# Human Milk Fat Substitutes from Lard and Hemp Seed Oil Mixtures
## 3 Results
### Free Fatty Acid Content and Oxidative Stability  
The content of free fatty acids was calculated based on determined values of the acid number (Figure 3). Their content in lard was 0.3%, while in hemp seed oil, it was 1.0%. The intereesterification process led to a remarkable increase in the content of free fatty acids in relation to initial chemical feeds. The percentage of free fatty acids in the intereesterification products ranged from 14.9% to 25.9%.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{5}{c}{**Fatty Acids (wt\%)**} \\ \cline{3-6}  & & **16:0** & **18:0** & **18:1** & **18:2** \\ \hline \multirow{3}{*}{sn-2} & Mix 60 \({}^{\circ}\)C\_2 h & 51.8 & 13.1 & 12.5 & 11.4 \\  & Mix 60 \({}^{\circ}\)C\_4 h & 47.1 & 8.5 & 16.5 & 15.1 \\  & Mix 60 \({}^{\circ}\)C\_6 h & 41.3 & 11.7 & 19.6 & 16.1 \\ \hline \multirow{3}{*}{sn-1,3} & Mix 60 \({}^{\circ}\)C\_2 h & 13.8 & 13.5 & 39.5 & 19.8 \\  & Mix 60 \({}^{\circ}\)C\_4 h & 21.1 & 14.1 & 34.4 & 16.6 \\ \cline{1-1}  & Mix 60 \({}^{\circ}\)C\_6 h & 21.7 & 14.5 & 32.8 & 17.8 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The fatty acid compositions of the sn-2 position and sn-1,3 positions of TAGs in human breast milk fat substitutes.  
Figure 1: The percentage (wt%) of a given fatty acid in the sn-2 position of TAGs in lard (L), hemp seed oil (HO), human breast milk fat substitutes, and human milk fat. HMF * (human milk fat) sample values were derived from [PERSON] [28].  
In order to determine fat oxidative stability, the content of primary oxidation products was measured using titration, and the induction time was calculated based on an accelerated test for oxidation with the help of DSC. The content of primary oxidation products is defined by the peroxide value (Figure 4).  
Figure 3: Free fatty acid (FFA) contents (wt%) in hard (L), hemp seed oil (HO), and human breast milk fat substitutes. Different letters indicate that the samples are significantly different at \(p<0.05\).  
Figure 2: Percentage (wt%) content of fatty acids (SFA—saturated fatty acid, MUFA—monounsaturated fatty acid, PUFA—polyunsaturated fatty acid) in hard (L), hemp seed oil (HO), human breast milk fat substitutes, and human milk fat. * HMF (human milk fat) sample values were derived from [PERSON] et al. [29]. Different letters indicate that the samples are significantly different at \(p<0.05\) separately for each group of fatty acids.  
The HMF substitutes were characterized by smaller peroxide values, within the range of 2.4 mEq O\({}_{2}\)/kg up to 3.5 mEq O\({}_{2}\)/kg, compared to the hemp seed oil, for which this parameter equaled 7.0 mEq O\({}_{2}\)/kg. However, lard featured a low peroxide value of 2.5 mEq O\({}_{2}\) kg\({}^{-1}\). Substitutes acquired via interestricification carried out for 6 h had higher peroxide values in comparison with substitutes acquired via interestricification for 2 or 4 h. Moreover, Figure 4 presents the oxidation induction times for the interestricification products and their original feeds. In studies on the stability of fats, a rule is taken into account that the longer the induction time, the higher the oxidative stability of the fat [30]. The determined induction times for the interestricification products, ranging from 26.2 min to 28.5 min, similarly to the peroxide value, indicate their lower oxidative stability than that of lard, for which the induction time was 48 min. Nonetheless, they were more stable than the hemp seed oil, for which the induction time was 19.4 min.