Changes In Polyphenol Content Research Articles

Bacterial and Fungal Communities in Pu'er Tea Samples of Different Ages

Pu'er is a major kind of postfermented tea and is made with a "large leaf" variety of Camellia sinensis (C. sinensis assamica), whose distribution is limited to the mountains of southern Yunnan, China. The quality of Pu'er tea is believed to increase with storage (aging, maturing) because of postfermentation by microbes. The effect of storage period (from < 1 to 192mo) on the bacteria and fungi in Pu'er tea was investigated by a culture-dependent and a PCR-DGGE method. The individual numbers of fungi and bacteria decreased with increasing storage time and were significantly greater in ripened tea than in raw Pu'er tea. Both methods indicated that yeast, Aspergillus spp., and Penicillium spp. were the dominant fungi in almost all the samples. However, the common bacteria detected by the culture-dependent method were species of Pseudomonas, Achromobacter, Alcaligenes, Sporosarcina, and Bacillus, whereas those detected by PCR-DGGE were species of Staphylococcus, Arthrobacter, and Streptomyces. According to ordination analysis, bacterial community structure differed between ripened and raw Pu'er tea. Bacterial diversity was positively correlated with aging time, while fungal diversity in both raw and ripened tea increased during the first 60 mo of aging and then decreased. Changes in polyphenol content were correlated with the changes in fungal diversity. These results suggest that the relationship between storage time and the quality of Pu'er tea is complex and involves changes in polyphenol content and microbial abundance and diversity.

Changes in polyphenol content during production of grape juice concentrate

The production of grape juice concentrate on an industrial scale was evaluated and samples from the main steps of processing have been collected and analyzed. The sampling steps included the selection and washing of grapes (Nevsehir Patlak variety), pressing in order to obtain the juice separate from the seed and the skin fraction, pasteurization, clarification, filtration, evaporation, and filling-packing at 27°C with a Brix of 45°. Samples from each of the processing steps were analyzed by a number of spectrophotometric analyses. A series of anthocyanin compounds was identified using HPLC-MS, and the fate of anthocyanins, quercetin rutinoside and procyanidins was followed using HPLC. The results indicate that the removal of seed and fruit skin removes most of the procyanidins and anthocyanins, while subsequent clarification and filtration treatments further reduce the anthocyanin content.

Changes in polyphenolic content and antioxidant activity after thermal treatments of grape seed extract and grape pomace

This study was undertaken to investigate the effect of heat treatment on polyphenolic content and antioxidant activity in grape pomace (GP) and grape seed extract (GSE). GP and GSE were heat treated in a furnace or autoclaved at 100 °C for 15, 30 and 60 min. Structural modifications of the polyphenols during thermal processes were determined by HPLC–MS, and the antioxidant activity was determined by ABTS, DPPH and photochemiluminescence methods. In general, furnace thermal treatment of GSE and GP did not affect the total extractable polyphenols content, tannin content, procyanidin components and the antioxidant activity. Autoclave treatment caused an extensive hydrolysis of gallocatechin (70%), catechin (61%), epicatechin (65%), procyanidin B1 (75%) and procyanidin B2 (73%) in GSE, and an increase in gallic acid (71%), gallocatechin (100%) and epicatechin gallate (129%) in GP. Autoclave treatment did not affect the antioxidant activity of GSE or GP. It can be concluded that the effect of autoclave was more severe than furnace heat treatment modifying the phenolic profile in a different manner depending on the grape seed product used. These modifications were not related with changes in antioxidant activity.

Stability of Varietal Thiols in Commercial Sauvignon blanc Wines

The intense passion fruit-type aroma of New Zealand Sauvignon blanc wines, attributed to high concentrations of the varietal thiols 3-mercaptohexan-1-ol (3-MH) and 3-mercaptohexan-1-ol acetate (3-MHA), is known to diminish rapidly over just one year in the bottle. It is thus important to understand the processes by which the aroma compounds are lost during storage to improve the shelf life of these wines. The loss of varietal thiols has been linked to polyphenol oxidation, catalyzed by metals, a process that can be inhibited by antioxidants such as sulfur dioxide (SO2), ascorbic acid, and glutathione. The evolution of 3-MH and 3-MHA was monitored in commercially bottled New Zealand Sauvignon blanc wines, stored in the dark at 15°C for 7 months, together with changes in polyphenol content and small molecule antioxidants. The acetate ester 3-MHA was the least stable of the varietal thiols and declined steadily in concentration following first-order kinetic decay, whereas 3-MH barely decreased over the first 3 months of bottle storage, and was instead followed by an increase in concentration after a further 4 months. These results pointed to hydrolysis of 3-MHA to 3-MH as the major loss mechanism in the commercial wines during the initial months of storage. Concomitantly, the flavan-3-ols exhibited a greater susceptibility to oxidation and polymerization reactions compared with the more stable hydroxycinnamic acids. Glutathione concentrations also declined steadily over the first year and would thus only provide protection against oxidative thiol losses up to that point. Free SO2 remained relatively stable in the commercially bottled Sauvignon blanc wines after an initial drop in concentration associated with oxygen entry at bottling.

Anatomical observation of polyphenol changes in epidermal cells during the development of Quercus acutissima–Scleroderma verrucosum ectomycorrhizae

Quercus acutissima seedlings were cultivated in growth pouches and inoculated with Scleroderma verrucosum in order to assess the changes in polyphenol contents in epidermal cells during ECM development. Semithin sections stained with metachromatic Toluidine Blue O (TBO) were compared among non-inoculated lateral roots, early mantled lateral roots, and mycorrhizal roots with a mature mantle. Hyphae adhered closely or were embedded in mucilage-like materials on the epidermis. Epidermal cells and root hairs of the non-inoculated second-order lateral roots developing from the taproot harbored polyphenolic compounds that were stained by TBO. At non-inoculated stage, the average numbers of epidermal cells stained entirely (PC2), stained partially (PC1) or remaining unstained (PC0) were 16.5 ± 0.7, 0 ± 0, and 0 ± 0, respectively. At the early mantled stage, the numbers were 6.5 ± 1.6, 5.2 ± 1.4, and 4.2 ± 1.0, and at the mycorrhizal stage, it was 0 ± 0, 0 ± 0, and 32.8 ± 1.3 for PC2, PC1, and PC0, respectively. Total phenolic content in the root tips at each developmental stage declined with ECM development. The early mantled stage involved a dynamic process of polyphenol localization. However, some epidermal cells and endodermal cells of the proximal zone accumulated polyphenols. Eventually, polyphenolic compounds, which were found abundantly in the epidermal cells and root hairs of the non-inoculated lateral roots of the host, disappeared at the mycorrhization process with the symbiont.

Effect of principal polyphenolic components in relation to antioxidant activity in conventional and organic red wines during storage

Wine phenolic composition depends on the grapes used to make the wine and on the vinification conditions and a wide range of variables such as cultivar, viticulture practices and vinification techniques can affect the phenolic composition of red wines. Changes in polyphenol content and antioxidant activity during storage over 6 months in bottles were studied in Monastrell varietal red wines from grapes obtained by organic and conventional agricultural practices. Also it was studied the relationship between antioxidant activity and phenolic compounds. The results showed that the contents of anthocyanins decreased during storage although hydroxycinnamics derivatives, stilbenes and flavonols do not suffer significative changes. The total antioxidant activity of conventional and organic wines was well correlated especially with anthocyanins at first month of storage and flavonols all time. Stilbenes had a high correlation with antioxidant activity in both types of wine especially in the last month of storage (r 2 = 0.74), and hydroxycinnamic derivatives had a poor correlation with antioxidant activity. Evolution of phenolics compounds and antioxidant activity in conventional and organic wines were similar during storage. Not significant differences were observed in conventional and organic wines.

Evaluation of Saskatoon Berry (Amelanchier alnifolia Nutt.) Cultivars for their Polyphenol Content, Antioxidant Properties, and Storage Stability

The polyphenol contents and antioxidant activities were assessed for 17 Saskatoon berry cultivars grown in Canada in fresh and stored fruits at -20 degrees C for 9 months. The Nelson cultivar was the richest in total polyphenol, anthocyanin, and procyanidin contents (801, 382, and 278 mg/100 g fresh weight, respectively). This cultivar was characterized also by the highest antioxidant potential measured with DPPH and ABTS radicals (2.8 and 5.0 mM/100 g FW, respectively). Cultivar-dependent changes in polyphenol content after freezer storage were observed. In the Lee 2 cultivar, significant increases in anthocyanin and flavonol contents occurred, while in the Lee 3 and Martin cultivars considerable decreases were observed. During the freezer storage, the antioxidant activity remained unchanged except for the Smokey which showed to be the most sensitive cultivar during storage. The Nelson and Lee 2 were the most stable cultivars during storage. The high polyphenol content and antioxidant activity of the Nelson cultivar and its good storage stability would make this cultivar the optimal material for fruit growers and food producers.

Changes in Polyphenolic Content and Radical-Scavenging Activity of Sweetpotato (Ipomoea batatasL.) during Storage at Optimal and Low Temperatures

Polyphenolic content and radical-scavenging activities (RSA) of four sweet potato (Ipomoea batatas L.) cultivars were characterized after storage at optimal (15 degrees C) or low temperature (5 degrees C) for 0, 13, 26, and 37 days. The polyphenolic content increased during storage in three cultivars but not in 'Murasakimasari'. The change in 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity (DPPH-RSA) correlated very well with polyphenolic content. The increases in polyphenolics and the RSA in 'Benimasari' were significantly greater during storage at 5 degrees C than at 15 degrees C. The main polyphenolic components in all cultivars were chlorogenic acid (ChA) and 3,5-di-O-caffeoylquinic acid (3,5-diCQA). ChA level increased more at 5 degrees C than at 15 degrees C, whereas that of 3,5-diCQA was greater at 15 degrees C. Caffeoylquinic acids and RSA in 'Murasakimasari', which contains a large amount of anthocyanin in flesh tissue, were extremely high at the beginning of storage and remained nearly constant or decreased over time. A non-caffeoylquinic acid component that increased during storage, especially in 'J-Red' at 15 degrees C, was purified by successive chromatographic steps. The isolate was identified as caffeoyl sucrose [CSu, 6-O-caffeoyl-(beta- d-fructofuranosyl-(2-->1))-alpha-D-glucopyranoside] by fast atom bombardment-mass spectroscopy (FAB-MS), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). These results suggest that storage under cultivar-dependent, controlled temperature is one approach for increasing desirable physiologic function associated with RSA of polyphenolic compounds in sweet potato roots.

Ripening Associated Phytochemical Changes in Mangos (Mangifera indica) Following Thermal Quarantine and Low‐Temperature Storage

ABSTRACT: Fresh mangos entering the United States must be subjected to a thermal quarantine treatment to eliminate invasive pests, commonly followed by cold storage to extend shelf‐life. Changes in phytochemicals and their resultant antioxidant capacity after such treatments are unknown. These studies evaluated mature, green mangos subjected to a simulated quarantine treatment using hot water immersion at 50°C for 60 min and subsequent storage at 5°C and 20°C against their respective controls. Fruit held at 5°C were transferred to 20°C after 8 d of storage to complete ripening, whereby symptoms of chill injury were observed. Phytochemical, antioxidant capacity, and quality parameters were then assessed every 4 d as the fruit ripened over the next 20 d. Storage temperature during ripening and not the hot water treatment was the major factor contributing to changes in polyphenolic content, with antioxidant capacity unaffected by either postharvest treatments or ripening. Major polyphenolics identified were free gallic acid and 4 gallotannins that collectively increased in concentration by 34% as the fruit ripened, also independent of postharvest and storage treatments. Carotenoid concentrations were highest in hot water‐treated fruit stored at 20°C, whereas storage at 5°C initially delayed ripening. Despite appreciable differences in fruit quality during quarantine treatment or low temperature storage, only minor differences in antioxidant phytochemicals were observed.

Changes in Polyphenol Content and Coloration of Apple Fruits over Time

The object of this study was to clarify the effect of experimental hydroponics (water culture : WC) on browning reaction of apple fruits. The changes in total polyphenol (TPP) content and coloration over time after crushing of apple fruits were investigated. The polyphenoloxidase (PPO) activity and property were analysed also. In this study, ripe conventional soil cultured fruits (SCF) and water cultured fruits (WCF) of two cultivars (Fuji and Hokuto) were used. The results were as follows. 1) Regardless of the cultivar, the absorbance of 450nm (OD45o) in SCF increased rapidly as time elapsed, but that in WCF increased to half degree of SCF until 60 minutes elapsed gradually. Especially, the OD45o in WCF of Hokuto was inhibited significantly. 2) The reflectance in SCF and WCF (Fuji and Hokuto) showed a similar tendency at OD450, which was measured with a spectro color meter. 3) Before browning reaction, there was no difference in the TPP content between WCF and SCF in Fuji. But in Hokuto, the TPP content in WCF was larger than that in SCF. Regardless of the cultivar, the TPP content in SCF decreased over time, especially quickly in the early stage. However the TPP content in WCF decreased slightly. 4) The decrease in the content of TPP due to browning showed a good negative correlation with the degree of enzymatic browning. After all, the TPP content was closely related to the browning degree. 5) The PPO activity was significantly lower in WCF than that in SCF. Isozyme patterns of PPO showed no difference between WCF and SCF. In conclusion, the low browning degree of WCF resulted from the revelation of PPO activity that was inhibited by WC. The browning degree was not affected by the PPO property.

セイヨウナシ果実の発育中および追熟中におけるポリフェノール含量の品種間差異と台木の影響

Changes in polyphenol content during fruit growth and ripening of pear cultivars on different rootstocks were investigated to clarify the possible cause of astringency in 'Le lectier' pears, as compared to the non-astringent 'Marguerite Marillat' and la France'.1. Polyphenol content on fresh weight basis was highest in the fruitlets at the end of May and then decreased until harvest in all cultivars tested in 1993. However, polyphenol content at harvest in 'Le Lectier' pears, which sometimes produce some astringent fruit, was two to four times higher than those of non-astringent 'Marguerite Marillat' and 'La France'.2. Polyphenol content on a fruit basis in 'Marguerite Marillat' and 'La France' showed little change throughout the fruit growth period, while it increased until harvest in 'Le Lectier'.3. Fruit produced on Old Home/Quince A interstock/rootstock had higher polyphenol content during fruit growth than those on Pyrus betulaefolia in both 1993 and 1994.4. Effect of rootstock on ethylene evolution during ripening period after harvest was not consistent in 'La France' and 'Le Lectier' pears.5. During fruit ripening after harvest, polyphenol content remained at an amount similar to that found at harvest in all cultivars.6. In 1994, fruit from potted trees on Pyrus betulaefolia had higher polyphenol content than those from field-grown trees on the same rootstock in 'La France' and 'Le Lecrier' pears, resulting in a higher degree of astringency in pot-grown 'Le Lectier' pears.

Relationship between Apple Ripening and Browning: Changes in Polyphenol Content and Polyphenol Oxidase

Changes in the browning of apple juice, polyphenol content, and polyphenol oxidase were examined during apple ripening. The degree of browning of apple juice, the phenol content per gram of flesh, and the polyphenol oxidase (PPO) activity per milligram of protein decreased during ripening. From 4.5 to 6 months after flowering, the amount of PPO per milligram of protein, determined by an enzyme-linked immunosorbent assay, was constant, but its specific activity decreased, suggesting that PPO had denatured. PPO was uniformly distributed in the immature and mature apple, but active PPO was mainly localized around the core in the mature apple.

Flavonoid and Non-Flavonoid Compounds During Fermentation and Post-Fermentation Standing of Musts from Cabernet Sauvignon and Tempranillo Grapes

Changes in polyphenol contents during fermentation and post-fermentation standing of musts from Cabernet Sauvignon and Tempranillo grapes were studied. Flavonoid contents were found to increase during alcoholic fermentation of Cabernet Sauvignon musts and decrease during subsequent post-fermentation standing. On the other hand, flavonoid contents in musts from Tempranillo grapes started to decrease markedly after removal of grape skins and even more sharply at the end of malolactic fermentation (96 days). The contents in non-flavonoid compounds increased more gradually along the studied period, except at the end in musts from Tempranillo grapes, from which they virtually disappeared. As a result of the decreased contents of non-anthocyanins compounds in the wines of Tempranillo variety and higher contents in anthocyanins, the flavonoid/ anthocyanin and non-flavonoid/anthocyanin ratios were higher for the Cabernet Sauvignon variety, even though this exhibited a more marked trend in forming polymeric pigment.

Changes in Polyphenol Content of Olives Stored in Modified Atmospheres

Changes in Polyphenol Content of Olives Stored in Modified Atmospheres