Glucosyl stevia composition

A process for producing a highly purified glucosyl stevia composition, comprising the steps of:

• adding starch into water to form a starch suspension;
• adding a mixture of α-amylase and CGTase into the starch suspension and incubating for about 0.5 to 2 hours at about 75-80° C., resulting in a liquefied starch suspension;
• inactivating the α-amylase by low pH heat treatment;
• cooling the liquefied starch suspension and adjusting the pH to about 5.5 to 7.0;
• adding freely soluble form of steviol glycosides into the liquefied starch suspension, resulting in a reaction mixture;
• adding a second batch of CGTase into the reaction mixture and incubating for about 12 to 48 hours at about 55-75° C.;
• inactivating the CGTase by low heat treatment;
• decolorizing the reaction mixture;
• cooling the reaction mixture and adjusting the pH to about 2.0 to 4.5;
• precipitating the unreacted steviol glycosides;
• separating the precipitated unreacted steviol glycosides crystal from filtrate;
• adjusting the pH of filtrate to about 5.5 to 7.0;
• removing impurities by contacting the filtrate with macroporous adsorbent resin and subsequently eluting adsorbed diterpene glycosides with aqueous ethanol to result in a glycoside-containing aqueous ethanol eluate;
• removing ethanol from the aqueous ethanol eluate, resulting in an aqueous eluate;
• and
• concentrating and drying the aqueous eluate to obtain the highly purified glucosyl stevia composition,
• wherein the highly purified glucosyl stevia composition comprises derivatives containing α-1,4-glucosyl residues attached to glycosidic residues of C13 position of steviol, and unmodified steviol glycosides.