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Total Phenols (total + phenol)

Distribution by Scientific Domains

Chemistry	96%

Terms modified by Total Phenols

total phenol content

Selected Abstracts

Flavonoids in Onion Cultivars (Allium cepa L.)

JOURNAL OF FOOD SCIENCE, Issue 8 2008
B. Rodríguez Galdón
ABSTRACT:, Total phenol and flavonoid contents were analyzed by HPLC coupled with a diode array detector in 5 traditional onion cultivars from Tenerife (Guayonje, San Juan de la Rambla, Carrizal Alto, Carrizal Bajo, and Masca) and a commercial cultivar (Texas Early Grano 502). Five quercetin chemical species (isoquercetin, quercetin diglucoside, quercetin monoglucoside 1, quercetin monoglucoside 2, and free quercetin) and kaempferol were identified and quantified in the onion samples. Quercetin monoglucoside 1 and quercetin diglucoside were the major flavonoids accounting for 80% of the total quercetin content. The mean quercetin monoglucoside 1: quercetin diglucoside ratio (QMG/QDG) was 1: 2.2. There were differences between the onion cultivars in the cases of total phenol, quercetin diglucoside, isoquercetin, QMG/QDG ratio, and kaempferol. The Texas cultivar had a higher QMG/QDG ratio and a higher kaempferol content than the traditional cultivars. The correlation study showed significant correlations between the analyzed phenolic components. [source]

Physicochemical properties, total phenol and tocopherol of some Acacia seed oils

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2008
Olumuyiwa S Falade
Abstract BACKGROUND: Recently, there has been an increase in the number of investigations into the possible use of vegetable oils as a source of oleochemicals to supplement petrochemicals. We have therefore determined the physicochemical properties of Acacia oils and compared them with groundnut oil as a first step toward their possible industrial utilization. RESULTS: The chemical properties of Acacia oils compared well and surpassed those of groundnut oil in iodine value (1549.3, 1783.3 and 1093.1 g iodine kg,1 oil for A. colei, A. tumida and groundnut oils, respectively), saponification value (201.74, 202.15 and 198.01 g KOH kg,1 oil for A. colei, A. tumida and groundnut oils, respectively). Total phenol and tocopherol content of Acacia oils were also higher compared with groundnut oil. Refractive index, specific gravity and viscosity were higher in Acacia seed oils than in groundnut oil but the smoke point of Acacia oil was lower than that of groundnut oil. Acacia oils were higher in some essential elements (Mg, Ca, Fe, Zn and Cu) when compare with groundnut oil. CONCLUSION: The properties of Acacia oils revealed that they could be useful as drying oils, in soap making and as lubricants at low temperatures. They could also be dietary sources of natural antioxidants and essential elements. Copyright © 2007 Society of Chemical Industry [source]

Biochemical changes in cut vs. intact lamb's lettuce (Valerianella olitoria) leaves during storage

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2009
Antonio Ferrante
Summary Consumers are oriented towards fresh-cut vegetables that provide phytonutrients useful for preventing stress-related diseases. The aim of this work was to evaluate the cut operations on the quality changes of lamb's lettuce (Valerianella olitoria L.) cv. Trofy during storage at 4 °C for 8 days. Results showed that chlorophyll and carotenoids reduction was observed after 8 days of storage. In both treatments, total carotenoids after 8 days decreased from 20 to 16 mg g,1 FW. Free and total phenols increased with storage in both treatments. Total phenols were 23% higher in control (32 ,mol g,1 FW) compared to cut leaves (25 ,mol g,1 FW) after 8 days of storage. Anthocyanins increased after 8 days and reached 30 mg 100 g,1 FW without significant difference between treatments. Ascorbic acid (AsA) and dehydroascorbic (DHA) acid increased in cut leaves compared to control. After 1 day AsA concentration was 3 300 nmol g,1 FW in cut leaves, while in control leaves was 1 500 nmol g,1 FW. Analogously AsA + DHA was higher in cut leaves, 4 100 nmol g,1 FW, while in control leaves the mean was 3 000 nmol g,1 FW. After 5 days of storage the values of AsA returned to initial values, while AsA + DHA were lower. [source]

Different postharvest dehydration rates affect quality characteristics and volatile compounds of Malvasia, Trebbiano and Sangiovese grapes for wine production

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004
Andrea Bellincontro
Abstract Experiments were carried out using an innovative technology for dehydration based on the passage of air through a tunnel. It was possible to study the postharvest behaviour, at different rates of dehydration, of Malvasia, Trebbiano and Sangiovese grapes. Malvasia and Trebbiano grapes were picked with 17.5% SSC (soluble solids content), while Sangiovese grapes were harvested fully ripe with 26% SSC. All the grapes, in different experiments, were placed in the tunnel with an air speed of 1,1.5 m s,1, 42% RH (relative humidity) and a temperature of 21 °C. After 18 days the weight loss was 50 and 34% respectively in tunnel-treated Malvasia and Trebbiano grapes, while it was only 13,14% in control grapes (outside the tunnel: RH around 65% and temperature about 20 °C without ventilation). The SSC rose to 35 and 27% respectively in tunnel-treated Malvasia and Trebbiano grapes compared with 23 and 21% respectively in control grapes. In the case of Sangiovese grapes, after 7 days (the end of treatment) the weight loss was 20.5% in tunnel-treated grapes and 10.5% in control grapes. The SSC rose to 32% and the acidity increased from 4.8 to 5.8 g l,1 in tunnel-treated grapes compared with 29% and 5 g l,1 respectively in control grapes. Total phenols and anthocyanins almost doubled in tunnel-treated Sangiovese berries. Volatile compound analysis revealed a higher ethanol concentration in all tunnel-treated grapes but a lower concentration of ethyl acetate and acetic acid. Copyright © 2004 Society of Chemical Industry [source]

Changes on Enological Parameters of White Wine Packaged in Bag-in-Box during Secondary Shelf Life

JOURNAL OF FOOD SCIENCE, Issue 8 2009
Y. Fu
ABSTRACT:, This study investigated the effects of temperature (22, 35, and 45 °C), storage time (48, 30, and 15 d), and packaging type on the quality of white wine in bag-in-box (BIB) during the secondary shelf life. Several enological parameters (color and contents of free and total SO2, total aldehyde, and total phenol) were monitored and correlated with oxygen transmission rate (OTR) and Fourier transform infrared (FTIR) spectral data. Time and temperature had significant effects on color development and SO2 depletion during storage. The increased absorbance at 420 nm was correlated with decreases of free SO2 and total SO2. Overall, total phenol content correlated negatively with total aldehyde content. The variance of the enological parameters can be correlated with the OTR data, indicating the barrier properties for the tested packages were different. FTIR,ATR spectra of the wine were analyzed chemometrically using PLS algorithm. The resulting models were able to predict the,A420, free SO2, total SO2, total phenol, total aldehyde, and storage time of the wines. This technique can potentially be used as an efficient tool to evaluate the quality of wine. [source]

Flavonoids in Onion Cultivars (Allium cepa L.)

Antioxidant properties of polar and non-polar extracts of some tropical green leafy vegetables

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2008
Ganiyu Oboh
Abstract BACKGROUND: The higher consumption of vegetables and fruits could be a practical approach to the management of oxidative stress. The present study sought to compare the antioxidant properties of polar and non-polar constituents of some tropical green leafy vegetables (Struchium sparganophora, Amaranthus cruentus, Telfairia occidentalis, Ocimum gratissimum, Talinium triangulare, Cnidoscolous aconitifolius and Vernonia amygdalina). RESULTS: The polar antioxidant constituents (total phenol (3330,17 572 mg kg,1), total flavonoid (1668,4306 mg kg,1) and vitamin C (224,642 mg kg,1)) were higher than the non-polar antioxidant constituents (total phenol (703,3115 mg kg,1), total flavonoid (130,1303 mg kg,1) and carotenoids (132,1303 mg kg,1)). Furthermore, the polar extracts had a significantly higher (P < 0.05) 1,1-diphenyl-2-picrylhydrazyl radical scavenging ability (except T. triangulare), total antioxidant capacity, reducing power (except T. triangulare and A. cruentus) and Fe(II) chelating ability (except C. aconitifolius and S. sparganophora). However, the polar and non-polar extract of O. gratissimum had the highest antioxidant properties while that of T. triangulare had the least antioxidant properties. CONCLUSION: The polar extract of most of the vegetables had higher antioxidant properties than the non-polar extract, with O. gratissimum extracts having the highest antioxidant properties. Copyright © 2008 Society of Chemical Industry [source]

Physicochemical properties, total phenol and tocopherol of some Acacia seed oils

The ripening and aging of noni fruits (Morinda citrifolia L.): microbiological flora and antioxidant compounds

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2007
Yanine Chan-Blanco
Abstract The juice of noni fruit (Morinda citrifolia L.) is claimed to be a natural functional beverage with a growing market both in the USA and Europe. It is traditionally produced by keeping harvested fruit in closed containers for several weeks as the fruit senesces or ages. Little is known about the changes that occur in the juice's microbiological, physicochemical, and functional characteristics during this treatment. Traditional processing was simulated in the laboratory, with samples being recovered and analyzed at various time intervals. At first, fermentation occurred and populations of molds, yeasts, and mesophilic bacteria increased significantly. After 2 weeks, microbial growth changed abruptly, stopping for yeasts, molds, and mesophilic bacteria, and decreasing suddenly for lactic bacteria. Analyses of pH, soluble solids, ethanol, and lactic acid in the fruits confirmed the microbial analyses, indicating initial sensitive variations, followed by values remaining comparatively steady during aging. Vitamin C and total phenol contents also remained constant at 300 ± 60 mg and 50 ± 20 mg GAE, respectively, per 100 g of pulp. Antioxidant capacity likewise remained relatively high at 8 ± 1.5 µmol Trolox® g,1. All phenolic compounds, including scopoletin and rutin, varied significantly immediately after harvest but remained more or less steady during aging. Copyright © 2007 Society of Chemical Industry [source]

Extraction of phenolic compounds during vinification of Pinot Noir wine examined by HPLC and cyclic voltammetry

AUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 3 2002
HONGLEI ZOU
Abstract The phenolic profiles of four Pinot Noir fermenting musts were examined over a period of 18 days prior to barrel storage, using HPLC levels of individual polyphenols, the Folin-Ciocalteu assay and absorbance at 280 nm for total phenols, and the cyclic voltammetry response of the musts, diluted in a pH 3.6 model wine solution, for their activity as reducing agents. These methods showed the early extraction of various hydroxycinammates from the grape, followed by skin anthocyanins and flavonol glycosides, and high levels of flavan-3-ols from the seeds towards the end of the fermentation. The appearance of the individual phenolics was matched by cyclic voltammetry peaks at electrode potentials expected for each compound. Cyclic voltammetry also produced a semi-quantitative measure of the level of galloyl and catechol groups present, which correlated well with other total phenol measures. [source]

Factors affecting biodegradation of 2-chlorophenol by Alcaligenes sp. in aerobic reactors

ENVIRONMENTAL TOXICOLOGY, Issue 4 2001
A. Gallego
Abstract The influence of variations in carbon source concentration, cell inocula, pH, presence of other substrates, and other organisms on the biodegradation of 2-chlorophenol (2-CP) was studied for Alcaligenes sp. isolated from natural sources. Assays of biodegradation were performed in batch and continuous-flow fluidized-bed aerobic reactors. Evaluation of biodegradation was performed by determining total phenols, chemical oxygen demand (COD), and 2-CP by ultraviolet (UV) spectrophotometry. Measurement of microbial growth was carried out by the plate count method. Bioassays of acute toxicity were performed to evaluate detoxification by using Daphnia magna. Results obtained show that under batch conditions with initial inocula of 106 cells/mL the strain grew exponentially with 100, 200, and 300 mg/L of 2-CP within 48 hr. A lag period was observed with low cell density inocula (105 cells/mL). The strain showed marked delay in the biodegradation of 2-CP at pH 5. Removal of target substrate from mixtures containing other carbon sources demonstrated the possibility of concurrent growth. Mineralization of 2-CP was assessed by gas chromatography carried out at the end of the batch assays and at the exit of the continuous-flow reactor. The presence of other organisms (bacteria, rotifers, ciliate, and algae) that developed in the fluidized-bed reactor did not affect the efficacy of the biodegradation of 2-CP. The removal of 2-CP in the two assayed systems was over 97% in all cases. Toxicity was not detected at the exit of the continuous reactor. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 306,313, 2001 [source]

Effect of convective solar drying on colour, total phenols and radical scavenging activity of olive leaves (Olea europaea L.)

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 12 2009
Neila Bahloul
Summary In this study, olive leaves, which are known for their therapeutic and antioxidant properties, were used to assess the effect of solar drying conditions (temperature and flow rate) on the drying time and quality parameters of olive leaves. Samples were dried at three drying temperatures (40, 50 and 60 °C) and at two drying air flow rates (1.62 and 3.3 m3 min,1) in a convective laboratory solar dryer. From the experimental results, it was noted that the drying time required to reduce the moisture content to 0.10 kg kg,1 d.b. depends mainly on the drying temperature. The quality attributes of the dehydrated olive leaf samples were investigated in term of colour, total phenols and radical scavenging activity. The effect of solar drying on L*, a* b* parameters was significant (P < 0.05) for all the studied olive leaves. Besides, the total phenols of olive leaves were significantly (P < 0.05) influenced by drying air conditions and tended to decrease with increased drying time. The DPPH radical scavenging activity was higher in fresh [EC50 39.40 (ZR)-39.95 (CH)] than in dried leaves. However, the radical scavenging activity was also high in leaves dried at 60 °C, 3.3 m3 min,1 [EC50 54.21 (ZR),68.79 (CL)]. [source]

Biochemical changes in cut vs. intact lamb's lettuce (Valerianella olitoria) leaves during storage

Comparative study on composition and antioxidant properties of mint and black tea extract

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 10 2008
Ekambaram Padmini
Summary The antioxidant properties of plants could be correlated with oxidative stress defence in different human diseases. The present study was undertaken to evaluate and compare the antioxidant potential and the phytochemical composition in the aqueous extracts of mint leaves, black tea and black tea enriched with mint extract. All the three preparations exhibited free radical-scavenging potential for nitric oxide (NO) radical, superoxide anion radical and hydroxyl radical, and the values were lesser than those of the antioxidants which acted as standards. In comparison, the mint extract exhibited higher free radical and NO scavenging effect. Hydroxyl radical and superoxide scavenging effects were more pronounced in tea with the mint extract, while the reducing power was exhibited more significantly by the black tea extract. The phytochemical compounds were identified and the total phenols and flavonoids were quantified and compared between these extracts. [source]

Antioxidant activities of organic grape, pomace, juice, must, wine and their correlation with phenolic content

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2005
Hatice K. Y
Summary The highest values of antioxidant activity (AOA), inhibition of low-density lipoproteins (LDL-diene, LDL-MDA) and total phenols were determined in pomace (82.30 and 82.60%), grapes (68.91%) and must [2750 mg L,1 gallic acid equivalents (GAE)], respectively. For all parameters (AOA, iLDL-diene, iLDL-MDA, total phenols) the highest values were obtained in Cabernet Sauvignon and Merlot grape varieties. Positive correlations were determined between AOA and iLDL-diene (r = 0.809); AOA and total phenols (r = 0.528); total phenols and iLDL-diene (r = 0.451) with significance of P < 0.005. The results of principal component analysis demonstrated that the location of iLDL-diene and AOA is the same for pomace, must and red wines. The total phenols are found in the same place in red wines, red grapes, pomace and must. The results emphasize the importance of must, pomace and red wine for inhibiting LDL-oxidation. [source]

Ascorbic acid improves the antioxidant activity of European grape juices by improving the juices' ability to inhibit lipid peroxidation of human LDL in vitro

INTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2001
Anne-Katrine Landbo
Antioxidant activities of red and white European grape juices towards copper induced lipid oxidation of human low-density lipoproteins (LDL) were examined in vitro. LDL lipid peroxidation was assessed spectrophotometrically by monitoring the development of conjugated lipid hydroperoxides at 234 nm. Red grape juice concentrate inhibited lipid peroxidation of LDL by prolonging the lag phase by 2.7 times relative to a control when evaluated at a total phenolic concentration of 10 ,M gallic acid equivalents (GAE). Both red grape juices tested blocked lipid peroxidation of LDL at 20 ,M GAE. White grape juice exerted prooxidant activity at 5,20 ,M GAE. The antioxidant activity, inhibition of lipid peroxidation of LDL in vitro, was correlated with the juices' levels of total phenols (r > 0.98, P < 0.01), anthocyanins (r > 0.99, P < 0.01), flavan-3-ols (r > 0.97, P < 0.05), and hydroxybenzoates (r > 0.96, P < 0.05) when the phenolic composition of each grape juices was analysed by HPLC. 5 ,M ascorbic acid alone did not exert antioxidant activity towards LDL, but combinations of 5 ,M ascorbic acid with 5 ,M GAE juice phenols eliminated the prooxidant activity of white grape juice, and significantly improved the antioxidant activities of red grape juices. [source]

PHENOLIC COMPOUND CONTENT, ANTIOXIDANT AND RADICAL-SCAVENGING PROPERTIES OF METHANOLIC EXTRACTS FROM THE SEED COAT OF CERTAIN THAI TAMARIND CULTIVARS

JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2010
MANEEWAN SUKSOMTIP
Methanolic extracts from the seed coats of five major tamarinds (Srichomphu, Sithong-nak, Sithong-bao, Priao-yak and Khanti) cultivated in Thailand were investigated for their content of phenolic compounds and their antioxidative properties. Antioxidative properties were evaluated by various different methods: scavenging effect on the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and hydroxyl radical, anti-lipid peroxidation and reducing power assay. The phenolic compound contents were determined by spectrophotometric methods. Extract of Priao-yak with the highest tannin content showed the strongest reducing power, while extract of Khanti with the highest proanthocyanidin content revealed high scavenging ability on both DPPH and hydroxyl radicals. Stronger antioxidative activity measured by most assays was noted for the extract of Sithong-bao with a high content of total phenols, proanthocyanidin and tannins. The results suggest that specific phenolic constituents in the extract could be responsible for the different antioxidant properties observed in different cultivars. Furthermore, seed coat extract of Sithong-bao may be a potential source of natural antioxidant to be developed into nutraceuticals. PRACTICAL APPLICATIONS Components of Tamarindus indica L., a tree indigenous to India and South-East Asia, have long been used as a spice, food component and traditional medicine. According To traditional medicine, the tamarind pulp is used as a digestive, carminative, laxative, expectorant and blood tonic; the seeds are used as an anthelmintic, antidiarrheal and emetic. In addition, the seed coat is used to treat burns and aid wound healing as well as as an antidysenteric. Recent studies have demonstrated polyphenolic constituents with more potent antioxidant and anti-inflammatory activities of T. indica seed coat extract. Therefore, seed coat extracts of T. indica have economic potential for development into health promotion products as well as natural preservatives to increase the shelf life of food by preventing lipid peroxidation. [source]

ANTIOXIDANT PROPERTIES OF WATER EXTRACTS FROM PARCHING GREEN TEA

JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2010
SHENG-DUN LIN
ABSTRACT Cold and hot water extracts (2, 6 and 10%) were prepared from parching green tea and its antioxidant properties studied and potential antioxidant components determined. Yields of hot water extracts (17.53,28.63%) were significantly higher than those of cold water extracts (13.34,16.14%). The half maximal effective concentration (EC50) values in antioxidant activity and reducing power were 2.17,2.75 and 0.22,0.30 mg/mL, respectively. Scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl radicals were comparable. EC50 values in scavenging ability on hydroxyl radicals and chelating ability on ferrous ions were 3.31,4.54 and 1.63,3.09 mg/mL, respectively. Contents of total phenols were 220.52,339.83 mg/g whereas those of total catechins in cold and hot water extracts were 130.22,146.28 mg/g and 136.40,191.33 mg/g, respectively. Based on the results obtained, hot water extracts were more effective in antioxidant activity, reducing power and scavenging ability on hydroxyl radicals but less effective in chelating ability on ferrous ions. PRACTICAL APPLICATIONS Tea is one of popular drinks in the world. The consumption of green tea is especially popular in Asia, mainly for its health benefits. Parched tea is a Chinese style green tea, which is different from the Japanese style steamed tea. Recently, the tea prepared by brewing tea leaves in cold water has become a new choice in Taiwan in addition to traditionally hot water-brewed tea. Results from this research, the cold and hot water extracts of green tea are good antioxidant. Besides, green tea is also reported to reduce serum cholesterol levels and inhibit hypertension, mutagenesis, and tumourigenesis in several experiments in vitro and in vivo. Therefore, the extract of green tea has the potential to be developed into new health foods, and the cold brewing would be a new alternative way to make a tea. [source]

LOCATION EFFECTS ON OXIDATIVE STABILITY OF CHÉTOUI VIRGIN OLIVE OIL

JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2006
SONIA BEN TEMIME
ABSTRACT The effect of growing area on the natural antioxidant and oxidative stability of Chétoui virgin olive oil was studied. Total phenolic content, tocopherol composition, fatty acid composition and oxidative stability were analyzed. The results obtained in this study showed that Chétoui virgin olive oil composition is greatly influenced by growing environment, i.e., mainly by the climatic and pedologic factors. The cumulative rainfall appears to have a major influence on phenolic and o -diphenol content. Among studied samples, Amdoun oil had the highest total phenolic content, which exceeded 700 mg/kg. Moreover, it contained the highest amounts of o -diphenols 286.08 ± 6.74 mg/kg and total tocopherols 405.65 ± 4.17 mg/kg. The amounts of total phenols and o -diphenols showed a good correlation (P , 0.001) with stability while tocopherols showed a very low relation to oxidative stability. [source]

SUPERHEATED STEAM-DRYING OF MATE LEAVES AND EFFECT OF DRYING CONDITIONS ON THE PHENOL CONTENT

JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2006
EVERTON FERNANDO ZANOELO
ABSTRACT Four drying experiments of mate leaves (Ilex paraguariensis St. Hilaire) were carried out in a packed bed superheated steam dryer by varying outlet steam temperature from 120 to 140C and equivalent particle diameter from 4.7 × 10,3 to 6.95 × 10,3 m. The influence of these variables on the drying coefficient calculated by assuming a simplified drying kinetic model was investigated. A classical statistical approach revealed the significant effect of both factors on this parameter. Two additional drying runs were performed at identical conditions with conventional hot air and low pressure superheated steam, respectively. The influence of drying atmosphere on the total content of phenols was evaluated. A conventional process of extraction by using an aqueous methanol solution was adopted. Analyses for total phenols were performed by spectrophotometry at 715 nm by applying Folin-Denis assay. The leaves dried with superheated steam had approximately 47% higher retention of these compounds. [source]

Impact of Harvesting and Processing Conditions on Green Leaf Volatile Development and Phenolics in Concord Grape Juice

JOURNAL OF FOOD SCIENCE, Issue 3 2010
M.M. Iyer
ABSTRACT:, The disruption of plant cell walls during fruit juice processing results in the enzymatic formation of herbaceous-smelling green leaf volatiles (GLVs). Our objective was to assess the impact of thermal processing conditions on resulting levels of GLVs (hexanal, trans -2-hexenal, hexanol, cis -3-hexenol, and trans -2-hexenol), total phenols, monomeric anthocyanins, and percent polymeric color in Concord grape juice. The effects of fruit maturity and stage of juice processing on juice GLV content was also assessed. Of the GLVs studied, only trans -2-hexenal routinely exceeded its published sensory threshold in finished juice. We observed an inverse linear correlation between berry maturity (total soluble solids) and trans -2-hexenal levels in finished juice (P,< 0.05, R 2= 0.91). Trans -2-hexenal was at a maximum immediately following crushing (569 ,g/kg, >30-fold over detection threshold [DT]), decreased to 100 ,g/kg following depectinization, pressing, and pasteurization, and to 32 ,g/kg following cold-stabilization. The loss of trans -2-hexenal could be explained primarily by its reduction to trans -2-hexenol, which increased from 53 ,g/kg after crushing to 500 ,g/kg after cold-stabilization. High temperature pretreatment of must immediately following crushing ("hot break") resulted in 5- to 6-fold higher concentrations of trans -2-hexenal in the final bottled juice as compared to conventional hot press. Contrary to expectations, no significant increase in phenolics and anthocyanins were observed in hot break conditions. These results indicate that hot break procedures may thermally inactivate enzymes responsible for transforming trans -2-hexenal under normal processing conditions and potentially alter the flavor qualities of the finished Concord juice. Different equivalent pasteurization regimes (82 to 93 °C) prior to bottling had no significant effect on GLV content of the finished Concord juices (P,> 0.05). Practical Application: Introducing new processing techniques to fruit juice production can potentially result in undesirable changes to organoleptic properties. We have observed significantly higher levels of trans- 2-hexenal, a potent herbaceous off-flavor, in Concord grape juice prepared with an initial high temperature heat treatment ("hot break"). Concord juice producers should be cautious in using hot break processing, especially with immature fruit, as it may result in persistence of green aromas in juice. [source]

Antioxidant Properties of Edible Basidiomycete,Phellinus igniarius,in Submerged Cultures

JOURNAL OF FOOD SCIENCE, Issue 1 2010
Ming Yeou Lung
ABSTRACT:, Dried mycelia and mycelia-free broths produced by submerged cultures of,Phellinus igniarius,under optimal culture conditions were extracted using methanol and hot water and investigated for antioxidant properties. Methanolic extracts from dried mycelia (MEM) and mycelia-free broth (MEB) showed significant antioxidant properties for all EC50 values less than 10 mg/mL except for MEB in scavenging effects on DPPH radicals. Hot water extracts from dried mycelia (HWEM) were evidenced by their low EC50 values (<10 mg/mL) to be effective in reducing power, chelating effect on ferrous ions, and scavenging effect on superoxide anions. ,-tocopherol was mainly found in MEM and ,-tocopherol in MEB. Ascorbic acid and total flavonoids were abundant in methanolic extracts (MEM + MEB), whereas total phenols were rich in HWEM. An excellent correlation between contents of total phenols and EC50 values was accomplished for antioxidant activity (R2= 0.996) and chelating ferrous ions ability (R2= 0.922). Practical Application: In our paper, the products by submerged culture of,Phellinus igniarius,exhibited powerful antioxidant properties. Results told that extracts from fermenting products by,P. igniarius,might be good sources for antioxidant-related functional foods and pharmaceutical industries. [source]

Characterization of fermented black soybean natto inoculated with Bacillus natto during fermentation

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2010
Yongjin Hu
Abstract BACKGROUND: To make nutrients more accessible and further increase biological activity, cooked black soybeans were inoculatedwith Bacillus natto and fermented at 37 °C for 48 h. The changes in physiochemical properties of fermented black soybean natto were investigated. RESULTS: The inoculation procedure significantly increased moisture, viscosity, color, polyphenol compounds and anthocyanin, and significantly decreased hardness after 48 h fermentation. Fibrinolytic and caseinolytic protease, ,-glucosidase activities, TCA-soluble nitrogen, and ammonia nitrogen contents in the inoculated samples significantly increased as fermentation time increased. Genistin and daidzin concentrations gradually decreased with increased fermentation time. However, genistein and daidzein increased with fermentation time, which reached 316.8 and 305.2 µg g,1 during 48 h fermentation, respectively. DPPH radical scavenging activities of the fermented black soybeans increased linearly with fermentation time and concentration. Compared with the soaked black soybeans and cooked black soybeans, the fermented black soybeans with B. natto resulted in higher scavenging activity towards DPPH radicals, which correlated well with the content of total phenols (r = 0.9254, P < 0.05) and aglycone isoflavone (r = 0.9861, P < 0.05). CONCLUSION: Black soybean natto fermented by B. natto has the potential to become a functional food because of its high antioxidant activity. Copyright © 2010 Society of Chemical Industry [source]

Radical scavenging activities, endogenous oxidative enzymes and total phenols in edible mushrooms commonly consumed in Europe

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2007
Ana Cristina Ramírez-Anguiano
Abstract Edible mushrooms are a good source of antioxidants. Methanol extracts of mushrooms such as Pleurotus sp., Agaricus bisporus, Morchella esculenta, Boletus edulis (approx. 2 mg mL,1) showed a high 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activity close to 90%. Water extracts showed even higher antioxidant activity. In this case, B. edulis, Lentinus edodes and Amanita cesarea showed the highest 2,2,-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) scavenging activity at approx. 0.14 mg mL,1. Other mushrooms such as Lactarius deliciosus and Cantharellus cibarius showed lower antioxidant activity in both extracts. Oxidative enzymes (peroxidases and polyphenol oxidases) present in the water fractions reduced their antioxidant activity by different extents since the phenols responsible for the antioxidant activity were not only those substrates of the oxidative enzymes. Other phenolic compounds and low-molecular-weight compounds were also involved in the antioxidant activity and differed depending on mushroom species. Copyright © 2007 Society of Chemical Industry [source]

Phenolic compounds and the colour of oranges subjected to a combination treatment of waxing and irradiation

JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 13 2004
Mostafa Moussaid
Abstract The effects of waxing, irradiation doses and storage on phenolic compounds and colour of irradiated oranges were investigated. Mature oranges (Citrus sinensis (L) Osbeck var Maroc late) waxed or unwaxed were treated with 0, 1 or 2 kGy radiation and stored up to 9 weeks at 20 °C and 40,50% RH. Colour of the oranges, total phenols and flavones in the peel were measured. Phenolic compounds increased with irradiation dose and storage time. Hue angle, L* value and chroma of the orange colour were more affected by waxing and storage time than the irradiation treatment. Changes in the phenolic compounds were linked with changes in the redness and saturation of the orange colour. Irradiation stimulated synthesis of flavones; waxing controlled changes induced by irradiation. These results may aid in maintaining the quality and safety of oranges during storage. Copyright © 2004 Society of Chemical Industry [source]

Extraction of phenolic compounds during vinification of Pinot Noir wine examined by HPLC and cyclic voltammetry

Effect of Pedoclimatic Conditions on the Chemical Composition of the Sigoise Olive Cultivar

CHEMISTRY & BIODIVERSITY, Issue 4 2010
Samia Dabbou
Abstract The present work focused on the quality and the chemical composition of monovarietal virgin olive oil from the Sigoise variety grown in two different locations in Tunisia, viz., a sub-humid zone (Béjaoua, Tunis) and an arid zone (Boughrara, Sfax). In addition to the quality characteristics (acidity, peroxide value, and the spectrophotometric indices K232 and K270) and the chemical composition (content of fatty acids, antioxidants, and volatile compounds) of the oil, the fruit characteristics of the olives were studied. Except for the content of the majority of the fatty acids, there were significant differences observed in the oil composition of olives that were cultivated in different locations. The content of total phenols and lipoxygenase (LOX) oxidation products was higher for olives grown at the higher altitude, whereas that of , -tocopherol, carotenes, and chlorophylls was higher for olives from the Boughrara region (lower altitude). Moreover, olives produced at the higher altitude showed a higher ripeness index and oil content than those cultivated at the lower altitude. [source]