PRODUCTION OF A STRUCTURED DAIRY LIPID BY INCORPORATING GAMMA-LINOLENIC ACID INTO MILK FAT USING LIPASE-CATALYZED ACIDOLYSIS

Fatouh, A. E.; Singh, R. K.; Pegg, R. B.

doi:10.21608/jfds.2009.115379

PRODUCTION OF A STRUCTURED DAIRY LIPID BY INCORPORATING GAMMA-LINOLENIC ACID INTO MILK FAT USING LIPASE-CATALYZED ACIDOLYSIS

Document Type : Original Article

Authors

¹ Food Science Department, College of Agriculture, Ain Shams University, Shoubra El-Khamia, Cairo, Egypt.

² Department of Food Science and Technology, College of Agricultural and Environmental Sciences, The University of Georgia, Athens, GA, USA.

10.21608/jfds.2009.115379

Abstract

A structured dairy lipid was synthesized enzymatically via acidolysis of gamma-linolenic acid (GLA; C_18:3 ω-6), concentrated from borage oil (Borago officinalis L.), and butter oil (BO) using two different lipases. Two hundred international units of immobilized lipase from Candida antarctica or Mucor miehei were added and the reaction was carried out at 50 °C in an orbital shaking water bath at 250 rpm. Incorporation of GLA into BO was confirmed by gas chromatography. The greatest incorporation of GLA into BO was 28.69 % after 24 h incubation using lipase from C. antarctica lipase and 24.75 % after 3.5 h when using lipase from M. miehei. Thermal properties including peak melting temperature (T_{p ) and melting enthalpy (E_{p ) lowered (P < 0.05) as more GLA was incorporated. T_{p and E_{p of the inherent BO were 30.54 °C and 85.24 J/ g, respectively. By the end of the acidolysis, T_{p values were 11.02 and 12.03 °C while E_{p values had reached 38.85 and 40.29 J/ g when using Candida antarctica and Mucor miehei immobilized lipases, respectively. Solid fat content (SFC) corresponded (P < 0.05) to changes occurred in fatty acids (FAs) composition. BO possessed the highest SFC that downward progressively over the reaction course for both enzymes. However, at the late stages of the acidolysis, reduction in SFC became less pronounced. Enzymatic interesterification (EIE) by immobilized lipases affords an efficient tool for restructuring milk fat triacylglycerols while preserving the delicate flavor of milk fat to be used as an ingredient in functional food formulations.}}}}}}

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