Enrichment of soybean oil with β-carotene and lycopene from Gac (Momordica cochinchinensis Spreng) powder using ohmic heating and ultrasound extraction

Abstract

This study was carried out to enrich soybean oil (SBO) with carotenoids from Gac (Momordica cochinchinensis Spreng.) powder using ohmic heating-assisted ultrasound extraction (OH-AU). The oxidative stability during the 28-day storage period was also evaluated. The moisture content of the powder Gac powder samples was adjusted by adding deionized water to achieve a 30% wet basis, and then they were ohmically heated at two levels of electric field strength (E) (E = 100 and 200 V/cm) or microwave-heated at 300 and 600 Watts before ultrasonic extraction using SBO as a solvent. Commercial SBO and ultrasound extractions were used as controls. Maximum concentrations of β-carotene (46.27 µg/g) and lycopene (35.47 µg/g) were observed in the enriched oil from OH-AU (E = 200 V/cm), while the oil extracted by ultrasound without OH had the lowest concentration. The enriched oils from OH-AU at E = 100 and 200 V/cm showed lower L* and higher b* values. The antioxidant activity of OH-AU-enriched oil evaluated by DPPH scavenging activity and FRAP was also stronger than enriched oils without OH and SBO. The enriched oils from OH-AU showed higher oxidative stability with a lower peroxide value (PV) and thiobarbituric acid (TBA) over 28 days of storage. The FFA concentrations of enriched oils were less than 5% by the end of the storage period. This suggests that applying OH could assist the ultrasound extraction in enriching Gac carotenoids in vegetable oil. It was an effective alternative technique for preparing a functional oil with high oxidative stability.