Traditional Tunisian butter: Physicochemical and microbial characteristics and storage stability of the oil fraction

Physicochemical and microbiological characteristics, fatty acid composition and thermal stability of traditional Tunisian butter (TTB) were studied. Changes in microbiological and physicochemical parameters were monitored during storage at 4 and 10 °C. The physicochemical characterisation shows a fat level lower than 80% and a high value of water activity. The content of saturated fatty acid was higher (71.84%) than the unsaturated one (27.09%). The major fatty acids of butter samples were myristic, palmitic, stearic and oleic acids. During storage at 4 and 10 °C, the pH decreased and the titratable acidity increased. Counts of lactic acid bacteria exhibited relatively small changes upon storage, at 4 and 10 °C, whereas yeasts and moulds' counts increased irrespective of storage temperature. Effect of heating on some quality characteristics (absorption at 232 and 270 nm, peroxide value, free fatty acid content, viscosity, texture, colour and fatty acid composition) of traditional Tunisian butter oil (TTBO) has been investigated at 60 °C. Results show that TTBO was resistant to oxidation. All these characteristics consolidate the incorporation of TTB on food formulation.