Organic Acid and Carbonhydrate Changes in Carrot and Wheat Bran Fortified Set-Type Yoghurts at the End of Refrigerated Storage

Abstract

The effects of using of wheat bran (1%), carrot (1%) and wheat bran (1%) +carrot ( 1%) as a supplement on pH, organic acids, carbohydrates and viscosity of yoghurt as well as overall acceptability were investigated. Fortification of milk with wheat bran resulted in a significant ( P<0.01) increase in oxalic, orotic, pyruvic, lactic, formic, acetic, propionic and hippuric acid contents, and a decrease in total sugar content of yoghurt. The lowest level of total organic acid and a slow post acidification rate were observed for yoghurt made with carrot which was much more prefered by panelists at the end of refrigerated storage. Fortification also led to an increase in viscosity of yoghurts. At the end of storage, there was a significant (P<0.05) increase in viscosity of control yoghurt, whereas fortified yoghurt did not any change. Increases in lactic acid (from 9084 to 10823 mgkg-1) and formic acid (from 665 to 802 mgkg-1) contents of control yoghurt resulted in a significant (P<0.05) decrease in overall acceptability score (from 7.5 to 6.2). It was concluded that yoghurt samples with wheat bran ( 1%) and wheat bran ( 1%) +carrot ( 1%) had the highest total organic acid content (about 14200 mgkg-1) and titratable acidity (about 1.85% as lactic acid) were received the lowest overall acceptability score ( 5.6 out of 9) by panelists.