Study On The Thermal Loss Rule And Oxidation Stability Of Plant Sterol Oleates

Phytosterol(esters)can effectively decrease serum cholesterol concentration in human body and prevent the happening of the disease of heart head blood-vessel.It was found that phytosterols had better solubility and bioavailability than free phytosterols.In recent years,phytosterols have attracted more and more attention.In the process of food processing,phytosterol esters are easily affected by high temperature,resulting in certain loss and harmful substances to human body.It was found that the loss rate of phytosterol(esters)and the production of their oxides were closely related to the structure of phytosterol esters,volume of addition,food matrix,heating temperature and time,and antioxidants.So this article selected the two most abundant natural phytosterols(stigmasterol and?-sitosterol)and oleic acid synthesis:stigmasterol oleate(SSO)and?-sitosterol oleate(STO),used them as raw material,added them into non-oil system and lipid system(lard and fish oil)with different saturation,by investigating the loss rate of SSO/STO and the composition and content of the oxidation products,inquiry the influence of structure,volume of addition,lipid matrix on the thermal stability of SSO/STO.In addition,the study found that antioxidants in oils had a protective effect on some naturally active components.Therefore,this paper has used the natural antioxidant V_E and synthetic antioxidants TBHQ,added them to the lipid system which was riched in SSO/STO,the loss rate and the change rules of the composition and content of the oxidation products of SSO/STO,explored the antioxidants of the influence rules of SSO/STO thermal stability in the lipid system.The main findings are as follows:(1)Taking the loss rate of phytosterol oleate as the evaluation index,the loss rate of SSO/STO in non-oil system and lipid system(lard and fish oil)was explored.The results were as follows:the loss rate of SSO/STO was closely related to temperature and time,and the loss rate gradually increased with the increase of temperature and time.The lipid matrix had a great influence on the stability of SSO/STO.The loss rate of SSO/STO in non-oil system was significantly higher than that in lipid system(lard and fish oil),and the loss rate of SSO/STO in lard was higher than that in fish oil.The addition amount of SSO/STO was negatively correlated with the loss rate of SSO/STO,and the SSO/STO with higher volume of addition suffered more losses.(2)The composition and content of the oxidation products of phytosterol oleate were used as evaluation indexes to investigate the change rules of composition and content of the oxidation products of SSO/STO in the non-oil system and lipid system(lard and fish oil).The results were as follows:In the two systems(except fish oil and non-oil system at180?),the longer the time and the higher the temperature,the more total content of oxidation products produced by SSO/STO;The oxidation products of SSO/STO include7-ketyl sterol,7-hydroxyl sterol,5,6-epoxidated sterol,and their contents decreased successively.The content of oxidation products produced by SSO and STO is similar.Compared with the lipid system,the total content of SSO/STO oxidation products in the non-oil system was the highest,and the total content of SSO/STO oxidation products in the lipid system(lard and fish oil)was higher than that in the fish oil.In the lipid system,the amount of SSO/STO added was negatively correlated with the oxidation stability of SSO/STO.(3)The influence of external antioxidants on the thermal stability of SSO/STO was studied by investigating the loss rate of SSO/STO in the oil with antioxidants(V_E and TBHQ)and the change rules of the content and composition of oxidation products.The main conclusions are as follows:both V_E and TBHQ showed good inhibitory effects on the heat loss of SSO/STO,and the inhibitory effect of TBHQ was stronger than that of V_E.When V_Eand TBHQ were added,the oxidation products of SSO/STO included 7-ketyl sterol,7-hydroxy sterol and 5,6-epoxidated sterol.V_E and TBHQ both could reduce the generation of oxidation products of SSO/STO.There was no significant difference in the effect of V_Eand TBHQ on the loss rate and of SSO and STO.The effects of V_E and TBHQ on the loss rate of SSO/STO in fish oil and lard were not significantly different,and V_E and TBHQ showed better thermal oxidation protection against SSO/STO in lard.