In‐situ alcoholysis of soybean oil with methanol, ethanol,n‐propanol, andn‐butanol was investigated, as well as the extraction of the oil with these solvents, to explain the progress ofin‐situ alcoholysis and to determine the parameters that affect this reaction. Because methanol is a poor solvent for soybean oil, the amount of oil dissolved in methanol and converted to methyl esters was low afterin‐situ alcoholysis. Ethyl, propyl, and butyl esters of soybean fatty acids could be obtained in high yields fromin‐situ alcoholysis of soybean oil with these alcohols.In‐situ alcoholysis proceeded through dissolution and alcoholysis of triglycerides successively, and the overall reaction rate was determined by the extraction and alcoholysis rates. The parameters, affecting yield and purity of the product esters, were mainly those that favor extraction rate.
The influence of specific factors on in situ methanolic esterification of rice bran oil (RBO) using sulfuric acid catalyst was investigated. Using high-FFA rice bran was found to be the most effective means to increase methyl ester yields. The ester content of the extract increased about 67% when the FFA content of oil was increased from 16.6 to 84.5%. Increasing the reaction time beyond 30 min did not affect yields. Increasing the temperature from 20 to 65°C elevated the FAME yield by about 30%, but increasing the amount of acid catalyst above 5 mL did not enhance yield, and increasing the methanol dose from 200 to 250 mL had a negligible effect.Paper no. J10128 in JAOCS 79, 611-614 (June 2002). KEY WORDS:Esterification, fatty acid, fatty acid methyl esters, in situ esterification, rice bran, rice bran oil. FAME are used, rather than FA, to produce a number of FA derivatives such as fatty alcohols, alkanolamides, α-sulfonated methyl esters, and sucrose esters because FAME are more stable, less corrosive, and more easily fractionated (1). Methyl esters have recently been used as a diesel additive and clean energy source in Europe (2) but are currently not competitive with diesel fuel prices. However, relatively inexpensive raw materials such as soapstock, agricultural wastes, tallow, and high-FFA-containing greases are being used, which may reduce production costs (3-5). In this study, factors affecting FAME production from rice bran oil (RBO), an inexpensive rice co-product, were investigated. Production costs may be further reduced by in situ esterification, i.e., simultaneous oil extraction and methyl esterification. In situ esterification was first performed by transesterification of sunflower seed oil with acidified methanol, and it resulted in a significant methyl ester yield (6,7). High-acidity oils, such as rice bran oil (RBO), can readily form FAME during extraction (8), and methanol acts as both an extraction solvent and reagent to produce FAME. In our first paper (8), we described in situ esterification of high acidity RBO with methanol and ethanol using an acid catalyst, and ester yields depended on the RBO FFA content. Esterification with ethanol did not produce pure esters, as did methanol esterification. This was probably due to the higher solubility of oil components in ethanol than methanol and thus the greater amounts of nonreacted substrate. In a second study (9) we investigated in situ alcoholysis and extraction of soybean oil with methanol, ethanol, n-propanol, and butanol. Ethyl, propyl, and butyl esters of soybean FA could be obtained in high yields from in situ alcoholysis of soybean oil with these
Extraction and in situ esterification of rice bran oil with ethanol were investigated by studying the effects of rice bran oil FFA content and water content of ethanol. Ethyl ester formation in the ethanol phase increased as FFA content increased. Neutral oil solubility in this phase fell considerably, resulting in a high ethyl ester content. The decrease of the water content in ethanol led to an increase in neutral oil solubility in ethanol and promoted the equilibrium of reaction to ethyl-ester formation, resulting in lower FFA content of the product. The main factor that affected yield and monoester content when using high-acidity bran and various monohydroxy alcohols was the solubility of neutral oil in alcohol. The highest monoester content was obtained with methanol.Paper no. J10283 in JAOCS 80, 81-84 (January 2003).
In this study, a systematic and detailed investigation on liquid‐liquid extraction of sulfur olive oil miscella in hexane with aqueous ethanol solutions was performed. Optimal extraction conditions for recovery of free fatty acids (FFA) with a minor loss of neutral oil were determined in bench‐scale single‐stage extractions. It was concluded that, to ensure deacidification with a low triglycerides loss, it is appropriate to extract the miscella with 30% or more dilute ethanol solutions. It was also noted that under these circumstances the free fatty acid percentage extracted is not affected by increases in contents of FFA and partial glycerides of sulfur olive oil, and the solvent must be saturated with hexane before extraction. Changing the oil:hexane ratio in miscella from 1:2 to 2:1 by weight did not have any significant effect on extraction results.
In situ esterifications of high‐acidity rice bran oil with methanol and ethanol and with sulfuric acid as catalyst were investigated. In the esterification with methanol, all free fatty acids (FFA) dissolved in methanol were interesterified within 15 min, and it was possible to obtain nearly pure methyl esters. The amount of methyl esters obtained from a given rice bran was dependent on the FFA content of the rice bran oil. In the esterification with ethanol, it was not possible to obtain pure esters as in methanol esterification, because the solubilities of oil components in ethanol were much higher than those in methanol.
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