ity should have a very low acid value, while crude oils or oils
which have been abused have greater quantities of free fatty
acids. The presence of significant quantities of free acids in an
oil will result in lowering the smoke point, an undesirable fea-
ture if the oil is to be used for frying purposes.

 Iodine Value.-The iodine value is the number of grams of
 12 absorbed per 100 gm of fat or oil, based on addition to carbon-
 carbon double bonds of the unsaturated fatty acids in the oil.
 The iodine value increases with increasing unsaturation of an
 oil and decreases with increasing melting point. Iodine value in-
 creases linearly with increasing refractive index, and this rela-
 tionship has been published for seed oils of the major citrus
 cultivars (24).
 Saponification Number.-This characteristic of seed oils is
 sometimes referred to as the Koettstorfer number, a term now
 in disuse. By definition, the saponification number is the milli-
 grams of potassium hydroxide necessary to saponify 1 gm of
 fat, and is a measure of the average length of the fatty acid
 chains attached to the glycerides in a fat. Generally, the sapon-
 ification value increases as the average molecular weight of the
 triglycerides in a fat decreases. For example, unusually high
 values are obtained from fats such as milk fat, coconut, and
 palm kernel oils, which have larger amounts of short chain fatty
 acids. Values for most citrus seed oils listed in Table 4 lie in
 the range of 185 to 200, although one report (12) gives an ab-
 normally high value for Bitter orange.
 Acetyl Value.-Most fats and oils contain only very small
amounts of hydroxy fatty acids. Hence the acetyl value, which
measures this property, is usually negligible, as in the case of
citrus seed oils.

 Reichert-Meissl Number.-By definition, this term is the
milliliters of 0.1 N alkali required to neutralize the volatile water-
soluble fatty acids distilled from 5 gm of fat or oil. The Reich-
ert-Meissl number is now obsolete and not useful for charac-
terization of most fats.
 Polenske Number.-This term is a measure of the milliliters
of 0.1 N alkali required to neutralize the volatile, water-insoluble
fatty acids distilled from 5 gm of fat or oil. Like the Reichert-
Meissl number, the Polenske number is obsolete; however, both
determinations can be used in differentiating butter from coco-
nut oil and for detection of adulteration of butter. Most oils,