Enhanced extraction of oleoresin from ginger (Zingiber officinale) rhizome powder using enzyme-assisted three phase partitioning

•Extraction of ginger oleoresin optimized by three phase partitioning.•Enzymatic pretreatment showed maximum yield of oleoresin.•Ultrasound pretreatment showed good yield with simultaneous separation of starch.•The effect of pretreatments was confirmed by SEM and FTIR.•The method required 4 h as compared to 12 h in conventional Soxhlet extraction.

Ginger (Zingiber officinale R.) is a popular spice used worldwide. The oleoresin consists of gingerols, shogaols and other non-volatiles as chief bioactive constituents. Three phase partitioning (TPP), a bioseparation technique, based on partitioning of polar constituents, proteins, and hydrophobic constituents in three phases comprising of water, ammonium sulphate and t-butanol, was explored for extraction of oleoresin and gingerols from dry powder. Parameters optimized for maximum recovery of gingerols and [6]-shogaol were ammonium sulphate concentration, ratio of t-butanol to slurry, solid loading and pH. Ultrasound and enzymatic pretreatments increased the yield of oleoresin and its phytoconstituents. Ultrasound pretreatment showed separation of starch in the bottom aqueous phase but is an additional step in extraction. Enzymatic pretreatment using accellerase increased the yield of [6]-, [8]-, [10]-gingerols and [6]-shogaol by 64.10, 87.8, 62.78 and 32.0% within 4 h and is recommended. The efficacy of the enzymatic pretreatment was confirmed by SEM and FTIR.