Mean Degree Of Polymerization Research Articles

Low-Viscosity Route to High-Molecular-Weight Water-Soluble Polymers: Exploiting the Salt Sensitivity of Poly(N-acryloylmorpholine).

We report a new one-pot low-viscosity synthetic route to high molecular weight non-ionic water-soluble polymers based on polymerization-induced self-assembly (PISA). The RAFT aqueous dispersion polymerization of N-acryloylmorpholine (NAM) is conducted at 30 °C using a suitable redox initiator and a poly(2-hydroxyethyl acrylamide) (PHEAC) precursor in the presence of 0.60 M ammonium sulfate. This relatively low level of added electrolyte is sufficient to salt out the PNAM block, while steric stabilization is conferred by the relatively short salt-tolerant PHEAC block. A mean degree of polymerization (DP) of up to 6000 was targeted for the PNAM block, and high NAM conversions (>96%) were obtained in all cases. On dilution with deionized water, the as-synthesized sterically stabilized particles undergo dissociation to afford molecularly dissolved chains, as judged by dynamic light scattering and 1H NMR spectroscopy studies. DMF GPC analysis confirmed a high chain extension efficiency for the PHEAC precursor, but relatively broad molecular weight distributions were observed for the PHEAC-PNAM diblock copolymer chains (Mw/Mn > 1.9). This has been observed for many other PISA formulations when targeting high core-forming block DPs and is tentatively attributed to chain transfer to polymer, which is well known for polyacrylamide-based polymers. In fact, relatively high dispersities are actually desirable if such copolymers are to be used as viscosity modifiers because solution viscosity correlates closely with Mw. Static light scattering studies were also conducted, with a Zimm plot indicating an absolute Mw of approximately 2.5 × 106 g mol-1 when targeting a PNAM DP of 6000. Finally, it is emphasized that targeting such high DPs leads to a sulfur content for this latter formulation of just 23 ppm, which minimizes the cost, color, and malodor associated with the organosulfur RAFT agent.

Soil effect on proanthocyanidins composition of red and white wines obtained from Nero d’Avola and Grillo Vitis vinifera L. Cultivars

In this study, the effects of the main soil chemical-physical parameters (i.e. texture, pH, total carbonates, cation exchange capacity, electric conductivity, organic matter and mineral endowment) on proanthocyanidin composition of Nero d’Avola red wines and Grillo white wines were investigated. Monomer proanthocyanidins (i.e. (+)-catechin and (-)-epicatechin) and oligomer proanthocyanidins (i.e. B1, B2, B3 and B4 dimers and C1 trimer), as well as proanthocyanidins subunit composition, percentage of galloylation, percentage of prodelphinidins and mean degree of polymerization, were studied for each wine. Results highlighted that the proanthocyanidins composition of both red and white wines is greatly affected by soil. In particular, the proanthocyanidins composition of Nero d’Avola red wines appeared to be affected by the soil physical–chemical parameters related to nutrients dynamics (CEC, EC, pH, organic matter, mineral endowment), whereas the proanthocyanidins composition of Grillo white wines was mainly influenced by the soil texture, that modulates soil water dynamics.

Determination of Polyphenolic Profile of Apple Pomace (Malus domestica Golden Delicious Variety) by HPLC-MS.

Apple (Malus domestica Borkh) is an appreciated source of polyphenols. Phenolic compounds are known as natural antioxidants and have a wide range of applications in different industries. Apple pomace has the potential of being an alternative source of polyphenols. To determine the polyphenolic profile of apple pomace, samples from the skin at two different stages of ripening were extracted with 80-20% EtOH-water/acetic acid 5% (S1) and 20-80% EtOH-water/acetic acid 5% (S2) in order to determine the solvent system. Ripe skins extracted with S1 showed a higher total polyphenol content or TPC (1.21 g of polyphenols per 100 g of fresh weight (FW)) than unripe apple skin, being the most effective system tested and a mean degree of polymerization of 2.47. Commercial apple pomace was extracted with S1, resulting in a TPC of 0.5615 ± 0.007 g of polyphenols per 100 g of FW. Meanwhile, the RP-HPLC-MS analysis led to the tentative identification of several polyphenolic compounds.

From waste to eco-friendly biofilms: Harnessing cottonseed hull proanthocyanidins for sustainable solutions

A circular sustainable bioeconomy model, utilizing renewable resources like agricultural waste biomass, can address environmental issues caused by the massive utilization of fossil resources. The study aims at exploring the potential utilization of underutilized cottonseed hulls (CSHs) as a source of bioactive proanthocyanidins (PAs), and investigate their applicability in the production of biodegradable films. FT-IR, HPLC-QTOF/MS, MALDI-TOF/MS analyses served for characterizing the structure of PAs extracted from CSHs, and thiolysis reaction revealed that they primarily consisted of (epi)catechins with a few (epi)gallocatechins and (epi)afzelechin units, forming oligomeric proanthocyanidins of which the mean degree of polymerization (mDP) was 2.99. Three monomers, ten dimers, one tetramer, one pentamer, and one hexamer were theoretically identified in CSHs for the first time. The unique structure of CSHs sets them apart from most plants. The extracts displayed high in vitro antioxidant activity with IC50 value of 0.074 in DPPH assay and 0.018 mg/mL in ABTS assay. Additionally, the CSH extracts were incorporated as antioxidants into chitosan (CS)-based biodegradable films. The addition of 0.25% CSH extracts significantly improved film thickness and water vapor resistance, and also reduced the water solubility and visible light transmission. Furthermore, the films enhanced the blueberry quality and extended the shelf-life. This comprehensive study not only addresses waste management issues but also offers avenues for innovative applications in sustainable agriculture and packaging.

Exploring separation patterns and mechanisms of proanthocyanidins in grape seeds and pomace with diverse molecular weights, compositions, and structures

The function of proanthocyanidins (PAs) relies on their structure and requires high-purity PAs. Though Sephadex LH-20 gel permeation chromatography (GPC) is expected to separate PAs based on structure, its usage rules and mechanisms remain unclear. This study delves into the PAs separation patterns on Sephadex LH-20, first confirming the purification mechanisms of PAs with various mean degrees of polymerization (DP) using the adsorption kinetic model. The study found that an increase in the molecular weight or mean DP of PAs results in decreased polarity, reduced hydrogen bonding actions, and intensified hydrophobic effect, causing delayed extraction of PAs on Sephadex LH-20, with galloylated PA as an exception, which was extracted first despite its high DP. Additionally, the principles for separating specific composition, such as monomers, dimers, etc., were evaluated. The study sheds light on enhancing the purification efficiency of PAs, thus advancing the precise separation technology of diverse proanthocyanidins.

Effect of fermentation technologies on the structural composition of polymeric polyphenols in aged red wines

Eight-year-old Syrah red wines were produced using various winemaking technologies. The structural composition of purified polymeric polyphenols (PPpure) from traditional fermentation (Wctrl), prolonged maceration with skins (Wskin), and prolonged maceration with stems (Wstem) was comprehensively analyzed using various depolymerization methods, followed by HPLC-FT-ICR-MS and HPLC/UPLC-QqQ/MS analysis. The results revealed that PPpure consisted of proanthocyanidins, anthocyanins, amino acids, and phenolic acids. Proanthocyanidins were present as both extension and terminal units, with the former being predominant. Amino acids, phenolic acids, and anthocyanins, on the other hand, were exclusively present as terminal units. The proportions of these constituent units in PPpure varied significantly depending on winemaking technologies. When comparing Wskin and Wstem with Wctrl, it was observed that Wskin and Wstem had lower anthocyanins and higher phenolic acids. Furthermore, Wstem exhibited the highest amino acids. Moreover, the mean degree of polymerization (MDP) of the PPpure was influenced by the different fermentation technologies, with MDP values of 25.25, 13.14, and 15.84 for Wctrl, Wskin, and Wstem, respectively. These results indicated that different winemaking technologies significantly affect the structural features of polymeric polyphenols. These findings are crucial in providing practical applications for winemakers to control the polymeric polyphenol composition of wines.

Development of Tannins and Methoxypyrazines in Grape Skins, Seeds, and Stems of Two Pinot Noir Clones during Ripening.

Two Pinot noir clones (AM10/5 and UCD5) were analyzed for tannin and methoxypyrazines (MPs) in different grape tissues during berry development using liquid chromatography and two-dimensional gas chromatography-mass spectrometry. On a per berry basis, skin tannins reached the maximum level about 2-3 weeks after véraison, seed tannins at around véraison, and stem tannins 4 weeks before véraison. Clone AM10/5 showed significantly higher levels of seed and stem tannins on a per berry basis at harvest. Tannin concentration and composition varied among the different tissues. On a per berry basis, stem tannin levels were comparable to skin tannins but were 3 to 4 times lower than seed tannins, while stem tannins had an intermediate galloylation (5-7%) between seed tannins (12-18%) and skin tannins (2%) and lower prodelphinidin (4-7%) than skin tannins (31-36%). The mean degree of polymerization of stem tannins was similar to seed tannins but lower than skin tannins. MPs, including 3-isopropyl-2-methoxypyrazine (IPMP), 3-s-isobutyl-2-methoxypyrazine (SBMP), and 3-isobutyl-2-methoxypyrazine (IBMP), showed significantly higher concentrations than their sensory thresholds in grape stems but not in skins. The MPs development in stems showed an increasing trend toward véraison and then a decreasing trend toward harvest. Compared to AM 10/5, UCD5 stems showed a higher level of MPs, especially significantly higher concentrations of IPMP and IBMP at harvest. The extraction of MPs from grape stems could contribute negative green and vegetative characters to Pinot noir wines.

Grape-Derived Polysaccharide Extracts Rich in Rhamnogalacturonans-II as Potential Modulators of White Wine Flavor Compounds.

Many authors have investigated the role of mannoproteins on wine quality, but very few have analyzed the use of grape-derived polysaccharides as they are not commercially available. In this study, purified grape-derived polysaccharides from red wine (WPP) and winemaking by-products (DWRP: Distilled Washing Residues Polysaccharides) were used as potential fining agents to modulate white wine flavor. Phenolics and volatile compounds were analyzed in the control and wines treated with WPP, DWRP, and commercial mannoproteins (CMs) after one and twelve months of bottling, and a sensory analysis was conducted. WPP and DWRP, rich in rhamnogalacturonans-II, showed themselves to be good modulators of wine aroma and astringency. Improvement in wine aroma was related to an increase in all volatile families expect higher alcohols and volatile acids. The modulation of astringency and bitterness was related to a reduction in the proanthocyanidin content and its mean degree of polymerization. Extracts with polysaccharides with higher protein contents presented a higher retention of volatile compounds, and DWRP extract had more positive effects on the overall aroma. Our novel results present the possibility of obtaining valuable polysaccharides from distilled washing residues of wine pomaces, which could promote its valorization as a by-product. This is the first time the potential use of this by-product has been described.

Affinity of Tannins to Cellulose: A Chromatographic Tool for Revealing Structure-Activity Patterns.

Food, feed and beverage processing brings tannins into contact with macromolecules, such as proteins and polysaccharides, leading to different chemical and physical interactions. The interactions of tannins with proteins are well known but less is known about the affinity of tannins to polysaccharides. We used bacterial cellulose from nata de coco as a model compound to investigate how tannins and cellulose interact by adsorption measurements using UPLC-DAD. We also explored how the structure of tannins influences these interactions. The model tannins included nine individual structurally different hydrolysable tannins (HTs) and eight well-defined proanthocyanidin (PA) fractions with different monomeric units, mean degree of polymerization and both A- and B-type linkages. Tannins were found to have both strong and weak interactions with bacterial cellulose, depending on the exact structure of the tannin. For HTs, the main structural features affecting the interactions were the structural flexibility of the HT molecule and the number of free galloyl groups. For PAs, prodelphinidins were found to have a higher affinity to cellulose than procyanidins. Similarly to HTs, the presence of free galloyl groups in galloylated PAs and the flexibility of the PA molecule led to a stronger interaction. Adsorption measurements by UPLC-DAD proved to be a sensitive and rapid tool to evaluate the affinity of tannins to cellulose.

Synthesis of Multiblock Copolymer Composed of Biodegradable Poly(butylene succinate) and Poly(2-pyrrolidone): Impact of Each Block Length on the Mechanical Properties.

A series of multiblock copolymers comprising a systematic combination of biomass-originated and biodegradable poly(butylene succinate) (PBS) and poly(2-pyrrolidone) (PA4) units is synthesized with various mean degrees of polymerization (mDP) of each unit. Despite the inherent immiscibility of PBS and PA4, multiblock structure allows to mix the two components in the solution-cast films from solution. The mechanical properties of the cast films are highly dependent on the mDP of each unit, as demonstrated by tensile tests. The film of the copolymer with the lowest mDP of each unit (PBS: 17, PA4: 10) is transparent and exhibits extremely high elongation at break (> 400%) and high tensile stress (39.5MPa) with strain hardening. The films with 50% or higher crystallinity are brittle and opaque, while a decrease in crystallinity can result in higher elongation, as revealed by wide-angle X-ray diffraction measurements.

Anthocyanin and proanthocyanidin from Aronia melanocarpa (Michx.) Ell.: Purification, fractionation, and enzyme inhibition.

Aronia melanocarpa (Michx.) Ell. is a rich source of anthocyanins and proanthocyanidins with confirmed health benefits. Individual cyanidin glucosides (cyanidin 3-galactoside, cyanidin 3-arabinoside, cyanidin 3-xyloside, and cyanidin 3-glucoside) of anthocyanins (calculated by individual cyanin glycoside fractions was 419.9 mg/100 g FW) were isolated by Sephadex LH-20 column and different parts of proanthocyanidins with a different mean degree of polymerization (mDP) were fractionated by the solubility differences in different solvents. The composition of different mDP of proanthocyanidins was as follows: monomers (1.51%), oligomer (mDP of 4.2 ± 0.9, 20.57%), CPP-50 (mDP of 78.9 ± 4.1, 22.17%), CPP-60 (mDP of 66.1 ± 1.2, 27.94%), CPP-70 (mDP of 36.8 ± 3.9, 36.8%), CPP-75 (mDP of 25.2 ± 1.3, 6.14%), CPP-L (mDP of 10.2 ± 2.6, 6.95%), and there were recycling loss of 0.34%. Cyanidin 3-glucoside showed the strongest inhibition effects on α-amylase and lipase and cyanidin 3-arabinoside showed the strongest inhibition effect on α-glucosidase, while cyanidin 3-xyloside has no inhibition effect on the α-amylase, and cyanidin 3-galactoside, cyanidin 3-arabinoside, and cyanidin 3-xyloside have no inhibition effects on lipase. The inhibition effect of proanthocyanidins with different mDP to the enzymes all showed high negative correlations between the mDP and IC50 (half-maximal inhibitory concentration). This study suggests that A. melanocarpa (Michx.) Ell. can have beneficial effects due to inhibition of the digestion enzyme.

Coupling Hydrophilic Interaction Chromatography and Reverse-Phase Chromatography for Improved Direct Analysis of Grape Seed Proanthocyanidins.

Acid-catalyzed depolymerization is recognized as the most practical method for analyzing subunit composition and the polymerization degree of proanthocyanidins, involving purification by removing free flavan-3-ols, as well as acid-catalyzed cleavage and the identification of cleavage products. However, after the removal of proanthocyanidins with low molecular weights during purification, the formation of anthocyanidins from the extension subunits accompanying acid-catalyzed cleavage occurred. Thus, grape seed extract other than purified proanthocyanidins was applied to acid-catalyzed depolymerization. Hydrophilic interaction chromatography was developed to quantify free flavan-3-ols in grape seed extract to distinguish them from flavan-3-ols from terminal subunits of proanthocyanidins. Reverse-phase chromatography was used to analyze anthocyanidins and cleavage products at 550 and 280 nm, respectively. It is found that the defects of the recognized method did not influence the results of the subunit composition, but both altered the mean degree of polymerization. The established method was able to directly analyze proanthocyanidins in grape seed extract for higher accuracy and speed than the recognized method.

Characterisation of Tannin and Aroma Profiles of Pinot Noir Wines Made with or without Grape Pomace

The contribution of grape pomace on tannin concentration, tannin composition and aroma profile of Pinot noir wine was studied using different fermentation media to make up four treatments: GJ-P, grape juice plus pomace; MJ-P, model juice plus pomace; GJ, grape juice; MJ, model juice. The MJ-P treatment showed significantly lower amounts of tannins, mean degree of polymerisation (mDP), similar amounts of anthocyanin, and a similar secondary aroma profile compared to the GJ-P treatment. Grape pomace addition significantly increased the tannin concentration in wines. This study was also revealed the importance of phenolics present in grape juice in tannin polymerisation and final tannin concentration in wines. Grape pomace addition significantly reduced some important aroma compounds such as acetate esters (except ethyl acetate), most of the volatile fatty acids, a few ethyl esters and β-damascenone but increased some primary aromas in wines due to the presence of their aroma precursors in skins. Hence, these results indicate that grape pomace may bind or delay the release of some aroma compounds and/or lose these compounds during cap management in GJ-P and MJ-P treatments compared to the respective juice treatments.

Exploring the anticomplement components from Fagopyrum dibotrys for the treatment of H1N1-induced acute lung injury by UPLC-Triple-TOF-MS/MS

In the present study, a procyanidins-enriched fraction (PCE) from the rhizome of Fagopyrum dibotrys was obtained by anticomplement activity-guided fractionation. PCE could alleviate H1N1-induced ALI in mice by reducing weight loss, decreasing lung index, and regulating cytokine levels in lung tissue. PCE contained 76.5 ± 1.1% procyanidins with a mean degree of polymerization (mDP) of 5.24 ± 0.16. Meanwhile, thirty-three chemical constituents, including 27 procyanidins and 6 other compounds, were recognized by UPLC-Triple-TOF-MS/MS. Among them, twenty recognized procyanidins were composed of (epi)catechin with B-type link, while the rest consisted of (epi)catechin gallate. Furthermore, six compounds were obtained by preparative HPLC on a C18 column (250 × 10.0 mm, 5 µm), and their structures were confirmed by mass spectrum (MS), nuclear magnetic resonance (NMR), and specific rotation. The structure-activity relationship analysis indicated that DP and galloylation were closely related to the anticomplement activity of procyanidins. The obtained results revealed that anticomplement procyanidins were one kind of the potentially effective materials of F. dibotrys against H1N1 influenza virus infection, and the in vivo efficacy of these compounds was worthy of further investigation.

Antioxidative properties of bayberry tannins with different mean degrees of polymerization: Controlled degradation based on hydroxyl radicals

The antioxidant properties of condensed tannins (CTs) are closely related to the mean degree of polymerization (mDP), and CTs with low mDP show stronger antioxidant effects. Therefore, obtaining CTs with a low mDP are very meaningful in improving their antioxidant properties and utilization. In this study, hydroxyl radicals generated by the decomposition of hydrogen peroxide under UV irradiation were used to degrade bayberry tannins in a clean and controllable manner. Taking the formaldehyde reactivity as an index to control the mDP of the degradation product, the changes in antioxidant properties of bayberry tannins with different mDP were studied by the method of 1,1-diphenyl-2-trinitrophenylhydrazine (DPPH), and 2,2-azido-di(3-ethyl-benzothiazole-6-sulfonic acid)diammonium salt (ABTS). Matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), gel permeation chromatography (GPC), carbon nuclear magnetic resonance (13C NMR), and reversed-phase HPLC-ESI-MS were used to characterize the mDP, molecular weight (Mw), and chemical structure of the degradation products of bayberry tannins in different degradation stages. Results showed that hydroxyl radicals could cause significant degradation of bayberry tannins, and the controllable degradation of bayberry tannins could be achieved with the formaldehyde reactivity as an index. At the degradation times of 0, 2, 4, 6, and 8 h, the mDP (Mw) of the degradation products were as follows: 5.22 (2457), 4.36 (1895), 3.36 (1534), 2.87 (1153), and 1.78 (813), respectively. The antioxidant activity of the degraded product increased with the decrease in the mDP, and the degraded products had the largest formaldehyde reactivity and the best oxidation resistance when degraded for 6 h. This study provided a new method to achieve clean and controllable degradation of tannins and supported those tannins with low mDP could provide higher antioxidant activity.

Developing novel oenological tannins from 44 plants sources by assessing astringency and color in model wine.

Oenological tannins are commercial natural products extracted from different botanical sources, which were widely reported as prominent contributors to wine quality. Research on wine quality affected by tannins extracts promoted the development of new oenological products with low cost and high accessibility. In the present study, the structure and concentration of tannin in polyphenol extracts, as well as their correlation with astringency and the color of model wine, was investigated by UV spectrophotometer, HPLC, fluorescence quenching, sodium dodecylsulfate-polyacrylamide gel electrophoresis, colorimeter and sensory evaluation. Resource extracts from 16 of 44 plants were screened as wine oenological tannins, according to the total polyphenol and total flavanol, as well as the intensity of astringency and bitterness. Polyphenols extracted from grape seeds and green tea were more effective in increasing the wine astringency compared to other plant tannins. Total flavanol content and tannin activity showed a strong correlation with wine astringency. Condensed tannins with mean degree of polymerization also exhibited strong color stability, and the concentrations of (-)-epigallocatechin were associated with the a* value, a negative qualitative factor for wine color. The present study provides new clues regarding the development of low-cost and highly accessible sources of polyphenol extracts and lays a theoretical foundation for the development of the oenological product. © 2022 Society of Chemical Industry.

Oligomeric Proanthocyanidin Complex from Avocado Seed as A Promising α-glucosidase Inhibitor: Characteristics and Mechanisms.

Although considered an abundant source of agricultural by-products, avocado (Persea americana Mill.) seed, with several biological activities and bioactive components, might become a promising resource for phytopharmaceutical development. In this study, through bioassay-guided isolation of the main α-glucosidase inhibitors in avocado seed, we discovered the major α-glucosidase inhibitor to be avocado seed oligomeric proanthocyanidin complex (ASOPC). Thiolysis and UPLC-DAD-HRESIMS showed the presence of A- and B-type procyanidins, and B-type propelargonidin with (epi)afzelechin as extension unit. Mean degree of polymerization (mDP) of ASOPC was calculated as 7.3 ± 1. Furthermore, ASOPC appeared to be a strong, reversible, competitive inhibitor of α-glucosidase, with IC50 value of 0.1 µg/mL, which was significantly lower than Acarbose (IC50 = 75.6 µg/mL), indicated that ASOPC is a potential natural α-glucosidase inhibitor. These findings would contribute to the direction of utilizing avocado seed bioactive components with the possibility to be used as natural anti-diabetic agents.

Guideline for measurement of condensed tannin

AbstractAstringency is a major sensory property and plays an important role in the overall quality of juice and wines. A major contributor to astringency is condensed tannins, which can precipitate with salivary glycoproteins. And thus, it is vital to develop methods to measure the tannin accurately. Recently, the interest in the application of condensed tannin assays has been increasing in various fields. Condensed tannin assays broadly include the determination of concentration, activity, mean degree of polymerization and its derivative flavan‐3‐ol sulfonates content. In this guideline, the mechanisms and the practice of the most common condensed tannin assays applied in research labs are discussed in detail.

Standardization of proanthocyanidin extract’s mean degree of polymerization using eutectic solvents

Proanthocyanidin’s molecular characteristics, especially mean degree of polymerization (mDP), have a high impact on their anti-inflammatory and antioxidant activities. Nevertheless, the mDP of proanthocyanidin’s extracts obtained from the same plant species can change due to the use of different plant varieties or by using plant material grown in different conditions/locations leading to extracts with compositional variabilities, that conventional extraction techniques cannot overcome, but that have a great impact on final applications.Eutectic solvents are a new class of solvents that can be prepared by combining a wide variety of compounds in variable proportion allowing for their customization to specific applications. By changing eutectic solvent’s composition it is possible to obtain proanthocyanidins with a specific mean degree of polymerization, regardless of the raw material.Herein, the use of a quaternary eutectic solvent system composed by choline chloride, glycerol, water and ethanol that was previously described as an efficient media for the extraction of proanthocyanidins was explored in the standardization of proanthocyanidin extracts’ mDP obtained from grape pomace by means of Response Surface Methodology. By adjusting the content of each eutectic solvent component to different grape pomaces, it was possible to overcome the limitations normally observed with conventional solvents. More specifically, the production of proanthocyanidin extracts with the desired mDP values (6.5 and 7.5 were selected for validation purposes) from three different grape pomaces that would otherwise lead to considerably different results.

Antioxidant Properties of Larch Tannins with Different Mean Polymerization Degrees: Controlled Degradation Based on Hydroxyl Radical Degradation.

Hydroxyl radical produced by hydrogen peroxide decomposition under UV radiation was used to degrade larch tannins in an environmentally friendly manner. The formaldehyde reactivity of the degraded products was used as an index to control the mean degree of polymerization (mDP) of the degraded products, and the effects of different mDP on the antioxidant activity of tannins were studied. Results showed that hydroxyl radical could significantly reduce the degree of polymerization (DP) and molecular weight (Mw) of larch tannins, and the mDP and Mw of degraded products could be controlled by considering the formaldehyde reactivity as the index. The antioxidant activity of larch tannins increased with the decrease in mDP. When the degradation time was 6 h, the formaldehyde reactivity was the highest at 0.823. The antioxidant activity of the degraded product was excellent, and the free radical scavenging rate was more than 98%.