Chemical and organoleptic properties of dried emulsions

Safflower oil was incorporated into a model emulsion system containing emulsifier, carbohydrates, antioxidants, and protein. Emulsions were spray dried and the dry powders were stored at 60 C. Their oxidation rates were measured by headspace gas analysis (Oxygen absorption and carbon dioxide generation); peroxide and carbonyl values also were run. Although these objective tests all gave good correlation with average flavor scores, results show that oxygen absorption was superior to others as an indicator of flavor deterioration. Stepwise, multiple linear regression analysis showed that oxygen absorption and carbonyl value gave an equation which can predict flavor scores with a high degree of accuracy.     

Study of lipid-protein interaction using pulsed NMR

Pulsed nuclear magnetic reasonance (NMR) measurements were made on freeze-dried emulsions containing fat and protein. It was demonstrated that this method can be used to determine the degree of lipid-protein interaction in the samples. Interaction is maximized near the isoelectric range of the protein, which supports the theory that hydrophobic interactions are predominant. Triglycerides and fatty methyl esters interact to nearly the same degree as do free fatty acids, which indicates that the carboxylate group plays a minor role in interaction. Degree of interaction increases when the emulsions are homogenized at higher pressures. There is an inverse relationship between interaction and foamability of the rehydrated emulsion suggesting that less protein is available for film formation after interaction. In addition, fat-protein interaction was shown to protect the protein from heat denaturation. These pulsed NMR measurements may represent an approach toward a better understanding of lipidprotein interactions in food systems.     

The reaction of picric acid with epoxides. II. The detection of epoxides in heated oils

A colorimetric method, based upon the reaction of the oxirane group with picric acid, was used to determine the epoxide content of heated vegetable oils. The picration method is particularly suitable for measuring small quantities of epoxide because it is much more sensitive than the common titrimetric methods, and it is not subject to interference from cyclopropene, conjugated dieneols, or α, β-unsaturated carbonyls. Thin-layer chromatography was used to separate mixtures of picrated, epoxidized methyl esters. Separation ofcis- andtrans-methyl epoxystearate, methyl epoxyoleate, and methyl diepoxystearate in a mixture of these four esters was achieved in this manner. The presence of saturatedcis- andtrans-epoxystearates and unsaturated epoxides was demonstrated in heated vegetable oils. Presented, in part, at the AOCS Meeting in Cincinnati, October 1965.     

A methodology to answer to individual queries : finding relevant and robust controls

Behaviormetrika - In this paper we present the guidelines for an estimation and inference method aimed to answer questions to databases about new potential entries. The idea is to classify the data...     

Applications of pulsed NMR to fatty emulsions

Pulsed NMR was used to measure solid fat content in oil-in-water type emulsions. The data obtained were useful in selection of optimum types and levels of emulsifiers for each system. By using a flow-through cell in the NMR magnet, the rate and extent of phase separation could be measured accurately. This approach provides a new, quantitative method to measure emulsion stability. Presented at the AOCS Fall Meeting in Cincinnati, September 1975.     

High temperature reactions of fats with amino acids

Heating of fatty esters with α-amino acids at temperatures above 150 C gave substantial yields of N-substituted amides. The reaction involves decarboxylation of the amino acid and displacement of the alcohol moiety by the amine which is formed. Decarboxylation is a ca. zero order reaction in which the ester group is involved directly. It is suggested that these observations are consistent with a concerted mechanism. Only the simple α-amino acids, which contain no additional functional groups, yielded significant amounts of N-substituted amides under these conditions.     

Methional as an antioxidant for vegetable oils

Brief heating of safflower oil with 1% by weight of DL-methionine at 200 C stabilized the oil to subse-quent autoxidation. Since this treatment also caused development of a strong cabbage-like aroma, it was difficult to follow the oxidation organoleptically. Measurements of oxygen absorption rate and per-oxide development confirmed that the heated oil was quite stable. The major product of the reaction between methionine and safflower oil, N(3-methyl-thiopropyl) linoleic amide, was found to be a pro-oxidant. There was evidence that methional (β-methylmercaptopropionaldehyde), formed by de-gradation of methionine, is the active antioxidant. Commercial methional contains significant quantities of a dimer and trimer, both of which were also found to have antioxidant activity. The dimer is a de-hydrated aldol condensation product whereas the trimer is cyclic, a substituted trioxymethylene. Meth-ional and its polymers have such strong objectionable odors, even at low concentrations in oil, that their usefulness as antioxidants may be very limited. Presented at the AOCS Meeting, New Orleans, April 1976.     

Analysis of lipids containing epoxy groups: The epoxy glycerides ofVernonia anthelmintica seed oil

Picration-TLC analysis ofVernonia anthelmintica seed oil shows that besides the known triglyceride of vernolic acid, it also contains two additional epoxy compounds. These were isolated by column chromatography and have been identified as the monoepoxy and the diepoxy triglycerides of vernolic acid by a rapid transmethylation-GLC micromethod. Lipase hydrolysis of these glycerides has shown that in the monoepoxy triglycerides the vernolic acid has marked preference for the 1,3-positions, while in the diepoxy triglycerides the 2-position is preferred.     

The reaction of picric acid with epoxides I. A colorimetric method

A colorimetric method has been developed for the analysis of epoxides by reaction with picric acid. Picric acid was found to be the best of several acidic chromophores in its reaction with epoxides. Despite a nonquantitative reaction, the product concentration is proportional to the original concentration, i.e., it follows Beer’s Law. The reaction variables were studied with methyl mono- and diepoxystearates, epoxidized cottonseed oil andVernonia anthelmintica oil. The general applicability of the method was demonstrated by reaction with butyl epoxystearate, styrene oxide, a number of 3-substituted propylene oxides and two commercial epoxy resins. Presented in part at the First World Fat Congress, Hamburg, Germany, in October, 1964, and at the AOCS Meeting in Houston, Texas, April 1965.     

Chemical and organoleptic properties of oxidized fats

Various commercial fats were oxidized at elevated temperatures, and the extent of off-flavor development was evaluated organoleptically. Objective test methods also were applied to these oxidized fats, and correlations were established between the data and flavor panel results. Good to excellent correlations were obtained with pentane values, oxygen absorption values, peroxide values, and the average flavor scores. Results with the benzidine and thiobarbituric acid spectrophotometric methods were unsatisfactory. The octanoic acid method was found to be too insensitive to be of value. An exception to the above observations was lard, in which case all of the objective test methods gave good correlations with the flavor panel data. Presented at the AOCS Meeting, New Orleans, April 1973.