# Human Milk Fat Substitutes from Lard and Hemp Seed Oil Mixtures
## 4 Discussion  
Fat in human breast milk occurs mainly in the form of triacylglycerlycerols that make up over 98% of all the milk fats. The discussed TAGs have a unique composition and structure, as palmitic acid is contained mainly in the sn-2 position (approximately 40-60%), whereas positions sn-1 and sn-3 are occupied by unsaturated fatty acids. In the sn-1,3 positions of TAGs, the most abundant are oleic and linoleic acids. To the contrary, in the majority of plant fats, the situation is reversed, i.e., palmitic acid occupies mainly positions sn-1 and sn-3 of TAGs, while unsaturated fatty acids take the central position [12; 31]. From a dietary point view, the distribution of acyls in the TAG molecules plays a key role. The type of a fatty acid and its location in the TAG molecule determine the physical properties of a given fat and its digestion and absorption [32]. The structure is responsible for normal fat absorption from food. It also prevents from the formation of insoluble calcium salts. This is because pancreatic lipase is an enzyme selectively hydrolyzing fatty acids in the sn-1,3 positions, with the production of free fatty acids and 2-monoacylglycerolcrols. Palmitic acid in the monoacylglycerolcerol form is more efficiently assimilated than free palmitic acid, as the former can bind calcium and magnesium ions, among others, with the formation of insoluble soaps excreted with feces. Hence, feeding an infant with fat of different TAG spatial structures from the one present in human breast milk gives rise to increased losses of calcium, magnesium, and the fat itself from the child's body [13; 15; 28; 29; 33; 34; 35; 36]. The best modified mixture mimicking human breast milk fat, in terms of the fatty acid composition, was the product of two hours of interestricification at the temperature of 60 \({}^{\circ}\)C.  
The composition of HMF features the best health-oriented and nutritional properties for infants and small children. The fat contains mainly palmitic acid (17.0-24.4%),  
Figure 4: Oxidation induction times (ITs) and peroxide values (PVs) of lard (L), hemp seed oil (HO), and human breast milk fat substitutes. Different letters indicate that the samples are significantly different at \(p<0.05\) separately for PV and IT. oleic acid (20.8-33.5%), and polyunsaturated fatty acids (13.2-22.7%) [37]. Among the polyunsaturated fatty acids, this fat contains such acids as linoleic, \(\alpha\)-linolenic, arachidonic, eicosapentenoic, and docosahexaenoic [29]. Compared to HMF, the studied lard featured a similar content of palmitic acid (approximately 27.7%), but a higher percentage of oleic acid and a lower percentage of polyunsaturated acids, i.e., 38.0% and 10.6%, respectively. The composition of fatty acids in the hemp seed oil was completely dissimilar from those in both lard and HMF. The hemp seed oil contained much more polyunsaturated fatty acids (approximately 78.0%) than the other two tested mixtures. However, the content of palmitic acid (6.2%) and oleic acid (9.6%) was lower in the hemp seed oil compared to the remaining two studied products. From among all the SFAs, palmitic acid dominated in the TAGs of the generated substitutes, a situation similar to that in HMF. Its content in the acquired substitutes was within the range of 26.7-29.8%. The analysis of the obtained intereesterification products revealed that oleic acid was the prevailing monounsaturated fatty acid in these products. Its content was approximate to the one present in HMF and ranged from 28.4% to 30.5%. From among the PUFAs identified in the synthesized substitutes, linoleic acid played a major role. A similar situation was recorded in the case of HMF. The intereesterification products contained between 16.1% and 17.0% of linoleic acid, belonging to the family of \(\omega\)-6 acids. The TAGs of the resulting substitutes also contained other essential fatty acids, such as \(\alpha\)-linolenic acid (0.6-0.7%, \(\omega\)-3 family) and \(\gamma\)-linolenic acid (approximately 1%, \(\omega\)-6 family).