Investigation of the effects of using natural flavors in different forms on the physicochemical and sensory properties of yogurts

Yogurt is one of the oldest fermented dairy products and has an important place in human nutrition due to its high nutritional value and positive effects on health. Today, changing consumer expectations and the increasing interest in functional foods have brought flavored yogurt production to the forefront. In this study, flavored yogurts were produced using natural strawberry and banana aromas in liquid and powder forms, and the effects of aroma form, aroma type, and concentration on yogurt quality characteristics were investigated. Within the scope of the study, pH, titratable acidity, fat, protein, dry matter, syneresis, viscosity, microbiological properties, aroma profile, and sensory characteristics were analyzed. With aroma addition, pH values ranged between 4.86–4.92, while titratable acidity increased to 0.720–0.754%. Fat content remained approximately constant at 3.5%, whereas protein content varied between 4.000–4.045%. Dry matter content ranged between 15.50–16.70% in liquid-flavored yogurts and 16.90–17.60% in powder-flavored samples. Syneresis increased during storage; in control samples from 3.94% to 6.90%, in liquid-flavored samples from 9.63–11.80% to 13.97–19.56%, and in powder-flavored samples from 13.72–16.53% to 20.20–30.26%. Viscosity values decreased from 2166 mPa·s to 1367 mPa·s. In sensory evaluation, liquid-flavored yogurts received scores between 2.7–4.5, while powder-flavored yogurts were scored between 3.5–4.1, with the highest acceptance observed at 1% concentration. Aroma profile analyses performed by SPME-GC-MS identified esters, ketones, alcohols, carboxylic acids, aldehydes, and terpenes. As a result, liquid aromas, particularly at 1% concentration, provided lower syneresis, more stable viscosity, and higher sensory acceptance. SPME-GC-MS analyses showed that liquid aroma forms preserved characteristic ester compounds more effectively, whereas acid and ketone compounds became more dominant in powder-flavored samples during storage.