Tapai is a dish served mainly in East and Southeast Asia and the Philippines. It is made up of a starch like rice which has been fermented for days until it develops a sweet taste and the sugars have been converted into alcohol. Tapai Dolce is considered a treatment or dessert in many regions and can be integrated with other sweet foods such as coconut or dried fruit. Although the dish is usually made from glutinous rice, it can also be made from the fermentation of plain rice, cassava root, plane tree or sweet potatoes. Once completed, the Tapai is traditionally wrapped in banana leaves for storage or sale in a market.
One aspect of Tapai preparation that gives it a unique character is the fermentation process. Using a mix of bacteria, yeasts and molds, the starches in the food are converted into other forms, such as sugar and alcohol. This is most often done using a product known as ragi. Ragi is a piece of dry, uncooked rice that has been powdered and mixed with water and various other ingredients so that it can support yeast and bacteria, creating a dry, solid appetizer. The ragi is used by crushing it in the food to be fermented, transferring all the starter cultures that take place in it.
The types of foods used to make Tapai usually have a high amount of starches. This is because starch is what cultures use as food and which is converted to provide flavor. The food chosen, whether it is rice, potatoes or cassava root, is first cooked until it is soft and the natural elements inside have developed. After the food is cooled to room temperature, the ragi is added and the whole mixture is placed in a container, where it is left to ferment for three days or more.
Like Tapai ferments, sugars develop to make sweeter and also expel liquid that collects on the bottom of the container. The liquid is actually an alcoholic rice wine and the quantity produced is directly related to the quantity of starch in the food that is fermenting. The longer the fermentation is allowed to progress, the more alcoholic the Tapai will become. There is a point in the process of fermentation when the character of the food will change and cause the sweet taste to turn into a sour taste as some acids begin to dominate the mixture. Although some people find this desirable, others feel it means that Tapai has spoiled.