Key Phytochemicals Contributing to the Bitter Off-Taste of Oat (Avena sativa L.)

Discovery of bitter masking compounds from Allspice (Pimenta dioica) using sensory guided isolation

Bitter substances in functional foods and beverages can act as nutraceuticals, offering potential health benefits. However, their unpleasant sensory impact reduces the consumption of these foods. Consequently, the discovery of bitter masking compounds is crucial for enhancing the intake of bioactive compounds in functional foods and beverages. Bitter taste is mediated by TAS2Rs, a sub-family of G-protein-coupled receptors. TAS2R14 is especially pivotal in the perception of bitterness, as it is one of the most broadly tuned bitter receptors. In this study, allspice was extracted and purified to yield five single compounds based on sensory guided fractionation. The structures of each compound were determined based on nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HR-MS). In a sensory evaluation, compound 1 exhibited bitter masking activity against quinine. Molecular docking analysis revealed that compound 1 could act as an antagonist of the TAS2R14 bitter receptor.

Characterization of key bitter compounds in Idesia polycarpa var. vestita Diels fruit by sensory-guided fractionation

Idesia polycarpa var. vestita Diels (I. vestita) has become a promising oil crop due to its easily digestible and highly nutritious fruit oil. However, the intense bitter taste of its fruit greatly limits its development and promotion in the food industry. Herein, five key bitter compounds from I. vestita fruit were isolated by sensory-guided fractionation and characterized using ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometer and nuclear magnetic resonance. The bitter taste of the identified compounds was subsequently validated by threshold tests and computational molecular docking. The bitterness threshold in water of idesin was the lowest (12.051 mg/L), and all bitter substances spontaneously bound to the bitter receptors hTAS2R16 and hTAS2R14, with a stronger affinity for the latter (approximately -6.5 - -9.0 kcal/mol). This is the first systematic study of bitter compounds in I. vestita fruit, providing a scientific basis for revealing the mechanism of bitterness formation and bitterness control.

Characterization of Seven New Steroidal Saponins from Korean Oat Cultivars by UPLC-QTOF-MS and UPLC-MS/MS

Oat saponins are composed of triterpenoid and steroidal saponins, and their potential biological activities, such as antibacterial, antifungicidal, osteogenic, and anticancer activities, have been reported. In this study, qualitative and quantitative analyses of oat saponins were conducted by using UPLC-QToF-MS and UPLC-Triple Q-MS/MS. A total of 22 saponins were analyzed in seven Korean oat cultivars. Among them, 7 saponins were identified as new compounds in this source, which were tentatively confirmed as nuatigenin-type saponins with 26-O-diglucoside and 3-O-malonylglucoside forms and (25S)-furost-5-en-3β,22,26-triol-type saponins. In addition, the total content of these saponins ranged from 70.61 to 141.38 mg/100 g dry weight, and it was affected by the type of oat cultivar and the presence or absence of hulling. These detailed profiles will be suggested as fundamental data for breeding superior oat cultivars, evaluating of related products, and various industries.

Oat-based milk alternatives: the influence of physical and chemical properties on the sensory profile

Introduction

Oat-based milk alternatives (OMAs) have become increasingly popular, perhaps due to their low allergenicity and preferred sensory attributes when compared to other milk alternatives. They may also provide health benefits from unique compounds; avenanthramides, avenacosides, and the dietary fibre beta-glucan. This has led to a variety of commercial options becoming available. Being a fairly new product, in comparison to other plant-based milk alternatives (PBMAs), means little research has been undertaken on the sensory profile, and how it is influenced by the physical and chemical properties.

Methods

This study investigated the sensory, physical and chemical profiles of current commercially available OMAs, that varied in fortification, use of stabilisers, and oat content. The volatile compounds and their respective aromas were analysed using solid phase microextraction followed by gas chromatography mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). Liquid chromatography mass spectrometry (LC-MS) was used for identification of avenanthramides and avenacosides. Particle size and polydispersity index (PDI) were analysed using a Mastersizer and Zetasizer, respectively, with colour analysis carried out using a colourimeter, and viscosity measurements using a rheometer. Descriptive sensory profiling was used to assess the impact on the sensory characteristics of the different samples and the sensory data acquired were correlated with the instrumental data.

Results

Samples with smaller particle size appeared whiter-both instrumentally and perceptually. The only clear plastic packaged product differed substantially in volatile profile from all other products, with a higher abundance of many volatile compounds, and high overall perceived aroma. Avenanthramides and avenacosides were present in all samples, but differed significantly in abundance between them.

Discussion

The results suggested smaller particle size leads to whiter colour, whilst differences in processing and packaging may contribute to significant differences in aroma. Astringency did not differ significantly between samples, suggesting that the variation in the concentrations of avenacosides and avenanthramides were below noticeable differences.

Steroidal Saponins from Solanum lyratum Thunb

Four undescribed steroidal compounds along with twenty known compounds were isolated from n-butanol extracted fraction of the whole plants of Solanum lyratum Thunb (SLNF). Their structures were assigned based on analyses of the extensive spectroscopic data (including MS, 1D/2D NMR, and ECD) or comparisons of the NMR data with those reported. Among the knowns, three compounds were isolated from Solanum plants for the first time, while one compound was isolated from S. lyratum for the first time. In addition, the cytotoxicities of these isolates against human colon SW480 and hepatoma Hep3B cells were evaluated by a MTT assay. And, nine of them and SLNF exhibited significant activities against both SW480 and Hep3B cells, while twelve of them significantly inhibited the activities of SW480 cells. This study allows for the exploitation of chemical markers with potential significance in discrimination of Solanum plants, and uncovers the diverse steroidal constituents from S. lyratum dedicated for its future application in cancer treatment.

Quantitative Analysis of Oat (Avena sativa L.) and Pea (Pisum sativum L.) Saponins in Plant-Based Food Products by Hydrophilic Interaction Liquid Chromatography Coupled with Mass Spectrometry

This work presents the sample extraction methods for solid and liquid sample matrices for simultaneous quantification of oat (Avena sativa L.) and pea (Pisum sativum L.) saponins: avenacoside A, avenacoside B, 26-desglucoavenacoside A, and saponin B and 2,3-dihydro-2,5-dihydroxy-6-methyl-4H-pyran-4-one (DDMP) saponin, respectively. The targeted saponins were identified and quantified using a hydrophilic interaction liquid chromatography with mass spectrometric detection (HILIC-MS) method. The simple and high-throughput extraction procedure was developed for solid oat- and pea-based food samples. In addition, a very simple extraction procedure for liquid samples, without the need to use lyophilisation, was also implemented. Oat seed flour (U-¹³C-labelled) and soyasaponin Ba were used as internal standards for avenacoside A and saponin B, respectively. Other saponins were relatively quantified based on avenacoside A and saponin B standard responses. The developed method was tested and successfully validated using oat and pea flours, protein concentrates and isolates, as well as their mixtures, and plant-based drinks. With this method, the saponins from oat- and pea-based products were separated and quantified simultaneously within 6 min. The use of respective internal standards derived from U-¹³C-labelled oat and soyasaponin Ba ensured high accuracy and precision of the proposed method.

An overview of bitter compounds in foodstuffs: Classifications, evaluation methods for sensory contribution, separation and identification techniques, and mechanism of bitter taste transduction

The bitter taste is generally considered an undesirable sensory attribute. However, bitter-tasting compounds can significantly affect the overall flavor of many foods and beverages and endow them with various beneficial effects on human health. To better understand the relationship between chemical structure and bitterness, this paper has summarized the bitter compounds in foodstuffs and classified them based on the basic skeletons. Only those bitter compounds that are confirmed by human sensory evaluation have been included in this paper. To develop food products that satisfy consumer preferences, correctly ranking the key bitter compounds in foodstuffs according to their contributions to the overall bitterness intensity is the precondition. Generally, three methods were applied to screen out the key bitter compounds in foods and beverages and evaluate their sensory contributions, including dose-over-threshold factors, taste dilution analysis, and spectrum descriptive analysis method. This paper has discussed in detail the mechanisms and applications of these three methods. Typical procedures for separating and identifying the main bitter compounds in foodstuffs have also been summarized. Additionally, the activation of human bitter taste receptors (TAS2Rs) and the mechanisms of bitter taste transduction are outlined. Ultimately, a conclusion has been drawn to highlight the current problems and propose potential directions for further research.

Effects of Pretreatment on the Volatile Composition, Amino Acid, and Fatty Acid Content of Oat Bran

Pretreatment improves the edible quality of oat bran and prolongs the shelf life, whereas the effect of pretreatments (i.e., steaming(S-OB), microwaving(M-OB), and hot-air drying(HA-OB)) on the flavor characteristics of oat bran is unknown. This study identified volatile composition using HS-SPME/GC−MS and an electronic nose of oat bran. The amino acid compositions were determined by a High-Speed automatic amino acid analyzer and the fatty acids were determined by gas chromatography. The results showed that steaming and microwaving pretreatments enhanced the nutty notes of oat bran. Sixty-four volatile compounds in four oat brans were identified. OB exhibited higher aroma-active compounds, followed by S-OB, and M-OB, and the HA-OB had the lowest aroma-active compounds. Hexanal, nonanal, (E)-2-octenal,1-octen-3-ol, 2-ethylhexan-1-ol, and 2-pentylfuran were the key volatile compositions in oat bran. The aldehyde content decreased and the esters and ketones increased in steamed oat bran. Microwaving and hot air drying increased the aldehyde content and decreased the ester and alcohol content. Steamed oat bran had the lowest levels of total amino acids (33.54 g/100 g) and bitter taste amino acids (5.66 g/100 g). However, steaming caused a significant reduction in saturated fatty acid content (18.56%) and an increase in unsaturated fatty acid content (79.60%) of oat bran (p < 0.05). Hot air drying did not result in an improvement in aroma. The results indicated that steaming was an effective drying method to improve the flavor quality of oat bran.

Flavor challenges in extruded plant-based meat alternatives: A review

Demand for plant-based meat alternatives has increased in recent years due to concerns about health, ethics, the environment, and animal welfare. Nevertheless, the market share of plant-based meat alternatives must increase significantly if they are to support sustainable food production and consumption. Flavor is an important limiting factor of the acceptability and marketability of plant-based meat alternatives. Undesirable chemosensory perceptions, such as a beany flavor, bitter taste, and astringency, are often associated with plant proteins and products that use them. This study reviewed 276 articles to answer the following five research questions: (1) What are the volatile and nonvolatile compounds responsible for off-flavors? (2) What are the mechanisms by which these flavor compounds are generated? (3) What is the influence of thermal extrusion cooking (the primary structuring technique to transform plant proteins into fibrous products that resemble meat in texture) on the flavor characteristics of plant proteins? (4) What techniques are used in measuring the flavor properties of plant-based proteins and products? (5) What strategies can be used to reduce off-flavors and improve the sensory appeal of plant-based meat alternatives? This article comprehensively discusses, for the first time, the flavor issues of plant-based meat alternatives and the technologies available to improve flavor and, ultimately, acceptability.

Selection for seed size has uneven effects on specialized metabolite abundance in oat (Avena sativa L.)

Plant breeding strategies to optimize metabolite profiles are necessary to develop health-promoting food crops. In oats (Avena sativa L.), seed metabolites are of interest for their antioxidant properties, yet have not been a direct target of selection in breeding. In a diverse oat germplasm panel spanning a century of breeding, we investigated the degree of variation of these specialized metabolites and how it has been molded by selection for other traits, like yield components. We also ask if these patterns of variation persist in modern breeding pools. Integrating genomic, transcriptomic, metabolomic, and phenotypic analyses for three types of seed specialized metabolites—avenanthramides, avenacins, and avenacosides—we found reduced heritable genetic variation in modern germplasm compared with diverse germplasm, in part due to increased seed size associated with more intensive breeding. Specifically, we found that abundance of avenanthramides increases with seed size, but additional variation is attributable to expression of biosynthetic enzymes. In contrast, avenacoside abundance decreases with seed size and plant breeding intensity. In addition, these different specialized metabolites do not share large-effect loci. Overall, we show that increased seed size associated with intensive plant breeding has uneven effects on the oat seed metabolome, but variation also exists independently of seed size to use in plant breeding. This work broadly contributes to our understanding of how plant breeding has influenced plant traits and tradeoffs between traits (like growth and defense) and the genetic bases of these shifts.

Steroidal Glycosides from the Aerial Parts of Avena sativa L. and Their Cytotoxic Activity

Twelve steroidal glycosides (1-12) were isolated from the aerial parts of Avena sativa L. (Poaceae). Among the isolated compounds, 1 was directly isolated from the plant for the first time, and 2-6 were new steroidal glycosides. The structures of 1-6 were determined by analysis of their spectroscopic data, chemical transformations, and chromatographic and spectroscopic analyses of the hydrolyzed products. Compounds 5 and 6 were novel steroidal glycosides with a B-ring contracted skeleton (B-nor steroid). Compounds 1, 9, 11, and 12 were cytotoxic to HL-60 human promyelocytic leukemia cells, MIA PaCa-2 human pancreatic carcinoma cells, and A549 human lung adenocarcinoma cells with IC₅₀ values ranging from 0.79 to 13.5 μM. HL-60 cells treated with 1 exhibited apoptotic characteristics, namely, condensed nuclear chromatin, accumulation of sub-G1 cells, and activation of caspase-3. Additionally, the loss of the mitochondrial membrane potential and the release of cytochrome c into the cytoplasm in 1-treated HL-60 cells suggested that 1 induced apoptosis through a mitochondrial-dependent apoptotic pathway.

Sensory evaluation, chemical structures, and threshold concentrations of bitter-tasting compounds in common foodstuffs derived from plants and maillard reaction: A review

The bitterness of foodstuffs is often associated with toxicity, which negatively influences product acceptability. However, bitter compounds have many benefits, and a slight bitter taste is sometimes favored. In this review, we summarize the methods used to isolate and evaluate the taste of bitter compounds in different foods. The chemical structures and threshold concentrations of these compounds are also recapped. Although the structures and thresholds of many bitter compounds have been confirmed, further studies are needed to develop detailed bitter-masking strategies and establish the relation between functional groups (hetero-cyclic substituents and bonding types) and taste quality. Furthermore, a comprehensive bitterness database and chemometric data must be provided in order to quickly assess the bitterness of unfamiliar products.

Physicochemical and Sensorial Evaluation of Meat Analogues Produced from Dry-Fractionated Pea and Oat Proteins

Pea protein dry-fractionated (P_DF), pea protein isolated (P_Is), soy protein isolated (S_Is) and oat protein (O_P) were combined in four mixes (P_DF_O_P, P_Is_O_P, P_DF_P_Is_O_P, S_Is_O_P) and extruded to produce meat analogues. The ingredients strongly influenced the process conditions and the use of P_DF required higher specific mechanical energy and screw speed to create fibrous texture compared to P_Is and S_Is. P_DF can be conveniently used to produce meat analogues with a protein content of 55 g 100 g^-1, which is exploitable in meat-alternatives formulation. P_DF-based meat analogues showed lower hardness (13.55-18.33 N) than those produced from P_Is and S_Is (nearly 27 N), probably due to a more porous structure given by the natural presence of carbohydrates in the dry-fractionated ingredient. P_DF_O_P and P_Is_P_DF_O_P showed a significantly lower water absorption capacity than P_Is O_P and S_Is_O_P, whereas pea-based extrudates showed high oil absorption capacity, which could be convenient to facilitate the inclusion of oil and fat in the final formulation. The sensory evaluation highlighted an intense odor and taste profile of P_DF_O_P, whereas the extrudates produced by protein isolates had more neutral sensory characteristics. Overall, the use of dry-fractionated protein supports the strategies to efficiently produce clean-labeled and sustainable plant-based meat analogues.

Characterization of Bitter and Astringent Off-Taste Compounds in Potato Fibers

Applying the sensomics approach, a combination of activity-guided fractionation and taste dilution analysis (TDA) followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), ultrahigh-performance liquid chromatography time-of-flight mass spectrometry (UHPLC-TOF-MS), and one-dimensional and two-dimensional nuclear magnetic resonance spectroscopy (1D/2D NMR) allowed the elucidation of key off-taste compounds in potato dietary fiber isolates. Previously already having been described as off-taste compounds in potato tubers, saponins α-chaconine and α-solanine were shown to be also major contributors to overall off-taste in potato fiber isolates. Moreover, fatty acids as well as fatty acid oxidation products, namely, E-9,10,13-trihydroxy-octadec-11-enoic acid as well as newly identified compounds hexadecyl(E/Z)-ferulate and octadecyl(E/Z)-ferulate, were shown to be key inducers to off-taste in the isolates, exhibiting taste recognition thresholds between 18 and 981 μmol/L. This paper demonstrates the isolation, structure determination, quantitation as well as sensory attributes of these key off-taste compounds.

Molecularization of Foam-Active Saponins from Sugar Beet Side Streams (Beta vulgaris ssp. vulgaris var. altissima)

This work focuses on the isolation and characterization of saponins with a very low bitter intensity originating from sustainable plant materials, in particular the sugar beet pulp by-product stream. Via a concise foam activity screening of saponin-containing materials, which gives indications for their emulsifying ability, sugar beet root extract was selected and examined for low bitter saponins by means of activity guided fractionation. Individual saponins were isolated from sugar beet pulp, which was identified as the most convenient sugar beet saponin source. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis and one-dimensional (1D) and two-dimensional (2D) nuclear magnetic resonance (NMR) spectroscopy led to the unequivocal identification of the major, slightly bitter tasting compounds as a series of eight saponins. The complete assignment of ¹H and ¹³C NMR signals for several saponins was carried out for the first time. A small-scale foam activity assay was established and applied to a broad spectrum of the isolated and commercially available saponins. Additionally, orosensory recognition thresholds were determined. Not only high recognition thresholds were determined (thresholds >1000 μmol/L) but also fundamental information about the foaming behavior of mono- and bidesmosidic saponins was collected. The obtained results are relevant to the utilization of saponins from other plant materials or by-product streams and for the use of sugar beet saponins as food additives.

In Silico Investigation of Bitter Hop-Derived Compounds and Their Cognate Bitter Taste Receptors

The typical bitter taste of beer is caused by adding hops (Humulus lupulus L.) during the wort boiling process. The bitter taste of hop-derived compounds was found to be mediated by three bitter taste receptors: TAS2R1, TAS2R14, and TAS2R40. In this work, structural bioinformatics analyses were used to characterize the binding modes of trans-isocohumulone, trans-isohumulone, trans-isoadhumulone, cis-isocohumulone, cis-isohumulone, cis-isoadhumulone, cohumulone, humulone, adhumulone, and 8-prenylnaringenin into the orthosteric binding site of their cognate receptors. A conserved asparagine in transmembrane 3 was found to be essential for the recognition of hop-derived compounds, whereas the surrounding residues in the binding site of the three receptors encode the ligand specificity. Hop-derived compounds are renowned bioactive molecules and are considered as potential hit molecules for drug discovery to treat metabolic diseases. A chemoinformatics analysis revealed that hop-derived compounds cluster in a different region of the chemical space compared to known bitter food-derived compounds, pinpointing hop-derived compounds as a very peculiar class of bitter compounds.

Molecularization of Bitter Off-Taste Compounds in Pea-Protein Isolates (Pisum sativum L.)

Activity-guided fractionations, combined with taste dilution analyses (TDA), were performed to locate the key compounds contributing to the bitter off-taste of pea-protein isolates (Pisum sativum L.). Purification of the compounds perceived with the highest sensory impact, followed by 1D/2D-NMR, (LC-)MS/MS, LC-TOF-MS, and MSE experiments, led to the identification of 14 lipids and lipid oxidation products, namely, 9,10,13-trihydroxyoctadec-12-enoic acid, 9,12,13-trihydroxyoctadec-10-enoic acid, 9,10,11-trihydroxyoctadec-12-enoic, 11,12,13-trihydroxyoctadec-9-enoic acid, (10E,12E)-9-hydroxyoctadeca-10,12-dienoic acid, (9Z,11E)-13-hydroxyoctadeca-9,11-dienoic acid, (9E,11E)-13-hydroxyoctadeca-9,11-dienoic acid, 1-linoleoyl glycerol, α-linolenic acid, 2-hydroxypalmitic acid, 2-hydroxyoleic acid, linoleic acid, (9Z,11E)-13-oxooctadeca-9,11-dienoic acid, and octacosa-6,9,19,22-tetraen. Herein, we present the isolation, structure determination, and sensory activity of these molecules. Depending on their structure, the isolated compounds showed human bitter recognition thresholds between 0.06 and 0.99 mmol/L in water.

Characterization of Bitter-Tasting Oxylipins in Poppy Seeds (Papaver somniferum L.)

Activity-guided fractionation of poppy seed (Papaver somniferum L.) extracts and analysis of fatty acid oxidation model experiments, followed by liquid chromatography time-of-flight mass spectrometry, tandem mass spectrometry, and one-/two-dimensional nuclear magnetic resonance experiments, revealed the chemical structures of five bitter-tasting fatty acids (1-5), three monoglycerides (6-8), six C₁₈-lipidoxidation products (9-14), and four lipid oxidation degradation products (15 and 17-19) as well as two previously unreported monoglyceride oxidation degradation products, namely, 9-(2',3'-dihydroxypropyloxy)-9-oxononaic acid (1-azeloyl-rac-glycerol, 16) and 1-(2',3'-dihydroxypropyl)-8-(5″-oxo-2″,5″-dihydrofruan-2″-yl)-octonoate (1-ODFO-rac-glycerol, 20). Sensory studies exhibited low bitter taste threshold concentrations between 0.08 and 0.29 mmol/L, particularly for the higher oxidated C₁₈-fatty acids trihydroxyoctadecenoic acid (THOE, 12), 12,13-dihydroxy-9-oxo-10-octadecenoic acid (12,13-diOH-9-oxo, 13), and 9,10-dihydroxy-13-oxo-11-octadecenoic acid (9,10-diOH-13-oxo, 14) as well as for the lipidoxidation degradation products 4-hydroxy-2-noneic acid (4-HNA, 17), 4-hydroxy-2-docecendienoic acid (HDdiA, 18), and 8-(5'-oxo-2',5'-dihydrofuran-2'-yl)-octanoic acid (ODFO, 20).

Quantitation and Taste Contribution of Sensory Active Molecules in Oat (Avena sativa L.)

A total of 59 taste-active molecules were quantitated and then rated for their individual taste impact on the basis of dose-over-threshold factors in oat flour (Avena sativa L.). A sensitive high-performance liquid chromatography-tandem mass spectrometry method was developed to quantitate bitter-tasting steroidal and furostanol saponins as well as avenanthramides. Four monoglycerides, five free fatty acids and four saponins were confirmed for the first time to be major contributors to the bitter off-taste of oats, among them 1-linoleoyl-rac-glycerol, 1-stearoyl-rac-glycerol, 1-oleoyl-rac-glycerol, 1-palmitoyl-rac-glycerol, linoleic acid, linolenic acid, oleic acid, palmitic acid, and stearic acid as well as avenacosides A and B and the recently identified furostanosides 3-(O-α-l-rhamnopyranosyl(1→2)-[β-d-glucopyranosyl(1→3)-β-d-glucopyranosyl(1→4)]-β-d-glucopyranosid)-26-O-β-d-glucopyranosyl-(25R)-furost-5-ene-3β,22,26-triol and 3-(O-α-l-rhamnopyranosyl(1→2)-[β-d-glucopyranosyl(1→4)]-β-d-glucopyranosid)-26-O-β-d-glucopyranosyl-(25R)-furost-5-ene-3β,22,26-triol. By means of a stable isotope dilution assay, quantitated avenanthramides 2c, 2p, 2f, 1p, 1c, 1f, and 3f were found in concentrations below their thresholds and, therefore, did not contribute to the bitter sensation of the tested oat flour.

A systematic review of phytochemicals in oat and buckwheat

Consumption of oat and buckwheat have been associated with various health benefits that may be attributed to their nutritional composition. We performed a systematic review to evaluate the profile and quantity of bioactive compounds present in oat and buckwheat. Among 154 studies included in final analysis, 113 and 178 bioactive compounds were reported in oat and buckwheat, respectively. Total phytosterols, tocols, flavonoids and rutin content were generally higher in buckwheat, β-glucans were significantly higher in oat, while avenanthramides and saponins were characteristically present in oat. The majority of studies included in current review were published before 2010s. The heterogeneous methodological procedures used across the studies precluded our possibility to meta-analyse the evidence and raises the need for harmonization of separation and extraction methods in future studies. Our findings should further stimulate the exploration of metabolites related to identified phytochemicals and their roles in human health.

Sensory Characteristics Contributing to Pleasantness of Oat Product Concepts by Finnish and Chinese Consumers

Oats are increasingly popular among consumers and the food industry. While data exist on sensory characteristics of oats as such, previous studies focusing on the pleasantness of oats, and especially investigations of a wide range of oat products by European and Asian consumers, are scarce. An online questionnaire was organized in Finland (n = 381; 83.7% Finnish) focusing on the liking and familiarity of oat products, followed by sensory tests in Finland (n = 65 and n = 73) and China (n = 103) using the Check-All-That-Apply method and hedonic ratings. A questionnaire revealed that the Finnish consumers rated the pleasantness and familiarity of several oat product categories, such as breads and porridges, higher compared to participants of other ethnicities. Sensory tests showed both similarities, e.g., porridges were described as “natural”, “healthy” and “oat-like”, and differences between countries, e.g., sweet biscuits, were described as “crispy” and “hard” by Finnish consumers and “strange” and “musty” by Chinese consumers. Sweet products were unanimously preferred. The ethnicity had an important role affecting the rating of pleasantness and familiarity of oat product categories, whereas food neophobia and health interest status also had an influence. The proved healthiness of oats was a crucial factor affecting the choices of consumers and their acceptance in both countries.

Identification of two bitter components in Zanthoxylum bungeanum Maxim. and exploration of their bitter taste mechanism through receptor hTAS2R14

Bitterness is an inherent organoleptic characteristic affecting the flavor of Zanthoxylum bungeanum Maxim. In this study, the vital bitter components of Z. bungeanum were concentrated through solvent extraction, sensory analysis, silica gel chromatography, and thin-layer chromatographic techniques and subsequently identified by UPLC-Q-TOF-MS. Two components with the highest bitterness intensities (BIs), such as 7-methoxycoumarin and 8-prenylkaempferol were selected. The bitter taste perceived thresholds of 7-methoxycoumarin and 8-prenylkaempferol were 0.062 mmol/L and 0.022 mmol/L, respectively. Moreover, the correlation between the contents of the two bitter components and the BIs of Z. bungeanum were proved. The results of siRNA and flow cytometry showed that 7-methoxycoumarin and 8-prenylkaempferol could activate the bitter receptor hTAS2R14. The results concluded that 7-methoxycoumarin and 8-prenylkaempferol contribute to the bitter taste of Z. bungeanum.

Comparative assessment of purified saponins as permeabilization agents during respirometry

Saponins are a diverse group of secondary plant metabolites, some of which display hemolytic toxicity due to plasma membrane permeabilization. This feature is employed in biological applications for transferring hydrophilic molecules through cell membranes. Widely used commercial saponins include digitonin and saponins from soap tree bark, both of which constitute complex mixtures of little definition. We assessed the permeabilization power of pure saponins towards cellular membranes in an effort to detect novel properties and to improve existing applications. In a respirometric assay, we characterized half-maximal permeabilization of the plasma membrane for different metabolites, of the mitochondrial outer membrane for cytochrome C and the full solubilization of mitochondrial inner membrane protein complexes. Beyond the complete list as repository for the field, we highlight several findings with direct applicability. First, we identified and validated α-chaconine as alternative permeabilization agent in respirometric assays of cultured cells and isolated synaptosomes, superior to digitonin in its tolerability for mitochondria. Second, we identified glycyrrhizic acid to form exceptionally small pores impermeable for adenosine diphosphate. Third, in a concentration dependent manner, tomatine proved to be able to selectively permeabilize the mitochondrial outer, but not inner membrane, allowing for novel states in which to determine cytochrome C oxidase activity. In summary, we provide a list of the permeabilization properties of 18 pure saponins. The identification of two saponins, namely tomatine and chaconine, with direct usability in improved or novel cell biological applications within this small subgroup demonstrates the tremendous potential for further functional screening of pure saponins.

Acute and Chronic Effects of Green Oat (Avena sativa) Extract on Cognitive Function and Mood during a Laboratory Stressor in Healthy Adults: A Randomised, Double-Blind, Placebo-Controlled Study in Healthy Humans

Green oat (Avena sativa) extracts contain several groups of potentially psychoactive phytochemicals. Previous research has demonstrated improvements in cognitive function following a single dose of these extracts, but not following chronic supplementation. Additionally, whilst green oat extracts contain phytochemicals that may improve mood or protect against stress, for instance species-specific triterpene saponins, to date this possibility has not been examined. The current study investigated the effects of a single dose and four weeks of administration of a novel, Avena sativa herbal extract (cognitaven^®) on cognitive function and mood, and changes in psychological state during a laboratory stressor. The study adopted a dose-ranging, double-blind, randomised, parallel groups design in which 132 healthy males and females (35 to 65 years) received either 430 mg, 860 mg, 1290 mg green oat extract or placebo for 29 days. Assessments of cognitive function, mood and changes in psychological state during a laboratory stressor (Observed Multitasking Stressor) were undertaken pre-dose and at 2 h and 4 h post-dose on the first (Day 1) and last days (Day 29) of supplementation. The results showed that both a single dose of 1290 mg and, to a greater extent, supplementation for four weeks with both 430 mg and 1290 mg green oat extract resulted in significantly improved performance on a computerised version of the Corsi Blocks working memory task and a multitasking task (verbal serial subtractions and computerised tracking) in comparison to placebo. After four weeks, the highest dose also decreased the physiological response to the stressor in terms of electrodermal activity. There were no treatment-related effects on mood. These results confirm the acute cognitive effects of Avena sativa extracts and are the first to demonstrate that chronic supplementation can benefit cognitive function and modulate the physiological response to a stressor.

Surface activity and foaming properties of saponin-rich plants extracts

Saponins are amphiphilic glycosidic secondary metabolites produced by numerous plants. So far only few of them have been thoroughly analyzed and even less have found industrial applications as biosurfactants. In this contribution we screen 45 plants from different families, reported to be rich in saponins, for their surface activity and foaming properties. For this purpose, the room-temperature aqueous extracts (macerates) from the alleged saponin-rich plant organs were prepared and spray-dried under the same conditions, in presence of sodium benzoate and potassium sorbate as preservatives and drying aids. For 15 selected plants, the extraction was also performed using hot water (decoction for 15 min) but high temperature in most cases deteriorated surface activity of the extracts. To our knowledge, for most of the extracts this is the first quantitative report on their surface activity. Among the tested plants, only 3 showed the ability to reduce surface tension of their solutions by more than 20 mN/m at 1% dry extract mass content. The adsorption layers forming spontaneously on the surface of these extracts showed a broad range of surface dilational rheology responses - from null to very high, with surface dilational elasticity modulus, E' in excess of 100 mN/m for 5 plants. In all cases the surface dilational response was dominated by the elastic contribution, typical for saponins and other biosurfactants. Almost all extracts showed the ability to froth, but only 32 could sustain the foam for more than 1 min (for 11 extracts the foams were stable during at least 10 min). In general, the ability to lower surface tension and to produce adsorbed layers with high surface elasticity did not correlate well with the ability to form and sustain the foam. Based on the overall characteristics, Saponaria officinalis L. (soapwort), Avena sativa L. (oat), Aesculus hippocastanum L. (horse chestnut), Chenopodium quinoa Willd. (quinoa), Vaccaria hispanica (Mill.) Rauschert (cowherb) and Glycine max (L.) Merr. (soybean) are proposed as the best potential sources of saponins for surfactant applications in natural cosmetic and household products.

Key Aroma Compounds in Oats and Oat Cereals

Oats possess a unique flavor, comprising grain and nut-like sensory characteristics. The first comprehensive study of oat flavor by Heydanek and McGorrin [ Heydanek , M. G. ; McGorrin , R. J. Gas chromatography-mass spectroscopy investigations on the flavor chemistry of oat groats . J. Agric. Food Chem. 1981 , 29 ( 5 ), 950 - 954 , 10.1021/jf00107a016 ] identified 110 volatile components in oat groats, including C₈-C₉ unsaturated aldehydes and ketones contributing raw oat grain, hay-feedy, and grassy aromas. A following study on heat-processed oats and cooked oatmeal by Heydanek and McGorrin ( Heydanek , M. G. ; McGorrin , R. J. Oat flavor chemistry: Principles and prospects . In Oats: Chemistry and Technology , 1 st ed.; Webster , F. H. , Ed.; AACC International : St. Paul, MN , 1986 ; pp 335 - 369 ) identified a series of Maillard-derived compounds, including furanones, thiazoles, and 2-methyl-, 2,5-dimethyl-, C₃-, and C₄-substituted pyrazines. In the subsequent 38 years since these initial research findings, additional identifications of aroma compounds in oat flakes and flours have been reported. This review addresses significant recent developments of the current understanding of oat flavor chemistry and the key aroma compounds that contribute to the unique flavor of oat cereals.

Kaempferol 3- O-(2‴- O-Sinapoyl-β-sophoroside) Causes the Undesired Bitter Taste of Canola/Rapeseed Protein Isolates

By means of activity-guided fractionation using taste dilution analysis, liquid chromatography-tandem mass spectrometry (LC-MS/MS), liquid chromatography-time-of-flight mass spectrometry, one-/two-dimensional nuclear magnetic resonance spectroscopy, LC-MS/MS quantitation, dose-over-threshold considerations, and sensory spiking experiments, kaempferol 3- O-(2‴- O-sinapoyl-β-sophoroside), exhibiting a bitter taste above the low threshold concentration of 3.4 μmol/L, was found for the first time as the key molecule contributing to the unpleasant bitter taste of rapeseed (canola) protein isolates. This finding opens new avenues for a biorefinery approach targeting an off-taste removal.

New Taste-Active 3-( O-β-d-Glucosyl)-2-oxoindole-3-acetic Acids and Diarylheptanoids in Cimiciato-Infected Hazelnuts

Activity-guided fractionation in combination with sensory analytics, LC-TOF-MS, and 1D/2D-NMR spectroscopy enabled the identification of the bitter tasting diarylheptanoids asadanin, giffonin P, and the previously not reported ( E)-7,9,10,13-tetrahydroxy-1,7-bis(2-hydroxyphenyl)hept-9-en-11-one and 4,12,16-trihydroxy-2-oxatricyclo[13.3.1.1^3,7]-nonadeca-1(18),3,5,7(20),8,15,17-heptaen as well as the yet unknown astringent compounds 2-(3-hydroxy-2-oxoindolin-3-yl) acetic acid 3- O-6'-galactopyranosyl-2″-(2″oxoindolin-3″yl) acetate and 3-( O-β-d-glycosyl) dioxindole-3-acetic acid in Cimiciato-infected hazelnuts exhibiting a bitter off-taste. Quantitative LC-MS/MS studies, followed by dose/activity considerations confirmed for the first time asadanin to be the key contributor to the bitter taste of Cimiciato-infected hazelnuts. Furthermore, quantitative studies demonstrated that neither the physical damage alone nor a general microbial infection is able to initiate a stress-induced asadanin generation, but most likely either specific Cimiciato-specific microorganisms associated with the bugs or specific chemical stimulants in the bugs' saliva is the cause triggering asadanin biosynthesis. Finally, also germination was found for the first time to activate diarylheptanoid biosynthesis, resulting in higher contents of bitter tasting phytochemicals and development of the bitter off-taste.