Preparation Technology Of CLA From Corn By Means Of Supercritical Fluid Extraction And Optimization Of Its Key Devices

Supercritical CO2fluid extraction is a new separation and refining technology. Supercritical CO2fluid can provide a low temperature and anaerobic inert environment that has no solvent residue and is suitable especially for the extraction, separation and purification of the ingredients with heat-sensitive function. Conjugated Linoleic Acid (CLA), which has a variety of important physiological activities, derives from linoleic acids of essential fatty acids and is a general reference of18-carton fatty acids that has multiple positions and geometrical isomers with conjugated double bonds. CLA is a kind of functional fatty acid that is widely applied in food, medicine, health care and cosmetics. Since natural CLA is rare and cannot meet people’s needs, the current CLA is mainly from artificial synthesis that takes plant oils as the main source. Corn is one of the major food crops in China and its deep processing has become an industry, which developed rapidly in recent years. In addition, corn starch production has accounted for more than half of the industrial consumption of maize. Corn germ is the main byproduct in the corn starch production and the contents of Linoleic Acid (LA) in the corn germ fat is about52%～62%, which is a good raw material for preparation CLA.This study takes rich and plentiful corn germ in China as the raw materials and by means of the technology of supercritical CO2fluid extraction to separate and purify, and recycle the organic solvent, prepares CLA that has many kinds of physiological functions, which will realize the aims of technological innovation, green production, energy conservation&emission reduction and so on. Moreover, the social efficiency and the economic value must be remarkable.This thesis first studies the processing conditions of separating and purifying CLA by means of the technology of supercritical CO2fluid extraction and recycling the solvent polyethylene glycol400. At the same time, it studies how extracting temperature, extracting pressure, distilling temperature, distilling pressure, CO2current capacity and distilling time have effect on the separating, purifying and recycling. The experimental results show that when the extracting pressure25MPa, extracting temperature40℃, distilling pressure is12MPa, distilling temperature20-30-40-50℃and CO2current capacity12L/h, the recycling rate reaches the maximum,89.11%and the recycling rate of the solvent polyethylene glycol400reaches91.86%.Based on the above first step, the thesis starts to design the technology of preparing the CLA from corn by the supercritical method, which is completed by means of the device of supercritical fluid extraction. Technical process:taking the corn germ as the raw material, extracting the corn germ oil from the germ in the solid cauldron, breaking it into the liquid cauldron and preparing CLA drawing on the conjugate method catalyzed by alkali. Reactants at high pressure and high temperature react in the extracting cauldron and they are separated and purified into high-purified corn CLA by means of the supercritical CO2fluid extraction and distillation process and at the same time, the solvent is recycledUnder the technology of preparing corn CLA with the supercritical method and its conditions of separation and purification, on the basis of the existing supercritical CO2extraction device, the thesis studies and optimize the composition of the process devices and key devices, which is a system with two extracts, four separations and a selective evaporation and is divided into three parts according to technological process:the extraction of solid materials, conjugate reaction of liquid materials and the separation and purification of the reacting products. The main experimental results are as follows:1、The key device is the extract cauldron in the process of the conjugate reaction of liquid materials and the extract cauldron works depending on electricity, its design heating temperature is150℃, its operating temperature is120℃, its maximum working pressure is50mpa, its working medium is the alkali mixtures, its producing material is Austenitic high-alloy steel marked by the grades0Gr18Ni9Ti, the ratio of length:diameter of body is1:8, the inner diameter is70mm and the volume is2L, simple single-layer integrated barrel structure is taken and its thickness is16mm, flat sealing head in the bottom is used and its thickness is32mm, threaded quick-opening high-pressure-tight containment structure is used for the sealing head in the cover, and the sealing part consists of the plug, the pressure ring and the O-shape sealing ring, PTFE O-shape sealing ring is used to be the sealing element of the extract cauldron.2、The key device is the distillation column and the CO2pressurized equipment in the process of reactants’separation and purification. In terms of the technological conditions, water box of distillation column I is designed for12L (300mm×200mm×200mm), in which a circulating pipe of cold water is placed, the range of temperature-lowing from15℃to room temperature, the inner diameter of the pipe is5mm, the diameter of pipe-coiling is100mm, coiling turns of the pipe is eight and the total length is2.5m.A CO2high-pressure pump with three plungers is taken for the pressurized equipment selection CO2high-pressure whose outlet pressure is PMax=50MPa and the current capacity is PVMax=50L/h.