The research is one of the few studies that look beyond the health benefits of green tea extracts and reports food formulation considerations for the polyphenols.
The potential health benefits of tea, which have mainly focused on green tea, have been receiving considerable levels of study, with scientists reporting a wide range of effects, including a lower risk of certain cancers, improved heart health, weight loss, and protection against Alzheimer's.
Wheat bread is a staple in the diet of millions worldwide, and the addition of green tea could be a suitable vehicle for tapping increasing consumer awareness of the extract.
"How much of the green tea catechins responsible for most of the sensory characteristics associated with bread quality as well as consumers' perception level is unknown at the present time," explained lead author Rong Wang.
The new research, published in the journal Food Research International, looked at the sensory aspects of bread formulated with green tea extract (GTE) at the levels of 1.5 and 5.0 g/kg flour. A panel of trained and untrained tasters analysed the resulting bread for brightness, porosity, hardness, stickiness, sweetness and astringency (dry, "mouth-puckering" sensation).
Wang and co-workers report that increasing GTE levels were associated with decreasing brightness and sweetness, which could be expected since polyphenols are bitter-tasting compounds.
On the other hand, hardness, stickiness and astringency increased with increasing GTE levels, leading the researchers to conclude that the threshold level of GTE was at 1.5 g/kg flour for brightness, hardness and stickiness, and 5.0 g/kg flour for astringency and sweetness.
The green tea extracts were not found to affect crumb porosity.
"Below the threshold value, both the product quality and sensory quality of GTE-fortified bread are not significantly compromised. Meanwhile the GTE-fortified bread is a functional food product with additional health benefits," wrote the researchers.
"This provides a good guide for those bread manufacturers who are to pursue the production of GTE-fortified bread."
Only recently the potential of green tea as a luxury flavour was reported by FoodNavigator.com. Japanese firm, Aiya, was at HIE in Frankfurt recently to promote its range of macha tea ingredients, which it believes has huge potential in a number of food categories.
The Japanese firm, which has its European head office in Vienna, was promoting macha primarily as a luxury tea flavour, or in other words a premium food and beverage ingredient.
Macha, which is used in Japanese tea ceremony and has been drunk for centuries, is different from traditional tea in that it is not infused but ground. It is also grown differently, and is notably more expensive.
Source: Food Research International (Elsevier)
Volume 40, Issue 4, Pages 470-479
"Comparison study of the effect of green tea extract (GTE) on the quality of bread by instrumental analysis and sensory evaluation"
Authors: R. Wang, W. Zhou, M. Isabelle