## 3 Results and Discussion
### Multivariate Lipid Signature
Sphingomyelins and ceramide phosphates, minor components of MFGM, were found upregulated in the milk of goats on the SCG diet. Protective properties of milk sphingomyelins against dysfunctional lipid metabolism, gut dysbiosis, and inflammation have been reported [30]. It was also established that sphingomyelins from milk contribute to the central nervous system myelination [31]. Sphingomyelins and their metabolites (ceramide phosphate) have been proposed as candidates for food additives and functional food development for the prevention and treatment of chronic metabolic diseases in humans [32]. A strong positive association between coffee consumption and sphingomyelins in human blood was found by [PERSON] et al. [33]. In the negative ionization mode (Table 3), when compared to control samples, we found, as expected, upregulated caffeine and the caffeine metabolites: theobromine, theophylline, and 6-amino-5-(formyl-N-methylamino)-1,3-dimethyluracil (1,3,7-DAU). Caffe, theobromine, and theophylline are purine alkaloids that share a methyl xanthine structure, which has a significant role in pharmacology and food chemistry. Once caffeine is absorbed, it promptly gets into all the body tissues and crosses the blood-brain, blood-placenta, and blood-testis barriers [11]. In humans, caffeine is subjected to demethylation in the liver, resulting mostly in the release of paraxanthine, theobromine, theophylline, and in urates after oxidation. Theophylline and theobromine share a similar chemical structure; however, in theophylline, the lack of one N-methyl group determines more potent effects than caffeine and theobromine [11]. Theophylline is widely used as an oral treatment for both asthma and pulmonary disease [34]. Furthermore, 1,3,7-DAU is an uracilic metabolite of methylxanthines, which, unlike 5-fluorouracilacil (5 FU), which was markedly cytotoxic, showed mild cytotoxicity [35]. The detected presence of theobromine, theophylline, and 1,3,7-DAU in the milk of lactating goats on the SCG-enriched diet suggests that in these small ruminants, caffeine metabolism follows the same routes as in humans. Furthermore, we were able to annotate nonesterified fatty acids (NEFA), such as myristic acid, palmitic acid, and oleic acid, ketone bodies (acetoacetic acid), lysophosphatidylethanolamineines (LysoPE), ceramides, and their glucosyl derivatives. Lower levels of NEFA (Table 3) were found in the milk of goats on the SCG diet compared to controls. The presence of blood NEFA in dairy cattle has been attributed to the mobilization of adipose tissue in cows with a negative energy balance [34]. Due to the need for energy, NEFA is broken down into ketone bodies, among which acetoacetic acid is downregulated (Table 3) [36]. Lower levels of NEFA and ketone bodies in the milk of goats on the SCG diet suggest a potential role for SCG in reducing the negative energy balance in ruminants; however, further studies are warranted. We also found propionic acid and propionyl-CoA as discriminants. In ruminants, propionyl-CoA is used as a primer in the lipogenesis of odd-chain fatty acids. The latter is not synthesized by mammalian tissues but originates from the rumen microbial population as a de novo lipogenesis [37]. In agreement, [PERSON] et al. [6] observed that although there was no substantial change in the overall contents of fatty acids, a statistically significant increase in C15:0 level was observed in the milk of goats on the SCG diet, compared to controls. The beneficial effects of C15:0 on human health have been reported [38]. Several sterols were found to be discriminant, although they were expressed differently (upregulated or downregulated). The 8,8\({}^{\prime}\)-methylenebis catechchin was found upregulated in goats on the SCG diet. Coffee does not contain catechins that are, however, found in its berries [39].