Production of triacylglycerols rich in palmitic acid at position 2 as intermediates for the synthesis of human milk fat substitutes by enzymatic acidolysis

Abstract

This paper studies the synthesis of triacylglycerols (TAGs) rich in palmitic acid (PA) at position 2, from palm oil stearin (POS), a vegetable oil highly rich in this acid (60%). The developed process consists of two steps: (1) obtaining PA enriched free fatty acids (FFAs), and (2) enrichment of POS in PA by acidolysis of this oil with PA enriched FFAs, catalyzed by lipase Novozym 435. In step (1) two PA enriched FFA mixtures were obtained: one by saponification of POS, and a PA concentrate (75.1% PA) obtained by crystallization at low temperature in solvents. The latter was obtained carrying out two crystallizations in acetone at -24 and -20 ºC, from which PA was recovered in the solid phases with a total yield of 84%. These PA enriched FFA mixtures were used in step (2) of acidolysis of POS, along with commercial PA (98% PA). In this acidolysis step four factors were studied: temperature, hexane/reaction mixture ratio, FFA/POS molar ratio and the intensity of treatment (IOT = lipase amount × reaction time/POS amount). The best results (TAGs with 79% PA and 75% PA at position 2) were obtained with commercial PA, at 37 ºC, 10 mL hexane/g reaction mixture, a FFA/POS molar ratio 3:1 (1:1 w/w) and an IOT = 9.6 g lipase × h/g POS (for example 48 h, 10 g lipase and 50 g POS). PA enriched TAGs were purified neutralizing the FFAs by KOH hydroethanolic solutions and extracting the TAGs with hexane. In this way 99% pure acylglycerols (TAG+DAG) were obtained; the recovery yield of this purification step was 95%. The experiments carried out with POS demonstrated that it is possible to use only this oil (60% PA, 23% PA at position 2) as a source of PA to obtain a TAG with 70.7% PA and 70.5% PA at position 2. This process consists of four steps:(1) saponification of POS, (2) crystallization of FFAs to obtain PA enriched FFAs (75.1% PA), (3) acidolysis of POS with these FFAs, catalyzed with Novozym 435, to produce PA enriched TAGs at position 2 (70.5% PA) and (4) purification of TAGs to obtain approximately 95% purity and yield. These PA enriched TAGs could be used to obtain structured TAGs rich in PA at position 2 and in oleic acid at positions 1 and 3 (OPO), which is the principal TAG of human milk fat.

Biotechnological and Novel Approaches for Designing Structured Lipids Intended for Infant Nutrition

“…40-60%) and unsaturated FAs mainly at the sn-1,3 positions [9]. The fatty acid composition and proportions of fatty acids at the sn-2 position of human milk as reported by several researchers are given in Tables 1 and 2, respectively. The most abundant fatty acids in human milk are palmitic, oleic, and linoleic acids, and their compositions are significantly influenced by maternal food consumption during lactation [10,11]. Palmitic acid is the major saturated fatty acid, representing about 20-25% of the total fatty acids.…”

“…Jiménez et al [11] used structured lipid rich in palmitic acid at the sn-2 position from a previous study. Their study was conducted in two steps: first, PA-enriched FFAs were synthesized, then palm oil stearin (POS) was enriched by acidolysis of POS with PA-enriched FFA.…”

Identification of triacylglycerols in coix seed extract by preparative thin layer chromatography and liquid chromatography atmospheric pressure chemical ionization tandem mass spectrometry

“…The knowledge of stereospecific positions of individual FA is highly important, because FAs at sn-1 and sn-3 of the TAG are hydrolyzed during digestion and absorption of food while FAs at the sn-2 position remain intact. 5,6 This results in the different bioavailability of FAs depending on their sn-position. 7,8 Thus, identification of TAGs and DAGs in coix seed is required for nutritional and pharmaceutical understanding of coix seed widely used as food and medicine.…”

Effects of triacylglycerol structure and solid fat content on fasting responses of mice

“…Since the metabolic pathway of fatty acids at the sn-2 position of the TAG is different from fatty acids at the sn-1,3 positions, TAGs with more saturated fatty acids at the sn-2 position may have different fat absorption [9,10], chylomicron clearance [3,11,12], fatty acid composition of very low-density lipoprotein (VLDL) [13], lipemia response [7,8], sn-2 fatty acid composition of tissue TAG [14] compared to TAGs with more saturated fatty acids at the sn-1,3 positions. In addition, TAGs high in solid fat content at body temperature may be emulsified less readily, resulting in a slower increase in lipemia response compared to TAGs low in solid fat content [6].…”