Objective  To identify the off-flavor compounds of liquid by-product from processing purple potato granules using freeze-thaw method, and study the enzymatic deodorization effect.

Method  Changes of volatile components in partially processed samples, liquid by-product and γ-amylase hydrolysate were analyzed using head space solid phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS).

Result  Significant differences were found in the sensory flavor and volatile components during the process of freeze-thaw separation of purple potato granules. We identified 16(mainly aldehydes and alcohols), 27(mainly aldehydes, alcohols and phenols), 18(mainly aldehydes and terpenes), 33(mainly alcohols and phenols) and 39 (mainly aldehydes, alcohols, ketones and phenols) kinds of volatile compounds from fresh potato chips, steamed potato, thawed and mashed potato, separation liquid and γ-amylase hydrolysate, respectively. The key substance from fresh potato chips was 1-octen-3-ol leading to the earthy smell of separation liquid. The main substances formed in steaming process were cis-3-nonen-1-ol and indole leading to sour smell and irritant odor of separation liquid respectively. γ-Amylase hydrolysis effectively removed the three odorants in separation liquid and increased the contents of aroma components including benzadehyde, aldehyde, decyl aldehyde, lauryl aldehyde, damascene, carvacrol and heterocyclic compounds such as pyrazines, benzothiazole.

Conclusion  γ-Amylase hydrolysis can effectively remove the off-flavor of liquid by-product from purple potato granules.