Method for producing a rosebay willowherb beverage with a high gamma-aminobutyric acid content

A method for producing rosebay willowherb tea beverage having a gamma-aminobutyric acid (GABA) content, comprising:

• freezing a first raw material comprising rosebay willowherb leaves at a temperature of from −45° C. to 0° C. or cooling the first raw material to a temperature below a dewpoint to produce a first raw material plant mass;
• heating the first raw material plant mass up to a temperature of 15-25° C. to produce a second raw material plant mass;
• grinding the second raw material plant mass to produce a third raw material plant mass;
• treating the third raw material plant mass with an aqueous solution of vitamin B6 in an amount of 0.10-0.25 g of vitamin B6 per 1 kg of the third raw material plant mass and additionally treating with either an aqueous suspension of glutamic acid in an amount of 6.4-10.6 g of glutamic acid per 1 kg of the third raw material plant mass or a salt of glutamic acid solution selected from a group consisting of:
• a sodium, potassium, magnesium, calcium, ammonium, lithium, and zinc salt of glutamic acid in an amount of 6.4-10.6 g of one of said sodium, potassium, magnesium, calcium, ammonium, lithium and zinc salts per 1 kg of the third raw material plant mass to produce a fourth raw material plant mass;
• fermenting the plant mass at 22-40° C. for 2-10 hours to produce a fifth raw material plant mass;
• and
• drying the fifth raw material plant mass at 30-55° C. for 6-12 hours to produce a final product,
• wherein a content of vitamin B6 in the aqueous solution of vitamin B6 is 0.5%-1% in mass percentage, and a content of glutamic acid in the aqueous suspension of glutamic acid is 5% in mass percentage, and a content of the salt of glutamic acid in the aqueous suspension is 20-25% in mass percentage.