# Extraction of Galactolipids from Waste By-Products:
## 3 Results and Discussion  
### Galactolipids in Processing By-Products  
The waste materials were analyzed for their galactolipid content, with a special emphasis on GOPO, which has the greatest pharmacological potential, as was highlighted earlier. The content of the analytes is presented in Table 2.  
The content of analytes varied significantly between the samples, which was partially the effect of using various morphological parts of plants. The subterranean parts of plants did not contain measurable levels of galactolipids, apples and beans were characterized by low levels, and broccoli had a high content of these compounds, as its green florets are abundant in chloroplasts. The rosibn was the richest source of galactolipids among the matrices analyzed, having an MGDGs/DGDGs ratio distinct from other resources.  
The rosibn was also characterized by a high content of GOPO, which accounted for almost 70% of galactolipids in the sample. This compound was also detected in broccoli, although its levels were much lower. Additionally, the broccoli wastes were characterized by a high water content, which would hinder the extraction with supercritical carbon dioxide and organic solvents of low polarity. The matrix could be dried prior to the process, although, depending on the technique selected, this would lead to the thermal decomposition of analytes (convection-drying) or generate substantial costs (freeze-drying). Therefore, only the rosibn pomace was selected for further experiments. Additionally, as levels of DGDGs in the material are much lower than those of MGDGs and require additional chromatographic analysis, only levels of MGDGs were evaluated in the later parts of the work.  
The galactolipid content in plants can be related to their physiological function because they are essential components of chromoplast membranes [1]. The review paper  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & **Total Content of** & **Content of** & **Total Content of** & **Dry Mass** \\  & **MGDGs** & **GOPO** & **DGDGs** & **Content** \\  & **(mg kg\({}^{-1}\))** & **(mg kg\({}^{-1}\))** & **(mg kg\({}^{-1}\))** & **(\%)** \\ \hline apple pomace & \(1.0\pm 0.4\) & \(\leq\)\(0.1\) & 0.5 \(\pm\) 0.2 & 27.4 \(\pm\) 0.3 \\ carrot pomace & \(\leq\)0.1 & \(\leq\)\(0.1\) & \(\leq\)\(0.1\) & 22.3 \(\pm\) 0.4 \\ rosehip pomace & 56.4 \(\pm\) 1.1 & 41.0 \(\pm\) 1.5 & 3.2 \(\pm\) 0.3 & 24.6 \(\pm\) 0.4 \\ broccoli wastes & 24.2 \(\pm\) 1.2 & 1.2 \(\pm\) 0.2 & 14.3 \(\pm\) 0.7 & 13.5 \(\pm\) 0.7 \\ fava bean wastes & 1.9 \(\pm\) 0.5 & \(\leq\)\(0.1\) & 1.2 \(\pm\) 0.2 & 43.2 \(\pm\) 0.2 \\ potato wastes & \(\leq\)0.1 & \(\leq\)\(0.1\) & \(\leq\)\(0.1\) & 31.1 \(\pm\) 0.2 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Content of galactolipids and dry mass in the waste materials analyzed.  
by [PERSON] et al. confirms this assumption. The authors reported that the levels of both MGDGs and DGDGs in leafy vegetables are by far the highest [2]. Such results were confirmed by other authors such as [PERSON] et al., who reported a total galactolipid content of 100-200 mg kg\({}^{-1}\) (of dry weight) in green leafy vegetables (parsley, spinach, and perilla) [20]. The only two literature reports on GOPO levels in rosehip are by [PERSON] and coworkers, who recorded a level of 270 mg kg\({}^{-1}\) in dried fruits [9], and [PERSON] at al., who reported 300 mg kg\({}^{-1}\) in a diet supplement based on dried rosehip [21], which is comparable to green vegetables. Our data provide a total galactolipid content of approximately 60 mg kg\({}^{-1}\) in rosehip and less than 40 mg kg\({}^{-1}\) in broccoli; the results are consistent with the literature considering the humidity of the samples and interspecies variations.