Antioxidant activity and phenolic content of fresh and dry nuts with or without the seed coat

Total antioxidant activities based on ABTS free radical scavenging activity and phenolic content of fresh or dry hazelnuts, walnuts and pistachios assayed with their seed coats changed between 3063 and 11,076 μmol trolox equivalents/100 g d.w. and 256 and 755 mg gallic acid equivalents/100 g d.w., respectively. The walnuts used in this study showed the highest antioxidant activity, followed by pistachios and hazelnuts. The removal of seed coat reduced the total antioxidant activity of hazelnuts, walnuts and pistachios almost 36, 90 and 55%, respectively. The total antioxidant activities of investigated fresh and dry nuts are not considerably different. However, phenolic content and antioxidant activity in hydrophilic and ethanolic fractions obtained by successive extraction of nuts showed some variation. The antioxidant activity in 1-serving portion of fresh or dry walnuts is equivalent to that in almost 2-serving portions of black tea, and 1.2–1.7-serving portions of green and Earl Grey tea. One-serving portions of dry hazelnuts and fresh or dry pistachios contained antioxidant activity equivalent to that in 0.7–1-serving portions of black tea. The antioxidant activity measurements correlated with phenolic content (r² = 0.70). This study showed the potential of using fresh or dry nuts to develop functional foods with high antioxidant activity.     

Antioxidant properties of extracts from a white mutant of the mushroom Hypsizigus marmoreus

A white mutant of Hypsizigus marmoreus (Peck) Bigelow (Tricholomataceae) is a new edible mushroom currently available in Taiwan. The ethanolic and hot water extracts were prepared from fruit bodies and mycelia and their antioxidant properties studied. In addition to EC₅₀ values in scavenging abilities on hydroxyl radicals, almost EC₅₀ values were less than 10 mg/mL indicating that these extracts were effective in antioxidant properties assayed. The major antioxidant components found in hot water extracts were total phenols (10.01–13.14 mg/g) and those in ethanolic extracts were total tocopherols (33.33–10.92 mg/g). Correlations of contents of total antioxidant components and total tocopherols (plus β-carotene) with EC₅₀ values of antioxidant activity, reducing power, scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radicals and chelating ability on ferrous ions were established (r=0.445–0.940), whereas the correlation of total phenol content was established only with that of scavenging ability on hydroxyl radicals (r=0.882).     

Radical scavenging,antioxidant and metal chelating activities of Annona cherimola Mill. (cherimoya) peel and pulp in relation to their total phenolic and total flavonoid contents

This study aimed to evaluate the total phenolic and flavonoid content, radical scavenging activity (by DPPH and ABTS tests) and antioxidant capacity (by β-carotene bleaching test) of Annona cherimola (cherimoya) fruits cultivated in Italy for human consumption. The metal chelating activity and ferric reducing power were also determined. A. cherimola peel and pulp were characterized by a total phenolic content of 14.6 and 12.6 mg chlorogenic acid equivalents/100 g fresh weight, respectively. A similar trend was observed with flavonoid content. Both extracts exhibited high antioxidant activity through different mechanisms of action. In particular, peel extract demonstrated the strongest free radical scavenging activity with an IC₅₀ value of 57.7 μg/mL. The same extract was more effective in preventing β-carotene oxidation (IC₅₀ value of 63.5 μg/mL after 60 min) and showed higher chelating ability (IC₅₀ value of 79.6 μg/mL) than pulp extract. This work demonstrated the high quality of cherimoya fruits cultivated in Italy, and recommends the peel of this fruit product that may be of interest from a functional point of view as a major source of natural antioxidants.     

Antioxidant activity,quality parameters and mineral content of Portuguese monofloral honeys

Physicochemical properties (pH, free, lactonic and total acidity, electrical conductivity and moisture), main mineral content (potassium, sodium, calcium, magnesium and iron) and antioxidant activity (total phenolics, 1,1diphenyl-2-picrylhydrazyl radical scavenging and ferric reduction antioxidant power) were determined for 39 Portuguese monofloral honeys (rosemary, orange, thyme, arbutus, locust podshrub and heather) with different geographical origins. Portuguese honeys showed good chemical and nutritional qualities fulfilling the criteria described in Directive 2001/110/CE. Potassium was the main mineral component representing 85% of total minerals. The mineral composition of sodium (4.63–200.60 mg/kg), calcium (0.43–72.30 mg/kg), magnesium (3.05–82.20 mg/kg) and iron (below 7.06 mg/kg) were higher for heather, eucalypt and arbutus honeys. Monofloral honeys of arbutus (Arbutus unedo), locust podshrub (Ceratonia siliqua L.) and heather (Erica umbellata) showed higher antioxidant activity with phenolic contents higher than 600 mg gallic acid equivalents (GAE)/kg, a DPPH scavenging activity higher than 50% and a ferric reduction antioxidant power above 600 μM Fe²⁺. Furthermore, the chemometric analysis revealed that total phenolic content was a crucial variable explaining the antioxidant activity of arbutus and locust podshrub honeys characteristic of the south of Portugal.     

Phenolic compounds and antioxidant activity of Spanish commercial grape juices

Evaluation of the antioxidant activity of components of the diet is important in order to establish healthy consumption patterns. Data are reported here on the antioxidant activity (FRAP and ABTS), of 20 commercial grape juices and 10 typical Spanish wines and on their content of total phenolic compounds, anthocyanins, flavonoids and 10 individual phenolic compounds (flavanols, benzoic acids and cinnamic acids, measured by HPLC-UV). Red grape juices had a significantly higher (p < 0.05) concentration of total phenols (1177 vs. 744 mg gallic acid/L), flavonoids (98 vs. 63 mg catechin/L) and a higher antioxidant activity (9.16 vs. 2.83 meq Trolox/L) in comparison to white grape juices. In comparison to the white wines, white grape juices contained more total phenols (744 vs. 286 mg gallic acid/L) and flavonoids (63 vs. 29 mg catechin/L) and evidenced higher antioxidant activity (p < 0.05). In comparison to the red wines, a lower content of total phenols (286 vs. 2358 mg gallic acid/L) and flavonoids (228 vs. 29 mg catechin/L) and an absence of anthocyanins were observed in the white wines, which are therefore less antioxidant. Although a two-fold higher concentration of antioxidant compounds was found in red wines than in red grape juices, the latter may be a good option for all age groups because of the absence of alcohol and the potentially beneficial health effects of their phenolic composition and elevated antioxidant activity.     

Effect of solvents in extracting polyphenols and antioxidants of selected raw vegetables

Thirty-seven raw vegetables were extracted using four solvent systems: 70% acetone, 70% ethanol, 70% methanol, and distilled water. The extracts were tested for their total phenolic content, total flavonoid content and antioxidant activities (using diphenylpicryl-hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays). The results revealed the effect of different extracting solvents in altering the quantitative analyses of all vegetables and 70% acetone was identified as the most efficient solvent for extracting polyphenolic antioxidants from the vegetables. The highest total phenolic content and total flavonoid content were obtained from 70% acetone extract of Portulaca oleracea (138.2 ± 2.1 mg GAE/g dw basis) and 70% methanol extract of Cosmos caudatus (27.7 ± 1.0 mg QE/g dw basis), respectively. The 70% acetone extract of Etlingera elatior with moderate amount of total phenolic content exhibited the highest antioxidant activity in both assays. The correlation analyses within 37 different extracts of each solvent extraction demonstrated weak to moderate relationships between all the studied parameters. The highest r value of 0.7139 (p < 0.001) was determined between total phenolic contents and FRAP values of the 70% methanol extracts. Meanwhile, a wide range of correlation coefficients was derived from correlation analyses within four different extracts of each vegetable, with the highest relationship between total phenolic contents and FRAP values for the extracts of Coriandrum sativum (r = 0.9998, p < 0.001).     

Antioxidant and free radical scavenging activity of methanol extract of chungkukjang

An assessment of chungkukjang (traditional fermented soyfood) fermented at 42 °C for 72 h with six sample groups of Korean black soybean (Glycine max) was carried out. Total phenol and isoflavone contents of large black soybean (LBS) group extracts were higher than that of small black soybean (SBS) group extracts. Genistein contents were higher than daidzein in all groups. In total anthocyanin pigment, LBS groups were similar to SBS groups. LBS group extracts exhibited good inhibition rate of about 70–90% in antioxidant and some scavenging activities of free radicals as well as hydrogen peroxide. Bacillus megaterium SMY-212 was a suitable fermenting strain to promote the antioxidant and free-radical scavenging activities in cooked black soybean.     

Anthocyanin profile and antioxidant capacity of black carrots (Daucus carota L. ssp. sativus var. atrorubens Alef.) from Cuevas Bajas,Spain

The present work deals with the study of the anthocyanin profile of two different black carrots (Daucus carota L. ssp. sativus var. atrorubens Alef.) cultivars, associated with Antonina and Purple Haze varieties, from Cuevas Bajas (Málaga, Spain) and some of their antioxidant features. The main anthocyanins detected by LC–MS were found to correspond to five cyanidin-based anthocyanins: cyanidin 3-xylosylglucosylgalactoside, cyanidin 3-xylosylgalactoside and the sinapic, ferulic and coumaric acids derivative of cyanidin 3-xylosylglucosylgalactoside. The anthocyanins present in the black carrots were essentially acylated and their levels were found to correspond to 25% and 50% of the total phenolic content for the Purple Haze and Antonina varieties, respectively. Moreover, the reducing capacity of the two black carrots extracts (86.4 ± 8.0 and 182.0 ± 27 μM TE/100 g fw) and the radical scavenging ability (17.6 ± 9.0 and 240.0 ± 54.0 μM TE/100 g fw) expressed in Trolox equivalents units were determined. The antioxidant features of the black carrot extracts were shown to be significantly higher than those of orange carrots used herein for comparison. Overall, this work highlights the Cuevas Bajas black carrots as rich sources of anthocyanins with significant antioxidant capacities and good nutritional value.     

Phenolic and antioxidant composition of cider

Forty-four Asturian ciders were analysed for total phenolic content, phenolic profiles, and antioxidant capacity by the FRAP and the DPPH radical assays. The Folin index of ciders ranged between 446 and 1180 mg gallic acid/L. The phenolic profile of Asturian cider is mainly constituted by phenolic acids, flavan-3-ols, volatile phenols and dihydrochalcones. The methods to determine the antioxidant activity of ciders were optimised in terms of suitable reaction times, within-day and between-day repeatability. Thus, time courses of ciders in the DPPH and the FRAP assays were performed. Mean values for antioxidant activity of cider, expressed in ascorbic acid equivalents were 2.9 mM (as determined by the DPPH assay). When the FRAP assay was used, the antioxidant capacity of cider increased with the reaction time from 3.8 mM (4 min) to 5.4 mM (40 min). Multivariate approaches based on phenolic composition can be useful to predict the antioxidant capacity of cider. Folin index and flavanols and hydrocaffeic acid contents were the best predictors for antioxidant activity.     

Antioxidant activity and phenolic content in three lupin species

Total phenolic compounds, phenolic acids and flavonoid contents and antioxidant activities were measured in extracts from seeds of Lupinus albus, Lupinus luteus and Lupinus angustifolius cultivars. The total phenolic compound contents varied from 491.51 to 731.14 mg/100 g d.m. for cvs. Butan (L. albus) and Parys (L. luteus), respectively. Protocatechuic acid was the most abundant in seeds of yellow lupin (up to 73.60 mg/kg d.m.), whereas p-hydroxybenzoic acid in narrow-leaf lupin (about 43 mg/kg d.m.). The HPLC (high performance liquid chromatography) analysis revealed two dominant flavonoid compounds, which were identified by HPLC/MSⁿ to be apigenin-6,8-di-C-β-glucopyranoside and apigenin 7-O-β-apiofuranosyl-6,8-di-C-β-glucopyranoside. The highest content of the apigenin glycosides was recorded in yellow lupin while the lowest in white lupin. A positive correlation between the content of the analyzed compounds and the antioxidant activity measured by 2,2′-diphenyl-1-picrylhydrazyl (DPPH) method was established, but no such relation was found using the radical-trapping antioxidant parameter (TRAP) method. Modification of the peroxyl radical-trapping potential of lupin extracts by formation of phenoxyl radicals is suggested.     

Profiling antioxidant activity of two primocane fruiting red raspberry cultivars (Autumn bliss and Polka)

Fruit extracts of two raspberry (Rubus idaeus L.) cultivars (Autumn Bliss and Polka) were analysed for total phenolic (TPC) and anthocyanin (TACY) content. Correlation of TPC with total antioxidant capacity (TAC) showed higher free-radical scavenging properties of Autumn Bliss (r² = 0.9999) compared to Polka (r² = 0.8972). Correlation coefficient between TACY and TAC were higher in Autumn Bliss (r² = 0.9939) compared to Polka fruits (r² = 0.8419). Although total protein concentrations were similar in both cultivars (∼0.35 mg mL⁻¹), activities of peroxidases and polyphenol oxidases were much higher in Polka, which were confirmed with isoelectric focusing in cationic (pI 9.3) and anionic (pI 3.6) range. HPLC detection showed that among detected flavonoids (catechin, epicatechin, epicatechin gallate, rutin, myricetin, resveratrol, quercetin and kaempferol) epicatechin appears to be the most abundant compound. Chlorogenic, caffeic and p-coumaric acid were also detected. The results indicate that the changes in enzymes activities related to content of substrates play an important role in nutrient quality definition of raspberry fruits.     

In vitro antioxidant activities of Stevia rebaudiana leaves and callus

Leaf extract of Stevia rebaudiana promotes effects on certain physiological systems such as the cardiovascular and renal and influences hypertension and hyperglycemia. Since these activities may be correlated with the presence of antioxidant compounds, leaf and callus extracts of Stevia rebaudiana were evaluated for their total phenols, flavonoids content and total antioxidant capacity. Total phenols and flavonoids were analyzed according to the Folin–Ciocalteu method and total antioxidant activity of water and methanolic extracts of stevia leaves and callus was assessed by ferric reducing/antioxidant power (FRAP) assay as well as 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay. The total phenolic compounds were found to be 25.18 mg/g for stevia leaves and 35.86 mg/g for callus on dry weight basis. The flavonoids content was found to be 21.73 and 31.99 mg/g in the leaf and callus, respectively. The total antioxidant activity was expressed as mg equivalent of gallic acid, ascorbic acid, BHA and trolox per gram on dry weight basis. Total antioxidant activity found was ranged from 9.66 to 38.24 mg and 11.03 to 36.40 mg equivalent to different standards in water and methanolic extract of stevia leaves, respectively. In case of stevia callus, it was found to be 9.44 to 37.36 mg for water extract and 10.14 to 34.37 mg equivalent to standards for methanolic extract. The concentrations required for 50% inhibition (IC₅₀) of DPPH radicals were 11.04, 41.04 and 57.14 μg/mL for gallic acid, trolox and butylated hydroxyanisole (BHA), respectively. The percent inhibition of DPPH radical of various extracts of stevia leaves and callus found were ranged from 33.17% to 56.82%. The highest percent of inhibition was observed in methanolic extract of callus.     

Effect of extraction solvents on the phenolic compounds and antioxidant activities of bunga kantan (Etlingera elatior Jack.) inflorescence

In the present study, we investigated the effect of methanol, acetone (50%, 90% and 100%, v/v) and distilled water on the extractability of some of the antioxidant compounds (total phenols, tannins, flavonoids, anthocyanins) of bunga kantan inflorescence (Etlingera elatior Jack.). The antioxidant activity of each individual extract was also evaluated through DPPH (2,2-diphenyl-1-pic-rylhydrazyl) radical scavenging activity and ferric reducing antioxidant power (FRAP) assay. Of all the solvents employed, 50% acetone extract showed highest amount of total phenols (687.0 mg GAE/100 g) and total flavonoids (1431 mg QE/100 g), while 50% methanol extract showed maximum (5.9 mg c-3-gE/100 g) recovery for anthocyanins. Tannin extractability was found to be highest with 100% methanol (467.8 mg CE/100 g). The results obtained suggest the use of bunga kantan inflorescence as a potential source of natural antioxidants for food and nutraceutical applications.     

Evaluation of the mutagenicity and antimutagenicity of extracts from oat,buckwheat and wheat bran in the Salmonella/microsome assay

This study examined the mutagenic and antimutagenic activities of the DMSO extracts from the oat, buckwheat and wheat bran, which are good sources of polyphenols with antioxidant and anticarcinogenic properties. Extracts from buckwheat and wheat bran showed no mutagenic activity. Oat extract showed slight mutagenic effect in Salmonella typhimurium TA102. The antimutagenic activities against direct-acting (3-(5-nitro-2-furyl)acrylic acid, 2-nitrofluorene, hydrogen peroxide) and indirect-acting (aflatoxin B1) mutagens were also investigated using Ames test with S. typhimurium TA98, TA100 and TA102. Cereal extracts exhibit concentration-dependent protective antigenotoxic activity against all used mutagens. The total phenolic content in studied cereal extracts expressed as gallic acid equivalent increases in the order: buckwheat < wheat bran < oat. Total flavonoid content expressed as rutin equivalent increases in the order: oat < wheat bran < buckwheat.     

Screening of antioxidant activity and phenolic compounds of various date palm (Phoenix dactylifera) fruits from Algeria

The phenolic contents of methanolic extracts from five varieties of date palm (Phoenix dactylifera) fruits from Algeria, Deglet Nour (DN), Degla Baidha (DB), Ghars (Gh), Tamjhourt (Tam), and Tafezauine (Taf) were measured in this work. The antioxidant activities of these extracts were also evaluated. Total phenolic content ranged from 41.80 to 84.73 mg gallic acid equivalents (GAE)/100 g and the total flavonoid content varied from 7.52 to 14.10 mg rutin equivalents (RE)/100 g. The antioxidant activities of methanolic extracts were evaluated in vitro using scavenging assays of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical ion (ABTS⁺) and potassium ferricyanide complex as reducing power assay. Effective scavenging concentration (IC₅₀) on DPPH radical ranged from 10.83 to 21.27 mg/l, the IC₅₀ values decreased in the order DN > Gh > Tam > DB > Taf. ABTS radical cation scavenging activity (trolox equivalent 1.66–3.35 mM), the trolox equivalent antioxidant capacity values decreased in the order of DN > Gh > DB > Tam > Taf. In the potassium ferricyanide complex assay, the antioxidant capacity of the extracts ranged between 2.06 and 4.21 mM ascorbic acid equivalents and the ascorbic acid equivalents antioxidant capacity values of the extracts decreased in the order Gh > Tam > DB > DN > Taf. These results suggest that all date varieties constitute a good source of natural antioxidants and could potentially be considered as a functional food.     

Ancient apple varieties from Croatia as a source of bioactive polyphenolic compounds

Several ancient apple varieties and a wild apple variety grown in Croatia were analysed for the polyphenol content and compared to two varieties grown in USA. In the flesh, flavanols, dihydrochalcones and phenolic acids (24 to 137, 23 to 109, 3 to 238 mg kg⁻¹ of fresh weight (FW), respectively) were found. Peel contained flavanols, dihydrochalcones, phenolic acids, flavonols and anthocyanins (65 to 690, 21 to 141, 0 to 107, 205 to 1223, 0 to 213 mg kg⁻¹ FW, respectively). The wild apple was characterized by much higher flavanol and phenolic acid content in the flesh (301 and 734 mg kg⁻¹ FW, respectively) while the peel was similar to other apples. The polyphenol profile was similar to apples from USA. The varieties Zimnjara, Lještarka and Adamova zvijezda could be highlighted as sources of polyphenols. Varieties are categorized by the content of dihydrochalcones and flavanols in the flesh (whether that content is high or low), and by the relative portion of phenolic acids and flavanols in the flesh (high phenolic acid proportion, lower flavanol proportion and vice versa). There was not observed to be as strong a pattern for categorizing differences in the peel.     

Antioxidant and flavor properties of Angelica sinensis extracts as affected by processing

Angelica sinensis (AS) was extracted with water or 20% ethanol for different time periods, and the antioxidant activity as well as flavor quality of the extracts were investigated. The AS extracts contained significant amount of phenolic acids, including nicotinic acid, phthalic acid, p-coumaric acid, and ferulic acid. Regardless the water or alcohol extraction, most of the phenolic acids reached their maximum values in 15 min. Assays including inhibition of 1,1-diphenylpicrylhydrazyl (DPPH), lipid peroxidation, and DNA relaxation activities also indicated that 15 min extraction resulted in a product with the highest antioxidant activity. The 15 min AS extracts in the concentration range of 20–200 μg/ml also showed inhibitory effects on NO production in LPS-activated RAW 264.7 macrophage in a dose-dependent manner. Statistical analysis revealed that the antioxidant activity and phenolic acid concentration for all AS extracts exhibited a positive and significant linear correlation, suggesting that the phenolic acids are the important contributors for the antioxidant activity of the AS extracts. The contents of volatile compounds of AS were much higher in the 20% ethanol extracts than those in water extracts. In the 20% ethanol extracts, the amount of ligustilide, butylidene phthalide and butyl phthalide were higher in the 30-min extracts than that prepared for longer time. Considering both of antioxidant activity and flavor quality, the AS extract should be prepared with 20% ethanol with extraction time less than 30 min.     

Effects of cooking on in vitro sinigrin bioaccessibility,total phenols,antioxidant and antimutagenic activity of cauliflower (Brassica oleraceae L. var. Botrytis)

Cauliflower (Brassica oleraceae L. var. Botrytis) is a good source of bioactive compounds, such as glucosinolates, phenolic compounds and vitamins. In this study, the effects of some processes (i.e. boiling, steaming) on the sinigrin bioaccessibility as a major glucosinolate found in cruciferous vegetables after in vitro digestion, also in vitro antimutagenic activities, total phenols and total antioxidant capacities of cauliflower were determined. The sinigrin content was reduced by approximately 9.6% and 29.1% in steamed and boiled cauliflower (p > 0.05), respectively. After in vitro simulated digestion, sinigrin content was decreased by 26.4% in raw samples, increased by 29.5% and 114.7% in steamed and boiled samples, respectively. In all samples, mutagenic effect to Salmonella typhimurium TA 100 was not seen. When samples were steamed, phenol content was increased by 14.83%. After boiling total phenol content of cauliflower was decreased by 1.8%. Total antioxidant capacities (TAC) measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3 ethylbenzothiazoline-6-sulfonic acid) (ABTS) methods were increased by 47% and 39%, respectively (p < 0.05) in steamed samples and decreased by 8% and 7% with boiling, respectively (p > 0.05). TAC in raw sample of cauliflower, which was investigated in phosphomolybdenum assays, was determined as 18.7 mg ascorbic acid equivalents (AAE)/100 g. In all cases, the highest antioxidant activity was determined in the steamed samples, while the lowest antioxidant activity was in boiled samples.     

Radical scavenging-linked antioxidant activities of commonly used herbs and spices in Korea

Herbs and spices not only variety and racy flavour to Korean foods, they also are the richest source for antioxidant power. The present study evaluates the radical scavenging-linked antioxidant activities of hot water extracts from commonly used herbs and spices in Korea. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide anion scavenging activities of bay extract were 39.5% and 22.1%, respectively. The hydroxyl radical scavenging activity was in order of dill (50.0%) > bay (31.3%) > garlic (27.9%) > white pepper and black pepper (15.1–15.3%) > onion (10.1%) extracts. Bay extract had the highest total phenolic content (17.86 μg CE/g). High correlation coefficients were found between the total phenol content and DPPH radical scavenging activity (R = 0.9162). These results indicate that herbs and spices had high antioxidant activity that is partly due to the phenolic compounds and provide basic data for further development of processed food products.     

Development of HPLC method for Cyclopia subternata phenolic compound analysis and application to other Cyclopia spp.

Analysis of phenolic compounds in Cyclopia spp. (honeybush) is very important because of commercial interest in the plant material as an herbal tea and in extracts for the nutraceutical and cosmeceutical markets. An existing HPLC-DAD method was adapted and proved reproducible as evidenced by good intra- and inter-day precision. The method allows the quantification of several well-known as well as unidentified phenolic compounds. Its suitability for quantification of the major phenolic compounds present in the water extracts of unfermented and fermented Cyclopia subternata, Cyclopia intermedia, Cyclopia genistoides and Cyclopia sessiliflora was evaluated. Known compounds that were identified and quantified include mangiferin (0.1–11.8 g/100 g), isomangiferin (0.1–3.2 g/100 g), eriocitrin (not detected–0.4 g/100 g), hesperidin (0.2–1.2 g/100 g) and scolymoside (not detected–1.8 g/100 g), while narirutin and luteolin were detected in most samples, but could not be quantified due to low concentrations and co-elution. An unidentified compound (traces–4.8 g hesperidin equivalents/100 g), unidentified hydroxycinnamic acid derivative (not detected–0.3 g mangiferin equivalents/100 g), unidentified flavanone (not detected–2.0 g hesperidin equivalents/100 g) and an eriodictyol-glycoside (not detected–0.5 g hesperidin equivalents/100 g) could also be quantified. Large variation was observed within a sample series of the same extract type due to the nature of the plant material. Qualitative and quantitative differences were observed between species, while “fermentation”, a high-temperature process involving non-enzymatic oxidation, decreased the content of most phenolic compounds. Results using DAD as the only detection method should be handled with care, as the tentative identification of compounds 9 and 10, based on retention time and UV–Vis spectrum, could not be confirmed using liquid chromatography–electrospray ionisation-mass spectrometry.