Search Results (3)

Phytosterol esters have attracted widespread academic and industrial interests due to their advantages in lowering cholesterol, as antioxidants, and in preventing or treating cancer. However, the generation of by-products limits the application of phytosterol esters in food fields. In this study, deep eutectic solvents (DESs), a series of green, nontoxic, low-cost and biodegradable solvents, were adopted as the catalyst for the synthesis of pine sterol esters. The results showed that the acidic DES which was prepared with choline chloride (ChCl) and p-toluene sulfonic acid monohydrate (PTSA) with a molar ratio of 1:3 performed best in the prescreening experiments. To further improve the efficiency of the pine sterol ester, the molar ratio of substrates, the amount of catalyst, the reaction temperature and the reaction time were optimized, and its yield was improved to 94.1%. Moreover, the by-products of the dehydration side reactions of the sterol can be efficiently inhibited. To make this strategy more universal, other fatty acids were also used as the substrate for the synthesis of pine sterol esters, and a yield of above 92.0% was obtained. In addition, the reusability of DES was also investigated in this study, and the efficiency of DES was well maintained within five recycled uses. Finally, DFT calculations suggested that the suitable H-bonds between ChCl and PTSA decreased the nucleophilic capacity and increased the steric hindrance of the latter, and further prevented the attack on ^βH and reduced the generation of by-products. This study developed a reliable and eco-friendly strategy for the preparation of high-quality phytosterol esters with low-dosage catalyst usage and high selectivity. Full article

The aim of the study was to quantify total extractive contents and lipophilic compounds, stilbenes, and lignans in Scots pine stem wood, stem bark, branch biomass, and sawmill residues in four climatic regions of Finland to evaluate the most optimal sources of extractives for bio-based chemical biorefining and bioenergy products. Data were derived from 78 chip samples from the before-mentioned raw materials, the samples being pooled by tree height position from the sample trees of 42 experimental forest stands, and sawdust lots from 10 log stands. Accelerated solvent extraction (ASE) was employed to determine total extractive contents, followed by gas chromatography with flame ionization detection (GC–FID) to quantify extractive groups and gas chromatography-mass spectrometry (GC–MS) to analyse individual extractive compounds. Resin acids and triglycerides followed by fatty acids were the dominant extractive groups. Resin acids were most abundant in stem wood from final fellings and in sawdust, fatty acids in bark and branch biomass, and triglycerides also in stem wood from thinnings and the top parts of trees. Of the minor extractive groups, stilbenes were the most abundant in stem wood from final fellings and in sawdust, and steryl esters, sterols, and lignans in bark and branch biomass, the two last groups almost missing from other biomass components. Regional differences in the contents of extractive groups were generally small, 1.0−1.5 percentage points at the maximum, but factor analysis distinguished northern and southern regions into their own groups. Bark was the most potential source of fatty acids and sterols in southern Finland, and triglycerides and steryl esters in northern Finland. In stem wood, steryl esters, triglycerides, and lignans decreased and stilbenes increased from north to south. Certain fatty acids and resin acids were more frequent in the north. The results highlighted the importance of focused procurement and efficient sorting of raw materials, purity, unique properties, and feasible isolation techniques for competitive ability as well as large raw material volumes or well-defined value-added products. Full article

Fatty and resin acids in bark residues generated by forest industries can be used to produce high-value green chemicals, but more information about their concentrations in potential sources is required. We examined variations in the content of lipophilic extractives from both pulpwood bark and timber bark of Norway spruce and Scots pine trees growing in homogenous stands in mid-Sweden. We found that spruce pulpwood bark had the highest total amounts of fatty and resin acids (average yield, 0.9 kg/m³ wood). The regression functions, based on readily available tree parameters (age, stem diameter, height, growth rate and inner bark proportions), can be used to predict the concentrations of fatty and resin acids, triglycerides, sterols and steryl esters in bark materials before harvesting stands that supply industrial plants. Full article