Degradation Of Polyphenols Research Articles

Metabolomics analysis reveals the non-enzymatic browning mechanism of green peppers (Piper nigrum L.) during the hot-air drying process

Non-enzymatic browning (NEB) reduced the colour quality of hot-air dried peppers, but the specific mechanism remains unclear. This may be related to the degradation of chlorophyll, ascorbic acid, and polyphenols. The findings revealed that the surface of pepper gradually browned during hot-air drying, with the ΔE⁎ value and browning degree (BD) significantly increasing by 119.4 % and 62.9 %, respectively. However, the total phenol content (TPC) and ascorbic acid content decreased by 74.2 % and 84.3 %, respectively. TPC was negatively correlated with BD (R = −0.86), and its value (31.7 %) was 300 times higher than that of other colour-related components (ascorbic acid, chlorophyll). UPLC-MS/MS analysis further identified 345 polyphenols, among which 1, 3-dicaffeoylquinic acid and 5,7-dihydroxy-3′, 4′, 5′-trimethoxyflavone were the two key monophenols influencing NEB (R = −0.87). The results suggested that NEB pathways involve chlorophyll and ascorbic acid degradation, the Maillard reaction, and polyphenol degradation, with the latter playing a major role.

The Effect of Combinations of Wall Materials on Encapsulation of Phenolic Contents from Extract of <i>Clitoria ternatea</i>

In our research, we demonstrate an innovative process for preserving polyphenolic compounds in a selected plant extract through a modified encapsulation technique. This can enhance preservation strategies and unlock potential industrial applications. The polyphenolic contents of butterfly pea (Clitoria ternatea) were extracted using the reflux extraction method using distilled water as a solvent. The flower-to-solvent ratio was 1:20 w/v. The total phenolic contents of C. ternatea extract were evaluated. To keep the stability of the phenolic contents in C. ternatea extract, the encapsulates of extract were performed using different combinations of wall material. In preparation for encapsulation, sodium alginate was used as the main wall material, which cooperated with other wall materials including gum arabic, maltodextrin, and casein sodium salt. The encapsulation which was performed using 3.0% w/v of sodium alginate mixed with 1.0% w/v of gum arabic, and C. ternatea extract in 5.0% w/v of CaCl2 solution provided a smooth surface and spherical shape of the particles. However, the optimized condition of encapsulation of C. ternatea extract using the combinations of wall materials which reveal thermal stability and degradation of polyphenolics was performed using 3.0% w/v of sodium alginate mixed with 1.0% w/v of casein sodium salt, and C. ternatea extract in 5.0% w/v of CaCl2 solution. This condition exhibited the highest thermal stability at 205°C and offered the lowest polyphenol contents degradation at 2.76±0.52 gallic acid equivalents/100 mg dried bead. The average particle sizes of encapsulates using the three conditions of 3.0% w/v of sodium alginate mixed with 1.0% w/v of casein sodium salt, gum arabic, and maltodextrin were 1247, 977, and 1210 µm in diameter, respectively. This method would be an alternative way to prevent polyphenolic compound degradation and boost shelf life at high temperatures in many potential applications.

The impact of visible light component bands on polyphenols from red grape seed extract powder encapsulated in alginate–whey protein matrix

Beads made of sodium alginate, whey protein concentrate, and red grape seed extract powder were exposed to white light and its red-orange, yellow-green-cyan, and cyan-blue-violet bands. The chemical analysis showed that encapsulation in the alginate–whey protein matrix protected polyphenols, flavonoids and cyanidin-3-O-glucoside when exposed to red-orange light. The reflectance spectra acquired from grape seed extract powder and grape seed extract beads were deconvoluted and anthocyanins-based moieties which contribute to the expression of bathochromic or hypsochromic effects were identified. The evolution of the peak areas assigned to the colored compounds confirms that the most intense polyphenol degradation occurred in grape seed extract powder and grape seed extract beads exposed to cyan-blue-violet light, as shown by the chemical analysis. The results of the study are important in choosing the light band from the visible spectrum which can be used to process food enriched with grape seed extract with minimal polyphenol degradation.

An aldolase-dependent phloroglucinol degradation pathway in Collinsella sp. zg1085.

Phloroglucinol (1,3,5-trihydroxybenzene) is a key intermediate in the degradation of polyphenols such as flavonoids and hydrolysable tannins and can be used by certain bacteria as a carbon and energy source for growth. The identification of enzymes that participate in the fermentation of phloroglucinol to acetate and butyrate in Clostridia was recently reported. In this study, we present the discovery and characterization of a novel metabolic pathway for phloroglucinol degradation in the bacterium Collinsella sp. zg1085, from marmot respiratory tract. In both the Clostridial and Collinsella pathways, phloroglucinol is first reduced to dihydrophoroglucinol by the NADPH-dependent phloroglucinol reductase (PGR), followed by ring opening to form (S)-3-hydroxy-5-oxohexanoate by a Mn2+-dependent dihydrophloroglucinol cyclohydrolase (DPGC). In the Collinsella pathway, (S)-3-hydroxy-5-oxohexanoate is then cleaved to form malonate semialdehyde and acetone by a newly identified aldolase (HOHA). Finally, a NADP+-dependent malonate-semialdehyde dehydrogenase converts malonate semialdehyde to CO2 and acetyl-CoA, an intermediate in carbon and energy metabolism. Recombinant expression of the Collinsella PGR, DPGC, and HOHA in E. coli enabled the conversion of phloroglucinol into acetone, providing support for the proposed pathway. Experiments with Olsenella profusa, another bacterium containing the gene cluster of interest, show that the PGR, DPGC, HOHA, and MSDH are induced by phloroglucinol. Our findings add to the variety of metabolic pathways for the degradation of phloroglucinol, a widely distributed phenolic compound, in the anaerobic microbiome.IMPORTANCEPhloroglucinol is an important intermediate in the bacterial degradation of polyphenols, a highly abundant class of plant natural products. Recent research has identified key enzymes of the phloroglucinol degradation pathway in butyrate-producing anaerobic bacteria, which involves cleavage of a linear triketide intermediate by a beta ketoacid cleavage enzyme, requiring acetyl-CoA as a co-substrate. This paper reports a variant of the pathway in the lactic acid bacterium Collinsella sp. zg1085, which involves cleavage of the triketide intermediate by a homolog of deoxyribose-5-phosphate aldolase, highlighting the variety of mechanisms for phloroglucinol degradation by different anaerobic bacterial taxa.

Investigating the quality of extraction and quantification of bioactive compounds in berries through liquid chromatography and multivariate curve resolution

Berries are a rich source of natural antioxidant compounds, which are essential to profile, as they add to their nutritional value. However, the complexity of the matrix and the structural diversity of these compounds pose challenges in extraction and chromatographic separation. By relying on multivariate curve resolution alternating least squares (MCR-ALS) ability to extract components from complex spectral mixtures, our study evaluates the contributions of various extraction techniques to interference, extractability, and quantifying different groups of overlapping compounds using liquid chromatography diode array detection (LC-DAD) data. Additionally, the combination of these methods extends its applicability to evaluate polyphenol degradation in stored berry smoothies, where evolving factor analysis (EFA) is also used to elucidate degradation products. Results indicate that among the extraction techniques, ultrasonication-assisted extraction employing 1% formic acid in methanol demonstrated superior extractability and selectivity for the different phenolic compound groups, compared with both pressurized liquid extraction and centrifugation of the fresh berry smoothie. Employing MCR-ALS on the LC-DAD data enabled reliable estimation of total amounts of compound classes with high spectral overlaps. Degradation studies revealed significant temperature-dependent effects on anthocyanins, with at least 50% degradation after 7 months of storage at room temperature, while refrigeration and freezing maintained fair stability for at least 12 months. The EFA model estimated phenolic derivatives as the main possible degradation products. These findings enhance the reliability of quantifying polyphenolic compounds and understanding their stability during the storage of berry products.Graphical abstract

Decoding polyphenol metabolism in patients with Crohn’s disease: Insights from diet, gut microbiota, and metabolites

Crohn’s disease (CD) is a chronic and progressive inflammatory disease that can involve any part of the gastrointestinal tract. The protective role of dietary polyphenols has been documented in preclinical models of CD. Gut microbiota mediates the metabolism of polyphenols and affects their bioactivity and physiological functions. However, it remains elusive the capacity of microbial polyphenol metabolism in CD patients and healthy controls (HCs) along with its correlation with polyphenols intake and polyphenol-derived metabolites. Thus, we aimed to decode polyphenol metabolism in CD patients through aspects of diet, gut microbiota, and metabolites. Dietary intake analysis revealed that CD patients exhibited decreased intake of polyphenols. Using metagenomic data from two independent clinical cohorts (FAH-SYSU and PRISM), we quantified abundance of polyphenol degradation associated bacteria and functional genes in CD and HCs and observed a lower capacity of flavonoids degradation in gut microbiota residing in CD patients. Furthermore, through analysis of serum metabolites and enterotypes in participants of FAH-SYSU cohort, we observed that CD patients exhibited reduced levels of serum hippuric acid (HA), one of polyphenol-derived metabolites. HA level was higher in healthier enterotypes (characterized by dominance of Ruminococcaceae and Prevotellaceae, dominant by HCs) and positively correlated with multiple polyphenols intake and abundance of bacteria engaged in flavonoids degradation as well as short-chain fatty acid production, which could serve as a biomarker for effective polyphenol metabolism by the gut microbiota and a healthier gut microbial community structure. Overall, our findings provide a foundation for future work exploring the polyphenol-based or microbiota-targeted therapeutic strategies in CD.

A new active packaging system based on chickpea-based edible coatings added with microcapsules of Cosmos sulphureus Cav. flower extract.

The Cosmos sulphureus Cav. plant is studied for its high polyphenolic content with antioxidant properties. Its flowers, rich in phenolic acids, flavonoids, and tannins, hold promise as antioxidants in food preservation. The inclusion of these compounds in chickpea-based coatings with a previously studied preservative effect would be an excellent option as a food preservation method and microencapsulation addresses challenges like dispersion and degradation of polyphenols in the coating. The objective of this research was to evaluate the in vitro antioxidant activity of Cosmos sulphureus leaves, seed, and flower extracts and explore the protective effects of chickpea-based coatings containing microcapsules of flower polyphenolic extract on the chemical quality of stored roasted sunflower seeds during storage. The ethanolic leaf extract exhibited the highest antiradical activity, followed by the aqueous flower extract. After a storage period of 15 days, at 40 °C, the chickpea-based coatings effectively delayed lipid oxidation in the roasted sunflowers seeds, and the inclusion of polyphenolic microcapsules with 0.01% extract (SMC 0.01%) in the coating significantly improved the protective effect. By day 15 of storage, SMC 0.01% showed comparable peroxide value, conjugated dienes, and linoleic acid content to samples containing the synthetic antioxidant BHT (butylated hydroxytoluene). Samples that only contained chickpea-based coating and coating with polyphenolic microcapsules with 0.005% extract exhibited significantly greater reduction in fatty acid content compared to the 0.01% SMC treatment. The chickpea-based coating with polyphenolic microcapsules demonstrated antioxidant activity akin to synthetic BHT, offering a promising biopackaging solution for lipid-rich foods like roasted sunflower seeds. © 2024 Society of Chemical Industry.

Encapsulation of three different types of polyphenols in casein using a customized pH-driven method: Preparation and characterization

Phenolic compounds represent natural compounds endowed with diverse biological functionalities. However, their inherent limitations, characterized by poor water solubility and low oral bioavailability, limit their broader applications. Encapsulation delivery systems are emerging as a remedy, able to ameliorate these limitations by enhancing the stability and solubility of phenolic compounds. In this study, a novel, customized pH-driven approach was developed by determining the optimal deprotonation and protonation points of three different types of polyphenols: ferulic acid, resveratrol, and rhein. The polyphenols were successfully encapsulated in a casein carrier. The solubility, stability, LogD, and LogS curves of the three polyphenols at different pH values were analyzed to identify the optimal deprotonation points for ferulic acid (pH 9), resveratrol (pH 11), and rhein (pH 10). Based on these findings, three different nanoparticles were prepared. The encapsulation efficiencies of the three phenolic compounds were 95.86%, 94.62%, and 94.18%, respectively, and the casein nanoparticles remained stable at room temperature for seven days. FTIR spectroscopy, fluorescence spectroscopy, and molecular docking study substantiated the encapsulation of phenolic compounds within the hydrophobic core of casein-based complexes, facilitated by hydrogen bonding interactions and hydrophobic interactions. Furthermore, the analysis of antioxidant activity elucidated that casein nanoparticles heightened both the water solubility and antioxidant efficacy of the phenolic compounds. This customized encapsulation technique, by establishing a transitional pH value, resolves the challenges of chemical instability and facile degradation of polyphenols under alkaline conditions in the application process of pH-driven methods. It presents novel insights for the application of polyphenols in the domains of food and biomedical fields.

Exploring the Biogenic Transformation Mechanism of Polyphenols by Lactobacillus plantarum NCU137 Fermentation and Its Enhancement of Antioxidant Properties in Wolfberry Juice.

This study investigated the transformation of polyphenols, including free and bound polyphenols during the fermentation of wolfberry juice by Lactobacillus plantarum NCU137. Results indicated that fermentation significantly increased the free polyphenols content and released bound polyphenols, enhancing the antioxidant activity. Analysis showed that there were 19 free polyphenols, mainly scopoletin, pyrogallol, and dihydroferulic acid, and 16 bound polyphenols, especially p-coumaric acid, feruloyl hexoside, and caffeic acid. A significant correlation was observed between the generation and degradation of polyphenols, and specific bound polyphenols peaked during the 24-48 h fermentation. Furthermore, reduced surface roughness and galacturonic acid content in wolfberry residue, along with increased pectinase activity, suggested substantial pectin degradation in the cell wall, which may be associated with the release of polyphenols, due to pectin serving as carriers for bound polyphenols. The fermentation also increased polyphenol oxidase and peroxidase activity, contributing to polyphenol breakdown. These findings provide insights for improving wolfberry juice production.

Chemometric analysis illuminates the relationship among browning, polyphenol degradation, Maillard reaction and flavor variation of 5 jujube fruits during air-impingement jet drying

This study was designed to reveal the relationship among browning, polyphenol degradation, Maillard reaction (MR) and flavor variation in jujube fruit (JF) during air-impingement jet drying (AIJD). Five kinds of JFs were dried by AIJD at 60 °C and vacuum freeze drying. Colorimeter and chemometric analysis found that AIJD induced color changes of JF pulp and peel. AIJD also reduced the total polyphenols content and total flavonoids levels in JF. The Fe3+ reducing capacity and 2,2′-Azinobis-(3-ethylbenzothiazoline-6-sulphonate) cationic radical scavenging capacity of JF were reduced by 31.6% and 8.2%, respectively. Seven polyphenols were identified in JF, and epicatechin was found related to change of JF pulp color by sparse partial least square (sPLS). sPLS revealed that 3-deoxy glucosone, N-ε-carboxymethyl-l-lysine and 5-hydroxymethylfurfural associated with JF color. sPLS found that MR generated 3-methyl-butanoic acid and cyclobutanone during AIJD of JF. Chemometrics is an effective tool to disclose mechanism of color changes in food.

The effect of pressure on degradation kinetics of polyphenols: Impact of polyphenol structure at hyperbaric storage conditions

Understanding reaction kinetics at elevated pressures is essential for developing efficient pressure-based technologies. It is especially vital for hyperbaric storage (HS), where pressure is applied for long durations. In single and multi-component models, the influence of pressure on the degradation kinetics of different catechins and anthocyanins was studied at accelerated conditions using neutral pH at pressures up to 200 MPa (HS levels) for several hours. In the neutral baroresistant buffer, pressure enhanced the degradation of all tested flavonoids with a negative activation volume. Despite the significant structural variety and major differences in the degradation rates within each tested subgroup, no significant structure-dependent effect of pressure on the activation volume was observed, which is suggestive of a similar mechanism by which pressure accelerates the degradation. The antioxidant capacity of catechins was not affected by pressure compared to control samples when the concentration of the original catechin was similar. Industrial relevanceA better understanding of pressure effects on the degradation reaction kinetics of food components can contribute to the general understanding of mechanisms related to food component degradation under high-pressure treatments. Plant-based foods are rich in polyphenolic compounds and responsible for sensory characteristics and their related health-promoting properties. In conditions similar to HS, that are known to inhibit and even, in some cases, inactivate microorganisms, when food is exposed to high pressures for a long time, it is imperative to investigate the effect of pressure on polyphenol degradation kinetics, which can lead to differences in the polyphenol compositions during the pressurized storage. However, the impact of pressure on polyphenol degradation kinetics is often overlooked. This study provides fundamental information regarding the polyphenol structure-dependent degradation kinetics of catechins and anthocyanins under pressure while taking into account the often overlooked pressure-induced pH shifts. The presented work can promote the development of novel storage and processing technologies based on high pressure that will better preserve oxidation-liable compounds with lower energetic costs.

P1227 Revealing lower capacity of microbial metabolism of flavonoids and associated metabolic changes in Crohn’s disease

Abstract Background Recent studies highlight the role of interplay between oxidative stress, gut microbiota, and immune response in the etiology of Crohn’s disease (CD). Polyphenols are natural antioxidants which are mainly metabolized by gut microbiota and could modulate the composition of gut microbiota. However, it’s yet reported whether there is difference in polyphenol-degradation capacity of gut microbiota in CD and healthy controls (HCs). Methods A comprehensive literature search was conducted on microbial metabolic pathway of polyphenols and the responsible organisms and genes were recorded. The polyphenol-degrading genes were quantified using shortBRED in three clinical cohorts (the First Affiliated Hospital of Sun Yat-sen University (FAH) cohort, PRISM cohort, and HMP2 cohort). Microbiota abundance was analyzed in FAH and PRISM cohort. Polyphenol intake and serum metabolites were assessed in the FAH cohort. Enterotype analysis was performed in FAH cohort. Correlation analysis among polyphenol intake, gene abundance, serum metabolites and bacterial abundance was conducted. Results Phylogenetic tree revealed that reported polyphenol-degrading bacteria were mainly distributed to Actinobacteria and Firmicutes. The abundance of flavonoid degradation related genes (mainly flavone reductase, chalcone isomerase and phloretin hydrolase) was significantly decreased in patients with CD in FAH cohort, but not in PRISM and HMP cohort. Difference in abundance of polyphenol-degrading bacteria was observed between CD patients and HCs in FAH and PRISM cohort. In addition, lower polyphenols intake and serum hippuric acid (HA) level were detected in CD patients. Enterotype analysis revealed that CD patients were mainly distributed to Enterobacteriaceae- and Bacteroidaceae-dominated enterotype while HCs were mainly distributed to Ruminococcaceae- and Prevotellaceae-dominated enterotype. Serum HA level was higher in healthier enterotypes (Ruminococcaceae and Prevotellaceae dominant) and positively correlated with flavonoid-degrading organisms and butyric acid-producing organisms. No positive correlation between abundance of polyphenol-degradation genes and polyphenols intake was detected. Conclusion The current study summarized the polyphenol metabolic pathway mediated by gut microbiota and quantified genes responsible for polyphenol degradation. Our comprehensive analysis of diet-microbiota-gene-metabolite data revealed a lower capability of flavonoid degradation in gut microbiota and lower HA level in CD patients. Finally, our findings provide a foundation for future work exploring the polyphenol or polyphenol-degrading microbiota interventions in preclinical models of CD.

Monitoring of Chemical and Fermentative Characteristics during Different Treatments of Grape Pomace Silage

Grape pomace is a fibrous food with satisfactory quantities of residual sugars. It meets the desirable characteristics for conservation in the form of silage for later use in animal feed, mainly for ruminant herbivores. Fresh grape pomace was subdivided into three treatment groups: grape pomace as a control, grape pomace treated with an inoculum of lactic acid bacteria, and grape pomace treated with zeolite. The treatments were performed in micro-silos over 90 days. There was a significant change (p < 0.05) in the chemical characteristics, content of biologically active compounds, and fermentative characteristics during the silage of all treatments. After 30, 60 and 90 days of ensiling, silages treated with inoculum and zeolite had better fermentation quality indicated by significantly (p < 0.05) lower pH and ammonia-nitrogen contents compared with those of the control. Also, the additives have decreased the total polyphenols and tannins for 97% in average which confirmed that lactic acid bacteria and zeolite positively effect on the degradation of polyphenols and tannins in grape pomace silage. The Flieg score was calculated and the values were above 80% what refers to excellent silage. In conclusion, our results suggest that inoculant and zeolite supplementation improves the quality of grape pomace silage for later use in animal feed.

Biochemical investigations of polyphenol degradation enzymes in the phototrophic bacterium Rubrivivax gelatinosus.

Phloroglucinol (1,3,5-trihydroxybenzene) is an important intermediate in the degradation of flavonoids and tannins by anaerobic bacteria. Recent studies have shed light on the enzymatic mechanism of phloroglucinol degradation in butyrate-forming anaerobic bacteria, including environmental and intestinal bacteria such as Clostridium and Flavonifractor sp. Phloroglucinol degradation gene clusters have also been identified in other metabolically diverse bacteria, although the polyphenol metabolism of these microorganisms remain largely unexplored. Here, we describe biochemical studies of polyphenol degradation enzymes found in the purple non-sulfur bacterium Rubrivivax gelatinosus IL144, an anaerobic photoheterotroph reported to utilize diverse organic compounds as carbon sources for growth. In addition to the phloroglucinol reductase and dihydrophloroglucinol cyclohydrolase that catalyze phloroglucinol degradation, we characterize a Mn2+-dependent phloretin hydrolase that catalyzes the cleavage of phloretin into phloroglucinol and phloretic acid. We also report a Mn2+-dependent decarboxylase (DeC) that catalyzes the reversible decarboxylation of 2,4,6-trihydroxybenzoate to form phloroglucinol. A bioinformatics search led to the identification of DeC homologs in diverse soil and gut bacteria, and biochemical studies of a DeC homolog from the human gut bacterium Flavonifractor plautii demonstrated that it is also a 2,4,6-trihydroxybenzoate decarboxylase. Our study expands the range of enzymatic mechanisms for phloroglucinol formation, and provides further biochemical insight into polyphenol metabolism in the anaerobic biosphere.

Protection of antioxidant components and production of a natural food colourant powder from Ardisia compressa juice

Ardisia compressa Kunth fruit juice is rich in bioactive compounds with proven health benefits and a characteristic intense purple colour. In this investigation the effect of the wall material (using soy protein isolate (SPI) and whey protein isolate (WPI)) and type of microencapsulation (spray drying (SD) and freeze-drying techniques (FD)) on the physicochemical properties, antioxidant properties and stability in different conditions storage of the microcapsules of the juice of Ardisia compressa Kunth was evaluated. The results obtained showed that the powders developed by FD and SD exhibited differences in colour parameters, as well as physicochemical and antioxidant properties. SPI and WPI powders obtained by FD exhibited higher retention of colour, polyphenols and antioxidant activity after the drying process and during storage. Stability tests revealed that the samples obtained presented first-order degradation of polyphenols and zero-order degradation of colour, and the conditions of greatest stability were found at low water activities (0.1–0.3) at a temperature of 25 °C. The microcapsules exhibited variable morphology depending on the production technique. In conclusion, freeze-drying, using WPI and SPI as wall material, improve stability to colour, polyphenols and antioxidant activity to microcapsules produced with Ardisia compressa juice, demonstrating potential for application as a natural colourant or functional additive.

Interaction of high amylose corn starch with polyphenols: Modulating the stability of polyphenols with different structure against thermal processing

Polyphenols are known to undergo thermal degradation and their bioactivity is reduced. In this study, the thermal degradation of polyphenols was modulated by the complexation between polyphenols and high amylose corn starch (HACS). The inclusion complex between ferulic acid with hydrophobic group methoxy and HACS had the highest encapsulation efficiency (EE = 26.15 %), loading efficiency (LE = 2.38 %) and thermal stability (DPPH radical scavenging activity was reduced by only 5.99 % after baking). After complexing with HACS, protocatechuic acid with ortho-position hydroxyl group had a higher encapsulation rate and thermal stability than 3, 5-dihydroxybenzoic acid with meta-position hydroxyl. In addition, soy isoflavone with the higher logarithmic value of octanol-water partition coefficient (Log P = 3.66) resulted in higher encapsulation rate and thermal stability than naringenin (Log P = 2.11). The results suggest that the complexation between polyphenols and starch protects the bioactivity of polyphenols and improves the processing suitability of polyphenols.

Microbial degradation of plant toxins.

Plants produce a variety of secondary metabolites in response to biotic and abiotic stresses. Although they have many functions, a subclass of toxic secondary metabolites mainly serve plants as deterring agents against herbivores, insects, or pathogens. Microorganisms present in divergent ecological niches, such as soil, water, or insect and rumen gut systems have been found capable of detoxifying these metabolites. As a result of detoxification, microbes gain growth nutrients and benefit their herbivory host via detoxifying symbiosis. Here, we review current knowledge on microbial degradation of toxic alkaloids, glucosinolates, terpenes, and polyphenols with an emphasis on the genes and enzymes involved in breakdown pathways. We highlight that the insect-associated microbes might find application in biotechnology and become targets for an alternative microbial pest control strategy.

Chemical Analysis of Various Tea Samples Concerning Volatile Compounds, Fatty Acids, Minerals and Assessment of Their Thermal Behavior.

Tea is the most consumed drink worldwide due to its pleasant taste and various beneficial effects on human health. This paper assesses the physicochemical analysis of different varieties of tea (leaves, flowers, and instant) after prior drying and fine grinding. The thermal decomposition behavior of the tea components shows that the tea has three stages of decomposition, depending on temperature. The first stage was attributed to the volatilization of water, while the second stage involved the degradation of volatiles, polyphenols, and fatty acids. The degradation of cellulose, hemicellulose, and lignin content occurs at the highest temperature of 400 °C in the third stage. A total of 66 volatile compounds, divided into eight classes, were identified in the tea samples. The volatile compounds were classified into nine odor classes: floral, fruity, green, sweet, chemical, woody, citrus, roasted, and alcohol. In all flower and leaf tea samples, monounsaturated (MUFAs), polyunsaturated (PUFAs), and saturated fatty acids (SFAs) were identified. A high content of omega-6 was quantified in acacia, Saint John's Wort, rose, and yarrow, while omega-3 was found in mint, Saint John's Wort, green, blueberry, and lavender samples. The flower and leaf tea samples studied could be a good dietary source of polyphenolic compounds, essential elements. In instant tea samples, a low quantity of polyphenols and major elements were identified. The physicochemical analysis demonstrated that both flower and leaf teas have high-quality properties when compared to instant tea.

Anaerobic phloroglucinol degradation by Clostridium scatologenes.

Polyphenols are abundant in nature, and their anaerobic biodegradation by gut and soil bacteria is a topic of great interest. The O2 requirement of phenol oxidases is thought to explain the microbial inertness of phenolic compounds in anoxic environments, such as peatlands, termed the enzyme latch hypothesis. A caveat of this model is that certain phenols are known to be degraded by strict anaerobic bacteria, although the biochemical basis for this process is incompletely understood. Here, we report the discovery and characterization of a gene cluster in the environmental bacterium Clostridium scatologenes for the degradation phloroglucinol (1,3,5-trihydroxybenzene), a key intermediate in the anaerobic degradation of flavonoids and tannins, which constitute the most abundant polyphenols in nature. The gene cluster encodes the key C-C cleavage enzyme dihydrophloroglucinol cyclohydrolase, as well as (S)-3-hydroxy-5-oxo-hexanoate dehydrogenase and triacetate acetoacetate-lyase, which enable phloroglucinol to be utilized as a carbon and energy source. Bioinformatics studies revealed the presence of this gene cluster in phylogenetically and metabolically diverse gut and environmental bacteria, with potential impacts on human health and carbon preservation in peat soils and other anaerobic environmental niches. IMPORTANCE This study provides novel insights into the microbiota's anaerobic metabolism of phloroglucinol, a critical intermediate in the degradation of polyphenols in plants. Elucidation of this anaerobic pathway reveals enzymatic mechanisms for the degradation of phloroglucinol into short-chain fatty acids and acetyl-CoA, which are used as a carbon and energy source for bacterium growth. Bioinformatics studies suggested the prevalence of this pathway in phylogenetically and metabolically diverse gut and environmental bacteria, with potential impacts on carbon preservation in peat soils and human gut health.

Predicting the storage time of green tea by myricetin based on surface-enhanced Raman spectroscopy

The quality of green tea changes rapidly due to the oxidation and degradation of polyphenols during storage. Herein, a simple and fast Surface-enhanced Raman spectroscopy (SERS) strategy was established to predict changes in green tea during storage. Raman spectra of green tea with different storage times (2020–2015) were acquired by SERS with silver nanoparticles. The PCA-SVM model was established based on SERS to quickly predict the storage time of green tea, and the accuracy of the prediction set was 97.22%. The Raman peak at 730 cm−1 caused by myricetin was identified as a characteristic peak, which increased with prolonged storage time and exhibited a linear positive correlation with myricetin concentration. Therefore, SERS provides a convenient method for identifying the concentration of myricetin in green tea, and myricetin can function as an indicator to predict the storage time of green tea.