Comparison of Hydrolysis from In Vitro Digestion Using Symmetric and Asymmetric Triacylglycerol Compounds by Enzymatic Interesterification

Abstract

For developing indigestible lipids, symmetric triacylglycerol (ST) and asymmetric triacylglycerol (AT) were produced by enzymatic interesterification using high oleic sunflower oil, palmitic ethyl ester, and stearic ethyl ester in a shaking water bath. Used enzymes were Lipozyme RMIM for ST and Lipozyme TLIM for AT. To remove ethyl ester from reactants, methanol fractionation (reactant : methanol=1:5, w/v, 25°C) and florisil separation (reactant : florisil=1:8, w/w) were applied. Acetone fractionation (reactant : acetone=1:9, w/v) was implemented to separate triacylglcerol (TAG) species into ST and AT. Fractions Ⅰ (before fractionation), Ⅱ (after fractionation, liquid phase) and Ⅲ (after fractionation, solid phase) were separated from ST, whereas fractions Ⅳ (after 1st fractionation, liquid phase) and Ⅴ (after 2nd fractionation, solid phase) were from AT. From sn-2 fatty acid composition analysis, the sum of palmitic acid (C16:0) and stearic acid (C18:0) was 4.9∼6.5 area% in ST (Ⅰ, Ⅱ, Ⅲ), and 41.9∼43.9 area% in AT (Ⅳ, Ⅴ). In vitro digestion was performed for 0, 15, 30, 60, and 120 minutes at 37°C in a shaking water bath. For the digestion results, hydrolysis of Ⅴ was only 40% compared to others (Ⅰ, Ⅱ, Ⅲ, Ⅳ) at 120 minutes due to its melting point (49°C). However, initially (15 minutes), hydrolysis (%) was as follows: Ⅴ＜Ⅲ＜Ⅳ＜Ⅰ, Ⅱ. This order was similar with that of melting point, and a higher TAG content (two saturated fatty acids) was associated with a higher melting point. On the other hand, fractions Ⅲ and Ⅳ showed similar complete melting points (32.5°C, 31.8°C) and different slip melting points (31.3°C, 19.5°C). Even though Ⅳ has a lower TAG content composed of two saturated fatty acids than Ⅲ, it had a similar melting point.

Regiospecific Positioning of Palmitic Acid in Triacylglycerol Structure of Enzymatically Modified Lipids Affects Physicochemical and In Vitro Digestion Properties

“…Most studies have focused on analyzing the physicochemical properties of TAGs that differ in the regiospecific positions of certain FAs [ 13 , 14 , 15 , 16 , 17 ]. Previous studies on lipid digestibility have measured and compared the relative digestion rates of edible oils (soybean oil, algae oil, DAG-rich algae oil) [ 18 ] and symmetrical or non-symmetrical TAGs based on the levels of hydrolyzed FFAs using the in vitro digestion method [ 19 ] or compared in vivo digestion rates of specific edible oils using animal models [ 11 ]. However, studies comparing the digestion characteristics of lipids containing TAGs with different types of FAs (such as P, O, or S) and the incorporated positions of the FAs are still limited.…”

In Vitro and In Vivo Digestibility of Soybean, Fish, and Microalgal Oils, and Their Influences on Fatty Acid Distribution in Tissue Lipid of Mice

“…In vitro digestion of oil was performed using a multi-step digestion model that simulated the complex digestion processes (oral, gastric, and intestinal) of the human body, step by step, to measure the sizes of hydrolyzed fat globules and the content of released FFA or unhydrolyzed TAG [ 9 , 10 ]. Recent studies that applied in vitro multi-step digestion models include a comparison of digestibility between symmetric TAG and asymmetric TAG [ 11 ], analysis of digestibility among various real foods (dairy, meat, fish, egg, nuts, oils, fats, etc.) [ 12 ], and evaluation of the impact of emulsifier type on lipid hydrolysis of soybean oil-in-water emulsions [ 13 ].…”