Free Polyphenols Research Articles

Free radical scavenging polyphenols isolated from Phyllanthus niruri L. ameliorates hyperglycemia via SIRT1 induction and GLUT4 translocation in in vitro and in vivo models

Type 2 diabetes milletus (T2DM) is a complex multifaceted disorder characterized by insulin resistance in skeletal muscle. Phyllanthus niruri L. is well reported sub-tropical therapeutically beneficial ayurvedic medicinal plant from Euphorbiaceae family used in various body ailments such as metabolic disorder including diabetes. The present study emphasizes on the therapeutic potential of Phyllanthus niruri L. and its phytochemical(s) against insulin resistance conditions and impaired antioxidant activity thereby aiding as an anti-hyperglycemic agent in targeting T2DM. Three compounds were isolated from the most active ethyl acetate fraction namely compound 1 as 1-O-galloyl-6-O-luteoyl-β-D-glucoside, compound 2 as brevifolincarboxylic acid and compound 3 as ricinoleic acid. Compounds 1 and 2, the two polyphenols enhanced the uptake of glucose and inhibited ROS levels in palmitate induced C2C12 myotubes. PNEAF showed the potent enhancement of glucose uptake in palmitate-induced insulin resistance condition in C2C12 myotubes and significant ROS inhibition was observed in skeletal muscle cell line. PNEAF treated IR C2C12 myotubes and STZ induced Wistar rats elevated SIRT1, PGC1-α signaling cascade through phosphorylation of AMPK and GLUT4 translocation resulting in insulin sensitization. Our study revealed an insight into the efficacy of marker compounds isolated from P. niruri and its enriched ethyl acetate fraction as ROS scavenging agent and helps in attenuating insulin resistance condition in C2C12 myotubes as well as in STZ induced Wistar rat by restoring glucose metabolism. Overall, this study can provide prospects for the marker-assisted development of P. niruri as a phytopharmaceutical drug for the insulin resistance related diabetic complications.

Reaction of barley varieties on the content of polyphenols on stress soil backgrounds

In order to assess the stress resistance of genotypes, we studied the influence of soil stressors on the content of polyphenolic substances in grain, straw, and roots of barley (Hordeum vulgare L.) of various varieties with differentiation by origin (domestic and foreign selection) and methods of production (hybridization and cell selection). The plants were grown in vegetative tanks with sod-podzolic soil in natural conditions until the seeds ripened. The experimental design included the following options: with excess cadmium (Cd2+ 6.4 mg/kg); increased acidity (pHKCl=4.8); simulated drought in the interphase period, emergence into the tube - earing; without stress load at pHKCl=6.5 (control). The content of polyphenols in terms of gallic acid was determined by the spectrophotometric method. The total accumulation of polyphenols in grain under drought conditions (9.18…11.13 mg/g) and in the presence of excess Cd2+ in the soil (9.07…9.10 mg/g) exceeded the control by 2.5…14.8 % and 2.8…8.5 %, respectively. On acidic soil, compared with the control, the amount of polyphenols in grain significantly decreased in all domestically bred barley varieties that underwent selection on acidic soils or selection on acidic selective media in vitro, in Vitrum - by 16.1 %, Rodnik Prikamye - by 11.8 %. In varieties of foreign selection (Zazersky 85, Triumph and Tallon), under acidic conditions, the value of this indicator, on the contrary, increased by 2.2…4.8 %. Most of the polyphenols were in a bound state. The distribution of free fraction polyphenols among organs (% of the total amount in the plant) was revealed: straw (41.4…49.1) > roots (32.4…42.5) > grain (15.6…22.6). Among the stressors studied, increased acidity contributed to a greater extent to the increase in the relative accumulation of free polyphenols and most significantly in the roots - in varieties and regenerants of the selection of the Federal Agrarian Research Center of the North--East by 19.0 %; foreign selection - by 35.7 %.

Extracting juice from dates (Phoenix dactylifera L.) using response surface methodology: Effect on pH, vitamin c, titratable acidity, free amino nitrogen (FAN) and polyphenols

The aim of this text is to investigate the effects of temperature, time, volume/mass ratio, and enzyme volume on various properties of date juice extracted from the "Bournow" cultivar, and to optimize the extraction process to maximize the levels of free amino acids, total polyphenols, vitamin C, and pH. The extraction technique was used to obtain date juice for use in the beverage industry from the "Bournow" cultivar. The effects of temperature, time, volume/mass ratio, and enzyme volume on free amino acid, total polyphenols, vitamin C, and pH levels were then investigated using a design centered on four parameters. All multivariate polynomial models of second degree with interactions were discovered and validated. To optimize responses, multiresponse optimization was utilized. The center composite design (CCD) determined the following response ranges: 4.21 to 5.62 pH; 45 to 126.66 mg/L vitamin C; 2.7 to 6.87 g GA/100 g total polyphenols; and 429.94 to 615.55 mg/L free amino acids. The selected factors had varying effects on the pH, vitamin C, total polyphenols, and free amino acid responses, with simple, quadratic, and interaction contributions leading to significant increases or decreases. Multi-response optimization, the objective of which was to maximize all responses besides pH in order to produce an abundant juice, resulted in the following compromise: 95 °C temperature; 10 min duration; 2:1 water/pulp ratio; and 0.5 ml of pectinase. The optimal values simulated yielded the following respective maxima: pH is 4.13; vitamin C is 116.5 mg/L; total polyphenols are 6.25 g GA/100 g; and free amino acids are 587.88 mg/L. This study successfully optimized the extraction technique for obtaining date juice from the "Bournow" cultivar. The results provide valuable insights for the beverage industry. Future prospects include further research on the sensory properties and shelf life of date juice, as well as exploring its potential applications in other food and beverage products.

Analysis of Characteristics in the Macro-Composition and Volatile Compounds of Understory Xiaobai White Tea.

Understory planting affects the growth environment of tea plants, regulating the tea plant growth and the formation of secondary metabolites, which in turn affects the flavor of Xiaobai white tea. The present research adopted biochemical composition determination, widely targeted volatilities (WTV) analysis, multivariate statistical analysis, and odor activity value (OAV) analysis to analyze the characteristics in the macro-composition and volatile compounds of understory white tea. The sensory evaluation results indicated that understory Xiaobai white tea (LWTs) was stronger than ordinary Xiaobai white tea (PWTs) in terms of the taste of smoothness, sweetness, and thickness as well as the aromas of the flower and sweet. Understory planting reduced light intensity and air temperature, increased air humidity, organic matter, total nitrogen, and available nitrogen contents, which improved the growth environment of tea plants. The phytochemical analysis showed that the water-extractable substances, caffeine, flavonoids, and soluble sugar contents of understory tea fresh-leaf (LF) were higher than those of ordinary fresh-leaf (PF). The phytochemical analysis showed that the free amino acids, theaflavins, thearubigins, water-extractable substances, and tea polyphenols contents of LWTs were significantly higher than those of PWTs, which may explain the higher smoothness, sweetness, and thickness scores of LWTs than those of PWTs. The 2-heptanol, 2-decane, damasone, and cedar alcohol contents were significantly higher in LWTs than in PWTs, which may result in stronger flowery and sweet aromas in LWTs than in PWTs. These results provide a firm experimental basis for the observed differences in the flavor of LWTs and PWTs.

Co-delivery of curcumin and quercetin in shellac nanocapsules for the synergistic antioxidant properties and cytotoxicity against colon cancer cells.

Synergistic bioactivity of dietary polyphenols can enhance functional food development to prevent chronic diseases like cancer. In this study, physicochemical properties and cytotoxicity of curcumin and quercetin co-encapsulated in shellac nanocapsules at different mass ratios were investigated and compared to nanocapsules with one polyphenol and their unencapsulated counterparts. At curcumin and quercetin mass ratio of 4:1, encapsulation efficiency was approximately 80% for both polyphenols, and the nanocapsules showed the highest synergistic antioxidant properties and cytotoxicity for HT-29 and HCT-116 colorectal cancer cells. The nanocapsules had discrete structures smaller than 50nm and remained stable during 4-week refrigerated storage, and the encapsulated polyphenols were amorphous. After simulated digestions, 48% of the encapsulated curcumin and quercetin were bioaccessible, the digesta retained nanocapsule structures and cytotoxicity, and the cytotoxicity was higher than nanocapsules with only one polyphenol and free polyphenol controls. This study provides insights on utilizing multiple polyphenols as promising anti-cancer agents.

Polyphenol Composition, Antioxidant Capacity and Xanthine Oxidase Inhibition Mechanism of Furong Plum Fruits at Different Maturity Stages.

An experiment was conducted on the polyphenol content, flavonoid content, anthocyanin content, and antioxidant capacity of Furong plum (Prunus salicina Lindl. cv. "furong") at different maturity stages to determine the most suitable maturity stage. The inhibition of plum polyphenols on xanthine oxidase (XOD) was measured, and its kinetics were studied to reveal the inhibitory mechanism. The experimental results showed that the polyphenol, flavonoid and anthocyanin contents of plums at the ripe stage were the highest, reaching 320.46 mg GAE/100 g FW, 204.21 mg/100 g FW, and 66.24 mg/100 g FW, respectively, in comparison those of the plums at the immature and mid-ripe stages. The antioxidant capacity of the ripe plums was stronger than it was during the other stages of the plums growth. Among them, the total polyphenols of the ripe plums exhibited the strongest antioxidant capacity (IC50 values against DPPH and hydroxyl radicals were 28.19 ± 0.67 μg/mL and 198.16 ± 7.55 μg/mL, respectively), which was between the antioxidant capacity of the free polyphenols and bound polyphenols. The major phenolic monomer compounds of plum polyphenols were flavan-3-ols (epicatechin, catechin, proanthocyanidin, and procyanidin B2), flavonols (myricetin), and phenolic acids (chlorogenic acid, ferulic acid, and protocatechuic acid). Additionally, plum polyphenols exhibited a strong inhibitory effect on XOD, with an IC50 value of 77.64 μg/mL. The inhibition kinetics showed that plum polyphenols are mixed-type inhibitors that inhibit XOD activity and that the inhibition process is reversible. The calculated values of Ki and α were 16.53 mmol/L and 0.26, respectively.

Valorizing Traditional Greek Wheat Varieties: Phylogenetic Profile and Biochemical Analysis of Their Nutritional Value

Research has highlighted the nutritional benefits of ancient grains, especially emmer (Triticum turgidum ssp. dicoccum) and einkorn (Triticum monococcum), compared to modern varieties of common and durum wheat, focusing on their higher levels of antioxidants and phytochemicals. In this study, grains from old Greek landraces of einkorn, emmer, durum and common wheat were compared to modern wheat cultivars, as well as barley, oats and rye grains, to investigate their unique genetic profile and nutritional properties. Genotyping of Triticum species was performed using SSR markers, which allowed differentiation up to cultivar level. Nutritional factors like the total content of bound and free polyphenols, flavonoids, antioxidant activity and fatty acid profile were assessed. The results showed that emmer and einkorn had the highest total polyphenol, flavonoid and mono-unsaturated fatty acids content, as well as higher antioxidant activity than common and durum wheat. Local landraces of common and durum wheat also exhibited higher values than commercial cultivars. The results of this study demonstrate the high nutritional value of ancient wheat varieties. Many of these cultivars have been put aside by more productive, yet with lower qualitative characteristics, commercial cultivars, underlining the importance of maintaining sustainable agricultural practices to ensure their continued cultivation.

Characterization of sacha inchi (Plukenetia volubilis) and taro (Colocasia esculenta) flours with potential application in the preparation of both gluten-free and high protein foods.

Background: Interest in alternative sources of tubers and legumes has increased in recent years because of the constant search for raw materials that provide bioactive compounds with antioxidant potential benefits for consumers. The functionality of new raw materials is sought through physical and/or chemical modifications to develop and innovate new foods. The objective of this study was to characterize taro (TF) (Colocasia esculenta) and sacha inchi (Plukenetia volubilis) flours, obtained by the wet (SIF-WM) and defatted method (SIF-DM), as an alternative for the formulation of new functional foods. Methods: The free polyphenols of the different mixtures were analyzed, and the antioxidant properties of the extracts obtained were measured using ABTS.* (2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). The ABTS radical method, which reacts with the phenolic compounds of the food matrix, using Trolox as a standard. The blends were subjected to pasting analysis, flow profile tests, determination of viscoelastic properties (temperature sweep). Characterization of common microorganisms in these foods was performed. Results: The highest protein value was obtained in the sacha inchi flour obtained by the defatted method (72.62). The majority of components in taro were carbohydrates (85.4%). About antioxidant and determination of free polyphenols, taro flour obtained values of 2.71 µmol ET/g and 7.47 mg EAG/g, higher than Sacha inchi flours. In the rheological analysis (pasting properties, flow profile, and viscoelasticity), we observed that adding taro flour in different mixtures increases the viscosity peak and a lower breakdown, while there was an increase in setback. Except for defatted sacha flour, the others presented a flow index >1 before heating, showing a dilatant fluid behavior. The presence of Taro flour improves gel formation and stability. Staphylococcus aureus and Salmonella were present in the taro flour. Conclusions: The flours analyzed represent a raw material with great potential for the development of gluten-free foods with functional properties.

Effect of free and bound polyphenols from Rosa roxburghii Tratt distiller's grains on moderating fecal microbiota.

Rosa roxburghii Tratt distiller's grains (R. roxburghii DGs), the main by-product of wine processing, showed functional value and potential for high-value usage which benefited from their rich polyphenols. In this study, the free and bound polyphenols from R. roxburghii DGs were extracted and their potential effect on modulating fecal microbiota was investigated using in vitro fecal fermentation. The free polyphenols (26.32-26.45mgGAE/g) showed higher antioxidant activity compared to the bound polyphenols (8.76-9.01mgGAE/g). The free and bound polyphenols significantly improved the fecal microbiota community structure and enhanced short chain fatty acids concentrations after the stimulated colonic fermentation for 24h. Furthermore, the effect of R. roxburghii DGs polyphenols on modulating fecal microbiota was primarily attributed to quercetin, catechin, kaempferol, cyanidin and baicalin. This research suggests that R. roxburghii DGs are a promising source of natural antioxidants and prebiotic foods.

Exploring the antioxidant “cut-off effect” of gallic acid alkyl esters in dried oysters (Crassostrea gigas) during storage

In some complex food matrices, lipophenols exert stronger antioxidant effects than free polyphenols due to their better amphiphilicity and solubility. The use of lipophenols of different chain lengths often presents a “cut-off effect” in real foods, but the reason is far from understood. This work compared the antioxidant capacity of ethyl gallate (EG), octyl gallate (OG) and myristyl gallate (MG) in dried oysters during storage. The oxidation rate of polyunsaturated fatty acids (PUFAs), oxidation inhibition rate of the antioxidants on PUFAs and the generation number of lipid hydroperoxides and aldehydes shown that the treatment of antioxidants effectively inhibited lipid oxidation during storage, and the inhibition ability in the OG group was significantly better than that in the other antioxidant groups, which was consistent with the as of the “cut-off effect”. The density functional theory (DFT) and the molecular dynamics (MD) simulation showed that this “cut-off effect” is related to the ability of the polyphenolic hydroxyl group at C4 to transfer hydrogen atoms and the effective concentration of lipophenols at the initiation site of lipid oxidation.

Antioxidant activities, phenolic compounds, and mineral composition of seed from Acacia retinodes, A. provincialis and A. tenuissima

Seeds of the species Acacia retinodes, A. provincialis, and A. tenuissima) from different growing locations were analysed for their mineral composition, free and bound polyphenols, and flavonoids. Previous research has studied these compounds in only a limited number of Acacia species, and only one study reports significant differences between three species. All species were rich in potassium (353 – 427 mg/100 g), sodium (14 – 240 mg/100 g) and iron (7 – 8 mg/100 g). The free polyphenol extracts of all species had higher total phenolic content, total flavonoid content and antioxidant activities than their bound counterparts, indicating the possibility of higher bioavailability than the bound polyphenol extracts. The predominant phenolic compounds found in the Acacia polyphenol seed extracts were 6-Hydroxy-2-methylindole and 2,2′-Methylenebis(6-tert-butyl-methylphenol), though no phenolic compounds were identified in the bound extracts of A. retinodes Grampians and A. provincialis Tarrington. Other compounds identified in the seed extracts include sucrose, d-fructofuranose and d-pinitol.

Fermentation of Betaphycus gelatinum Using Lactobacillus brevis: Growth of Probiotics, Total Polyphenol Content, Polyphenol Profile, and Antioxidant Capacity.

Little information is available regarding polyphenol variations in the food processing of edible and medicinal red seaweed, Betaphycus gelatinum. This study investigated the effects of Lactobacillus brevis fermentation on total polyphenol content (TPC), polyphenol profile, and antioxidant activity in Betaphycus gelatinum pretreated by ultrasound-assisted mild acid hydrolysis for the first time. During 60 h of fermentation, the viable colony number significantly increased, pH significantly decreased, and reducing sugar content significantly decreased initially, then significantly increased. Free TPC significantly increased to 865.42 ± 29.29 μg GAE/g DW (163.09% increase) with increasing antioxidant activity, while bound TPC significantly decreased to 1004.90 ± 87.32 μg GAE/g DW (27.69% decrease) with decreasing antioxidant activity. Furthermore, 27 polyphenol compounds were identified by ultra-high-performance liquid chromatography with Xevo triple quadrupole mass spectrometry. In total, 19 and 23 free polyphenols and 24 and 20 bound polyphenols were identified before and after fermentation, respectively. Before fermentation, bound trans-cinnamic acid (56.75%), bound rosmarinic acid (26.62%), and free trans-cinnamic acid (3.85%) were the main components. After fermentation, free rosmarinic acid (43.57%), bound trans-cinnamic acid (15.19%), bound rosmarinic acid (13.33%), and free trans-cinnamic acid (5.99%) were the main components. These results provide information for the food processing of Betaphycus gelatinum.

Characterization of the Sensory Properties and Quality Components of Huangjin Green Tea Based on Molecular Sensory-Omics.

Huangjin green tea (HJC) is one of the most famous regional green teas in China, and has gained attention for its unique flavor. Research on HJC has focused mainly on the synthesis of L-theanine, with fewer studies concentrating on sensory characteristics. In this study, molecular sensory science techniques, including color analysis, gas chromatography-ion mobility spectrometry, and E-tongue, were used to characterize the sensory properties of HJC, with Fuding Dabai and Anji Baicha teas used as conventional and high amino acid controls, respectively. The sensory characteristics and main quality components of HJC lie somewhere between these two other teas, and somewhat closer to the conventional control. They were difficult to distinguish by color, but significant differences exist in terms of volatile organic compounds (VOCs), E-tongue values on bitterness and astringency, and their contents of major taste components. VOCs such as (E)-2-octenal, linalool, ethyl acrylate, ethyl acetate, and 2-methyl-3-furanethiol were found to be the main differential components that contributed to aroma, significantly influencing the tender chestnut aroma of HJC. Free amino acids, tea polyphenols, and ester catechins were the main differential components responsible for taste, and its harmonious phenol-to-ammonia ratio was found to affect the fresh, mellow, heavy, and brisk taste of HJC.

Equilibrium and fixed-bed kinetics study on hazelnut skin polyphenols extraction using choline chloride –lactic acid-based NADES and water as solvents

This paper focuses on the potential of Hazelnut Skin, a waste product from the food industry, as a source of polyphenols in line with circular economy principles. Two environmentally friendly solvents, water and Natural Deep Eutectic Solvent (NADES), were utilized for the extraction process. First of all, the extraction potential of both solvents was evaluated and an amount of 172.2 mg/g and 470.2 mg/g of free polyphenols per unit mass of solid were obtained using Water and NADES respectively. The solid–liquid equilibrium was also deeply investigated observing that two main phenomena are involved during the process: solubilisation and adsorption. An innovative model based on the combination of Langmuir isotherm and the introduction of a partitioning coefficient to describe a progressive approach to the solubility limit was then proposed to characterize the thermodynamics of the system. While NADES showed promising results compared to water in terms of amount of polyphenols extracted, there are several challenges that need to be addressed before implementing NADES in large-scale extraction processes. Hence, in this study continuous tests were conducted to observe the behavior of both solvents in a fixed-bed column that emulates a section of an industrial belt extractor. The experimental data collected were fitted by means of the Broken Intact Cells (BIC) Model. It was found out that the internal mass transfer resistance is the controlling one and the correspondent mass transfer coefficient estimated was 1.3·10-3 min−1 for Water and 6.67·10-4 min−1 for NADES. The results obtained from this study can be considered valuable resources for improving the existing methods of extracting polyphenols from waste matrices using water and for developing innovative approaches that utilize NADES as a solvent.

Identification of macronutrients by FT-IR analysis and physicochemical characterization of snacks elaborated from quinoa (Chenopodium quinoa Willd) and sacha inchi (Plukenetia volubilis)

Background: Currently, the consumption of high-protein foods that replace animal sources is increasing, a trend that promotes the design of new food systems. Spectroscopy methods with physicochemical tests allow for rapid and reliable identification of macronutrients and bioactive compounds. Methods: Snacks were made using hyperproteic quinoa flour (HPQF) and sacha inchi flour (SIF) through an extrusion process and subsequent compression molding. Spectra infrared (IR) analysis was used to identify macronutrients such as starch, proteins, lipids, and fiber. Specific frequencies were selected that provided the greatest discrimination of the sample. Physicochemical measurements were performed using extractable (EPC) and hydrolyzable (HPC) phenolic compound analyses, carotenoid content, and antioxidant capacity through ABTS• + (2,2-azinobis- 3-ethylbenzothiazoline-6-sulphonic acid), DPPH (2,2-diphenyl-1-picrylhydrazyl), and FRAP (ferric reducing antioxidant power) methods. Color and texture parameters of the snacks were also measured. Results: The identification of macronutrients using Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR–ATR) was as follows: lipids showed two characteristic peaks at 2870 and 2960 cm−1; protein showed three peaks at 1540, 1630, and 1660 cm −1; starch showed two peaks at 1170 and 1155 cm −1. Regarding the content of free polyphenols, hydrolyzable polyphenols and carotenoids, the mixtures added with the highest inclusion of quinoa, i.e. 50%, showed the highest values of 3.05 mg GAE/g, 14.16 mg GAE/g and 14.06 µg-β carotene/g of dry base sample, respectively. The snacks showed significant differences (p<0.05) in the antioxidant properties determined by the ABTS and FRAP methods, with the highest values in the samples with 50% HPQF. The inclusion of HPQF was associated with a higher browning index, and snacks with a higher quinoa content exhibited greater hardness and crispness. Conclusions: Snacks were obtained with protein percentages between 26–33%, containing bioactive compounds, gluten-free, and without the addition of oil during their production.

Enhancing the antioxidant and antifungal properties of polyphenols through encapsulation in β-lactoglobulin nanoparticles using emulsification-evaporation technique

Numerous studies have demonstrated the potential of banana blossom polyphenols as antioxidants and antifungal agents. However, their application in the food field is extremely limited due to their vulnerability to environmental conditions. This study aims to increase the stability of banana blossom polyphenols and explore their potential in food preservation, particularly against fungal infections. To achieve this, β-lactoglobulin@ferulic acid-quercetin-vanillic acid nanoparticles (N-β-LG@FA-QT-VA) with a particle size of 74.5–80.7 nm were successfully obtained using β-lactoglobulin (β-LG) as the encapsulating material, combined with protein heating modification and emulsification-evaporation techniques. The encapsulation process resulted in a significant increase in antioxidant activity, with an improvement of 42.3% over the free polyphenols. Furthermore, N-β-LG@FA-QT-VA nanoparticles displayed significantly higher antifungal activity and fruit preservation abilities compared to β-LG and FA-QT-VA mixtures. They effectively inhibited the germination and expansion of Penicillium digitatum, a common fruit pathogen. Applying this knowledge, these nanoparticles were tested on orange fruits inoculated with P. digitatum. A successful delay in green mold infection and decay was observed, demonstrating the potential of N-β-LG@FA-QT-VA nanoparticles as a natural alternative to synthetic fungicides, all while maintaining fruit quality.

α-Amylase reactive extrusion enhances the protein digestibility of saponin-free quinoa flour while preserving its total phenolic content

The original cellular structure and the presence of starch are known to reduce quinoa protein digestibility. Here, we aimed at optimizing an integrated single-step process exploiting the synergisms of amylolysis (<0.42% thermostable α-amylase, starch basis) and extrusion (at different temperature profiles) to enhance protein digestibility in saponin-free quinoa flour while minimizing polyphenol losses. In vitro protein digestion rate (velocity of substrate depletion) and extension (percentage of digested substrate at the end of the reaction) were significantly enhanced with every extrusion treatment, reaching up to four-fold faster protein digestion rate and up to 47% reduction of residual non-digested protein at 100 °C (last barrel temperature) and 0.36 g/100 g α-amylase concentration compared to native flour. Generally, reactive extrusion lowered the content of extractable (free) polyphenols and non-extractable proanthocyanins, but this effect was minimized at lower extrusion temperatures and higher α-amylase concentration. Contrarily, the more thermoresistant hydrolysable bound polyphenols increased in all cases, especially at harsh extrusion conditions.

Study on the interaction and functional properties of Dolichos lablab L. protein-tea polyphenols complexes

Tea polyphenols (TP) and plant proteins are significant materials in the food industry, the interactions between them are beneficial for their stability, functional properties, and biological activity. In this study, the mechanism and interaction between Dolichos lablab L. protein (DLP) obtained from nine treatments and three tea polyphenol monomers (EGCG, ECG, and EGC) were investigated. The results showed that the fluorescence of DLP was noticeably quenched and exhibited static quenching after the addition of polyphenols. DLP exhibited 1–2 binding sites for EGCG and ECG, but weakly binding to EGC (<1). The binding sites of DLP-TP were found to be in close proximity to the tyrosine residues, primarily interacting through hydrophobic interactions, van der Waals forces, and hydrogen bonds. The antioxidant capacity of DLP-TP compound was significantly improved after digestion. ECG showed a strong resistance to intestinal digestion. Compared with ECG (653.456 μg/mL), the content of free tea polyphenols of 20/40 kHz-ECG after digestion was 732.42 μg/mL. DLP-TP complexes significantly improved the storage stability, thermal stability, and bioaccessibility of tea polyphenols. The interaction between TP and DLP, as a protein-polyphenol complex, has great potential for application in preparing emulsion delivery systems due to their antioxidant activity and improved stability.

Fluidized-Bed-Roasted Cocoa Has Different Chemical Characteristics than Conventionally Roasted Cocoa.

The roasting process can modulate sensory and physicochemical characteristics of cocoa. This study compared the chemical characteristics of cocoa nibs roasted by a convective oven [slow roasting─(SR)] vs cocoa nibs roasted in a fluidized bed roaster [fast roasting─(FR)] at two temperatures (120 and 140 °C). The contents of sugars, free amino acids (FAAs), polyphenols, acrylamide, 5-hydroxymethylfurfural, and melanoidins were monitored. Roasting reduced fructose, glucose, and sucrose contents by 95, 70, and 55%, respectively. The concentration of total FAAs was reduced up to 40% at 140 °C. The FAA profile revealed that FR favored the reactivity of some amino acids (Leu, Lys, Phe, and Val) relevant in the formation of aroma compounds and melanoidins. FR resulted in the generation of more intense brown melanoidins, a significant increase in catechin content, a higher formation of acrylamide, and a lower formation of 5-hydroxymethylfurfural in cocoa compared to SR.

Date seeds (Phoenix dactylifera): antioxidant potential and profile of free and bound polyphenols fromdifferent cultivars.

In this study, the antioxidant activities and detailed phenolic profiling of extracts from seven cultivars of date seeds were investigated. Significant differences were detected among cultivars. Total phenolic content (TP) ranged between 135.9±12.1 and 284.86±21.9 mg GAE/g DM. The total flavonoid value varied between 34.20±0.34 and 94.46±1.04 mg RE/g DM. The condensed tannin ranged from 24.17±1.13 to 201.60±9.95 mg CTE/g DM. Phloroglucinolysis was used to depolymerize the bound polyphenols. Results show the presence of phenolic acids: Hydroxybenzoic acid, hydroxycinnamic acid, and a high amount of flavan-3ols (monomers, dimers, and trimers). Before depolymerization, the highest amount of total polyphenols was identified in Kenta (8.48 g/kg) and the lowest was detected in Hessa (4.74 g/kg). After depolymerization, the flavan-3-ols increased significantly, ranging between 46.91g/kg in Hessa and 72.38 g/kg in Deglet Nour, with a high degree of polymerization (DP) in all cultivars. It can be concluded that date seeds represent a good source of bioactive compounds.