After discovering that mixing green tea with yoghurt made it denser and darker, with a potent smell that affected the overall sensory quality and physical properties, inulin was measured into the yoghurt at 3%, 6% and 9% as part of a test to improve the eating experience.
Not only did it improve the yoghurt, inulin a type of dietary fibre, has several proven health benefits including helping to control diabetes, and aiding weight loss and it is good for digestive health.
The study was created by researchers at the University of Warsaw’s Institute of Human Nutrition Sciences where the assessment was carried out by ten trained experts who were made up of women also from the institute, between the ages of 35 and 53 with experience in profile assessment and yoghurt evaluation.
First the volunteers were asked to smell the yoghurts by slightly tilting the lids of the package and then after opening, the general appearance was assessed, by among other things, dipping a spoon and seeing how it looked and then how the consistency felt in the mouth as well as the taste, flavour, body and overall sensory quality.
In all cases, analysis of the yoghurt revealed a similar consistency – thick, compact, smooth, creamy and well-melting in the mouth and slightly viscous.
The taste and flavour were changed when the green tea was added making it sour and less sweet.
Once the inulin mixed through it significantly influenced the taste perception with the sweet taste becoming more pronounced and the sour taste less so.
The researchers said: “While many studies have been carried out on the effect of inulin addition on yoghurt quality to the best of our knowledge, no specific studies have been conducted on the effect of both infused green tea and inulin addition on sensory quality evaluated by a panel of experts.
“By using tea addition and infusion technology we can achieve a natural functional food, while the use of inulin as a prebiotic can increase both nutritional value by increasing the fibre content and the health promoting value. However, the question arises whether the product will also be attractive from a sensory point of view.”
The main objective of the project, they said, was therefore to investigate the influence of the addition of inulin while being assessed by the panel, and the physical properties tested instrumentally.
Bitter taste improved
Green tea is characterised by a bitter, floral, grassy or burnt leaf flavour which was one of the factors in making eating the yoghurt a less pleasant experience.
The results show that adding inulin, particularly at 9% increased the perception of sweet smell and taste and peach taste in yoghurt and reduced the perception of a sour taste. This increased the overall quality and the body of the yoghurt.
The lack of similar, detailed studies on expert evaluation of sensory quality of yoghurts with infused tea and the inulin addition makes comparing the results difficult but it does point to a new research area being addressed.
Published online: doi.org/10.3390/foods11040566
‘The Sensory Quality and the Physical Properties of Functional Green Tea-Infused Yoghurt with Insulin’
Authors: Katarzyna Swiader and Anna Florowska