ISSN 1330-9862 preliminary communication (FTB-2773) Chemical Composition and Rheological Properties of Set Yoghurt Prepared from Skimmed Milk Treated with

The aim of this work is to determine the impact of an enzymatic treatment on the fer-mentation and rheological properties of set yoghurt prepared from skimmed milk. Skim-med bovine milk was treated with horseradish peroxidase added at the level of 645 U per g of proteins in the presence (addition level of 7.8 mmol per L of milk) or absence of ferulic acid as a cross-linking agent, and used to prepare set yoghurt with commercial direct vat set starter culture. The evaluation showed that the treatment of skimmed milk with horse-radish peroxidase enhanced its apparent viscosity, and storage and loss moduli. The pre-pared yoghurt contained protein, fat and total solids at 3.49–3.59, 0.46–0.52 and 15.23–15.43 %, respectively, had titratable acidity of 0.83–0.88 %, and no significant difference in the compo-sition was found among the yoghurt samples (p>0.05). Compared to the control yoghurt, the yoghurt prepared from the milk treated with horseradish peroxidase had a higher appar-ent viscosity, storage and loss moduli and flow behavior indices, especially when ferulic acid was added. Yoghurt samples from the skimmed milk treated either with horseradish peroxidase only or with the additional ferulic acid treatment had better structural reversi-bility, because their hysteresis loop area during rheological analysis was larger (p<0.05). Key words: skimmed milk, set yoghurt, horseradish peroxidase, ferulic acid, rheological propertie