engleski

An improved spectrophotometric method for the determination of peroxide value in fats for chocolate production

Chocolates are confectionery products with contents of fat, predominantly cocoa butter. Along with cocoa butter, different cocoa butter equivalents can be used. During storage, oxidation of fats may occur and influence shelf-life of chocolate. Usually, iodometric titration is used for the determination of peroxide value. However, the spectrophotometric method, based on the ability of peroxides to oxidize ferrous ions to ferric ions, uses fewer chemicals and is faster compared to the titration method. The aim of this research was to evaluate if the spectrophotometric method can be used in routine analysis of peroxide value. Five types of fats used in chocolate production were examined: four different samples of cocoa butter and blend of vegetable fats. To determine the span of peroxide value, and to accelerate the increase of the peroxide value of fats, samples were kept in a ventilator oven at 98 °C until limit of spectrophotometric method was reached (conditions based on the Oven test). Before the experiment, the spectrophotometric method was validated and limits of detection and quantification were determined. For all analysed fats, samples were taken in regular intervals of storage and peroxide value was determined both spectrophotometrically and by titration. Results showed limits and advantages of the spectrophotometric method for peroxide value determination compared to iodometric titration. Results showed that spectrophotometric method can be used for determination of peroxide value of fats for chocolate production. Also, the resistance of non-deodorized cocoa butter to peroxide formation was recorded.

chocolate ; fat ; peroxide value ; spectrophotometric method ; titration

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