The Study of Ultrasound-assisted Enzymatic Extraction of Oil from Peanut Seeds Using Response Surface Methodology

Abstract

The present study evaluates the suitability of ultrasound pretreatment in n-hexane solvent as well as enzymatic treatment with cellulase enzyme to extract oil from peanut seed powders. To optimize this process, the effects of ultrasonic time (0-70 min), cellulase enzyme concentration (0-2%) and pH (4-5.5) were investigated on peanut oil extraction yield (EY) as well as the quality attributes of the extracted oil containing total phenolic content (TPC), peroxide value (PV), and color parameters of L, a and b using response surface methodology (RSM). The optimum condition of ultrasound-assisted enzymatic extraction using n-hexane solvent (UAEE) was found as ultrasonic pretreatment time of 33.23 min, cellulase concentration of 1.47%, and pH of 4.61 before incubation process at temperature of 56°C for 120 min. Scanning electronic microscopy (SEM) represented considerable interspaces, holes and porous structure of peanut meal after optimal UAEE treatment compared to that after shaking incubation extraction using n-hexane solvent (SIE). It was found that the peanut oil extracted by optimal UAEE treatment had considerable high levels of L color parameter and TPC and significantly more EY and b color parameters than those extracted by SIE, ultrasound- assisted aqueous enzymatic extraction (UAAEE) and aqueous shaking incubation extraction (ASIE) treatments.

Practical applications: This paper describes an innovative oil extraction method of ultrasound-assisted enzymatic process using n-hexane solvent. This new extraction technique makes it possible to increase the extraction yield, total phenolic content and yellowness of extracted peanut oil. The results illustrated that ultrasound-assisted enzymatic extraction using n-hexane solvent method was a far more efficient extracting technique than the individual shaking incubation extraction using n-hexane solvent, ultrasound- assisted aqueous enzymatic extraction and aqueous shaking incubation extraction treatments and would be a promising alternative for conventional oil extraction techniques.

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