Despite the widespread use of artichoke-based food supplements for obesity control (FSOC), studies on evaluation of the quality/authenticity of these commercial products are scarce. To that aim, a new multi-analytical strategy, based on the use of gas chromatography coupled to mass spectrometry (GC–MS) and high performance liquid chromatography coupled to ultraviolet and mass spectrometry detection (HPLC-UV-MS), in combination with chemometrics, has been developed. Twenty-one artichoke FSOC and different bract and leaf extracts (used as reference samples) were analysed. Sugars, inositols, caffeoylquinic acids, dicaffeoylquinic acids, flavonoids and their glycosides were detected in reference samples and in most artichoke FSOC. Low concentrations of bioactives, and the presence of other compounds probably related to heat treatment during manufacturing (difructosyl anhydrides, 3-deoxyglucosone), or to the addition of caloric additives (maltose, maltotriose) or non-declared plants (e.g. pinitol, disaccharides, silybin derivatives) were also detected in some FSOC by either GC–MS or HPLC-UV-MS. Application of Principal Component Analysis to the combined GC–MS + HPLC-UV data matrix, proved that this multi-analytical strategy provides advantages over single analytical techniques for the detection of the wide variety of fraudulent practices affecting authenticity of artichoke FSOC and for assessment of their quality. © 2021

Despite the nutritional properties of alfalfa, its production is mainly for animal feed and it is undervalued as a food source. In this study, the valorization of alfalfa as a potential source of bioactive carbohydrates [inositols, α-galactooligosaccharides (α-GOS)] is presented. A Box– Behnken experimental design was used to optimize the extraction of these carbohydrates from leaves, stems, and seeds of alfalfa by solid–liquid extraction (SLE) and microwave-assisted extraction (MAE). Optimal extraction temperatures were similar for both treatments (40◦C leaves, 80◦C seeds); however, SLE required longer times (32.5 and 60 min vs. 5 min). In general, under similar extraction conditions, MAE provided higher yields of inositols (up to twice) and α-GOS (up to 7 times); hence, MAE was selected for their extraction from 13 alfalfa samples. Pinitol was the most abundant inositol of leaves and stems (24.2–31.0 mg·g−1 and 15.5–22.5 mg·g−1, respectively) while seed extracts were rich in α-GOS, mainly in stachyose (48.8–84.7 mg·g−1). In addition, inositols and α-GOS concentrations of lyophilized MAE extracts were stable for up to 26 days at 50◦C. These findings demonstrate that alfalfa is a valuable source of bioactive carbohydrates and MAE a promising alternative technique to obtain functional extracts. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

Kale (Brassica oleracea) is a cool-season vegetable widely employed in the elaboration of diverse products such as tea and smoothies in USA or in the Northern German cuisine in wintertime. Besides, kale is gaining attention due to the diverse health benefits reported in the literature for its consumption, e.g. antigenotoxic and anticarcinogenic effect, protection of cardiovascular system and gastrointestinal tract. Low molecular weight carbohydrates (LMWC) are compounds directly related with kale flavour and nutritional quality. Despite different studies focusing on the chemical composition of kale, few information on LMWC is available. Thus, in this work a multianalytical approach was conducted in order to perform a comprehensive study of kale LMWC; their evolution during plant development and acclimation to cool temperatures was also evaluated. Gas chromatography coupled to mass spectrometry allowed the identification of 13 LMWC, being myo-inositol, galactinol, maltose and melibiose described for the first time in kale. Eight major LMWC were quantified in three different commercial kale cultivars using hydrophilic interaction liquid chromatography coupled to mass spectrometry to monitor possible differences in their content during plant development and as consequence of plant acclimation to cold temperatures. Overall, for all types of kales under study, the content of maltose and sucrose decreased during the plant development while the concentration of fructose, melibiose, maltose, raffinose and galactinol was increased in all kale types exposed to low temperatures. These results underline the importance of controlling the temperature during kale cultivation in order to obtain products with a high nutritional value. © 2019 Elsevier Ltd

A microwave-assisted extraction (MAE) method was developed for the extraction of bioactive inositols (D-chiro- and myo-inositols) from lettuce (Lactuca sativa) leaves as a strategy for the revalorization of these agrofood residues. Gas chromatography-mass spectrometry was selected for the simultaneous determination of inositols and sugars (glucose, fructose, and sucrose) in these samples. A Box–Behnken experimental design was used to maximize the extraction of inositols based on the results of single factor tests. Optimal conditions of the extraction process were as follows: liquid-to-solid ratio of 100:1 v/w, 40°C, 30 min extraction time, 20:80 ethanol:water (v/v), and one extraction cycle. When compared with conventional solid-liquid extraction (SLE), MAE was found to be more effective for the extraction of target bioactive carbohydrates (MAE 5.42 mg/g dry sample versus SLE 4.01 mg/g dry sample). Then, MAE methodology was applied to the extraction of inositols from L. sativa leaves of different varieties (var. longifolia, var. capitata and var. crispa). D-chiro- and myo-inositol contents varied between 0.57–7.15 and 0.83–3.48 mg/g dry sample, respectively. Interfering sugars were removed from the extracts using a biotechnological procedure based on the use of Saccharomyces cerevisiae for 24 h. The developed methodology was a good alternative to classical procedures to obtain extracts enriched in inositols from lettuce residues, which could be of interest for the agrofood industry. © 2020 Wiley-VCH GmbH

Currently there is great interest in exploitation of agrofood by-products, such as those from legumes, as source of bioactive ingredients. To that aim, characterization of cyclitol and sugar composition of pods and seeds from different legume species has been carried out. A green Microwave Assisted Extraction (MAE) method was optimized for extraction of bioactive inositols, and both pod and seed yields were compared with those obtained by conventional reflux extraction. A subsequent Saccharomyces cerevisiae treatment was also evaluated for removal of interfering coextracted sugars. myo-Inositol was present in all legume pods and seeds and galactinol in most seeds. chiro-Inositol was found in soybean and basul, whereas outstanding pinitol concentrations were only detected in soybean. The optimized MAE method provided extracts rich in pinitol from soybean pods (41.5–58.0 mg g−1) and seeds (5.3–7.5 mg g−1). Removal of 97\% of interfering sugars in MAE soybean pod extracts was achieved by yeast treatment. © 2020 Elsevier Ltd

Novel methodologies for the improved extraction of bioactive carbohydrates that fulfill the principles of green chemistry have been reviewed in this manuscript. As an alternative to conventional water extraction methods, advantages of the use of new green solvents such as ionic liquids and deep eutectic solvents have been discussed. Recent applications of advanced techniques such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pressurized liquid extraction (PLE), supercritical fluid extraction (SFE) and enzyme-assisted extraction (EAE) have also been revised. Special attention has been paid to those procedures based on the combination of several of these techniques which provide a better performance [e.g. ultrasound-microwave-assisted extraction (UMAE)] or show an improved selectivity [e.g. microwave-assisted aqueous two-phase extraction (MAATPE), microwave-assisted enzymatic extraction or enzymolysis-ultrasound-assisted extraction (MAEE or EUAE), etc.]. Finally, future perspectives regarding the possible application of these new eco-friendly methodologies at industrial scale together with the advances required to that aim are presented. © 2019 Elsevier B.V.

Five commercial ionic liquid (IL) columns have been evaluated for the first time for the gas chromatography-mass spectrometry (GC-MS) analysis of low molecular weight carbohydrate (LMWC) standards (mono-, di-, and trisaccharides, inositols, and iminosugars). A previous derivatization step was necessary to convert the LMWCs into their volatile and stable derivatives. Compared with conventional GC stationary phases, such as HP-1 and Supelcowax® 10, IL columns have shown a different selectivity in the separation of target compounds. Among the IL columns, only SLB™-IL82 allowed the elution of all the LMWCs studied. Its performance in terms of peak width and asymmetry, evaluated under different oven temperature conditions, was shown to be dependent on the carbohydrate class considered. As an example of application, a SLB™-IL82 column was successfully used to separate the complex mixtures of LMWCs in hyacinth and mulberry extracts. This column is an interesting alternative to the conventional stationary phases used in the GC analysis of LMWCs in real-world samples. [Figure not available: see fulltext.]. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature.

Oligosaccharides are gaining importance because of their beneficial properties in human health. They normally appear in natural and synthetic products as complex mixtures of different monomeric units, glycosidic linkages and degrees of polymerization, being disaccharides and trisaccharides usually the most abundant ones. Although liquid chromatography-mass spectrometry is a useful technique for oligosaccharides analysis, the similarity of their structures makes difficult their characterization. Moreover, there is still scarce information about the relationship between carbohydrate chemical structure, mass spectra and chromatographic data. Then, in this work, chromatographic parameters for 23 disaccharides with different linkages and monomeric units (glucose, galactose, mannose and fructose) were determined using porous graphitized and hydrophilic interaction liquid chromatography columns. Moreover, diagnostic ions of these disaccharides obtained by tandem mass spectra (MS2) were established by stepwise linear discriminant analysis. The relationship between carbohydrate chemical structure and their chromatographic retention data and characteristic ions obtained by multiple-stage mass spectrometry (MSn) was successful in establishing some specific criteria that allowed the characterization of trisaccharides with different structural features. © 2019

Byproducts from artichoke represent the majority of the mass collected from the plant and constitute an interesting source of bioactive compounds such as inositols and caffeoylquinic acids. In this work, a microwave assisted extraction (MAE) methodology was developed for the simultaneous extraction of these compounds from artichoke stalks, leaves, receptacles and external bracts. Optimal MAE conditions to maximize the extraction of these bioactives and the antioxidant activity were 97 °C, 3 min, ethanol:water (50:50, v/v). Moreover, a GC–MS methodology was also developed for the simultaneous determination of these compounds in a single run; optimal derivatization conditions were achieved using hexamethyldisilazane and N,O-bis(trimethylsilyl)trifluoroacetamide with 1\% trimethylchlorosilane. Artichoke receptacle extracts were the richest in caffeoylquinic acids (28–35 mg g−1 dry sample), followed by the bracts (9–18 mg g−1 dry sample), while those from leaves showed the highest concentrations of inositols (up to 15 mg g−1 dry sample). Receptacle extracts also had the highest antioxidant activity (123 mg TE g−1 dry sample) and the greatest concentration of total phenolic compounds (47 mg GAE g−1 dry sample). Therefore, the developed methodology could be considered as a valuable procedure to obtain and characterize bioactive ingredients with industrial interest from artichoke byproducts, opening new routes of revalorization of artichoke agro-industrial residues. © 2019

Carbohydrates are one of the most important ingredients in foods. They are normally present as complex mixtures with different glycosidic linkages, monomeric units and degrees of polymerization. This structural heterogeneity impairs their comprehensive characterization and requires the use of analytical techniques with high resolving power and sensitivity. The use of chromatographic techniques, especially liquid chromatography (LC), has been extremely helpful for the analysis of carbohydrates. However, in many cases, the use of monodimensional LC is not enough to resolve these complex mixtures; then, the use of techniques with a higher resolving power, as multidimensional LC, could be a good alternative. To the best of our knowledge, our findings are pioneer in applying online LC × LC for the analysis of carbohydrate mixtures. For this purpose, different conditions such as stationary phases (BEH amide, C 18 and PGC columns) and chromatographic conditions for the separation of di- and trisaccharide mixtures were optimized. The BEH amide × C 18 combination was selected for the LC × LC analysis of carbohydrate standards with different degrees of polymerization, linkages and monomeric units. In order to allow their proper UV detection, carbohydrates were previously derivatized using p-aminobenzoic ethyl ester. This method also resulted to be successful for the separation of commercial prebiotic mixtures of galacto-oligosaccharides and gentio-oligosaccharides. This is the first time that LC × LC has been applied for the separation of bioactive carbohydrate mixtures and it could be considered as a powerful analytical technique for the characterization of other oligosaccharide complex mixtures. © 2019 Elsevier B.V.

The low molecular weight carbohydrate (LMWC) profile of cocoa beans has recently been studied using hydrophilic interaction liquid chromatography coupled to electrospray ionization-time of flight mass spectrometry (HILIC-ESI-TOF MS) and HILIC-ESI-tandem mass spectrometry (HILIC-ESI-MSn). However, different LMWC could not be unambiguously identified. Thus, as a first approach in this paper, gas chromatography coupled to mass spectrometry (GC–MS) was used as a complementary analytical technique to characterize LMWC of cocoa beans. Different mono-, di-, tri- and tetrasaccharides, as well as myo-inositol, galactinol and a diglycosil glycerol were detected. scyllo-Inositol, 1-kestose and 6-kestose were identified in unfermented cocoa beans for the first time. Moreover, other minor LMWC were tentatively assigned as fructosyl-fructose, fructosyl-glucose and glucosyl-sucrose. As a second step, in order to evaluate new possible indicators of cocoa bean origin or fermentation status, scyllo-inositol, 1-kestose and galactinol were selected as target compounds and a HILIC-ESI-TOF MS method was optimized for their analysis. The optimized conditions, using an acetonitrile:water gradient with 0.05\% ammonium hydroxide at 40 °C showed narrow peaks (wh: 0.3-0.5 min) with good resolution values (Rs: 0.83–2.83). The validated HILIC-ESI-TOF MS method was applied to the analysis of 35 cocoa bean samples from different origins and fermentation status. The content of scyllo-inositol, 1-kestose and galactinol in unfermented beans (n = 21) was in the range of traces-504.9, 36.1–133.5 and traces-1970.4 μg g−1 cocoa DM respectively. In fermented beans (n = 14), the content of scyllo-inositol and 1-kestose was in the range of 15.5–491.9 and traces-115.5 μg g−1 cocoa DM respectively. Galactinol was absent in fermented beans, indicating that it could be a potential indicator of fermentation status. The methodology proposed could be used for quality control of natural products and other food ingredients containing inositols and oligosaccharides. © 2018

Goat colostrum is a rich source of carbohydrates, mainly constituted by lactose, although several minor bioactive oligosaccharides are also present. Analysis of these caprine milk oligosaccharides (COS) is not straightforward, and usually requires a previous fractionation step to remove lactose. In this work, a biotechnological fractionation methodology based on the use of a β-galactosidase from Kluyveromyces lactis was optimised (pH, incubation time, goat milk:enzyme volume ratio) to hydrolyse lactose, preserving the COS profile. Best results were obtained after 15 min of enzymatic treatment using 0.68 U mL −1 of enzyme at 37 °C and pH 7. Efficient removal of resulting monosaccharides was finally carried out by the incubation of these samples with Saccharomyces cerevisiae (37 °C, 24 h). Fractionation of these carbohydrates could help to better determine COS structures and to expand the applications of the purified COS in the food and pharmaceutical industries. © 2019 Elsevier Ltd

Due to the great interest in obtaining natural bioactive carbohydrates to be used as functional ingredients, a selective microwave assisted extraction (MAE) method was optimized to ensure the exhaustive extraction of inositols and α-galactooligosaccharides (α-GOS) from mung bean. Thereafter, a comprehensive characterization of these compounds was carried out by gas chromatography coupled to mass spectrometry (GC–MS). Apart from free inositols and α-GOS, several glycosyl-methyl-scyllo-inositols and glycosyl-inositols were detected for the first time in this legume. Under optimized MAE conditions (0.5 g dry sample, 2 cycles of 3 min, 50 °C, 10 mL 50:50 ethanol:water, v:v), bioactive carbohydrates yields were similar to those found using solid–liquid extraction (SLE), but with shorter analytical times. Concentrations of bioactive carbohydrates in MAE extracts from samples of different geographical origins ranged between 74.1 and 104.2 mg.g−1 dry sample. MAE was proved a good alternative to SLE to obtain extracts enriched in bioactive carbohydrates. © 2018

Characterization of the volatile composition by analytical techniques usually requires the previous isolation, and occasionally the concentration, of these compounds. For these purposes, headspace (HS) techniques, both static headspace (S-HS) and dynamic headspace (D-HS), are usually considered. HS techniques are commonly coupled to gas chromatography; however, the direct coupling to mass spectrometry, without prior separations systems, is an operation mode that is gaining popularity for the development of fast and economic methods of analysis. In this chapter, fundamentals and instrumentation of HS sampling are described and the specific parameters that need to be optimized before applying an HS method are also discussed. Special emphasis has been put in covering the most relevant advances of these techniques, discussing specific examples of the most extended applications regarding food, environmental and pharmaceutical analysis. © 2017 Elsevier B.V.

Several cyclitol glycosides have been characterised as trimethylsilyl derivatives by their gas chromatographic (GC) retention data (linear retention indices) and electron impact mass spectrometric (MS) profiles. Both GC–MS results have been related to cyclitol glycosides structural features. Abundance ratios of characteristic m/z ions 133/129 and 260/265 have been proposed to distinguish glycosyl-inositols from glycosyl-methyl-inositols. These ratios in combination with the presence or absence of m/z 375 ion allowed the unequivocal characterization of cyclitol glycosides. These criteria have been applied to the characterization of new cyclitol glycosides in chickpea (Cicer arietinum) and adzuki bean (Vigna angularis) and in leaves of Coriaria myrtifolia and Coriaria ruscifolia. © 2017 Elsevier B.V.

Changes of the abundance of caprine milk oligosaccharides (CMO) at different lactation stages have been evaluated by hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-Q MS) and nanoflow liquid chromatography-quadrupole-time-of-flight mass spectrometry (nano-LC-Chip-QTOF MS). Eight major oligosaccharides (OS) were quantified at different lactation stages by HILIC-Q MS, while the use of nano-LC-Chip-QToF MS allowed expanding the study to forty-nine different OS by monitoring neutral non- and fucosylated species, as well as acidic species containing not only N-acetyl-neuraminic acid or N-glycolyl-neuraminic acid residues but also the combination of both sialic acids. Overall, the most abundant OS decreased with lactation time, whereas different trends were observed for minor OS. 6′-Sialyl-lactose was the most abundant acidic OS while galactosyl-lactose isomers were identified as the most abundant neutral OS. This is the first time that a comprehensive study regarding the changes of the abundance of CMO, both neutral and acidic, at different lactation stages is carried out. © 2017 American Chemical Society.

A detailed qualitative and quantitative characterization of goat colostrum oligosaccharides (GCO) has been carried out for the first time. Defatted and deproteinized colostrum samples, previously treated by size exclusion chromatography (SEC) to remove lactose, were analyzed by nanoflow liquid chromatography-quadrupole-time of flight mass spectrometry (Nano-LC-Chip-Q-TOF MS). Up to 78 oligosaccharides containing hexose, hexosamine, fucose, N-acetylneuraminic acid or N-glycolylneuraminic acid monomeric units were identified in the samples, some of them detected for the first time in goat colostra. As a second step, a hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS) methodology was developed for the separation and quantitation of the main GCO, both acidic and neutral carbohydrates. Among other experimental chromatographic conditions, mobile phase additives and column temperature were evaluated in terms of retention time, resolution, peak width and symmetry of target carbohydrates. Narrow peaks (wh: 0.2-0.6min) and good symmetry (As: 0.8-1.4) were obtained for GCO using an acetonitrile:water gradient with 0.1\% ammonium hydroxide at 40°C. These conditions were selected to quantify the main oligosaccharides in goat colostrum samples. Values ranging from 140 to 315mgL-1 for neutral oligosaccharides and from 83 to 251mgL-1 for acidic oligosaccharides were found. The combination of both techniques resulted to be useful to achieve a comprehensive characterization of GCO. © 2015 Elsevier B.V..

Chitosan (Chit) was submitted to the Maillard reaction (MR) by co-heating a solution with glucose (Glc). Different reaction conditions as temperature (40, 60 and 80 °C), Glc concentration (0.5\%, 1\%, and 2\%, w/v), and reaction time (72, 52 and 24 h) were evaluated. Assessment of the reaction extent was monitored by measuring changes in UV absorbance, browning and fluorescence. Under the best conditions, 2\% (w/v) of Chit, 2\% (w/v) of Glc at 60 °C and 32 h of reaction time, a chitosan-glucose (Chit-Glc) derivative was purified and submitted to structural characterization to confirm its formation. Analysis of its molecular weight (MW) and the degree of substitution (DS) was carried out by HPLC-Size Exclusion Chromatography (SEC) and a colloid titration method, respectively. FT-IR and 1H NMR were also used to analyze the functional groups and evaluate the introduction of Glc into the Chit molecule. According to our objectives, the results obtained in this work allowed to better understand the key parameters influencing the MR with Chit as well as to confirm the successful introduction of Glc into the Chit molecule obtaining a Chit-Glc derivative with a DS of 64.76 ± 4.40\% and a MW of 210.37 kDa. © 2015 Elsevier Ltd. All rights reserved.

β-Galactosidases from Kluyveromyces lactis and Kluyveromyces marxianus isolated from artisanal ewes' milk cheeses, were used to transgalactosylate lactose from cheese whey permeate (WP). The content of galactooligosaccharides (GOS) obtained by transgalactosylation was comparable with that formed using pure lactose as substrate. In order to obtain a mixture with higher prebiotic oligosaccharide content, isomerisation of the transgalactosylated WP was carried out using sodium aluminate as catalyst. The transgalactosylated mixtures at 6 h of reaction contained amounts of prebiotic carbohydrates (tagatose, lactulose, GOS and oligosaccharides derived from lactulose, OsLu) close to 50 g/100 g of total carbohydrates for all the strains tested, corresponding to 322 g prebiotics/kg whey permeate. Thus, the suitability of this methodology to produce mixtures of dietary non-digestible carbohydrates with prebiotic properties from WP has been demonstrated, which is interesting for the food industry since it increases the value and the applicability of this by-product from cheese manufacture. © 2015 Proprietors of Journal of Dairy Research.

BACKGROUND: α-Dicarbonyl compounds (α-DCs) such as 3-deoxyglucosone (3-DG) and glucosone are markers of both Maillard and degradation reactions of sugars and also of certain enzymatic processes. However, quantitation of these compounds is not straightforward when more abundant carbohydrates are present in real samples. Therefore in this work a GC/MS method was developed to separate monosaccharides, 3-DG and glucosone and applied to analyze them in carbohydrate-rich food products. Difructose anhydrides (DFAs), known markers of sugar degradation, were also determined. The effect of time and temperature in the production and storage of these compounds was also evaluated. RESULTS: Under optimized conditions, good separation between monosaccharides and α-DCs was achieved. Must syrups showed the highest concentrations of 3-DG and glucosone (average values 9.2 and 5.8 mg g-1 respectively). Coffee substitutes based on carob, chicory and blends showed the highest content of DFAs. Heating and storage assays proved that production of 3-DG was influenced by temperature, while glucosone was more affected by storage time. CONCLUSION: The proposed method allows the rapid quantitation of 3-DG and glucosone along with carbohydrates and DFAs in different food products, which is essential to determine their degradation level. Moreover, the α-DC content in several foods is reported for the first time. © 2015 Society of Chemical Industry.