Impact of Ultrasound-Assisted Extraction on the Physicochemical Properties and Bioactive Compound of Crude Gac Seed Oil

Eo, Chai Chuen (2025) Impact of Ultrasound-Assisted Extraction on the Physicochemical Properties and Bioactive Compound of Crude Gac Seed Oil. Final Year Project (Bachelor), Tunku Abdul Rahman University of Management and Technology.

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Abstract

Gac fruit (Momordica cochinchinensis Spreng.) is valued for its nutrient-rich profile, yet its seeds are often discarded as agricultural waste, despite their valuable bioactive compounds. This study evaluates the efficacy of ultrasound technology in the extraction of oil and bioactive compounds from Gac seeds. It aims to assess the potential of utilising ultrasound-assisted extraction (UAE) to maximize oil yield and bioactive compound content in whole gac seed and gac kernel oil, offering a higher-performing alternative to the conventional Soxhlet method. The proximate composition of major gac seed parts (whole seed, kernel, and seed coat) was analyzed, along with the impact of the ultrasound temperature (30 oC, 40 oC, and 45 oC) on oil yield, extraction efficiency, total β-carotene content, physicochemical properties (peroxide value, p-anisidine value, free fatty acid, acid value, and colour). An in-vitro digestion study of UAE-extracted whole gac seed oil and gac kernel oil was also conducted. Increased ultrasound temperature significantly influenced oil yield, extraction efficiency, colour, total β-carotene content, and in-vitro digestion (p < 0.05). However, it also resulted in higher peroxide value, p-anisidine value, free fatty acid, and acid value, which could influence the oil’s stability. The optimal UAE extraction was achieved at a temperature of 40 oC using gac kernel oil yielding up to 54.68 % oil, 99.25 % extraction efficiency, total β-carotene content of 14.76 mg/ g oil, a peroxide value of 23.54 meq O2/ kg oil, p-anisidine value of 10.26, free fatty acid of 0.37 % (% oleic acid), acid value of 0.75 mg KOH/ g oil, L* value of 12.83, a* value of 13.20, b* value of 6.23, 95.05 % total oil release from gastric digestion and 89.96 % oil release from both gastric and intestinal digestion.