Principles and applications of GABA Generators
by Houqing Liu, Manager, Grain Analysis Office, Satake Manufacturing (Suzhou) Co, Ltd, People's Republic of China
In the 1980s, researchers from Japanese Ministry of Agriculture, Forestry and Fisheries, private companies and universities jointly developed a technique for producing germinated brown rice enriched with GABA (γ-aminobutyric acid) and conducted a series of animal tests and human clinical experiments.
As a result, it was clarified that when germinated brown rice containing natural GABA was used for a long period of time, it was effective in suppressing the increase of blood pressure, and that it had an alleviation effect on menopausal syndromes, presenile psychiatric disorder, and psychiatric stress, etc. Functionality and safety of germinated brown rice were confirmed by animal studies and clinical studies.
At first, the GABA enrichment process imitated the germination process of seed rice and the product was named 'germinated brown rice'. However, this method required a sterilisation and a drying step after the germination treatment because of the longer germination time, the fermentation odor produced, and the propagation of bacteria.
Furthermore, the method of processing of germinated brown rice lost the original taste of rice, making it difficult for consumers to accept it as a food product. Additionally, observed were problems such as loss of nutritional components along with the wastewater during germinating, energy consumption during drying, longer production time, and deterioration of taste quality.
Based on the above problems, Satake developed a new-type functional rice manufacturing technology and its equipment, which combined functionality and taste. The principle is to break down the dormant aspect of the germ by combined action of water and temperature under low water content, and to 'kick start' the vital activity to germinate, thereby promoting the biochemical reaction. The result was that a variety of amino acids were isolated while GABA was produced, and in particular, the content of essential amino acids increased by more than double. Rice enriched in both functional and natural nutrients was ready.
In the manufacturing process of GABA rice, first, rice paddy of about 15 percent moisture content (W.B.) is humidified to about 19 percent. When humidified, constant temperatures are applied to activate the GADs and promote the formation of GABA. Next, the paddy is dried to 15 percent to retain the resulting GABA.
The sequence of steps is completed in the same equipment. When enriched from paddy, the enrichment and drying are completed in about 10 hours. The configuration of this process is as follows.
Humidification and GABA formation
Rice paddy (about 15% moisture, germination rate over 90%) are humidified with humid air. During the humidification process, the rice germ absorbs water first. After the moisture in the germ increases to a certain point, thermal stimulation is used to activate the enzyme (GAD). Followed by repeated thermal stimuli, the GULs contained in the germ generates GABA with reaction of GAD.
Transfer of components
During the process of humidification, there is a large structural difference between the germ and endosperm. The germ is mainly composed of fibres and has a well water-absorbing structure. On the other hand, the endosperm is composed of relatively dense reconstituted starch and has a structure of poor water absorption.
When humidified, there is a large moisture difference between the germ and the endosperm. At the same time, GABA is a water-soluble, and the generated GABA immediately dissolves in water, and moves into the endosperm, based on the potential energy and concentration of water due to the moisture difference. The formation and transfer of the GABA takes place simultaneously and successively prior to drying.
Before the biochemical reaction is completed, drying is carried out to drop the paddy moisture to around 15 percent. At this time, the change in moisture, the biochemical reaction, and the transfer of components are all stopped.
Rice GABA enriched by the wet-air method retains 70-80 percent of the GABA in the endosperm even after the rice milling. This milled rice has very similar taste, if not better, compared to regular white rice, yet contains more than 10 times the GABA.
Furthermore, the GABA enrichment equipment is capable of enriching not only rice, but also beans and grains such as barley and wheat. For example, the GABA content after enrichment of the soybean with Satake's equipment is approximately four times or more than that of the original rice. Intake of sufficient amounts of GABA to have a pharmacological effect may be easily achieved through a diet combining GABA enriched rice and beans.
For any type of functional food, it is most important that one eats it regularly as a part of a normal diet. Satake's GABA generator opens the possibility of turning many different varieties of foods that people are all familiar with such as rice, beans and grains, into foods that are nutritiously functional.