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Application of ultrasonic waves in bleaching of soybean oil and determination of time and temperature for ultrasonic bath
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R Abbasi *   , M Gharachorlo , M Ghavami , Gh-H Asadi |
| , royaabbasi63@yahoo.com |
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Abstract: (7916 Views) |
| Background and objective: So far there is no report in the literature on bleaching vegetable oils by using ultrasonic waves in Iran. The aim of this study was to bleach soybean oil by ultrasonic waves and attempt to reduce the temperature and length of time required for the bleaching process.
Materials and methods: Bleaching of the oil was carried out by adding 1% w/w acid-activated bleaching earth to the soybean oil sample, followed by operating an ultrasonic bath (150 W, 20 kHz frequency) at two temperatures (45 and 60 °C) for 10, 20 and 30 minutes. Several tests, including chlorophyll and carotenoid measurements, peroxide value, acidity, fatty acid composition (with GC), and induction periods measuring the resistance to oxidation were carried out on both the unbleached and bleached samples. The results were compared using a factorial design with random blocks with 3 iterations.
Results: Bleaching by ultrasonic waves could reduce the chlorophyll and carotenoid contents of the soybean oil to a desirable level, the magnitude of reduction being 94.5% and 74.4%, respectively, when the ultrasonic waves were applied at 60 °C for 30 minutes. The induction periods of resistance to oxidation increased due to a reduction in the peroxide value and uptake of peroxides in the bleaching earth. Finally, the bleaching process produced no noticeable changes in the acid value or the fatty acid composition.
Conclusion: Based on the findings, it can be concluded that ultrasonic wave treatment can be used as a safe method in bleaching vegetable oils without effecting their fatty acid composition.
Keywords: Bleaching, Ultrasonic Waves, Ultrasonic Bath, Soybean oil |
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| Keywords: Bleaching, Ultrasonic Waves, Ultrasonic Bath, Soybean oil |
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Full-Text [PDF 1479 kb]
(3749 Downloads)
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Article type: Research |
Subject:
Food Science
Received: 2013/09/18 | Accepted: 2014/02/19 | Published: 2014/07/27
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