Insoluble Tannins Research Articles

Immature persimmon residue as a novel biosorbent for efficient removal of Pb(II) and Cr(VI) from wastewater: Performance and mechanisms

Owing to the powerful affinity of tannin toward heavy metal ions, it is frequently immobilized on adsorbents to enhance their adsorption properties. However, natural adsorbents containing tannin have been overlooked owing to its water solubility. Herein, a novel natural adsorbent based on the immature persimmon residue (IPR) with soluble tannin removed was fabricated to eliminate Pb(II) and Cr(VI) in aquatic environments. The insoluble tannin in IPR endowed it with prosperous properties for eliminating Pb(II) and Cr(VI), and the IPR achieved maximum Pb(II) and Cr(VI) adsorption quantities of 68.79 mg/g and 139.40 mg/g, respectively. Kinetics and isothermal adsorption analysis demonstrated that the removal behavior was controlled by monolayer chemical adsorption. Moreover, the IPR exhibited satisfactory Pb(II) and Cr(VI) removal efficiencies even in the presence of multiple coexisting ions and showed promising regeneration potential after undergoing five consecutive cycles. Additionally, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analysis unveiled that the elimination mechanisms were primarily electrostatic attraction, chelation and reduction. Overall, the IPR, as a tannin-containing biosorbent, was verified to possess substantial potential for heavy metal removal, which can provide new insights into the development of novel natural adsorbents from the perspective of waste resource utilization.

Evolution of Seed-Soluble and Insoluble Tannins during Grape Berry Maturation

Condensed tannins (CT) in wine are derived from the seeds and skins of grapes, and their composition and content contribute to the bitterness/astringency characteristics and ageing potential of the wine. Global warming has accelerated the ripening process of grape berries, making them out of sync with seed ripening. To understand the influence of berry ripening on the seed CT composition and content, we analyzed the changes in the soluble and insoluble CT in the seeds of 'Cabernet Sauvignon' grapes from two vineyards over two years. The results showed that the seed-soluble CT presented a slight downward trend in fluctuation during grape berry development, while the insoluble CT increased continuously before the véraison and remained at a high level afterwards. Relatively speaking, a lower sugar increment in developing grape berries favored the conversion of seed CT towards a higher degree of polymerization. The terminal unit of soluble CT was dominated by epigallocatechin gallate, the content of which decreased as the seeds matured. It is suggested that the seeds should be fully matured to reduce this bitter component in tannins. This study provides a reference for us to control the grape ripening process and produce high-quality grapes for wine making.

Diversity of Fruit Quality in Astringent and Non−Astringent Persimmon Fruit Germplasm

Persimmon (Diospyros kaki Thunb.) is an economically important tree with a long history of cultivation in China. So far, a total of approximately 1000 varieties have been found in China. To systematically evaluate the diversity of persimmon fruit quality, 22 quality measures of appearance, intrinsic, and sensory quality were evaluated using 61 typical persimmon fruit. According to the findings, the coefficient of variation (CV) of 15 appearance and intrinsic quality index values ranged from 13.81% (fruit shape index) to 165.80% (firmness), and the CV values of 7 intrinsic quality attributes were all higher than 50%, with the CV of total polyphenols and ironic soluble pectin contents (ISP) being as high as 159.82% and 143.80%, respectively. These findings showed that several persimmon germplasm resources had a highly diverse range of fruit quality, wide variation, and distribution. Insoluble tannin and soluble sugar were shown to have a substantial positive correlation with the sensory flavor indexes (p < 0.05), indicating their significance in influencing the flavor quality of persimmon fruit. Cluster analysis was performed utilizing 15 indexes of appearance, intrinsic quality, and 7 indexes of sensory quality. The samples were divided into two groups: group I consisted of 52 pollination−constant and astringent (PCA) and 1 pollination−-variant astringent (PVA) persimmon resources, and group II consisted of 6 pollination−constant non−astringent (PCNA) and 2 pollination−variant non−astringent (PVNA) persimmon resources. The results were consistent with the classification based on the mode of astringency loss, indicating that there was a significant difference in the quality of astringent and non−astringent persimmon fruit. This study provides theoretical references for the development and application of persimmon germplasm resources.

A comprehensive metabolomics analysis of Torreya grandis nuts with the effective de-astringent treatment during the postharvest ripening stage

Astringency removal is important for the quality of Torreya grandis nut and occurs after harvest. Here, we evaluated the effect of NaHCO3 treatment on astringency removal and compared the differential metabolites of the seed coat and kernel using a UHPLC QQQ-MS-based metabolomics approach. The result revealed the nut astringency was primarily enriched in the seed coat with more soluble tannins. The NaHCO3 treatment greatly shortened the de-astringency process, as indicated by a faster conversion of soluble tannins to insoluble tannins and more acetaldehyde production. Besides, a total of 293 metabolites, including 92 phenolic acids and 37 flavonoids, were tentatively characterized in the seed coat. A further comparative analysis of the metabolomics indicated epigallocatechin, gallocatechin, catechin, procyanidin B1, B2, B3 and C1 to be the major metabolites influenced by the NaHCO3 treatment. This study provides new insights regarding the metabolite differences of Torreya grandis nuts processed with different de-astringent treatments.

Characterization of browning during CO2 deastringency treatment in astringent persimmon fruit

Deastringency treatment with CO2 is an effective and convenient method for improving the marketability of persimmon fruit. However, the main persimmon cultivars in China turn brown very quickly following exposure to a high-CO2 atmosphere, causing significant economic loss. However, the mechanisms of persimmon browning under CO2 treatment remain largely unknown. In this study, we evaluated components and enzymes related to persimmon fruit browning. The results revealed that astringency was alleviated by simultaneous reduction of soluble tannin content and accumulation of insoluble tannin. During persimmon browning, fruit firmness, total phenolic content, and phenylalanine ammonia lyase (PAL) activity decreased significantly, whereas malondialdehyde (MDA), superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and polyphenol oxidase (PPO) activity increased significantly, suggesting that reactive oxygen species (ROS)-scavenging enzymes and non-enzymatic antioxidants cannot effectively maintain redox reaction balance to protect cell membranes from oxidative damage during CO2 treatment. An untargeted metabolomics analysis identified 19 polyhydroxyphenols that were downregulated in CO2-treated fruit, suggesting that phenolics may act as a substrate for persimmon browning. We also identified 11 metabolites associated with abiotic stress. Together, these results study provide valuable information on the mechanism of persimmon fruit browning induced by CO2 treatment and will contribute to the ongoing development of the persimmon fruit industry.

Effect of Soil Type: Qualitative and Quantitative Analysis of Phytochemicals in Some Browse Species Leaves Found in Savannah Biome of South Africa.

In semi-arid regions, browse plant species are used as feed and for medicinal purposes for both animals and humans. The limitation of the utilization of these species to medicinal purposes or as feed for livestock is a lack of knowledge on the concentration level of phytochemicals and other bioactive compounds found in these plants. The study sought to assay the qualitative and quantitative bioactive constituents of some browse species found in the savannah biome of South Africa, viz. Adansonia digitate, Androstachys johnsonii, Balanites maughamii, Berchemia discolor, Berchemia zeyheri, Bridelia mollis hutch, Carissa edulis, Catha edulis, Colophospermum mopane, Combretum Imberbe, Combretum molle, Combretum collinum, Dalbergia melanoxylon, Dichrostachys cinerea, Diospros lycioides, Diospyros mespiliformis, Euclea divinorum, Flueggea virosa, Grewia flava, Grewia flavescens, Grewia monticola, Grewia occidentalis, Melia azedarach, Peltophorum africanum, Prosopis velutina, Pseudolachnostylis maprouneifolia, Pterocarpus rotundifolius, Schinus molle, Schotia brachypetala, Sclerocarya birrea, Searsia lancea, Searsia leptodictya, Searsia pyroides, Senegalia caffra, Senegalia galpinii, Senegalia mellifera, Senegalia nigrescens, Senegalia polyacantha, Strychnos madagascariensis, Terminalia sericea, Trichilia emetic, Vachellia erioloba, Vachellia hebeclada, Vachellia karroo, Vachellia nilotica, Vachellia nilotica subsp. Kraussiana, Vachellia rechmanniana, Vachellia robusta, Vachellia tortilis, Vachellia tortilis subsp. raddiana, Vangueria infausta, and Ziziphus mucronata. These browse species’ leaf samples were harvested from two provinces (Limpopo and North-West) of South Africa. The Limpopo province soil type was Glenrosa, Mispah, and Lithosols (GM-L), and the soil types in the North-West Province were Aeolian Kalahari Sand, Clovelly, and Hutton (AKS-CH). The harvested browse samples were air dried at room temperature for about seven days and ground for analysis. The methanol and distilled water extracts of the browse species leaves showed the presence of common phytoconstituents, including saponins, flavonoids, tannins, phenols, cardio glycosides, terpenoids, and phlobatannins, as major active compounds in browse species leaves. In the quantitative analysis, phytochemical compounds, such as soluble phenols, insoluble tannins, and condensed tannins, were quantified for common species found in both sites. Two-way ANOVA and multivariate analysis were used to test soil type and species effect on soluble phenols, insoluble tannins, and condensed tannins of woody species. Dichrostachys cinerea (0.1011% DM) in GM-L soil type and Z. mucronata (0.1009% DM) in AKS-CH soil type showed the highest (p < 0.05) concentration of soluble phenols. In AKS-CH soil type, D. cinerea (0.0453% DM) had the highest insoluble tannins concentration, while V. hebeclada had the lowest (0.0064% DM) insoluble tannins content. Vacchelia hebeclada had lower (p < 0.05) condensed tannins concentration levels than all other browse plants in both soil types. Under multivariate analysis tests, there was a significant effect (p < 0.001) of soil type, species, and soil type x species interaction on soluble phenols, insoluble tannins, and condensed tannins of woody species. In this study, most of the woody species found in GM-L soil type showed a lower amount of tannins than those harvested in AKS-CH soil type. There is a need to identify the amount of unquantified phytochemicals contained in these browse species and valorize the high-bioactive-compound browse species to enhance and maximize browsing of these browse species for animal production.

Effect of intermittent microwave drying on nutritional quality and drying characteristics of persimmon slices

The novelty of this paper was to evaluation the effect of intermittent microwave drying (IMD) on the nutritional quality and drying characteristics of persimmon slices. Persimmon slices were treated with IMD at the microwave power levels of 280, 350, 420, 490, and 560 W, and the drying characteristics, nutritional components, and sensory properties were determined and analyzed. The results showed that the drying process of persimmon slices could be divided into three stages; increasing speed, constant speed, and decreasing speed. Meanwhile, the higher the microwave power, the shorter the drying time and the higher the drying rate. With the increase of microwave power, the contents of soluble sugar, soluble tannin, vitamin C, and ash increased gradually, but had no obvious effect on the content of insoluble tannin, while the contents of soluble protein and vitamin E decreased gradually, and the overall acceptability score increased first and then decreased. In this study, the comprehensive scoring method was used for dried persimmon slices. The optimal microwave power for IMD persimmon slices was determined to be 490 W, which could effectively improve the drying rate and nutritional value, and has good sensory acceptability.

An in vitro digestion study of tannins and antioxidant activity affected by drying “Rojo Brillante” persimmon

This study focuses on the evaluation of soluble and insoluble tannins and their antioxidant activity in fresh and dehydrated “Rojo Brillante” persimmon after in vitro digestion. Persimmon and its derived products contain a high amount of tannins with high antioxidant activity. An inversely proportional relationship between soluble and insoluble tannins was observed marked by the deastringency and hot air-drying treatments. Furthermore, the antioxidant activity after the hydrolysis of insoluble tannins was greater compared to soluble tannins. After small intestine in vitro digestion, the recovery of soluble tannins was higher in samples dehydrated at 40 and 60 °C, and insoluble tannins remained intact. Therefore, soluble tannins could be absorbed in the small intestine and insoluble tannins could reach the colon microbiota, both indicating potential health-promoting properties. Therefore, hot air drying and freeze-drying are alternative treatments to develop dehydrated persimmon snacks or powdery ingredients to improve nutritional properties of new foods.

In vitro and in vivo evaluation of the bile acid-binding properties of dried persimmon and its non-extractable proanthocyanidin fraction

Dried persimmons contain abundant insoluble tannins comprised of non-extractable proanthocyanidins (NEPAs). To determine the beneficial function of NEPAs, we studied the bile acid-binding ability of NEPAs using in vitro and in vivo experiments. For the in vitro evaluation, 70% (v/v) acetone-insoluble solids (AIS) with different NEPA levels was prepared from persimmon fruits during drying. AIS with higher NEPA levels displayed stronger bile acid-binding activity, and the highest NEPA levels can be obtained from mostly-dried fruits. The in vivo bile acid-excreting effect of dried persimmon powder (DP) and AIS was verified by feeding experiments using C57BL/6J mice. The average bile acid-excretion was in order of low-fat group (1.07 µmol/day) < high-fat (HF) group (3.03 µmol/day) < HF + AIS group (4.44 µmol/day) < HF + DP group (6.74 µmol/day). These results suggest that the bile acid-excreting function of the fruit is related to the presence of NEPAs, which are constitutive ingredients of dried persimmon.

The roles of soluble poly and insoluble tannin in the enzymatic browning during storage of dried persimmon

The roles of total soluble polyphenols (TSP) and insoluble tannins (IST) in the enzymatic browning during the storage of dried persimmon slices packaged by different methods was studied. The color evolution was comprehensively evaluated within 18 weeks of storage, as well as determination the content variation of TSP, IST, and carotenoids. A series of simulated reactions were conducted to investigate the involvement of TSP and IST in PPO-catalyzed reaction. The results showed that N2-opaque packaging was a good way to alleviate this browning issue. The IST contributed preponderantly to the browning during the whole storage, while the contribution of TSP was little. And the degradation of carotenoids might be related to the color deterioration in the early storage. The IST participated in PPO-catalyzed reaction directly with the insoluble state. By contrast, only a small amount of TSP participated in PPO-catalyzed browning reaction, since it preferentially interacted with IST.

Removal of astringency in persimmon fruits (Diospyros kaki) subjected to different freezing temperature treatments.

The effects of two different freezing temperatures (- 20°C and - 80°C) on the astringency trait of persimmon fruits during 15 to 60days of storage were investigated. The levels of soluble and insoluble tannins, proanthocyanidins and other physicochemical characteristics were evaluated. Storage at - 20°C and - 80°C temperatures up to 60days has been found to be an effective method to remove astringency of persimmon fruits. Proanthocyanidin concentration was negligible at both temperatures during storage. Total soluble solid contents were decreased as 3.34 from 4.59 (mg/g DW) whereas, insoluble tannin contents were increased as 20.30 from 16.45 (mg/g DW) by freezing temperatures treatment during storage. Comparatively, higher soluble tannin content 11.68 (mg/g DW) and lower insoluble tannin content 10.02 (mg/g DW) was observed in control (day 0). Therefore, the astringency of persimmon fruits incubated at - 20°C and - 80°C was markedly reduced and after 15 up to 60days of storage, the astringent taste virtually disappeared. The proanthocyanidin contents were decreased as 0.02 from 0.52 (mg/g DW) at - 20°C storage and 0.17 from 0.47 (mg/g DW) at - 80°C storage, in comparison with the control 2.65 (mg/g DW). The moreover, along with the removal of astringency, other physicochemical parameters including color, pH, moisture content, total soluble solid, and sensory attributes were also conserved on freezing at both the temperatures. These findings suggest that freezing temperature treatments aid the removal of astringency from persimmon fruits which could be used in different food preparations or as supplements.

Effect of Hot Water Treatment on Astringency Removal in Persimmon Cultivars

ABSTRACT The aim of this study was to investigate the effect of hot water treatments on the removal of astringency in ‘MKU Harbiye,’ ‘Kaki Tipo,’ and ‘Vainiglia’ persimmon cultivars. Fruits were dipped in tap water at hot water at 40°C for 5 h (HW 40°C-5 h) or hot water at 50°C for 1 h (HW 50°C-1 h). Untreated (Control 1), 20°C for 1 (Control 2, 20°C-1 h), or 5 h (Control 3, 20°C-5 h) and treated fruits were then kept at 20ºC for 10 days of shelf life period. Changes in weight loss, appearance, firmness, total soluble solids, taste, fungal decay, fruit skin color, soluble and insoluble tannin content were determined during shelf life. In all cultivars, HW 40°C-5 h was found to be successful in reducing the astringency and maintained firmness above the marketability limit for 10 days of shelf life period. The fruit treated with HW 40°C-5 h became edible after 7 days at 20°C while control fruits remained astringent based on soluble tannin content the entire shelf-life period. Although the HW 50°C-1 h and Control 2 and 3 (20°C-1 h or 20°C-5 h) treatments received acceptable taste scores after 10 days, fruits from these treatments were slightly astringent.

Ensiling of total mixed ration containing persimmon peel: Evaluation of chemical composition and in vitro rumen fermentation profiles.

The effects of inclusion of persimmon peel (PP) in total mixed ration (TMR) silage on its nutrient composition, tannin content, and in vitro ruminal fermentation were studied. Four types of TMR silages containing 0, 50, 100, and 150 g/kg of PP on a dry matter basis were prepared. The dietary contents of non‐fiber carbohydrate (NFC) decreased, while soluble protein fraction increased after ensiling of the TMR. In the TMR silages, the content of insoluble tannin increased (p < .05) with increasing PP level. The fraction of soluble protein decreased linearly (p < .01), while that of neutral detergent insoluble protein increased linearly (p < .01) with increasing the PP level in the TMR silages. The total gas and methane yields from the in vitro rumen fermentation of the TMR silages were lower (p < .01) than those of pre‐ensiled TMR and declined linearly (p < .01) with increasing PP level. These results indicate that adding PP to TMR silage may resist the breakdown of dietary protein during the ensiling process, although the ruminal fermentability of TMR possibly decreased after ensiling due to the loss of NFC.

Assessment of a Fenton reaction driven by insoluble tannins from pine bark in treating an emergent contaminant

Iron ligands as 1,2-dihydroxybenzenes (1,2-DHBs) have been used to increase the oxidizing ability of Fenton systems. However, these kinds of ligands become toxic quinones in the process creating an environmental problem since these compounds cannot be easily separated from a solution. To avoid this problem, in the present work, water-insoluble tannins, obtained from Pinus radiata bark, were used as a source of 1,2-DHBs to promote the oxidizing ability of the Fenton process. The developed system was tested using atrazine, as a substrate, which is a toxic and recalcitrant compound, present in different sources of water. The best reaction conditions established by the experimental design were as follows: pH of 3.6; 2.4 mmol L−1 of H2O2; 150 μmol L−1 of Fe(III); and 800 mg L−1 of tannins. A significant increase in the efficiency of the degradation of atrazine by the heterogeneous Fenton process was observed under these conditions. The repetitive use of the insoluble tannins for Fenton-like processes showed a similar oxidizing ability and did not produce the lixiviation of phenols or other aromatic compounds. Together, the results showed that insoluble tannins could be used safely at least five times to promote the reactivity of Fenton systems.

Electrochemical reverse engineering to probe for drug-phenol redox interactions

Phenolics are among the most abundant organics in nature but their biological activities remain poorly understood. Traditional approaches to characterize materials starts with structure determination yet this approach has been less successful for phenolics because of their structural complexity and heterogeneity. Here an electrochemical reverse engineering approach that focuses on materials properties (vs structure) was used to infer function. We studied three phenolics that are abundant in food: the small molecule chlorogenic acid, the macromolecule proanthocyanidins, and the insoluble tannin from persimmon. We observed that all three phenolics are redox active and can repeatedly donate and accept electrons. Further, we provide evidence that all three kinds of phenolics can undergo redox-cycling with the analgesic acetaminophen. These results suggest that the reversible redox properties of phenolics may confer important biological activities even under conditions that would suggest they are unavailable biologically because their size would restrict absorption into the bloodstream or even dissolution.

Persimmon peel deastringency by CO2 and ethanol combination: Product quality and polyphenols bioavailability

Persimmons are popular worldwide owning to their unique flavor and nutritional value, while for the astringent cultivars, deastringency treatment is needed before processing. The current deastringency methods are limited to CO2 and ethanol. The aim of this work was to select optimal deastringency methods and assess the bioavailability of polyphenols in persimmon peels treated with 12 different combination of CO2 and ethanol. The level of soluble and insoluble tannins, total polyphenols bioaccessibility, antioxidant properties, color, and soluble solids were also determined. Results indicated that soluble tannin contents decreased with increasing ethanol concentration, and with an increase in carbon dioxide concentration, the insoluble tannins content increased. Application of 30% ethanol solution and 80% carbon dioxide for 24 hr has a best deastringency effect, while this treatment does not show good phenolics bioaccessibility and antioxidant activity. Therefore, the combination of 30% ethanol solution with 70% CO2 fumigation for 24 hr at 10 °C is the best deastringency method. Practical applications This project invented a novel deastringency method by CO2 and ethanol combination, with a feature of applying to lower temperature. The aim of this work was to select optimal deastringency methods and assess the bioavailability of polyphenols in persimmon peels treated with 12 different combination of CO2 and ethanol.

Pharmacognostic studies and elemental analysis of the aerial parts of &lt;i&gt;Cassytha filiformis&lt;/i&gt; Linn. (Family: Lauraceae)

Cassytha filiformis Linn. (family Lauraceae) a leafless and perennial vine with small scales as a replacement of the leaves is currently being used in the treatment of various disease conditions including jaundice. The aim of this work is to study the pharmacognostic characters of C. filiformis Macroscopic/organoleptic characters, microscopic, chemo-microscopic characters, numerical standards, and elemental analysis were determined from the whole plant of C. filiformis. Findings from this study revealed the presence of some diagnostic microscopical features such as paracytic stomata, unicellular covering trichomes with cystoliths, prismatic calcium oxalate crystals and annular xylem vessels. Quantitative physical constants include moisture contents (5.5 %), ash value (17 %), acid insoluble ash value (1 %), total tannins (27.3 %), swelling index (165 %), water, alcohol and oil extractive indices (20.6 %, 13.6 % and 1.6 % respectively). Trace metals detected in C. filiformis such as Fe (165.4279 ppm), Mn (14.4093 ppm) and Ni (2.7933 ppm) which are essential were higher than FAO/WHO (1984) permissible limit for edible plants. While others: Pb (0.0568 ppm) Zn (0.1094 ppm), Cd (0.0103 ppm) and Cu (0.0535 ppm) were found to be within the safety limit.Keywords: Cassytha filiformis; Rumfar gada; Lauraceae; Pharmacognostic characters

Hydroxyl radical production by a heterogeneous Fenton reaction supported in insoluble tannin from bark of Pinus radiata.

Fenton reactions driven by dihydroxybenzenes (DHBs) have been used for pollutant removal via advanced oxidation processes (AOPs), but such systems have the disadvantage of DHB release into the aqueous phase. In this work, insoluble tannins from bark can be used to drive Fenton reactions and as a heterogeneous support. This avoids the release of DHBs into the aqueous phase and can be used for AOPs. The production of ·OH was investigated using a spin-trapping electron paramagnetic resonance technique (5-dimethyl-1-pyrroline-N-oxide/·OH) in the first minute of the reaction and a high-performance liquid chromatography-fluorescence technique (coumarin/7-hydroxycoumarin) for 20min. The ·OH yield achieved using insoluble tannins from Pinus radiata bark was higher than that achieved using catechin to drive the Fenton reaction. The Fenton-like system driven by insoluble tannins achieved 92.6±0.3% degradation of atrazine in 30min. The degradation kinetics of atrazine was linearly correlated with ·OH production. The increased reactivity in ·OH production and insolubility of the ligand are promising for the development of a new technique for degradation of pollutants in wastewater using heterogeneous Fenton systems.

ADH and PDC genes involved in tannins coagulation leading to natural de-astringency in Chinese pollination constant and non-astringency persimmon (Diospyros kaki Thunb.)

Pollination constant non-astringency (PCNA)-type persimmons are the most desirable cultivar because the fruit loses astringency naturally and does not require any treatments for edibility. The mechanism of natural astringency loss in Chinese PCNA (C-PCNA)-type persimmon is probably related to the coagulation of soluble tannins into insoluble tannins, which is quite different from that in the Japanese PCNA (J-PCNA) type. In this work, three types of persimmon cultivars were sampled: ‘Luotian-tianshi’ (C-PCNA), ‘Maekawa-jirou’ (J-PCNA), and ‘Mopanshi’ (pollination constant astringent (PCA)) were sampled. Three DkADH and four DkPDC genes were isolated from C-PCNA plants. Three candidate genes for soluble tannins coagulation identified in C-PCNA fruit (DkADH1, DkPDC1, and DkPDC2) were characterized through combined analysis of spatiotemporal expression patterns and tannin and acetaldehyde contents during fruit development. Transient over-expression in persimmon leaves showed that DkADH1 and DkPDC2 led to a significant decrease in the levels of soluble tannins in infiltrated leaves. These results indicated that DkADH and DkPDC genes should be considered key genes for natural astringency loss in C-PCNA types.

Antioxidant and anti-adipogenic activities of persimmon tannins

Soluble and insoluble tannins from 5 different types of persimmon-unripe, astringent Cheongdobansi (CU); red-ripe Cheongdobansi (CR); unripe, astringent Daebong (DU); red-ripe Daebong (DR); and unripe, non-astringent Fuyu (FU)-were prepared. The antioxidant activity of the tannins was determined by measuring the DPPH radical scavenging activity (RSA), ABTS RSA, and reducing power. The strongest DPPH RSA and reducing power were found in the soluble tannins from CU. Soluble tannins from CR, CU, and DU at a concentration of 1,000 μg/mL scavenged most of the ABTS radicals. Approximately 83 and 42% suppression of adipogenesis in 3T3-L1 cells were observed in the 100 μg/mL treatments of the soluble tannins from CU and CR, respectively. Soluble tannins showed relatively higher antioxidant and anti-adipogenic activities than insoluble tannins. These results demonstrate that soluble and insoluble persimmon tannins showed different antioxidant and anti-adipogenic activities according to persimmon types.