Modified Research Of Phytosterol

Plant sterols have been shown the function to reduce the levels of serum low-density lipoprotein(LDL) cholesterol in humans,but enrichment of food products with plant sterols is difficult from a technological and food quality point of view since they are insoluble in water and poorly soluble in dietary fats.Improving its water and oilsolubility was always the key point in PS research scopes.Phytosterol esters were effective in reducing both blood cholesterol levels and triglycerides and could be used as biological compounds in food,pharmaceutics and cosmetics.Methods of phytosteryl ester production were various,but mostly had its limitation.The selective synthesis of phytosterol esters from natural sterols and free fatty acids was investigated on new grounds by a chemical process using a basic solid catalyst(ZnO) that were active,reusable,less corrosive and more selective than the currently used homogeneous catalysts.It was found that esterification reaction of phytosterol could also be carried out by ZnO in more mild reaction conditions simultaneously had higher conversion rate and selectivity than transesterification;it was also found that trans-fatty acid formed in esterification was low and trans-fatty acid(%) in phytosterol oleate esters fraction(3.26%) was much lower than in free oleic oil(7.35%) suggested that fatty acid in esters are more stable than free fatty acid.Immobilized ZnO could be a promising catalyst for replacing homogeneous and corrosive catalysts for esterification reaction of sterol.Emulsification method was the most used in the water-solubility aspect of plant sterol,First we used this method to improve water-dispersion and stability,for the three systems researched(pure water,protein-water,oil-water),sodium stearyl lactylate had a good effect.Its spray dryer products had a preferable stability in milk drink that no deposition was observed after one month.But their chalky taste and turbidity maked it can't succeed applied in clear ade and jam.In order to obtain a water-solubility modified phytosterol product,in this study, cyclodextrin was used to improve the water-solubility of phytosterol and the reaction conditions were optimized.The results of DSC showed the inclusion complex of phytosterol inβ-cyclodextrin can be formed. Reaction conditions were optimized.It was determined that phytosterol inclusion ratio of 90%can be reached,when reaction was carried out at temperature of 40℃for 12h,with a molar ratio ofβ-CD to phytosterol of 4:1 in n-butanol system.Water-solubility of phytosterols improve significantly.β-cyclodextrin which is most commonly used in the pharmaceutical and food field is limited by its rather low aqueous solubility.Hydroxypropylβ-cyclodextrin(HP-β-CD),the hydroxypropyl derivatives of cyclodextrins which has the advantages of enhanced solubility,as well as lower hemolytic activity and reduced nephrotoxicity was applied in this study.Differential scanning calorimetry(DSC),gas chromatography(GC),scanning electron microscopy(SEM) and fourier transform infrared spectroscopy(FT-IR) results showed plant sterols(PS) which were structurally similar to cholesterol in animals could form inclusion complexes with HP-β-CD.Aqueous solubility and dissolution improved significantly.The response surface methodology(RSM) was used to optimize the reaction conditions,the results showed that phytosterol inclusion ratio of 85%can be reached,when reaction was carried out at temperature of 50℃for 12h,with a molar ratio of HP-β-CD to phytosterol of 3:1and phytosterol concentration at 1%in absolute alcohol system.Aqueous solubility of Phytosterol reached almost 1% which could well applied in water-solubility food systems and also had important influence on steroid drug translation.