• Food Science of Animal Resources
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• v.39 no.5
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• pp.820-830
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• 2019

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.

• Korean Journal of Clinical Laboratory Science
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• v.47 no.2
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• pp.59-64
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• 2015

Lactic acid-producing bacteria such as Lactobacillus spp. function to ferment carbohydrates and produce ATP. Such Lactobacillus spp. are used for the production of commercial yogurts. Lactobacillus spp. are beneficial to the intestinal tract, and Lactobacillus acidophilus-containing yogurts have received considerable attention because of their preventive effects against early-stage cancer of the large intestine. In this study, lactic acid-producing bacteria were cultured from three different groups: commercial solid yogurt (for eating), commercial liquid yogurt (for drinking), and Lactobacillus acidophilus-containing yogurt. We first determined the optimum culture conditions for Lactobacillus spp. and then analyzed turbidity and pH in order to compare the growth abilities and lactic acid-production capacities among the groups. Finally, high-performance liquid chromatography was used to measure the lactic acid content in the culture supernatants, and the antibacterial activities against Staphylococcus aureus and Escherichia coli were compared among the three groups. The optimum culture conditions for Lactobacillus spp. were MRS medium at $25^{\circ}C$, for 24 h. The highest turbidity was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Similarly, the highest lactic acid production ability was found in L. acidophilus-containing yogurt, followed by liquid yogurt and solid yogurt. Culture supernatants from the three groups did not show any antibacterial activity towards S. aureus; however, supernatants derived from L. acidophilus-containing yogurt resulted in a 1.8 mm inhibitory zone against E. coli in a paper disk diffusion test. These results revealed the high level of lactic acid-production capacity and antibacterial activity in L. acidophilus-containing yogurt.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.863-866
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• 1994

This study was carried out to estimate aluminum contents of commercial beverage foods by atomic absorption spectrophotometer. The contents of aluminium in drinking yogurt, curd yogurt, fruit beverage, carbonated beverage, fruit canned food and commerical teas ranged from 161.667 to 173.333ppm 139, 300 to 293, 925ppm, 1.481 to 7.130 ppm, 1.803 to 6.026ppm, 4.600 to 7.053ppm 194.437 to 846.056 ppm, respectively.

• Applied Biological Chemistry
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• v.37 no.3
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• pp.143-147
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• 1994

Four samples of commercially manufactured yogurts (plain, drinking type) were purchased and evaluated their physico-chemical properties, buffering capacity. And the survival rate of lactic acid bacteria and their ${\beta}-galactosidase$ activity under the acidic conditions (in vitro) were investigated. The values of pH, titratable acidity, viscosity and viable cell counts of yogurts were $3.71{\sim}4.08$, $0.990{\sim}1.045%$, $256{\sim}3164\;cps.$ and $10^8{\sim}10^9\;cfu/ml$, respectively. The volume of 1.0 M-HCl required to reduce the pH of yogurt (50 ml) to minus 2 value was $3.58{\sim}4.33\;ml$. When commercial yogurts were incubated at $37^{\circ}C$ for 120 minutes under the acidic conditions (pH 3.5, 2.5, 1.5), the survival rates of lactic acid bacteria in yogurt were $3.5{\times}10^{-2}{\sim}3.6{\times}10^{-1}%$ at pH 2.5, $8.3{\times}10^{-5}{\sim}4.2{\times}10^{-3}%$ at pH 1.5, respectively, but there was no significant difference at pH 3.5. The remaining activities of ${\beta}-galactosidase$ were $9.4{\sim}36.2%$ at pH 2.5, $4.2{\sim}19.0%$ at pH 1.5, respectively. These results suggested that a significant number of lactic acid bacteria in yogurt might be destroyed in the hostile environment of the stomach, but ${\beta}-galactosidase$ activity from yogurt might be somewhat maintained probably due to the protecting effect by its cell wall and membrane.