ABSTRACT
A method for the analysis of phytostanyl fatty acid esters, the functional ingredients of cholesterol-lowering enriched foods, was developed. The procedure is based on (i) separation of the intact esters via reversed-phase ultrahigh-performance liquid chromatography; (ii) detection by atmospheric pressure chemical ionization-mass spectrometry; and (iii) quantitation using selected ion monitoring (SIM) mode. Employing a C8 column, phytostanyl fatty acid esters sharing the same stanol nucleus could be separated according to the esterified fatty acids while esters with different stanol moieties could be distinguished via SIM based on the formation of an intense fragment ion [M - fatty acid + H](+). The suitability of the approach was demonstrated using different types of enriched foods reflecting the diversity in potential matrices (skimmed milk drinking yogurt, margarine, and soft-cheese-style spread). The developed methodology extends the analytical basis for authenticity and quality assessments of functional foods enriched with phytostanyl fatty acid esters.
Subject(s)
Chromatography, High Pressure Liquid/methods , Cultured Milk Products/chemistry , Fatty Acids/analysis , Food, Fortified/analysis , Margarine/analysis , Mass Spectrometry/methods , Chromatography, Reverse-Phase/methods , Mass Spectrometry/instrumentationABSTRACT
PURPOSE: The objective was to investigate the metabolic fate of phytosteryl/-stanyl fatty acid and ferulic acid esters upon consumption by healthy humans. METHODS: A capillary gas chromatographic methodology was employed to follow a randomized, single-blind three group crossover clinical trial and to quantify simultaneously individual intact esters, liberated phytosterols/-stanols and their metabolites in feces. Skimmed milk drinking yogurts enriched with complex mixtures of phytosteryl/-stanyl fatty acid esters and ferulates, respectively, were employed as food carriers. RESULTS: On average, 73 % of total plant stanyl fatty acid esters and 80 % of total plant steryl fatty acid esters were hydrolyzed. Among the individuals, the hydrolysis rates ranged from 40 to 96 %. In addition, there were subject-dependent discrepancies between the amounts of phytosterols/-stanols actually determined in the feces and the calculated hydrolysis rates. On average, 69 % of the amounts of sterols/stanols expected from the amounts of remaining intact esters were found. CONCLUSIONS: The study revealed large interindividual variability regarding the recoveries of dietary phytosteryl/-stanyl esters upon gastrointestinal passage in healthy humans. Nevertheless, there was a significant impact of the acid moiety (oleate=linoleate=linolenate>eicosanoate>palmitate>ferulate) on the hydrolysis rates; the influence of the phytosterol/-stanol moiety was less pronounced.
Subject(s)
Cholesterol/analogs & derivatives , Coumaric Acids/metabolism , Diet , Digestion , Fatty Acids/metabolism , Feces/chemistry , Phytosterols/metabolism , Sitosterols/metabolism , Adult , Anticholesteremic Agents/administration & dosage , Anticholesteremic Agents/analysis , Anticholesteremic Agents/chemistry , Anticholesteremic Agents/metabolism , Beverages , Cholesterol/administration & dosage , Cholesterol/analysis , Cholesterol/chemistry , Cholesterol/metabolism , Coumaric Acids/administration & dosage , Coumaric Acids/analysis , Coumaric Acids/chemistry , Cross-Over Studies , Diet, Fat-Restricted , Esterification , Fatty Acids/administration & dosage , Fatty Acids/analysis , Fatty Acids/chemistry , Food, Formulated , Humans , Hydrolysis , Male , Phytosterols/administration & dosage , Phytosterols/analysis , Phytosterols/chemistry , Single-Blind Method , Sitosterols/administration & dosage , Sitosterols/analysis , Sitosterols/chemistry , Yogurt , Young AdultABSTRACT
An approach based on solid-phase extraction for the effective separation of free phytosterols/phytostanols and phytosteryl/phytostanyl fatty acid and phenolic acid esters from cereal lipids was developed. The ester conjugates were analyzed in their intact form by means of capillary gas chromatography. Besides free sterols and stanols, up to 33 different fatty acid and phenolic acid esters were identified in four different cereal grains via gas chromatography-mass spectrometry. The majority (52-57%) of the sterols and stanols were present as fatty acid esters. The highest levels of all three sterol and stanol classes based on dry matter of ground kernels were determined in corn, whereas the oil extract of rye was 1.7 and 1.6 times richer in fatty acid esters and free sterols/stanols than the corn oil. The results showed that there are considerable differences in the sterols/stanols and their ester profiles and contents obtained from corn compared to rye, wheat, and spelt. The proposed method is useful for the quantification of a wide range of free phytosterols/phytostanols and intact phytosteryl/phytostanyl esters to characterize different types of grain.
Subject(s)
Edible Grain/chemistry , Esters/analysis , Fatty Acids/analysis , Hydroxybenzoates/analysis , Phytosterols/analysis , Plant Extracts/analysis , Gas Chromatography-Mass SpectrometryABSTRACT
Approaches for the capillary gas chromatographic (GC) based analysis of intact plant stanyl esters in enriched foods were developed. Reference compounds were synthesized by enzyme-catalyzed transesterifications. Their identities were confirmed by means of mass spectrometry. Using a medium polar trifluoropropylmethyl polysiloxane stationary phase, long-chain plant stanyl esters could be separated according to their stanol moieties and their fatty acid chains. Thermal degradation during GC analysis was compensated by determining response factors; calibrations were performed for ten individual plant stanyl esters. For the analysis of low-fat products (skimmed milk drinking yogurts), the GC separation was combined with a "fast extraction" under acidic conditions. For fat-based foods (margarines), online coupled LC-GC offered an elegant and efficient way to avoid time-consuming sample preparation steps. The robust and rapid methods allow conclusions on both, the stanol profiles and the fatty acid moieties, and thus provide a basis for the authentication of this type of functional food ingredients.
