Sep 21th, 2020

By Carl

1. What is the half-solid fermentation?

The half-solid fermentation mainly has two processes. Generally, there are 1~3 days for solid fermentation and then to liquid fermentation. Above all, most period of this process is liquid state from days to months. Because of the solid state, We called it half-solid fermentation. Most of time, people add some water to change the fermentation state from solid to liquid.

The chosen of material is diversity to half-solid fermentation. Actually, in most areas, rice is the main material to make spirit with half-solid fermentation.

2. Where the half-solid fermentation used in?

Many kinds of distilled spirit is produce by half-solid fermentation.

China: rice wine and rice spirit are two kinds of alcohol beverage that brewing by half-solid fermentation.

Japan: shochu is more and more popular than sake.

Vietnam and other Southeast Asian countries: the rice spirit fermentation workshop covers most of the country. Even some vodka in Vietnam is brewing by this fermentation process.

3. the main microorganisms in half-solid fermentation process

There are two main kinds of microorganisms in half-solid fermentation process.

a. Mould fungi

1.Rhizopus

Rhizopos is a core microorganism in this process. Its main work in this process is to produce enzymes like glucamylase. These basic enzymes insure the nutrition for all the organisms and the materiel for the alcohol fermentation.

Most of areas that did this fermentation use Rhizopus, like in south of China, Vietnam and other southeast Asian countries.

2.Aspergillus

This kind of organism is mainly used in Japan for sake and chochu, and in China for rice wine. For most of time, the aspergillus is used for non-distilled alcohol beverage, but the whole process is also half-solid fermentation process. Its function is the same as rhizopus.

b. Yeast

Yeast is a single cell organism which does all the magic in alcohol production. Yeastfeeds on the sugars in the mash for spirits and produces Ethyl Alcohol . Yeast plays a major role in Alcohol Production.

4. how the half-solid fermentation works

The whole half-solid fermentation process can be divided into two parts. The solid state part and liquid state part.

The purpose of these two part is different. In fact, the solid state create a good condition for microorganism’s growth. At the beginning of solid state, the number of microorganism such as mould and yeast is very low. and with the solid fermentation goes on, the number of microorganism is much more growth, and the enzyme is be produced a lot at the same time. We can say that the whole solid fermentation is a preparation for the next fermentation part.

Generally, after adding water , the liquid fermentation started. It is easy to understand the liquid fermentation part, because all the things are the same. There are kinds of enzymes to degrade the starch and protein to glucose and amino acid which is the main materiel for alcohol and flavor bioreaction. At the same time, the yeast has been growth in plenty, all its work is to change the glucose into alcohol, and release some flavor at the same time. When the liquid fermentation finished, the whole half-solid fermentation is done, and the mash can be distilled.

*Common half-solid fermentation process and control points