# Human Milk Fat Substitutes from Lard and Hemp Seed Oil Mixtures
## 1 Introduction  
Inter- and intraesterification are industrial transformation processes based on the redistribution of fatty acids between separate molecules of triacylglyceroll (intermolecularly) or inside them (intramolecularly), respectively. Such reactions take place until thermodynamic equilibrium is reached, and they change the physico-chemical properties of mixtures of fats and oils. Compared to the original mixtures, the resulting products feature a similar degree of saturation and fatty acid profile. However, they are different in terms of triacylglycerollocycl stereochemistry, which affects their physicochemical and nutritive properties [1, 2, 3, 4, 5]. The reaction of inter- or intraesterification may be carried out in the presence of chemical or enzymatic catalysts. An enzymatic intereesterification is a simpler process than a chemical one as it involves a smaller number of stages, and the temperature used is relatively low (from 55 \({}^{\circ}\)C to 70 \({}^{\circ}\)C). Chemical intereesterification usually takesplace at higher temperatures within the range of 70-120 \({}^{\circ}\)C. Enzymatic intereesterification may be controlled and discontinued at every stage [6; 7]. Its advantage over chemical intereesterification stems from the fact that the discussed process becomes more specific in the presence of an enzyme, particularly if lipases of various specificity are used. As a result of using specific lipases, scientists may synthesize fats with the required physical and nutritional properties--a process unaccomplishable by means of chemical intra- or intereesterification. Further, due to the relatively low temperatures used during the process, unstable fatty acids do not undergo oxidation, and the remaining components contained in the oil, such as vitamin E, do not degrade. Also, from a dietary point of view, no harmful trans fatty acid isomers are formed during the process [7; 8; 9]. However, not all trans fatty acid isomers are undesirable. Some of them, such as, for example, conjugated linoleic acids (CLA), which are present in dairy products and ruminant meats, may present benefits for health, e.g., protection against cancer and obesity [10]. Breast milk is only natural food for newborns, but due to occasional problems with lactation, people have always tried to find alternative solutions. Breast milk is a source of the nutritive elements needed for normal infant growth and development. Human milk contains 1-2% proteins, 6-8% carbohydrate, and 3-5% fat [11]. To add more benefits, it is characterized by an adequate temperature, antibacterial properties, and constant freshness, and it does not require any special preparation [12]. Human breast milk contains fats, i.e., substances of peculiar physiological significance for infants and younger children. Fats are nutritive agents necessary for the normal development of infants and small children. This is true mainly due to the fact that fats introduce polyunsaturated fatty acids (PUFAs) into small children's bodies, compounds required for normal development of the brain, nervous system, and cellular membranes. The PUFAs also constitute carriers for fat-soluble vitamins and milk-contained hormones [13]. A specific feature of breast milk fat is the content of long-chain polyunsaturated fatty acids (LCPUFAs). The predominant LCPUFAs contained in breast milk fat are eicosapentenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (ARA). These are the acids responsible for normal growth and bone mineralization and for proper development of the central nervous system. LCPUFAs are also precursors of prostaglandandins and eicosanoids, which play regulatory roles. Furthermore, they are mediators of immunological reaction, vascular blood flow, and platelet aggregation, among other things [14]. Breast milk fat features not only a specific content of fatty acids but also their specific distribution in the molecules of triacylglycerecols.