Peroxide value

The US. Pharmacopeia (USP XXII) or National Formula (NFXVII) (20) also provide a similar description however, the peroxide value is not defined (Table 9). These specifications are also given in the Handbook of Pharmaceutical Excipients (HPE), pubhshed jointiy by the American Pharmaceutical Association and The Pharmaceutical Society of Great Britain (21), which defines lecithins both from plants and eggs. The Merck Index (22) specifies a slightiy lower acid value. The Japanese Monograph (ISCI-II) (23) specifies a slightiy lower acetone-insoluble matter and a lower heavy-metal content. 

The desked characteristics of a fat or oil used in imitation dairy foods are bland flavor, low peroxide value and good flavor stabiUty, low level of free... 

At this point, the problem of measurement of rancidity would appear to be relatively simple, in that one would merely determine the peroxide value at arbitrary intervals, and at a given point the sample would be considered rancid. This paper points out some of the difficulties involved in such a procedure from the standpoint of obtaining useful data. 

Dopamine, a strong water-soluble antioxidant, was identified in banana fruit (Musa cavendishii) by Kanazawa and Sakakibara (2000). Banana fruit contained high levels in the pulp and peel 2.5-10 mg/100 g and 80-560 mg/100 g, respectively. A banana water extract was reported to suppress the autoxidation of linoleic acid by 65-70% after a 5-day incubation in an emulsion system, as determined from peroxide value and thiobarbituric acid reactivity (Kanazawa and Sakakibara 2000). 

Iodine liberation is one of the oldest and most commonly used methods for assessing lipid substrate oxidation. In this method, hydroperoxides and peroxides oxidize aqueous iodide to iodine, which is then titrated with standard thiosulfate solution and starch as endpoint indicator. The peroxide value is calculated as milliequivalents of peroxide oxygen per kilogram of sample. 

This method is relatively easy to use for anhydrous systems, but not for emulsions, foods, or biological media where the presence of water is detrimental. The method has been applied for determining antioxidant activity of both individual natural polyphenols and vegetable extracts. Methods based on this one have been used to evaluate the peroxide value in walnuts (Wilson-Kakashita and others 1995), mango seeds (Joseph 1995), almonds (Uthman and others 1998), and coconut cream powder (Yusof and others 2007). 

The thiocyanate method involves measurement of the peroxide value using linoleic acid as substrate and has also been widely used to measure the antioxidant activity in plant-based foods such as ginger extracts (Kikuzaki and Nakatani 1993), fruit peels (Larrauri and others 1996 1997), extracts from vegetable by-products (Larrosa and others 2002 Llorach and others 2003 Abas and others 2006 Peschel and others 2006), blueberry juice, wines, and vinegars (Su and Chien 2007). 

Apart from specifications as to origin, e.g. palm kernel oil, fats are normally supplied on the basis of established parameters. One of these is the iodine value. This reflects the tendency of iodine to react with double bonds. Thus, the higher the iodine value the more saturated the fat is. An iodine value of 86 would approximate to one double bond per chain, while an iodine value of 172 approximates to two double bonds per chain. Another parameter is the peroxide value. This attempts to measure the susceptibility of the fat or oil to free radical oxidation. The test is applied on a freshly produced oil and measures the hydroperoxides present. These hydroperoxides are the first stage of the oxidation process. Obviously, this test would not give reliable results if applied on a stale sample. 

Peroxide value Not greater than 0.02 (milli-equivalents of oxygen per kilo... 

This specification is for butter oil, which is butter with the water removed. The free fatty acid limit is to detect lipolytic rancidity while peroxide value specification is to limit oxidative rancidity. The copper limit arises because copper catalyses the oxidation of fats. The absence of neutralising substances is to prevent a high titration for free fatty acids being covered up by the addition of alkali. 

Peroxide titanate complexes, 25 98 Peroxide value, 20 827 in soap making, 22 736 Peroxidic compounds, 25 42 Peroxoborates, names, CAS numbers, and IUPAC names of, 18 398t Peroxocarbonates, 28 401 Peroxo compounds, 28 392-393, 397 Peroxodisulfate ion, 28 408 Peroxodisulfates, 28 392, 408-410 Peroxodisulfate salts, 28 418 uses for, 28 408-409 Peroxodisulfuric acid, 28 407 408 Peroxohydrate(s), 24 40 28 411—415 of melamine, 28 415 stabilization of, 28 413 Peroxo molybdate complexes, 2 7 22 Peroxomonophosphate ion, 28 403 Peroxomonophosphoric acid, 28 403 Peroxomonosulfates, 28 406 407... 

Peroxide value General quantitative measure of peroxides or hydroperoxides produced by oxidative degradation 0... 

The peroxide value measurement is a general quantitative measure of peroxide/hydroperoxide intermediates produced during oxidative degradation. 

Results for the hydroxyl value determination were inconclusive the precision of the method and the normal range of results for receipts of EO were not significantly different. Combined with the finding of zero for the peroxide value, the oxidation hypothesis seems less likely. Moisture content and pH results were more interesting. Normally, pH readings on the ethoxylate were above 10. The moisture values were somewhat above typical values. These two results do not really support or refute the hypothesis of EO oxidation, but when solving a problem, any unusual or unexpected results are noteworthy. 

In Table 21.2 and on page 808, it is stated that the peroxide value was determined to be zero. Why is this incorrect ... 

An important consideration for quality control in industry and commerce relates to the trend of developing faster analytical methods than those described in official sfandards the question in such cases is whether a proposed method is acceptable as replacement for the standard. This problem relates to the concepts fitness for purpose and measurement uncertainty, the latter serving for the estimation of the LOD and LOQ parameters of analytical quality. An example of this dilemma relating to the peroxide value is discussed in Section IV.B.5. 

Active carbon, hydrogen peroxide determination, 638 Active oxygen see Peroxide value ACV see Acidity value... 

Butter, peroxide value, 658, 660, 665 t-Butyl alcohol, tetroxide formation, 740 t-Butyl cumyl peroxide air pollutant, 622 determination, 707 hydroperoxide determination, 685 t-Butyl hydroperoxide (TBHP)... 

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