| As an important kind of interesterification reactions, enzymatic acidolysis isapplied widely in lipid modification and producing structured lipids and is playing adecisive role in food and oil industries. Many western and Japanese food andfood-specific fat companies have taken enzymatic acidolysis as the research priorities.Two reaction systems, namely saturated triacylglycerol and unsaturatedtriacylglycerol conditions, were investigated in this paper using regio-specific lipaseas the catalyst to explore the effect of different reaction conditions on the componentof the products.Firstly, for unsaturated triacylglycerol reaction system, in solvent-free system,enzymatic acidolysis of camellia oil and palmitic acid was carried out using LipozymeRM IM. The effect of water activity, temperature, substrate mole ratio (camellia oil topalmitic acid), enzyme dosage and reaction time on the incorporation of palmitic acidto the triacylglycerol (TAG), Sn-1,3and Sn-2positions, the TAG content and otheracylglycerols in the products wereinvestigated. The results of single factorexperiments showed that the palmitic acid content of the Sn-1,3position has apositive correlation of the substrate mole ratio and the enzyme dosage; as the timeproceeds to6hours, palmitic acid content increases slowly, however, when thereaction continued to20-24hours, the palmitic acid content of the Sn-1,3positiondrops a lot. The palmitic acid content of Sn-2position has a positive correlation to thewater activity, temperature and time; long reaction time will lead to a steep rise incontent, and temperature has the greatest impact on the Sn-2position content ofpalmitic acid. The content of1-palmitoyl-2,3-dioleoyl glyceride (POO) and1,3-dipalmitoyl-2-oleoyl glyceride (POP) are mainly influenced by the time, substratemole ratio and enzyme dosage, and the extent of the influence on the content of POOis as the follows: substrate mole ratio bigger than enzyme dosage, and which is biggerthan time; the extent of the influence on the content of POP is as the follows: enzymedosage bigger than time, and which is bigger than substrate mole ratio. Water activity,substrate mole ratio, temperature have little influence on the content of1,3-diacylglycerol (1,3-DAG) and1,2-diacylglycerol (1,2-DAG), namely, in the initial5minutes, the content of1,3-DAG is almost4%higher than that of1,2-DAG, and astime going on, the difference between them gradually becomes stable, about2%.Then, for the saturated triacylglycerol reaction system, in solvent-free system, enzymatic acidolysis of fully hydrogenated soybean oil and oleic acid was carried outusing Lipozyme RM IM. The aforementioned influcing factors were also investigatedon the incorporation of palmitic acid to the TAG, Sn-1,3and Sn-2positions, the TAGcontent and other acylglycerols of the products. The results showed that, withparaments increasing, including the factors: time, substrate mole ratio (hydrogenatedsoybean oil to oleic acid) and enzyme dosage, the oleic acid content of the Sn-1,3firstly has an increase, and then decreased. The oleic acid content of Sn-2position hasa positive correlation to the water activity, temperature and time, and times course hasthe greatest impact. Temperature has the greatest impact on the palmitic acid of Sn-2position content. The content of1,2-distearoyl-3-oleoyl glyceride (SSO) and1,3-dioleoyl-2-stearoyl glyceride (OSO) are mainly influenced by the time, substratemole ratio and enzyme dosage, and the extent of the influence on the content of SSOis as the follows: substrate mole ratio bigger than enzyme dosage, and which is biggerthan time; the extent of the influence on the content of OSO is as the follows: enzymedosage bigger than time, and which is bigger than substrate mole ratio. Water activity,substrate mole ratio, enzyme dosage and temperature also have little influence on thecontent of1,3-DAG and1,2-DAG, in the initial5minutes, the content of1,3-DAG is1%lower than that of1,2-DAG, and as time going on, the difference between themgradually becomes stable (the content of1,3-DAG is almost4%higher than that of1,2-DAG).By comparing the two reaction systems catalyzed by region-specific lipase, thefatty acid content of the Sn-1,3is mainly affected by the temperature, reaction timeand the water activity, index that indicates the degree of acyl migration--fatty acidcontent of Sn-2is mainly affected by temperature and reaction time. Substrate moleratio, enzyme dosage and reaction time have a major impact on the final componentof the triacylglycerols. The reaction conditions have little impact on the component ofthe other acylglycerols in both reaction systems. |
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