Effect of portion size on long-term acceptability as affected by consumers' neophobia level: A case study on flavored green-tea drinks

The effect of portion size on long-term acceptability was examined in two types of novel green-tea drinks containing flavors (passion-fruit flavor or osmanthus flavor). The drinks were formulated by adding each flavor to green-tea infusion and served at 10 ± 2 °C. For passion-fruit drink, two groups of participants consumed either a small (15 ml) or a large-portion (75 ml) and rated their liking using 15 cm line scale over 10 sessions. For osmanthus drink, ad libitum protocol was added besides small and large-portion protocols. Repeated exposure led to an overall increase in liking of the drinks and the patterns of increase differed according to the portion size as well as the type of flavor. For the passion-fruit drink, the mean liking scores of large-portion group were higher than those of small-portion group throughout the sessions but the patterns of increase were not greatly different. For the osmanthus drink, more consistent increase in liking was shown in large-portion group than in small-portion group. The most rapid increase was observed in ad libitum protocol. However, an issue of uncontrolled amount of intake remains to be studied. It was also found that the liking of osmanthus drink of high-neophobic group showed gradual increase in large-portion protocol, whereas a significant increase didn't occur in small-portion protocol. From the result of this study, large-portion size of sample is recommended in long-term acceptability test of new food products.