Study On The Synthesis Of L-ascorbic Acid Cinnamic Acid Ester And Its Activities

L-ascorbic acid (Vitamin C, Vc) is widely used in food industry as a kind ofsafety and effective antioxidant for its great water solubility and antioxidation.However, Vc is unstable and it is almost insoluble in the oil phase, which limits itsapplication range. Therefore, this paper introduced the cinnamic acid into themolecular structure of the Vc because of the antimicrobial activity of cinnamic acid.We designed and synthesized two Vc cinnamic acid derivatives by esterificationreaction. At the same time, their antioxidant and antimicrobial properties and theapplication in the peanut oil and chilled pork, the results are as follows:(1) Using Vc and cinnamic acid as raw materials, two Vc cinnamic acid estersderivatives were synthesized via acyl chloride method. The two derivatives aredicinnamic acid ester in C5,C6position of Vc and cinnamic acid ester in C2,C3position of Vc, named as Vc-5,6-dicinnamic acid ester and Vc-2-cinnamic acidester. Their structures are confirmed by1H NMR and IR.(2) The two kinds of Vc cinnamic acid esters have good stability in the solventand the buffer solution compared with Vc. They can keep good nature under thesolution at37℃for24h. Also, theircontent are almost unchanged within onemonth in phosphate buffer solution and room temperature environment.(3) Vc-5,6-dicinnamic acid ester has good antioxidant effect derivated fromVc, its EC50of cleaning hydroxyl and DPPH free radical are7.84mmol/L and63.96μmol/L. Also the concentration is more than6mmol/L, the hydroxyl free radicalscavenging effect of Vc-5,6-dicinnamic acid ester is better than that of commercialantioxidant TBHQ. However, antioxidant activity of Vc-2-cinnamic acid ester isworse than Vc, the modification in C2,C3enol hydroxyl of Vc may reduce itsoxidation resistance.(4) The two Vc cinnamic acid esters have good concentration-responserelationship in bacteriostatic effect including escherichia coli, bacillus subtilis, andstaphylococcus aureus. Their bacteriostatic effect are stronger than cinnamic aciditself in the same concentration.(5) The antioxidant effect of Vc cinnamic acid esters in peanut oil are studiedusing forced oxidation method. The results show that the0.05%adding can reducethe oxidation of peanut oil to a certain extent, its antioxidant effect is slightly lower than TBHQ; at100℃forced oxidation for16h, peroxide value (POV) of TBHQ,Vc-5,6-dicinnamic acid ester and Vc-2-cinnamic acid ester are43.04meq/kg,61.27meq/kg and68.86meq/kg.(6) Vc cinnamic acid esters are applied in chilled meat by soaking method for itsantimicrobial preservation. The results show that Vc cinnamic acid esters can slowbacteria breeding, prolong the refreshing time to more than7d; also the fatoxidation speed is effectively reduced and its TBA values is still less than0.5mg/Kg until the ninth day. Their antimicrobial preservation effect are better thancinnamic acid itself.