Comprehensive evaluation of microbiological and physicochemical properties of commercial drinking yogurts in Korea

Most consumers consider yogurt to be a healthy food because it contains probiotic microorganisms. Although a plethora of commercially produced yogurts exists, nutritional and functional aspects of the commercial yogurts have not been well characterized. In this study, the microbiological and physicochemical properties of popular drinking yogurts in Korea were extensively characterized. The viability of lactic acid bacteria, including lactobacilli and bifidobacteria, varied between yogurt samples. These lactobacilli and bifidobacteria showed effective antimicrobial activities against foodborne pathogenic bacteria. Unlike the titratable acidity and pH, the soluble solids content varied between yogurt samples. All the yogurt samples contained high levels of potassium (average 143.53 mg/100 g) and calcium (average 133.92 mg/100 g), as well as phosphorus and sodium. Lactose, fructose, and glucose were the major sugar components in most yogurt samples, whereas the levels of sucrose and maltose were relatively low. Among several organic acids analyzed in the yogurt samples, lactic acid (average 767.67 mg/100 g) and citric acid (average 170.91 mg/100 g) were the most predominant. Taken together, this study provides preliminary information about the nutritional and functional characteristics of commercially available drinking yogurts.