Effects of ultrasonication and thermal cooking pretreatments on the extractability and quality of cold press extracted rice bran oil

Abstract

This research investigates the effects of different extraction processes on the extractability and quality of rice bran oil. The extraction processes included hexane extraction (HE) as Control 1, cold press extraction (CE) as Control 2, ultrasonic pre-treatment combined with cold press extraction (UCE), and thermal cooking combined with cold press extraction (CCE). The results showed that oil extractability was positively correlated to ultrasonic power and duration; and to thermal cooking time. Meanwhile, the oil quality and ultrasonic intensity and thermal cooking period were inversely correlated. Specifically, the oxidative stability, and unsaturated fatty acids of short-period CCE oil were significantly higher than those of long-period CCE oil and higher-power and longer-duration UCE oil. Similar to HE and CE oils, oleic, linoleic, and palmitic acids were the dominant fatty acids in short-period CCE oil. Essentially, short-period CCE is optimal for rice bran oil extraction due to improved oil extractability and quality. Practical applicationsRice bran oil is an excellent source of unsaturated fatty acids and natural antioxidants. It also has many proven health benefits. There are two conventional production methods of rice bran oil:pressing and solvent extraction. While the pressing method achieves low oil extractability, solvent extraction could deteriorate the oil quality. This research, thus, proposes two chemical-free extraction techniques for rice bran oil that improves the oil extractability and preserves the oil quality: ultrasonic pretreatment combined with cold press extraction (UCE) and thermal cooking pretreatment combined with cold press extraction (CCE). The findings are expected to offer a possible solution to the extractability-quality challenges associated with the conventional extraction methods.

Optimized ultrasonic‐assisted extraction of papaya seed oil from Hainan/Eksotika variety

“…It was found that the specific gravity, refractive index, PV, AV, iodine value, TV, saponification value, and the content of free fatty acid of the oil extracted by UAE were significantly lower than those extracted by SE ( p < 0.05). However, the extraction methods did not make significant impact ( p > 0.05) on the fatty acid composition of PSO, or on the fatty acid compositions of sour cherry kernel oil (Samaram et al, ) and PSO (Phan, Junyusen, Liplap, & Junyusen, ).…”

Supercritical Carbon Dioxide Extraction, Antioxidant Activity, and Fatty Acid Composition of Bran Oil from Rice Varieties Cultivated in Portugal

“…The extraction of RBO is usually accomplished with solvent extraction techniques using hexane, whereas short chain alcohols such as ethanol and isopropanol have also been proposed for their greater safety (lower volatility, lower toxicity, lower risk of explosion) [12][13][14][15][16][17][18]. Solvent extraction assisted by microwaves and ultrasounds has also been employed [18][19][20][21][22] as well as hot or cold press extraction [22][23][24][25]. Following bran extraction, two products are obtained: crude bran oil as the main product, that is, typically, further refined (degumming, dewaxing, deodorizing) [26,27], and defatted rice bran as a by-product, that can be used as a source of dietary fiber [28] and protein [29,30].…”

Rice‐bran oil: An emerging source of functional oil

“…Additionally, oil extracted by this method has better nutritive properties, safety, efficiency, and chemical free end products which enhance the interest of cold‐pressed plant oils. Conventional methods have some drawbacks, that is, low extractability and deteriorate oil quality (Phan et al, 2019). For extracting RBO with improved quality, Phan et al.…”

“…For extracting RBO with improved quality, Phan et al. (2019) adopted a combination of ultra‐sonication followed by cold pressing to enhance the quality and extraction rate of RBO. This combination brought structural changes, fissures/cavities in the rice‐bran fractions which agrees with the findings of Kurian et al.…”