The Study And Application Of Methylpentane For Extracting Expanded Soybean

Commercial hexanes,hexane and other vegetable oil extraction solvents are the main solvents for extracting edible vegetable fats and oils in current China.The main composition,n-hexane belongs to one of 189 air pollutants,whose metabolite have the clear central nervous system toxicity.Therefore,methylpentane,n-hexane and vegetable oil extraction solvent were used to four-stage countercurrent extract expanded soybean based on the analysis of residue solvent levels of marketable vegetable oils.Then the extraction effect and the quality of crude oils of different solvents were compared,aimed to provide the scientific basis of replacing hexanes with methylpentane.The main contents are as follows:Firstly,3412 marketable vegetable oils were collected and the residue solvent content of them was determined.The residual solvent contents in 52.17% of the collected samples were not higher than 10 mg/kg,69.05% of the samples were not higher than 20 mg/kg,and 99.41% of the samples were not higher than 50 mg/kg.In general,The overall qualification rate was 98.81% according to the former GB 2716,and the figure decreased to 69.04% according to the new standard.n-Hexane and methylcyclopentane,the major components of the extracted solvent,had higher percentages,while 2-methylpentane and 3-methylpentane,the other components,had lower content.It is possibale for methylpentane used as extraction solvent to meet the new standard.Secondly,four-stage countercurrent extraction of expanded soybean was conducted using n-hexane,vegetable oil extraction solvent and methylpentane.The extraction solvent effect on leaching,the quality of the crude oil,as well as trace elements of the leaching process were analyzed and compared.It was found that miscella concentration obtained from methylpentane at initial leaching was the highest,while was exceeded by vegetable oil extraction solvent at subsequent stages.However,the residual oil rate of dry meal and static adsorption rate of methylpentane,the minimum belong three solvents,were 0.57% and 19.00%,respectively.The fatty acid compositions of oils extracted by three solvents were the same,and there were no significant differences among the sterols content.The crude oil extracted by methylpentane showed lower acid value,lower phosphorus content,lower nonhydratable phospholipid content,higher squalene content and easier evaporation of solvent,while the tocopherols content was slightly lower than that of n-hexane and vegetable oil extraction solvent.In addition,the content of tocopherols,sterols,squalene,phospholipids along with extracting stages were also studied,suggesting that the tocopherols and sterols contents of crude oils extracted by n-hexane and vegetable oil extraction solvent increased slightly with the extracting stages,the squalene and phospholipids contents increased rapidly with the extracting stages which showed that they were extracted mainly at subsequent extracting process.As for methylpentane,the sterols and squalene contents were similar with that of n-hexane and vegetable oil extraction solvent,while the tocopherols content decreased rapidly,and the phosphatides content was lower and had no significant change.Finally,the energy saving situation of methylpentane and the steam consumption in the first long tube evaporation were discussed theoretically based on the performance of methylpentane on laboratory scale.Compared with n-hexane,2-methylpentane as extraction solvent could save 13.80% energy by the theoretical calculation,and the indirect steam required in the first long tube evaporation process consumption of methylpentane saved 7.32%.After methylpentane replaced commercial hexanes in 4 oil enterprises,the solvent consumption saved 12.5%~36.8%,the steam consumption saved 3.6%~11.9%,the residue solvent content of soybean meal significantly reduced(the methylpentane leaching one was 253.78 mg/kg,while the commercial hexanes was 487.29 mg/kg).In conclusion,methylpentane was an ideal extraction solvent to substitute commercial hexanes and other vegetable oil extraction solvent whose main composition is n-hexane.