Characterization of seven sterols in five different types of cattle feedstuffs

Extending beyond traditional forage: potential nutritional benefits of native plants in extreme arid insular regions

The scarcity, unstable nutritional quality and environmental cost of imported forages in arid insular regions like Fuerteventura in the Canary Islands (Spain) need exploring sustainable local alternatives. This study evaluated the nutritional quality of twelve native and endemic plant species categorized into legumes, grasses, and a mixed group, cultivated under controlled conditions. The bromatological profiles, focusing on fiber, protein, lipids, and minerals, showed significant differences among plants in key parameters of forage quality: neutral detergent fiber (NDF; 24.2-71.3%), acid detergent fiber (ADF; 9.0-40.5%), acid detergent lignin (ADL; 2.0-15.8%), crude protein (CP; 6.1-20.9%), total lipids (TL; 1.5-6.3%), ash content (25.4-88.6%), enzymatic organic matter digestibility (EOMD; 5.9-10.9 MJ/kg), metabolizable energy (ME; 5.9-10.9 MJ/kg), and relative feed value (RFV; 74.8-317.9). Among lipids, all species had a high proportion of polyunsaturated fatty acids (PUFA; 34.7-63.1% of total fatty acids), mainly α-linolenic acid (ALA; 18:3 n-3; 24.8-54.4%) and linoleic acid (LA; 18:2 n-6; 6.4-25.0%). Other beneficial lipid molecules for animal health such as γ-linolenic acid (GLA; 18:3 n-6), stearidonic acid (SDA; 18:4n-3) and phytosterols (PTS) were detected in specific species. Mineral composition analysis revealed that only Ca, Na, Fe and Cu levels were near or above the established maximum tolerable levels (MTLs) in some species. According to literature, most of the species had a similar or slightly lower nutritional value compared to conventional forages such as alfalfa. Thus, the evaluated native species pool could serve as alternative feed for ruminants during forage shortages, suggesting their combined use to improve livestock health and product quality. This research emphasizes the untapped potential of native plant biodiversity to enhance sustainable agro-livestock practices in arid regions, supporting livestock nutrition and conserving unique botanical heritage.

Virgin Olive oil Authenticity Assays in a Single Run Using Two-Dimensional Liquid Chromatography-High Resolution Mass Spectrometry

Sterols and triterpenic alcohol analyses are one of the officially established parameters for assessing the authenticity of virgin olive oil (VOO). Most of the applications described for sterol analysis, including the official method, only allow the determination of the total sterol content but not its distribution in free or esterified form. This work proposes a two-dimensional liquid chromatography/high-resolution mass spectrometry (2D-LC-HRMS) method for the simultaneous analysis of triterpenic alcohols, free sterols and steryl esters. A reversed phase liquid chromatography (RPLC)-RPLC coupling was performed through a multiple heart-cutting interface equipped with an active solvent modulation (ASM) valve. Additionally, a selection valve was coupled to the 2D-LC system, allowing the simultaneous data acquisition from both dimensions in a single analysis. A simplified sample treatment based on solid phase extraction was also proposed to avoid tedious steps such as saponification or derivatization before gas chromatography analysis. To evaluate the content of these compounds in different olive oil categories, the proposed 2D-LC-HRMS system was applied to a set of samples from different commercial olive oil categories (extra virgin olive oil, virgin olive oil, olive oil, pomace olive oil) and sunflower oil. The results revealed significant differences in the distribution of free and esterified sterols of the analyzed samples, highlighting the free/esterified sterol ratio as a powerful tool to unveil olive oil fraud practices and fat manipulation.

Resolving phytosterols in microalgae using offline two-dimensional reversed phase liquid chromatography-supercritical fluid chromatography coupled with quadrupole time-of-flight mass spectrometry

Sterols are unsaponifiable lipids resulting from plant metabolism that exhibit interesting bioactive properties. Microalgae are a major source of specific phytosterols, most of which are still not fully characterized. The similarity in sterol structures and the existence of positional isomers make the separation of phytosterols challenging. A method was developed based on an offline two-dimensional (2D) system, reversed-phase liquid chromatography (RPLC)-supercritical fluid chromatography (SFC)/quadrupole time-of-flight (Q-ToF) mass spectrometry, for the identification of sterols in microalgae. Subsequent positive-mode MS/MS was used to confirm the identified phytosterols. The 2D chromatogram exhibited a pattern related to the positions of the double bonds, which were confirmed by standard injection, enabling structural elucidation. The analysis of the unsaponifiable fraction of two algae, namely Scenedesmus obliquus, a freshwater microalgae, and Padina pavonica, a marine macroalgae, highlighted the ability of the method to distinguish a large number of sterol isomers.

Presence of cholesterol oxides in milk chocolates and their correlation with milk powder freshness

Cholesterol oxidation products (COPs) of non-enzymatic origin are mainly found in meat, fish, eggs and milk, mostly originating from the type of feeding, processing and storage. To verify the significance of COPs as biomarkers of cholesterol autoxidation and milk freshness, we quantified them in chocolates containing whole milk powders (WMPs) of increasing shelf-lives (i.e. 20, 120, and 180 days). Non-enzymatic total COPs (both free and esterified) ranged from 256.57 ± 11.97 to 445.82 ± 11.88 ng/g, increasing proportionally to the shelf-life of the WMPs, thus reflecting the ingredients’ freshness. Based on the expected theoretical COPs, the effect of processing was quantitatively less significant in the generation of oxysterols (41–44%) than the contribution of the autoxidation of the WMPs over time (56–59%), pointing to the shelf-life as the primary determinant of COPs. Lastly, we quantified COPs of major commercial milk chocolates on the Italian market, which followed a similar distribution (from 240.79 ± 11.74 to 475.12 ± 12.58 ng/g). Although further replications of this work are needed, this study reports preliminary results and a practical example of a first application of non-enzymatic COPs as markers to further quantify and characterize the nutritional quality and freshness, not only of ingredients but also of composite products.

Oxysterols: From redox bench to industry

More and more attention is nowadays given to the possible translational application of a great number of biochemical and biological findings with the involved molecules. This is also the case of cholesterol oxidation products, redox molecules over the last years deeply investigated for their implication in human pathophysiology. Oxysterols of non-enzymatic origin, the excessive increase of which in biological fluids and tissues is of toxicological relevance for their marked pro-oxidant and pro-inflammatory properties, are increasingly applied in clinical biochemistry as molecular markers in the diagnosis and monitoring of several human and veterinary diseases. Conversely, oxysterols of enzymatic origin, the production of which is commonly under physiological regulation, could be considered and tested as promising pharmaceutical agents because of their antiviral, pro-osteogenic and antiadipogenic properties of some of them. Very recently, the quantification of oxysterols of non-enzymatic origin has been adopted in a systematic way to evaluate, monitor and improve the quality of cholesterol-based food ingredients, that are prone to auto-oxidation, as well as their industrial processing and the packaging and the shelf life of the finished food products. The growing translational value of oxysterols is here reviewed in its present and upcoming applications in various industrial fields.

A new look at edible and medicinal mushrooms as a source of ergosterol and ergosterol peroxide - UHPLC-MS/MS analysis

Ergosterol (ES) and ergosterol peroxide (EP) are secondary metabolites common for different mushrooms and responsible for health promoting effects, including anti-inflammatory, anticancer, antiviral activity, and reduction of the incidence of cardiovascular disease. In this study, a new method for determination of both ES and EP in mushroom extracts was developed. Two methods for UHPLC-MS/MS with the use of APCI and APPI sources were developed and compared. The UHPLC-APPI-MS/MS method was found to be more effective and convenient for the analysis of both compounds in 21 edible and 9 medicinal mushrooms. Among the investigated mushrooms, M. procera was found to contain the highest level of ES, while G. dryophilus constituted the richest source of EP. Therefore, it can be suggested that mushrooms are a valuable source of ES and EP in everyday human diet and can be used for development of nutraceuticals and functional food ingredients.

Effect of industrial processing and storage procedures on oxysterols in milk and milk products

Oxysterols are products of enzymatic and/or chemical cholesterol oxidation. While some of the former possess broad antiviral activities, the latter mostly originate from the deterioration of the nutritional value of foodstuff after exposure to heat, light, radiation and oxygen, raising questions about their potential health risks. We evaluated the presence of selected oxysterols in bovine colostrum and monitored the evolution of their cholesterol ratio throughout an entire industrial-scale milk production chain and after industrially employed storage procedures of milk powders. We report here for the first time the presence of high levels of the enzymatic oxysterol 27-hydroxycholesterol (27OHC) in concentrations of antiviral interest in bovine colostrum (87.04 ng mL^-1) that decreased during the first postpartum days (56.35 ng mL^-1). Of note, this oxysterol is also observed in milk and milk products and is not negatively affected by industrial processing or storage. We further highlight an exponential increase of the non-enzymatic oxysterols 7β-hydroxycholesterol (7βOHC) and 7-ketocholesterol (7KC) in both whole (WMPs) and skimmed milk powders (SMPs) during prolonged storage, confirming their role as reliable biomarkers of cholesterol oxidation over time: after 12 months, 7βOHC reached in both SMPs and WMPs amounts that have been found to be potentially toxic in vitro (265.46 ng g^-1 and 569.83 ng g^-1, respectively). Interestingly, industrial processes appeared to affect the generation of 7βOHC and 7KC differently, depending on the presence of fat in the product: while their ratios increased significantly after skimming and processing of skimmed milk and milk products, this was not observed after processing whole milk and milk cream.