Analysis of triacylglycerol isomers in Malaysian cocoa butter using HPLC–mass spectrometry

Recent advances in plant-based fat formulation as substitute for lard

Lard is one of the main animal fats used as shortening and frying medium. Religious prohibitions and negative health perceptions regarding animal fats have caused concerns about the consumption of lard among communities living around the world. Various research efforts have been made in the past to formulate plant-based fats and shortenings as substitutes for the exclusion of lard from food. This would eventually help countries to regularize food formulations according to their religious compliance. As the existence of a single plant fat as substitute for lard has not been discovered from nature, researchers attempted to study the possibility of mixing native fats and oils such as enkabang fat, canola oil, guava oil, palm oil, palm stearin, soybean oil and cocoa butter as raw materials. The compatibility of the formulated plant-based fat substitute for lard was assessed in terms of chemical composition and thermo-physical properties. The formulated plant-based shortenings and lard shortening were simply plastic fats based on their consistency value and existence of β’ and β-form polymorphs of which the β’ -form was dominant. The functional properties of formulated plant-based shortenings and lard were also compared in the formulation of cookies. Although a substantial amount of work has been done over the past decade, there was hardly any discussion on the pros and cons of the approaches used for raw material selection and the criteria adopted in the assessment of the formulated products. Hence, this review intended to bring an update of the progress of studies with regard to these two aspects.

Metabolite Storage in Theobroma cacao L. Seed: Cyto-Histological and Phytochemical Analyses

Cocoa (Theobroma cacao L.), an economically important tropical-fruit crop as source of chocolate, has recently gained a considerable attention; its seeds contain a large amount of different bioactive compounds that have attracted interest because may be beneficial to humans by improving cardiovascular health, by cancer chemo-preventive effects and also through neuroprotective activities. The morphological and anatomical characteristics of cocoa seeds are closely related to the aroma and to the nutritional properties. This study aimed to provide more information about the storage of some metabolites in the various components of cocoa seed by microscopical and phytochemical analyses. Polyphenols, sterols, tocopherols and fatty acids were detected in different portions of the seeds (teguments, cotyledons, embryo axis and pulp). Quali and quantitative differences were observed and a characteristic polyphenol pattern was detected in the different portions of the seed; cytological analysis demonstrated the presence of these compounds in big vacuolated polyphenolic cells. Among the analyzed fatty acids, the stearic and oleic acids were the most abundant in all the seed components (teguments, cotyledons and embryo axis). Fatty acids, usually found in the form of esters, thioesters and amides, represent one of the storage substances of cocoa seed probably localized in lipid globules, which in our observations occupied almost the entire volume of small isodiametric cells of cotyledon mesophyll. In the cocoa seeds we observed also a different distribution of sterols: β-sitosterol and Δ5-avenasterol were the most abundant, above all in the embryo axis; stigmasterol and campesterol were less present in embryo axis and more abundant in teguments; campestanol level was again higher in teguments but lower in cotyledons. The specific localization of different kind of sterols was probably related to a peculiar function. Our experiments demonstrated that all seed components contribute to the metabolites storage, but with interesting differences in the localization and amount of each metabolite.

Research advances based on mass spectrometry for profiling of triacylglycerols in oils and fats and their applications

Vegetable oils and animal fats are dietary source of lipids that play critical and multiple roles in biological function. Triacylglycerols (TAGs) are the principal component of oils and fats with significant difference in profile among different oils and fats. TAG profiling is essential for nutritional evaluation, quality control and assurance of safety in oils and fats. However, analysis of TAGs is a challenging task because of the complicated composition of TAGs and their similar physicochemical properties in oils and fats. The rapid development of mass spectrometry (MS) technology in recent years makes it possible to analyze the composition, content and structure of TAGs in the study of the physical, chemical and nutritional properties of oils, fats and related products. This review described the research advancement based on MS for profiling of TAGs in oil, fat and their applications in food. The application of MS, including direct infusion strategies, and its combination with chromatography, gas chromatography-MS (GC-MS) and liquid chromatography-MS (LC-MS), in the analysis of TAGs were reviewed. The advantages and disadvantages of these analytical methods with relevant applications for TAGs analysis in food were also described.

Enzymatic synthesis of cocoa butter equivalent from olive oil and palmitic-stearic fatty acid mixture

The main goal of the present research is to restructure olive oil triacylglycerol (TAG) using enzymatic acidolysis reaction to produce structured lipids that is close to cocoa butter in terms of TAG structure and melting characteristics. Lipase-catalyzed acidolysis of refined olive oil with a mixture of palmitic-stearic acids at different substrate ratios was performed in an agitated batch reactor maintained at constant temperature and agitation speed. The reaction attained steady-state conversion in about 5 h with an overall conversion of 92.6 % for the olive oil major triacylglycerol 1-palmitoy-2,3-dioleoyl glycerol (POO). The five major TAGs of the structured lipids produced with substrate mass ratio of 1:3 (olive oil/palmitic-stearic fatty acid mixture) were close to that of the cocoa butter with melting temperature between 32.6 and 37.7 °C. The proposed kinetics model used fits the experimental data very well.

Triacylglycerol profile in cocoa liquors using MALDI-TOF and LC-ESI tandem mass spectrometry

Triacylglycerols are responsible for chocolate's peculiar melting behavior: the type and position of fatty acids on the glycerol molecule strongly affect the melting range of cocoa butter. For this reason, the characterization of triglyceride composition in cocoa products is particularly important. In this work, triacylglycerols extracted from cocoa liquor samples were analyzed by matrix-assisted laser desorption/ionization time-of-flight (TOF) and electrospray ionization tandem mass spectrometry (MS/MS) coupled to liquid chromatography. Extracted samples were initially analyzed by direct injection in MS to obtain information on triglyceride molecular weights; relevant MS parameters were optimized, and the possible formation of the adducts [M + Na](+) and [M + NH(4)](+) was studied. Tandem mass experiments (both with triple quadrupole and TOF/TOF) were performed to study the fragmentation pathways (in particular, the loss of palmitic, stearic and oleic acid) and identify the triacylglycerols in cocoa liquors. Some signals of the spectra obtained with both MS techniques could indicate the presence of diacylglycerols in the cocoa extract, but different experimental evidences demonstrated that they were generated by the in-source fragmentation of triglycerides. A nonaqueous reversed-phase chromatographic separation was also developed and used to support the identification of the analytes; nine triacylglycerols were recognized in the cocoa liquor extracts. The three different batches of Ecuador cocoa liquor did not show significant differences in the triacylglycerol profile.

Nutritional composition and fatty acids profile in cocoa beans and chocolates with different geographical origin and processing conditions

Nutritional composition and fatty acids (FA) profile were determined in cocoa and chocolates of different geographical origin and subject to different processing conditions. Cocoa butter was the major nutrient in cocoa beans and carbohydrates were the most important in chocolates. Cocoa composition and FA profile varied depending on geographical origin whilst in chocolates only carbohydrates and fat content varied significantly due to the effect of origin and no significant effect was observed for processing conditions. Both for cocoa and chocolates differences in FA profile were mainly explained as an effect of the geographical origin, and were not due to processing conditions in chocolate. For cocoa, differences in FA profile were found in C12:0, C14:0, C16:0, C16:1, C17:0, C17:1 and C18:0 whilst for chocolates only differences were found in C16:0, C18:0, C18:1 and C18:2. For all samples, C16:0, C18:0, C18:1 and C18:2 were quantitatively the most important FA. Ecuadorian chocolate showed a healthier FA profile having higher amounts of unsaturated FA and lower amounts of saturated FA than Ghanaian chocolate.

Determination of triacylglycerol regioisomers using electrospray ionization-quadrupole ion trap mass spectrometry with a kinetic method

The kinetic method was applied to differentiate and quantify mixtures of regioisomeric triacylglycerols (TAGs) by generating and mass selecting alkali ion bound metal dimeric clusters with a TAG chosen as reference (ref) and examining their competitive dissociations in a quadrupole ion trap mass spectrometer. This methodology readily distinguished pairs of regioisomers (AAB/ABA) such as LLO/LOL, OOP/OPO and SSP/SPS and consequently distinguished sn-1/sn-3, sn-2 substituents on the glycerol backbone. The dimeric complex ions [ref, Li, TAG((AAB and/or ABA))](+) generated by electrospray ionization mass spectrometry were subjected to collision induced dissociation causing competitive loss of either the neutral TAG reference (ref) leading to [Li(AAB and/or ABA)](+) or the neutral TAG molecule (TAG((AAB and/or ABA))) leading to [ref, Li](+). The ratio of the two competitive dissociation rates, defined by the product ion branching ratio (R(iso)), was related via the kinetic method to the regioisomeric composition of the investigated TAG mixture. In this work, a linear correlation was established between composition of the mixture of each TAG regioisomer and the logarithm of the branching ratio for competitive fragmentation. Depending on the availability of at least one TAG regioisomer as standard, the kinetic method and the standard additions method led to the quantitative analysis of natural TAG mixtures.

Theobroma cacao L., "The food of the Gods": quality determinants of commercial cocoa beans, with particular reference to the impact of fermentation

The quality of commercial cocoa beans, the principal raw material for chocolate production, relies on the combination of factors that include the type of planting material, the agricultural practices, and the post-harvest processing. Among these, the fermentation of the cocoa beans is still the most relevant since it is the process whereby the precursors of the cocoa flavor arise. The formation of these precursors depends on the activity of different microbial groups on the beans pulp. A comparison of fermentations in different countries showed that a well-defined microbial succession does not always take place and that the role of Bacillus spp. in this process remains unclear. Considering the overriding importance of the fermentation to achieve high quality commercial cocoa beans, we discuss the need of addressing the impact of the farming system, the ripeness state of the pods, and the role of microbial interactions on the fermentation in future research. In addition, the problem of high acidification cocoa beans, aspects dealing with the volatile fraction of the flavor, and the cocoa butter properties, all were identified as critical aspects that need further investigation. The standardization of the microbiological methods and the application of metagenomic approaches would magnify the knowledge in this domain.

Regioisomer characterization of triacylglycerols by non-aqueous reversed-phase liquid chromatography/electrospray ionization mass spectrometry using silver nitrate as a postcolumn reagent

Triacylglycerols (TAGs) provide a challenge for mass spectrometry (MS) analysis because of their complexity. In particular, for dietary, nutritional and metabolic purposes, the positional placement of fatty acids on the glycerol backbone of TAGs is a crucial aspect. To solve this problem, we have investigated the TAGs' fragmentation patterns using an ion trap mass spectrometer. A series of pure regioisomeric pairs of TAGs (POP/PPO, POO/OPO and OSO/SOO) were cationized by Ag(+) after their separation by non-aqueous reversed-phase liquid chromatography (NARP-LC) before MS to improve MS sensitivity. Electrospray ionization-MS (ESI-MS) conditions were optimized in order to produce characteristic [M + Ag + AgNO(3)](+) ions from each TAG, which were then fragmented to produce MS/MS spectra and then fragmented further to produce up to MS(5) spectra. The observation of ions produced by LC-MS(5) of on-line Ag(+)-cationized TAG provided unambiguous information on the fatty acid distribution on the glycerol backbone. These strategies of MS to MS(5) experiments were applied to identify components and to determine the regiospecificity of TAG within a complex mixture of lipids in natural oils.

Atmospheric pressure covalent adduct chemical ionization tandem mass spectrometry for double bond localization in monoene- and diene-containing triacylglycerols

We report a method to elucidate the structure of triacyl-glycerols (TAGs) containing monoene or diene fatty acyl groups by atmospheric pressure covalent adduct chemical ionization (APCACI) tandem mass spectrometry using acetonitrile as an adduct formation reagent. TAGs were synthesized with the structures ABB and BAB, where A is palmitate (C16:0) and B is an isomeric C18 monoene unsaturated at position 9, 11, or 13 or an isomeric diene unsaturated at positions 9 and 11, 10 and 12, or 9 and 12. In addition to the species at m/z 54 observed in previous CI studies of fatty acid methyl esters, we also found that ions at m/z 42, 81, and 95 undergo covalent reaction with TAGs containing double bonds to yield ions at m/z 40, 54, 81, and 95 units greater than that of the parent TAG: [M + 40]+, [M + 54]+, [M + 81]+, and [M + 95]+ ions. When collisionally dissociated, these ions fragment to produce two or three diagnostic ions that locate the double bonds in the TAG. In addition, ions [RCH=C=O + 40]+ and [RCH=C=O + 54]+ formed from collisional dissociation are of strong abundance in MS/MS spectra, and collisional activation of these ions produces two intense confirmatory diagnostic ions in the MS3 spectra. Fragment ions reflecting neutral loss of an sn-1-acyl group from [M + 40]+ and [M + 54]+ are more abundant than those reflecting neutral loss of an sn-2-acyl group, analogous to previous reports for protonated TAGs. The position of each acyl group on the glycerol backbone is thus determined by the relative abundances of these ions. Under the conditions in our instrument, the [M + 40]+ adduct is at the highest signal and also yields all information about the double bond position and TAG stereochemistry. With the exception of geometries about the double bonds, racemic TAG isomers containing two monoenes or dienes and a saturate can be fully characterized by APCACI-MS/MS/MS.

Analysis of triacylglycerols in fat body of bumblebees by chromatographic methods

Triacylglycerols (TAGs) from the fat body of several bumblebee species (Bombus lucorum, B. terrestris, B. lapidarius, B. hypnorum, B. hortorum, and B. confusus) were studied using chromatographic techniques. Semi-preparative thin-layer chromatography was used to isolate the TAGs from the tissue extract. Gas chromatography (GC) enabled us to identify the fatty acids (FAs) that form bumblebee TAGs and to quantify their relative proportions. The TAGs were subsequently analysed by high-performance liquid chromatography-atmospheric pressure chemical ionisation mass spectrometry. Two chromatographic systems, including non-aqueous reversed-phase chromatography and silver ion chromatography on cation exchange resin in silver (I) ionic form, were optimised and their performance compared. The most abundant fatty acids in bumblebees TAGs contained 18 or 16 carbon atoms; oleic acid predominated in most samples. TAGs were found to be a complex mixture of isomers; some of them, e.g. OLnO, PLnO, PoPoO, PoPoP, POO, or OOO (where Po is palmitoleic, P is palmitic, Ln is linolenic, and O is oleic acid) were abundant in particular species. The composition of both FAs and TAGs was found to be species-specific. Only minor differences were found among specimens of the same species.