Comparison of high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and ultra-high performance liquid chromatography with evaporative light scattering (UHPLC-ELSD) for the analyses of fructooligosaccharides in onion ( Allium cepa L.)

Recent advances in dietary polysaccharides from Allium species: Preparation, characterization, and bioactivity

Allium plants, including garlic, onions, shallots, and leeks, belong to the Alliaceae family and are utilized as vegetable, medicinal, and ornamental plants. These plants are consumed both raw and cooked and are noted in traditional medicine for their antibacterial, antitumor, and diuretic properties. Allium plants are a rich source of polyphenols, organosulfur compounds, flavonoids, alkaloids, and polysaccharides, which contribute to their health benefits. As consumer interest in the association between diet and health grows, there is an increasing market demand for foods that promote health, particularly those rich in dietary fiber or non-starch polysaccharides. Allium polysaccharides (APS) have molecular weights of 1 × 103-1 × 106 Da containing small amounts of pectin, glucofructan, or glycoproteins and large amounts of fructans. APS, despite its complex structure, is one of the principal active components of Allium plants but is often overlooked, which restricts its practical application. This paper provides a comprehensive overview of the extraction and purification, structural and functional characteristics, bioactivities, structure-function relationships, and chemical modifications of APS, as well as the effects of APS processing and storage. Additionally, this paper outlines future research directions for APS, which will inform its development and application in the food, pharmaceutical, and cosmetic industries.

Ion Chromatography and Related Techniques in Carbohydrate Analysis: A Review

Ion chromatography and related techniques have been the most popular separation methods used in the determination of organic and inorganic anions and cations, predominantly in water and wastewater samples. Making progress in their development and introducing new stationary phases, methods of detection and preparation of samples for analyses have given rise to the broadening of their analytical range. Nowadays, they are also used for substances that are not ionic by nature but can convert to such forms under certain conditions. These encompass, among others, carbohydrates, whose role and significance in humans' lives and environment is invaluable. Their presence in the air is mostly due to the industrial burning of biomass for energy production purposes. In addition, the content of sugars in plants, fruits and vegetables, constituting the base of human diets, affects our health condition. Given that, there is not only a need for their determination by means of routine methods but also for searching for novel analytical solutions. Based on literature data from the past decade, this paper presents the possibilities and examples of applications regarding ion chromatography and related techniques for the determination of carbohydrates in environmental samples, biomass and plants constituting food or raw materials for food production. Attention has been paid to the virtues and limitations of the discussed separation methods in this respect. Moreover, perspectives on their development have been defined.

Liquid-Phase Adsorption Behavior of β-D-Glucooligosaccharides When Using Activated Carbon for Separation, and the Antioxidant Stress Activity of Purified Fractions

The adsorption characteristics of β-glucooligosaccharides on activated carbon and the purification were systematically investigated. The maximum adsorption capacity of activated carbon reached 0.419 g/g in the optimal conditions. The adsorption behavior was described to be monolayer, spontaneous, and exothermic based on several models' fitting results. Five fractions with different degrees of polymerization (DPs) and structures of β-glucooligosaccharides were obtained by gradient ethanol elution. 10E mainly contained disaccharides with dp2a (G1→6G) and dp2b (G1→3G). 20E possessed trisaccharides with dp3a (G1→6G1→3G) and dp3b (G1→3G1→3G). 30E mainly consisted of dp3a and dp4a (G1→3G1→3(G1→6)G), dp4b (G1→6G1→3G1→3G), and dp4c (G1→3G1→3G1→3G). In addition to tetrasaccharides, 40E and 50E also contained pentasaccharides and hexasaccharides with β-(1→3)-linked or β-(1→6)-linked glucose residues. All fractions could inhibit the accumulation of intracellular reactive oxygen species (ROS) in H2O2-induced Caco-2 cells, and they could improve oxidative stress damage by increasing the activity of superoxide dismutase (SOD) and reduced glutathione (GSH), which were related to their DPs and structures. 50E with high DPs showed better anti-oxidative stress activity.

An ethnopharmacological, phytochemical, and pharmacological overview of onion (Allium cepa L.)

ETHNOPHARMACOLOGICAL RELEVANCE

Onion (Allium cepa L.) is one of the most widely distributed species within the Allium genus of family Amaryllidaceae. Onion has been esteemed for its medicinal properties since antiquity. It has been consumed for centuries in various indigenous cultures for the management of several ailments including microbial infections, respiratory, gastrointestinal, skin and cardio-vascular disorders, diabetes, renal colic, rheumatism, sexual impotence, menstrual pain, and headache. However, so far, there is a scarcity of recent data that compiles the plant chemistry, traditional practices, biological features, and toxicity.

AIM OF THE WORK

The aim of this review is to provide a comprehensive and analytical overview of ethnopharmacological uses, phytochemistry, pharmacology, industrial applications, quality control, and toxicology of onion, to offer new perspectives and broad scopes for future studies.

MATERIALS AND METHODS

The information gathered in this review was obtained from various sources including books, scientific databases such as Science Direct, Wiley, PubMed, Google Scholar, and other domestic and foreign literature.

RESULTS

Onion has a long history of use as a traditional medicine for management of various conditions including infectious, inflammatory, respiratory, cardiovascular diseases, diabetes, and erectile dysfunction. More than 400 compounds have been identified in onion including flavonoids, phenolic acids, amino acids, peptides, saponins and fatty acids. The plant extracts and compounds showed various pharmacological activities such as antimicrobial, antidiabetic, anti-inflammatory, anti-hyperlipidemic, anticancer, aphrodisiac, cardioprotective, and neuroprotective activities. In addition to its predominant medicinal uses, onion has found various applications in the functional food industry.

CONCLUSION

Extensive literature analysis reveals that onion extracts and bioactive constituents possess diverse pharmacological activities that can be beneficial for treating various diseases. However, the current research primarily revolves around the documentation of ethnic pharmacology and predominantly consists of in vitro studies, with relatively limited in vivo and clinical studies. Consequently, it is imperative for future investigations to prioritize and expand the scope of in vivo and clinical research. Additionally, it is strongly recommended to direct further research efforts towards toxicity studies and quality control of the plant. These studies will help bridge the current knowledge gaps and establish a solid basis for exploring the plant's potential uses in a clinical setting.

Characterization of phytochemicals from twisted-leaf garlic (Allium obliquum L.) using liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry

INTRODUCTION

Twisted-leaf garlic (Allium obliquum L.) is a wild Allium species, which is traditionally used as aroma plant for culinary purposes due to its unique, garlic-like flavor. It represents an interesting candidate for domestication, breeding and cultivation.

OBJECTIVES

The objective of this work was to explore and comprehensively characterize polar and semi-polar phytochemicals accumulating in leaves and bulbs of A. obliquum.

METHOD

Plant material obtained from a multiyear field trial was analyzed using a metabolite profiling workflow based on ultra-high performance liquid chromatography-coupled electrospray ionization quadrupole time-of-flight mass spectrometry (UHPLC/ESI-QTOFMS) and two chromatographic methods. For annotation of metabolites, tandem mass spectrometry experiments were carried out and the resulting accurate-mass collision-induced dissociation (CID) mass spectra interpreted. Onion and garlic bulb extracts were used as reference samples.

RESULTS

Important metabolite classes influencing nutritional, sensory and technological properties were detected and structurally characterized including fructooligosaccharides with a degree of polymerization of 3-5, S-alk(en)ylcysteine sulfoxides and other S-substituted cysteine conjugates, flavonoids including O- and C-glycosylated flavones as well as O-glycosylated flavonols, steroidal saponins, hydroxycinnamic acid conjugates, phenylethanoids and free sphingoid bases. In addition, quantitative data for non-structural carbohydrates, S-alk(en)ylcysteine sulfoxides and flavonoids are provided.

CONCLUSION

The compiled analytical data including CID mass spectra of more than 160 annotated metabolites provide for the first time a phytochemical inventory of A. obliquum and lay the foundation for its further use as aroma plant in food industry.

Purification and identification of oligosaccharides from Cimicifuga heracleifolia Kom. rhizomes

Even though Cimicifuga sp. is widely used in functional foods around the world, the content and structure of its oligosaccharides remain unclear. Here, we isolated a mixture of oligosaccharides from Cimicifuga heracleifolia Kom. rhizomes with a yield of 9.5% w/w. Twenty-six oligosaccharide monomers from the mixture were purified using optimized SEC and HILIC techniques. The oligosaccharides were identified as belonging to two groups by using HPAEC-PAD, MALDI-TOF-MS, NMR and GC-MS methylation analyses. One group belongs to sucrose and inulin type fructo-oligosaccharides (FOS) {β-d-Fruf-(2 → 1)-[β-d-Fruf-(2 ↔ 1)]_n=1-12-α-d-Glcp} with a 3-14 degree of polymerization (DP). Oligosaccharides in the other group belong to the inulo-n-ose type FOS {β-d-Fruf-(2 → 1)-[β-d-Fruf-(2 → 1)]_m=0-12-β-d-Frup} with a DP of 2-14. This appears to be the first time that these oligosaccharides have been purified from Cimicifuga heracleifolia Kom., thus providing useful information concerning the utilization of Cimicifuga heracleifolia Kom. in functional foods.

Characterization and Comparison of Bioactive Polysaccharides from Grifola frondosa by HPSEC-MALLS-RID and Saccharide Mapping Based on HPAEC-PAD

Grifola frondosa polysaccharides (GFPs) from different regions in China were characterized and compared using HPSEC-MALLS-RID and saccharide mapping based on HPAEC-PAD analysis for achieving and improving its quality control. The results showed that HPSEC chromatograms and molecular weight distributions of GFPs were similar. The average contents of each polysaccharide fraction (Peaks 1, 2, and 3) showed that Peak 3 was the main component and much higher than the other two polysaccharide fractions, which also contained protein. The result of saccharide mapping showed that α-1,4-glycosidic, β-1,4-glycosidic and few β-1,3-glycosidic linkages were existed in GFPs. The similarity result showed that HPAEC-PAD fingerprints of the oligosaccharide fragments after hydrolysis by endoglycosidase were certainly different, especially α-amylase with a mean similar index of only 0.781 ± 0.207. The result of hierarchical cluster analysis (HCA) showed that different batches of GFPs from China can be divided into different clusters. Furthermore, immune-enhancing activity based on RAW 264.7 cells showed significant differences among different GFPs. Based on grey relational analysis (GRA), the fractions of Peak 3 were regarded as the major contributors to its immuno-enhancing activity in GFPs. Overall, the implications from these results were found to be stable, comprehensive, and valid for improving the quality control of GFPs.

Functional characterization and vacuolar localization of fructan exohydrolase derived from onion (Allium cepa)

Fructans such as inulin and levan accumulate in certain taxonomic groups of plants and are a reserve carbohydrate alternative to starch. Onion (Allium cepa L.) is a typical plant species that accumulates fructans, and it synthesizes inulin-type and inulin neoseries-type fructans in the bulb. Although genes for fructan biosynthesis in onion have been identified so far, no genes for fructan degradation had been found. In this study, phylogenetic analysis predicted that we isolated a putative vacuolar invertase gene (AcpVI1), but our functional analyses demonstrated that it encoded a fructan 1-exohydrolase (1-FEH) instead. Assessments of recombinant proteins and purified native protein showed that the protein had 1-FEH activity, hydrolyzing the β-(2,1)-fructosyl linkage in inulin-type fructans. Interestingly, AcpVI1 had an amino acid sequence close to those of vacuolar invertases and fructosyltransferases, unlike all other FEHs previously found in plants. We showed that AcpVI1 was localized in the vacuole, as are onion fructosyltransferases Ac1-SST and Ac6G-FFT. These results indicate that fructan-synthesizing and -degrading enzymes are both localized in the vacuole. In contrast to previously reported FEHs, our data suggest that onion 1-FEH evolved from a vacuolar invertase and not from a cell wall invertase. This demonstrates that classic phylogenetic analysis on its own is insufficient to discriminate between invertases and FEHs, highlighting the importance of functional markers in the nearby active site residues.

Application of ATR-FTIR spectroscopy for profiling of non-structural carbohydrates in onion (Allium cepa L.) bulbs

Qualitative and quantitative composition of non-structural carbohydrates comprising glucose, fructose, sucrose and fructooligosaccharides (FOS) is one of the key determinants of market suitability, storability and technological processability of onions. To develop a cost-effective and rapid tool for carbohydrate profiling, applicability of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy of onion juice was investigated with special regard to FOS patterns. As reference, detailed carbohydrate profiles of onion juices were generated by high-performance liquid chromatography coupled with evaporative light scattering detection (HPLC-ELSD). Hierarchical cluster analysis (HCA) of ATR-FTIR spectra was successfully applied for classifying onions into fresh market, storage and dehydrator type according to HPLC-ELSD profiles. A bootstrapping method for automatized test-set validation by projection to latent structures (PLS) algorithms using HPLC and ATR-FTIR spectroscopy data was developed. Model statistics showed promising perspectives for reliable quantification of individual saccharides and sum parameters. The presented methodology allows estimating the nutritional and pre-biotic value directly during cultivation and processing.

Recent approaches for the quantitative analysis of functional oligosaccharides used in the food industry: A review

Functional oligosaccharides (OS) are diverse groups of carbohydrates that confer several health benefits stemming from their prebiotic activity. Commonly used oligosaccharides, fructooligosaccharides and galactooligosaccharides, are used in a wide range of applications from food ingredients to mimic the prebiotic activity of human milk oligosaccharides (HMOs) in infant formula to sugar and fat replacers in dairy and bakery products. However, while consumption of these compounds is associated with several positive health effects, increased consumption can cause intestinal discomfort and aggravation of intestinal bowel syndrome symptoms. Hence, it is essential to develop rapid and reliable techniques to quantify OS for quality control and proper assessment of their functionality in food and food products. The present review will focus on recent analytical techniques used to quantify OS in different matrices such as food and beverage products.

Atractylodis Rhizoma: A review of its traditional uses, phytochemistry, pharmacology, toxicology and quality control

ETHNOPHARMACOLOGICAL RELEVANCE

Atractylodis Rhizoma (AR), mainly includes Atractylodes lancea (Thunb.) DC. (A. lancea) and Atractylodes chinensis (DC.) Koidz. (A. chinensis) is widely used in East Asia as a diuretic and stomachic drug, for the treatment of rheumatic diseases, digestive disorders, night blindness, and influenza as it contains a variety of sesquiterpenoids and other components of medicinal importance.

AIM OF THE REVIEW

A systematic summary on the botany, traditional uses, phytochemistry, pharmacology, toxicology, and quality control of AR was presented to explore the future therapeutic potential and scientific potential of this plant.

MATERIALS AND METHODS

A review of the literature was performed by consulting scientific databases including Google Scholar, Web of Science, Baidu Scholar, Springer, PubMed, ScienceDirect, CNKI, etc. Plant taxonomy was confirmed to the database "The Plant List".

RESULTS

Over 200 chemical compounds have been isolated from AR, notably sesquiterpenoids and alkynes. Various pharmacological activities have been demonstrated, especially improving gastrointestinal function and thus allowed to assert most of the traditional uses of AR.

CONCLUSIONS

The researches on AR are extensive, but gaps still remain. The molecular mechanism, structure-activity relationship, potential synergistic and antagonistic effects of these components need to be further elucidated. It is suggested that further studies should be carried out in the aspects of comprehensive evaluation of the quality of medicinal materials, understanding of the "effective forms" and "additive effects" of the pharmacodynamic substances based on the same pharmacophore of TCM, and its long-term toxicity in vivo and clinical efficacy.

Non-thermal Processing of Pineapple (Ananas comosus [L.] Merr.) Juice Using Continuous Pressure Change Technology (PCT): Effects on Physical Traits, Microbial Loads, Enzyme Activities, and Phytochemical Composition

A comprehensive study using continuous pressure change technology (PCT) for the non-thermal processing of fresh pineapple juice on pilot scale was conducted (1 L/min, 50 MPa, argon, 3 min, <35 °C). The immediate effects of a single and a twofold PCT treatment on the most important quality parameters were examined and compared with those of fresh and thermally pasteurised (90 °C) juices. In comparison to the fresh juice, both PCT-treated samples exhibited slightly brighter and less yellowish colour (CIE L*a*b*). A significant reduction in the mean particle size resulted in diminished centrifugable pulp contents and enhanced cloud stability. Moreover, a slightly improved microbial quality (−0.9 to −1.2 log10 CFU/mL) in terms of total aerobic and yeast and mould counts was attained. Noteworthy, PCT retained a high bromelain activity (−3 to −15% reduction) and efficiently inactivated polyphenol oxidase. Water-soluble vitamins, phenolic compounds, and all further constituents assessed were mostly preserved. However, the high residual peroxidase activity (−10 to −23%) and microbial loads are likely to affect juice quality during storage. In contrast, thermal pasteurisation ensured a complete reduction in both microbial counts (−4.4 to −4.5 log10 CFU/mL) and effective inactivation of peroxidase. However, bromelain activity was strongly affected (−83%) by heat treatment, and colour was darkened and even less yellowish. Overall, this study highlighted the potential of PCT for the production of fresh-like pineapple juices; however, its current limitations were revealed as well.

Metabolite profiling of onion landraces and the cold storage effect

Today, commercial onion breeders focus almost entirely on conventional farming which reduces diversity in the market and leads to loss of desirable traits such as those that impact nutritional and sensory aspects of onions. A way to preserve phenotypic and genetic diversity is to re-evaluate traditional landraces to introduce their benefits to the broader public. Common onion genotypes vary greatly in their storability. In particular, temperature and relative humidity during storage have significant impact on the metabolites in onions after storage. The aim of this study was to assess changes in the metabolite profile of ten onion genotypes after five months of cold storage. In addition, a characterization of onion landraces in their fresh state was also conducted in order to compare their properties against a commercial genotype. Onion genotypes were grown under organic farming conditions. After harvest and curing, bulbs were stored for up to 22 weeks. Before and after storage, bulb samples were analyzed through targeted and untargeted methods. Out of 189 identified metabolites, 128 showed a storage effect. Mainly fructans decreased because of respiration and energy demand, while monosaccharides increased. Further, amino acids were altered in their concentration after storage with an effect on aroma precursors. Eight of the nine landraces had good storability without critical losses. In their fresh state, the onion genotypes clustered into three major groups. For instance, landraces of group III showed consistently and substantially higher levels of amino acids and certain sugars, indicating a high potential of aromatic properties in those onion landraces.

Oligosaccharide-based quality evaluation of Atractylodis rhizome and a strategy for simplifying its quality control

Background

Atractylodis rhizoma, is the dried rhizomes of Atractylodes lancea (Thunb.) DC. or A. chinensis (DC.) Koidz. Both of two are pharmacologically and economically important, while with differences in efficacy. Therefore, an authentication system is vital for evaluation the quality and discrimination adulteration of Atractylodis rhizoma. Fructooligosaccharides (FOS), which are regarded as functional ingredients in Atractylodis rhizoma, have not been used for quality control of Atractylodis rhizoma for shortage of reference compounds.

Results

A HPLC-ELSD method was developed for the quantification of FOS in Atractylodis rhizoma. And chemometrics analysis showed that 2 markers including content of degree of polymerization (DP) 12 and total content of DP 3-15 could be used as the main distinctive elements for quality evaluation of Atractylodis rhizome. Actually, the separation and purification of high DP FOS, such as DP 12, is still a challenge because of high polarity. Then DP 5-based qualification evaluation was investigated for quality control of Atractylodis rhizoma. The results showed that A. lancea and A. chinensis could be clearly separated.

Conclusions

DP 5-based quantification method was credible and effectively adopted for solving the shortage of reference compounds and improving the quality control of Atractylodis rhizoma.

Impact of Cultivation Method and Cultivar Selection on Soluble Carbohydrates and Pungent Principles in Onions ( Allium cepa L.)

The composition of soluble carbohydrates such as fructooligosaccharides (FOS) in onions ( Allium cepa L.) plays a role regarding their digestibility, long-term storability, and processability. Qualitative and quantitative profiles of soluble carbohydrates were determined in 23 different onion samples comprising 20 cultivars grown at two different locations in 2014 and 2015. FOS concentrations were 1.1-fold higher in set grown onions than in seed grown onions ( p = 0.001). FOS levels of dehydrator cultivars were higher (overall average: 130.8 ± 42.4 g/L FOS) than those of common set and seed (61.8 ± 20.0 and 29.4 ± 14.7 g/L FOS) grown cultivars. Consequently, cultivation method (seed vs. set planting) and cultivar selection were crucial when aiming at onions with defined FOS contents. Besides FOS and other carbohydrate-related parameters, levels of alk(en)yl cysteine sulfoxides, indicating onion oil yield and pungency of onions, were determined to be different in dehydrator onions (13.1 ± 2.6 μmol/mL), seed (8.4 ± 1.3 μmol/mL), and set grown onions (7.5 ± 1.6 μmol/mL).

High intake of orange juice and cola differently affects metabolic risk in healthy subjects

BACKGROUND

Higher consumption of sugar-containing beverages has been associated with an elevated risk of type 2 diabetes and gout. Whether this equally applies to cola with an unhealthy image and orange juice (OJ) having a healthy image remains unknown.

METHODS

In order to investigate whether OJ and cola differently affect metabolic risk 26 healthy adults (24.7 ± 3.2 y; BMI 23.2 ± 3.3 kg/m²) participated in a 2 × 2-wk intervention and consumed either OJ or caffeine-free cola (20% Ereq as sugar from beverages) in-between 3 meals/d at ad libitum energy intake. Glycemic control, uric acid metabolism and gut microbiota were assessed as outcome parameters.

RESULTS

Fecal microbiota, body weight, basal and OGTT-derived insulin sensitivity remained unchanged in both intervention periods. Levels of uric acid were normal at baseline and did not change with 2-wk cola consumption (-0.03 ± 0.67 mg/dL; p > 0.05), whereas they decreased with OJ intervention (-0.43 ± 0.56 mg/dL; p < 0.01) due to increased uric acid excretion (+130.2 ± 130.0 mg/d; p < 0.001). Compared to OJ, consumption of cola led to a higher daylong glycemia (ΔiAUC: 36.9 ± 83.2; p < 0.05), an increase in glucose variability (ΔMAGE-Index: 0.29 ± 0.44; p < 0.05), and a lower 24 h-insulin secretion (ΔC-peptide excretion: -31.76 ± 38.61 μg/d; p < 0.001), which may be explained by a decrease in serum potassium levels (-0.11 ± 0.24 mmol/L; p < 0.05).

CONCLUSION

Despite its sugar content, regular consumption of large amounts of OJ do not increase the risk of gout but may even contribute to lower uric acid levels. The etiology of impaired insulin secretion with cola consumption needs to be further investigated.