Optimization Erythritol Producing Technology By Candida Mycoderma

Erythritol is a natural existed sugar polyols, which has four carbons, chemical name is 1,2,3,4-butanetetrol, molecular formula is C₄H₁₀O₄ and molecular weight is 122.12, boiling point is 329 - 331℃, melting point is 126℃, its appearance is white and crystal powder. It can absorb more energy when it is soluted in water, dissolution is -97.4J/g, erythritol has a positive enthalpy of solubilization, thus providing a strong cooling effect in ingestion. It can give a better tasty.Erythritol occurs widely in nature and has been found naturally in several foods including mushroom, watermelon, pear, grape, wine, sake, beer, soy sause and fermented foods. It is a kind of polyhydric compound in chemcial constitution, it's molecular weight is small and the style of metabolism is different from other alditols in human body and mammal body. Erythritol can't join in glycometabolism and physiological tolerance dose is high, so it can play an important role in lower energy foods. Therefore, it could be used advantageously in special foods for people with diabetes and fatness. It has a 60%～70% sweetness relative to sucrose, the residual time of erythritol in oral cavity is very short. And erythritol is safe for people in many animal experiment. It is a non-caloric and non-cariogenic sweetner, Erythritol has great potential for application in food.The method of fermentation is a major method to produce erythritol. Ground substance can be used to cultivate microorganism and produce erythritol in this method. For example starch can produce glucose by amylase, erythritol can be made by microorganism in hyperosmosis and can be concentrated, separated, purified, crystallized, dryed. Now in our country a strain of torula was screened from the nature world, this strain can grow in the concentration of 40% glucose and production of erythritol is 120.0 mg/ml. In abroad a strain of hyperosmotic yeast can use 30% glucose, 4% corn steep liquor to produce erythritol, 35℃, cultivante 3d, the production of erythritol is 141.0 mg/mL.Now, the price of erythritol is too high to develop industry. It is a pathway to impulse the industry cutting down the producing cost of erythritol. For erythritol producing yeast, to select fermentation medium, not only the high production of erythritol was considered, but also the cost price can be considered. The level of erythritol and substrate conversion efficiency not only have relation with the physio-biochemistrical characteristics of the strain oneself, but also have a direct relation with nutritional ingredient, content of medium and fermentation condition. So substrate conversion efficiency can raise efficiently by optimizing main nutritional factors and fermentation condition. In the study the medium and the fermentation condition of this Candida mycoderma were studied, and erythritol was separated, purified, crystallized, evaluated, the better technology can be attained.During the fermentation condition was optimized, first single factor screening method was designed containing carbon source, nitrogen source, inorganic salt, seed quality, temperature, pH, fermentation time and so on. Then orthogonal experiment was designed containing above factors. The relations among each factor were evaluated to attain the optimal nutritional factors and fermentation condition and result was analyzed by SPSS software. Finally the Candida mycoderma RH-UV-L4-F9 optimal condition is that 30%glucose, 0.5% yeast extract, 0.1% carbonylamines, 0.5%MgSO₄.7H₂O, 32℃, exponential phase of growth 10～18h, pH 5.0, cycle of fermentation is 144h, amount of inoculation is 10%o. After fermentation the contents of erythritol is 157.5mg/ml in broth, it has more higher lever in the world.In the study the elution curve of erythritol was studied, elution volume, elution process were determined. The quantity of sample is 50ml, the volume of eluent is 200ml, the optimal flow rate is 3ml/min and yield of decoloring rate are 83.8%,100% respectivly. Commpared with fore-purifing, except for erythritol there isn't any other foreign material, erythritol in dry matter is 96.91%. The purpose of separating erythritol was achieved. Then the broth was concentrated by rotary evaporation. When the concentration of erythritol was 40%～50%, the alcohol and seed-crystal were joined in, the volume ofalcohol is four times than broth at 4℃for 10～12h, then erythritol can be crystaled. Then crystal was attained at 40℃drying for 10h. The purity coefficient of erythritol was evaluated by TLC and HPLC. The sample only have one sugar alcohol, erythritol by TLC. The purity coefficient is 95.6% by HPLC.In a word, the study and application for erythritol not only can increase people's health level, push our country functional food's development. By biotechnology method can also transform JiLin Province's corn for high added value and to supply new way for JiLin Province's agro-product processing.