Polphenol, vitamin C, caffeine, protein, ash, free fatty acid and peroxide profiles of green tea-based yoghurts, Abiodun Olapade, Shamsideen Aroyeun and Ghanivah Ajibola
Purpose: To develop a new functional food incorporating green tea infusions into yoghurt.
Design/methodology/approach: The concentrations of green tea infusions used were 0.5%, 1.0%, 1.5%, 2.0% and 2.5% (v/v). Yoghurt was produced using standard methods. The effects of incorporating green tea in the formulation were studied by measuring the chemical parameters such as free radical scavenging activity, polyphenols, minerals, vitamin C, caffeine, pH, total soluble solids, titratable acidity and other proximate chemical compositions. The effects of adding green tea to yoghurt were also determined by measuring the free fatty acids and the peroxide values of the yoghurts stored for fourteen days under ambient storage. All measurements were done in triplicate. Sensory evaluation of the yoghurts was carried out by a panel of tasters comprising students of the food technology department of the University of Ibadan who are accustomed to consuming yoghurts.
Findings: The yoghurts contained 0.5-16.67 gGAE/100g of polyphenols which were significantly different with respect to concentrations (P<0.05). Significant differences also occurred in their radical scavenging activity, which fell between 8–22.2%. The peroxide values as well as the free fatty acid concentration of the yoghurts reduced as a result of the inclusion of green tea in the formulation after fourteen days of storage, which confirmed its bio-preservative properties. The mean caffeine content of the yogurts increased with the increase in concentration of green tea infusion. The pH value of the control yoghurt was 4.50± 0.12, while green tea incorporated samples ranged between 4.30 and 4.63. The taste became bitter, the colour became duller and overall quality became lower.
Practical implications: This paper shows that incorporation of tea in yoghurt can make a functional food capable of enhancing the health status of its consumers.
Originality/value: The development of this product can create good markets for tea farmers because it gives added value to green tea.
Keywords: Green tea, Yoghurts, Polyphenols, Health