Biologic Synthesis Of Vitamin A Palmitate And Its Process Design Of Industrial Production

Vitamin A is widely used in nutrition health care,food and feed additives.Vitamin A palmitate is a relatively stable form compared to vitamin A.At present,vitamin A palmitate in the market is basically chemical synthesized,however there are many problems,such as pollution,high energy consumption,producing toxic substances and easy to generate the isomers of defects,in chemical-synthesis way.With the deepening research of enzyme catalysis,it can efficiently solve the defects existing in the chemical synthesis method.In addition,the enzymatic synthesis of vitamin A palmitate has important strategic significance and application value.This study designed a reasonable enzymatic synthesis way to produce vitamin A palmitate in industrial scale through a series of experiments.The conditions of fermentation to produce enzyme production were researched.The optimum conditions were fermentation process to maintain pH 5.0 at 30 °C,200 rpm,10% inoculated quantity,dissolved oxygen for 25%,incubation time for 144 h,the revulsant methanol flow amount to 90 L in the 700 L fermentation tank.In this study,the conditions of vitamin A palmitate synthesized by immobilized lipase in 200 L pilot scale were further studied.The optimal esterification conditions: 240 g/L vitamin A acetate and 260 g/L KOH at 21 °C to hydrolyze vitamin A acetate.Molar ratio of vitamin A acetate and the palmitic was 1:1.1,immobilized enzyme was 25 g/L,the amount of anhydrous Na2SO4 was 15 g/L,the reaction temperature was 32 °C and reaction time was 2 h.In this study,we researched crystallization temperature,time,type of organic solvent and ratio to optimize the best purification process: mixing the esterification liquid under-3 °C for 16 h to remove remaining palmitic acid.The crude product was diluted with acetone in the ratio of 1:4 and stirred lightly at-15 °C to remove retinol,vitamin A acetate,and vitamin A palmitate cis-isomer.The vitamin A palmitate was recovered with more than 99% purity and its active unit is more than 1.75 million.Finally,the biological catalysis way of fermentation process,the esterification process and separation process were designed.Meanwhile,we planned material and equipment relating to the industrial production and estimated the budget.