Date of Award:

1976

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Science

Advisor/Chair:

Von T. Mendenhall

Abstract

Many objective chemical tests have attempted to correlate with organoleptic evaluation of oxidative rancidity. Major chemical tests used to detect oxidative rancidity of lipids measure nonvolatile high molecular weight carbonylic substances which make no considerable contribution to rancid flavors. High molecular weight carbonyls are present at much greater concentrations than volatile low molecular weight carbonyls. Peroxides and other unknown substances also react in these chemical tests to give at best an empirical evaluation. A 3-methyl-2-benzothiazolinone hydrazone chemical test is proposed which corrected some deficiencies of earlier procedures, and was correlated with organoleptic evaluation of rancid turkey samples. The proposed test measures oxidative rancidity in terms of milligrams of acetaldehyde per kilogram of sample.

A comparison of the 3-methyl-2-benzothiazolinone hydrazone method with a widely used chemical test was conducted. The thiobarbituric acid test was selected because it is used most often as an indicator of rancidity. The thiobarbituric acid test values increased followed by a definite leveling off as formation of malonaldehyde reached a maximum even though rancid flavor continued to increase. The 3-methyl-2-benzothiazolinone hydrazone test measured a continuing increase of volatile aliphatic aldehydes as rancid flavor increased .

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