Enzymatic hydrolysis extraction and optimization of spray drying technology in processing instant longan powder

In order to establish the processing technology of instant longan powder，the uniform design was used to optimize the enzymatic hydrolysis extraction conditions for the total soluble solids(TSS) in dried longan pulp, and the response surface methodology was used to optimize the spray drying parameters. The results showed that using dried longan pulp (13.62% moisture content) as the material, extracted with pectinase and cellulose enzyme, pH3.1, enzymatic hydrolysis temperature 52℃, enzymatic hydrolysis time 160 min, pectinase addition 0.6‰, cellulose addition 0.15‰, the extraction rate of total soluble solids could reach up to 85.26%. When the content of total soluble solids reached 25%, maltodextrin(MD) was chosen as filler (MD:TSS, 0.8:1). Spray drying was conducted at hot air temperature of 185℃, hot air flow rate of 26.47 m3·h-1 and feeding rate of 0.20 L·h-1, and the yield of instant longan powder of 48.58% was obtained, with the moisture content of the instant longan powder below 5%. The longan powder had good color, flavor and solubility. Thus it can be concluded that it is possible to produce instant longan powder efficiently with the technologies of enzymatic hydrolysis extraction and spray drying.