more volatile compounds formed. The less volatile products, mainly deca‐2,4‐dienal, were not efficiently removed. Accordingly, it was observed that the oils containing higher proportions of linoleic acid contained more residual monocarbonyl compounds after frying.

Carbonyls in oxidizing fat. VII. A comparison of methods of isolating monocarbonyl compounds

AbstractComparison of quantitative methods for the isolation of aldehydes from lard oxidized at 23C showed an extreme sensitivity of precursors to isolation conditions. Differences existed in the quantity and class compositions of the monocarbonyl compounds isolated. Acid conditions caused considerable breakdown of alkanal and alk‐2‐enal precursors. Steam distillation (100C) released alkanals, alk‐2‐enals, and alk‐2,4‐dienals. The mild Girard T method apparently produced a small amt of alk‐2‐enals from precursors, but except in the initial stages isolated the lowest amounts of aldehydes. Complete evaluation of the method for isolation of free aldehydes was not possible because alkanals were released from precursors during the vacuum distillation procedure (50C). The Schwartz (dilute phosphoric acid), Girard T, and vacuum distillation methods isolated similar amounts of alk‐2,4‐dienals. Curious changes in relationships, possibly indicative of oxidation stages, were observed as autoxidation progressed.

Fractionation and Study of Compounds in Wood Smoke

SUMMARYHard‐maple sawdust was sifted on a con‐trolled‐temperature hotplate for smoke production. The acids, total phenols, and carbonyl compounds were determined on the steam‐volatile and non‐steam‐volatile portions of both whole smoke and the vapor phase. Most of the compounds in these groups were found to be steam‐volatile.Several steam‐volatile monocarboxylic acids and monocarbonyl compounds were isolated and identified from smoke. The C1–C10 acids were found to be present in whole smoke, with the C1–C10 acids occurring in the greatest concentrations. Only C1–C10acids were found in the vapor phase of the smoke. The following monocarbonyls were identified in the steam‐volatile portion of whole smoke: 2‐pentanone, valeraldehyde, 2‐butanone, butanal, acetone, propanal, crotonaldehyde, and ethanal. In addition, tentative identification of isovalderaldehyde and methanal was made on the basis of a comparison of chromatographic behavior and absorption spectra of the known and unknown compounds.

Food Flavor Changes, Relationship between Monocarbonyl Compounds and Flavor of Potato Chips

Food Flavor Changes, Relationship between Monocarbonyl Compounds and Flavor of Potato Chips

Linear elution adsorption chromatography : X. Electronic and steric effects in hetero-aromatic solutes. Separation of the di-aza-aromatics, quinones and related solutes on alumina

Hetero-aromatic solutes in which the hetero group is strongly adsorbing and forms part of the aromatic ring ( e.g. pyridine, fluorenone) are markedly affected in their adsorption on alumina by intramolecular electronic and steric effects. Crowding of the hetero group by adjacent solute groups in these compounds results in strong reduction of the hetero group adsorption energy. The presence of electron withdrawing substituents in the derivatives of the fluorenones, quinones, di-aza-aromatics and pyridines also reduces the adsorption energy of the hetero group; because the nitrogen atom in the aza-aromatics and the carbonyl group in the quinones are strongly electron withdrawing, the di-aza-aromatics are generally no more strongly adsorbed than corresponding mono-aza-aromatics, while the quinones are about as strongly adsorbed as corresponding mono-carbonyl compounds. The presence of two strongly adsorbing solute groups in adjacent positions, however, as in the ortho quinones and pyridazine derivatives, strongly increases solute adsorption energy, because both solute groupscan simultaneously bond with a single strong adsorbent site. Similar factors appear to determine the relative separability of the cis and trans azobenzene isomers. Using the theory of intramolecular electronic effects derived elsewhere from the study of organic reaction rates and equilibria, it is possible to quantitatively calculate the changes in solute adsorption energy which occur in the pyridines, di-aza-aromatics, fluorenones and quinones as a result of substituent electronic interactions. Electronic effects in other solute types are also examined theoretically, and concluded to be generally much smaller, with the exception of certain cases where the solute may function as either an acid or base. Less strongly adsorbing hetero-aromatic solutes ( e.g. thiophenes, furans) show similar, but smaller responses to substituent steric and electronic interactions.

Carbonyl Compounds in Salted Cod.: II. Separation and Identification of Volatile Monocarbonyl Compounds from Heavily Salted Cod

Volatile monocarbonyl compounds were isolated from heavily salted cod (Gadus morhua) as the 2,4-dinitrophenylhydrazones. These compounds were separated by thin-layer chromatography first into classes and then according to chain length. n-Alkanals C1–5 and n-alk-2-enals C5–6 were conclusively identified. n-Alkanals C8,10 and n-alk-2-enals C4,7,8 were tentatively identified. An unknown compound corresponding to n-hexanal, except in the melting point, was isolated. Formaldehyde, and to a lesser extent, acetaldehyde and propanal, were the major monocarbonyls present in salted cod.

Carbonyl Compounds in Salted Cod.: I. Thin-Layer Chromatography of Aliphatic Monocarbonyl 2,4-Dinitrophenylhydrazones

Methods are described for the separation of 2,4-dinitrophenylhydrazones of normal aliphatic monocarbonyl compounds by thin-layer chromatography. Magnesia-cellulose thin-layer plates are used to separate mixtures of these compounds into classes (n-alkanals, n-alkan-2-ones, n-alk-2-enals, and n-alka-2,4-dienal). Propylene glycol- and petrolatum-impregnated silica gel plates were also used to separate each class into homologues. The former impregnant resolved the compounds with less than seven carbons and the latter with more than six carbons. Two-dimensional separation was accomplished by resolving a mixture of these compounds into classes on magnesia-cellulose in the first dimension and the classes into homologues on either petrolatumor propylene glycol-impregnated silica gel plates in the second dimension.

Direct Quantitative Isolation of Monocarbonyl Compounds from Fats and Oils.

Direct Quantitative Isolation of Monocarbonyl Compounds from Fats and Oils.

Determination of the classes of free monocarbonyl compounds in oxidizing fats and oils.

AbstractSimultaneous equations were derived to distinguish and account for the major free monocarbonyl classes in oxidizing fats and oils. The procedure of Pool and Klose was modified to accommodate the equations. The procedure involves conversion of the free monocarbonyls to DNP‐hydrazones by passage of a benzene solution of the sample over an alumina‐DNP‐hydrazine reaction column. The alkanals, alk‐2‐enals and alk‐2,4‐dienals were measured by absorbance readings at 430, 460, and 480 mॖ of a benzene alcoholic‐KOH hydrazone solution. The average error of the procedure in the analysis of total carbonyls in authentic mixtures was 2.4%.It was found that the qualitative composition of the DNP‐hydrazones obtained from milk fat by the reaction column were identical to the volatile carbonyl fraction. Moreover, there was less than 5% difference in the volatile monocarbonyl content of milk fat and the quantity measured by the modified Pool and Klose procedure. The data suggest that the procedure affords a means of measuring volatile or free monocarbonyls of oxidizing lipids. Since the volatile monocarbonyls are directly related to flavor deterioration of oxidizing lipids, it would appear that the free monocarbonyls, as measured by the modified Pool and Klose procedure, should exhibit a corresponding relationship.

Identification of Volatile Unsaturated Mono-carbonyl Compounds evolved from Oxidation of Rape-seed Oil

The refined rape-seid oil was oxidized with dried air at 96°C, for 1224 hr. The volatile carbonyl compounds evolved were caught in two traps of 2, 4-dinitrophenylhydrazine solution. Hydrazone compounds were then passed through alumina column with benzene to collect only mono-carbonyl compounds. C6- and C8-unsaturated carbonyl compounds in this monocarbonyl compounds were separated with preparative paper-chromatography and re-crystalized. The constituents of these compounds were investigated by U. V., I.R.-spectra and paper-chromatography of oxidation product with ozone. As a result;1) The constituents of C6-unsaturated carbonyl compounds were CΔ : 26, CΔ : 36 and CΔ2 : 46.2) The costituents of C8-unsaturated carbonyl compounds were CΔ : 28, CΔ2 : 48 and trace CΔ : 58.

Studies on Carbonyl Compounds in Fatty Oils. VII.

To clarify the re-odorization mechanism, the refined rape seed oil was oxidized with dried air. The volatile carbonyl compounds were caught in a trap of 2, 4-dinitrophenylhydrazine solution, while the non-volatiles in the oil were extracted with Girard reagent to convert into 2, 4-DNPH compounds. These compounds were then passed through alumina column with benzen to collect only monocarbonyl compounds. Saturated and unsaturated mono-carbonyl compounds were determined by applying paper chromatography and ultra-violet absorption spectrum analysis with the following results : 1) C4 and C6 aldehydes covered over 70% of the volatile carbonyl compounds and over one half of the C8 and C10 components was consisted of unsaturated compounds.2) The non-volatile carbonyl compounds contained more saturated ones compared with the volatiles.

Carbonyls in oxidizing fat. V. The composition of neutral volatile monocarbonyl compounds from autoxidized oleate, linoleate, linolenate esters, and fats

AbstractThe steam volatile monocarbonyl compounds in mildly autoxidized esters of oleic, linoleic, linolenic acids, and animal and vegetable fats were quantitatively estimated. The major aldehydes in oleate and linoleate were those that might be expected from the scission of reported monomeric hydroperoxide isomers. The predominance of hept‐2,4‐dienal and propanal in linolenate suggested that the major monomeric hydroperoxides were 12‐and 16‐hydroperoxy conjugated dienoic isomers. The number of minor aldehydes increased with degree of unsaturation of the fatty acid. The amounts of monocarbonyl compounds in the fats examined generally agreed with their average fatty acid composition. Appreciable amounts of heptanal in lamb and beef fat and heptanal and decanal in butterfat, under the conditions of oxidation, could not have come from the three unsaturated acids. Heating at 165ŶC. in all samples increased the proportions of the most unsaturated major aldehydes.

Autoxidation of Fish Oils. I. Identification of Volatile Monocarbonyl Compounds from Autoxidized Salmon Oila, b, c

SUMMARYIsolation and identification of a number of volatile monocarbonyls from autoxidized salmon oil were accomplished. The carbonyls, volatile by vacuum steam distillation, were reacted with 2,4‐dinitrophenylhydrazine. The 2,4‐dinitrophenyl‐hydrazones were separated by partition and paper chromatograpy. Spectrophotometric analyses and melting‐point determinations were made. The data show that, in addition to malonaldehyde previously reported, positive identification was made on 15 monocarbonyls: the C2, C3, C5, C6, C7, C8, and C9 alkanals; the C3, C4, C5, C6, C8, C9, and C10 2‐enals; and hept‐2,4‐dienal. Tentative identification of butanal, dec‐2,4‐dienal, and undec‐2‐enal was based upon a comparison of chro‐matographic behavior and absorption spectra of the authentic with the unknown. The isolated ketones, tentatively identified as 2‐hexanone, 2‐octanone, 2‐nonanone, and 2‐decanone, were characterized by the preceding methods and by their behavior in alcoholic potassium hydroxide. Five additional compounds of unknown identity were isolated; three provided sufficient material for melting‐point determinations. Including the forerun, at least 28 carbonyls were found in the volatile portion of rancid salmon oil.

Autoxidation of Milk Lipids. I. Identification of volatile Monocarbonyl Compounds from Autoxidized Milk Fat

Summary The C 1 through C 10 n-alkanals, the C 5 through C 11 alk-2-enals, and acetone were conclusively identified as 2,4-dinitrophenylhydrazones, from the volatile material of milk fat oxidized to a TBA No. of 15 and a peroxide value of 14.3. In addition, presumptive evidence is presented for the identification of but-2-enal and the odd-numbered C 5 through C 15 n-alkan-2-ones. Approximately 63% of the isolated monocarbonyl compounds were n-alkanals and 34% alk-2-enals. The possible origin of the identified compounds, their role in the oxidized flavor of milk fat, and the relationship of the results of this paper to the findings of other workers are discussed.

Some effects of ionizing radiations on lipids. I. Monocarbonyl production in vegetable oils

Summary and ConclusionsIrradiation of refined vegetable oils by high‐energy cathode rays resulted in the production of monocarbonyl compounds. The yield was about 0.2 µM per gram per 106 rep. for doses up to about 107 rep. Some of the products were themselves sensitive to the radiations, and the net yield was dependent upon a function of the concentrations and reactivities of the precursors and of the end‐products.Concurrently with the formation of the monocarbonyls there was an attack on the conjugated triene systems in the media and an increase in ultraviolet absorption in the 225–240 mµ region. However the irradiation products resulted from other mechanisms in addition to those involving the trienes.Irradiation under reduced temperature or in vacuum or with the addition of antioxidants did not decrease the yield of monocarbonyl compounds. However the use of a vacuum and the inclusion of antioxidants were partially effective in reducing the irradiation attack on triene groups.The net yields of monocarbonyls were dependent upon the concentrations and sensitivities of the products as well as of their precursors. Thus, although methods commonly successful in inhibiting oxidations of oils did not reduce these yields, they did suppress some irradiation‐induced reactions, particularly those involving unsaturated compounds. In this respect their action was similar to that which has been demonstrated in inhibition studies of antioxidations in oils.

Chromatographic Separation of Aliphatic Monocarbonyl Compounds.

Chromatographic Separation of Aliphatic Monocarbonyl Compounds.

Estimation of monocarbonyl compounds in rancid foods

SummaryA convenient method for the determination of monocarbonyl compounds in rancid foods is described. The quantitative procedure is based on the formation of the 2,4‐dinitrophenylhydrazones of monocarbonyl compounds in benzene solution, the removal of excess hydrazine reagent and the hydrazones of dicarbonyl compounds with alumina, and the colorimetric determination of the remaining hydrazones of monocarbonyl compounds in alkaline solution. Applicability to aldehydes varying in molecular size and degree of unsaturation has been demonstrated. The method may be used on the crude benzene extracts of rancid foods. Illustrative data are presented.

Action of Vitamin K1 on α-Amino-Acids

THE term Strecker degradation has been coined1 for the degradation of α-amino-acids into aldehydes or ketones containing one less carbon atom by the action of carbonyl groups (for example, phenyl amino-acetic acid → benzaldehyde). Mono-carbonyl compounds are unable to bring about this degradation; at least two carbonyl groups must be present in an agent which can effect it, and the carbonyl groups must be parts in the grouping CO.(C=C)n.CO. (I), where n = 0 or an integer ; at least one carbonyl group must be aldehydic or ketonic. The mechanism of the Strecker degradation may be illustrated as follows: