Effects of Preheat on the Flavor and Texture Properties of Yoghurt Made of Reconstituted Milk

Abstract

Reconstituted milk replaced fresh milk has been applied in the production of yoghurt. The flavor compounds and texture profile analysis of yoghurt produced from reconstituted milk were investigated. Using SPME-GC-MS, 24 and 22 volatiles were found in reconstituted whole milk and reconstituted skim milk, while 32 and 28 volatiles were found in their yoghurt products, respectively. Levels of aldehydes, methyl ketones, alkanes olefinic aldehydes, ketenes in liquid milk and yoghurt increased with increasing the intensity of heat treatments. Two-Pentanone, 2, 3-butanedione, 2, 3-pentanedione, 3-hydroxy-2-butanone, ethyl butyrate and 2-octanone that were metabolized by starter culture organisms showed an opposite tendency. Principle component analysis for flavor impact compounds indicated that the main difference occurred among the treatments. On the other hand, firmness, adhesiveness, chewiness and viscosity of yoghurt increased with increasing the heat intensity, while springiness, cohesiveness and resilience decreased. There was a significant difference in the textural property between the reconstituted whole milk and reconstituted skim milk (p<0.05).