It is possible to sell and give products at the event. But notice that you should ask for a separate permission to sell or give products that don’t go with the theme of the event (Helsinki Coffee Festival / Ice Cream and Chocolate Carnival).
The organizers of the event have the right to forbid selling the unappropriated products. The exhibitors have to take care of the permits and regulations related to the sold and given products are properly taken care of.
Companies that offer food product samples, need to submit a notification of temporary food sales. When selling only coffee or tea, this is not necessary. NOTE! The notification needs to be filled in the latest four (4) business days prior to starting the activities.
Information about submitting the notification here.
You can find information about fairs by the City of Helsinki that includes for example hygiene policy here.