Determination of free and bound phenolics using HPLC-DAD,antioxidant activity and in vitro digestibility of Eragrostis tef

White and brown Eragrostis tef were assessed for total flavonoid and phenolic content, HPLC profile of the most common phenolics and antioxidant activity including both free and bound phenolics. Antioxidant activity was evaluated in correlation with free and bound phenolics and in vitro digestibility was determined. Content of flavonoids (0.52–1.02 mg RE/g) and phenolics (0.90–1.42 mg GAE/g) as well as antioxidant activity (1.70–4.37 μmol TEAC/g using ABTS method) was higher in free phenolic fraction. Correlation showed that bound flavonoids were not significant contributors to antioxidant activity (R² = 0.4513 and 0.4893, respectively). The main free phenolics in brown teff were trans-p-coumaric, protocatechuic, ferulic and gallic acids, while the major free phenolics in white teff were rutin, protocatechuic and ferulic acids. The main bound phenolics in brown teff were ferulic and gallic acids, quercetin and catechin, in white teff ferulic acid, rutin, catechin and quercetin. Cooked teff showed very high level of in vitro organic matter digestibility (80.5–85.1%), whereas brown teff was significantly more digestible than white teff (P < 0.05).     

Geographical discrimination of Italian honey by multi-element analysis with a chemometric approach

In this study the concentrations of K, Ca, Mg, Na, Al, Zn, Fe, Mn, Cu, Cr, Ni, Se, Pb, Cd, and As in 39 honey samples of different botanical (orange-blossom, lemon-blossom, chestnut, eucalyptus, acacia, sulla and wildflower honeys) and geographical (Sicily and Calabria, Italy) origin were determined by ICP-OES and ICP-MS. The most abundant minerals decreased in the following order: K (mean value: 1.57 mg g⁻¹) > Ca (0.2 mg g⁻¹) > Mg (0.121 mg g⁻¹) > Na (0.092 mg g⁻¹). Recommended Dietary Allowance (RDA) values and benchmark levels were employed to assess the honey quality and safety. The data excluded toxicological risks: for an adult of 60 kg, a daily intake of 2 g of honey covered maximum 0.40% of Tolerable Weekly Intake (TWI) for Al, 0.33% of Benchmark Dose of 1% Extra Risk (BMDL01) for Pb, and 0.07% of Tolerable Daily Intake (TDI) for Ni. Mineral content marks the differences in honey samples from different geographical origin despite the botanical factor weight and can be used as a tool to assess the traceability of honeys. The discrimination between Sicilian and Calabrian honeys was achieved by Principal Component Analysis (PCA), and also the results of Canonical Discriminant Analysis (CDA) indicate that the 100% of total samples are correctly classified. This research contributes to the studies to determine the geographical origin of honeys.     

Seed composition of ten industrial hemp cultivars approved for production in Canada

The objective of this study was to determine the seed chemical composition of ten industrial hemp cultivars grown in Québec. The fatty acid and tocopherol composition, as well as the concentrations of crude protein, oil, ash, cellulose, hemicellulose and lignin were quantified. The seed oil concentration varied between 269 and 306 g/kg, while the crude protein concentration ranged between 238 and 280 g/kg. The hemp seed oil is mainly composed of unsaturated fatty acids, and the dominant fatty acids are linoleic acid (597 g/kg) and α-linolenic acid (170 g/kg). For all ten cultivars, γ-tocopherol was present at a much higher concentration than δ-tocopherol (2481 vs. 774 μg/g). Out of the ten cultivars analyzed, Anka was the richest in phenolics (5.16 g/100 g), whereas CRS-1 had the lowest phenolic content (1.37 g/100 g). Seed ash concentration ranged between 51 and 58 g/kg, while neutral detergent fibre and acid detergent fibre concentrations ranged between 327 and 388, and 259 and 298 g/kg, respectively. In conclusion, our results reveal noticeable differences among cultivars in terms of the essential fatty acid, oil, protein, and antioxidant content of industrial hemp seed. Collectively, this study suggests that the seed of Canada-grown hemp is a balanced health product.     

Quantification of bioactive constituents and antioxidant activity of Chinese yellow wine

Rice wines have been consumed in China for more than 9000 years. Chinese yellow wine (CYW) is one of the traditional fermented alcoholic beverages of rice. Studies have shown that CYW improves atherosclerotic plaque in LDL-receptor-knockout mice. Rice wine consumption at a level of alcohol >12.8 g/day in Chinese women has been associated with a 34% lower risk of developing metabolic syndrome compared to non-drinkers. However, evidence for the health benefits of CYW is still very limited. In the present study, phenolic compounds, amino acids, γ-aminobutyric acid and hydroxymethylfurfural in 5-year-old Guyuelongshan CYW were characterized and quantitated as a first step in launching the studies of potential health benefits of CYW. Our results show that three of the nine phenolic compounds characterized by HPLC-DAD-ESI-MS/MS were not previously documented in the CYW. Fifteen free amino acids and γ-aminobutyric acid quantitated by the HPLC-fluorescence method and the protein assay demonstrate that CYW is a good source of amino acids (2923 μg/mL), γ-aminobutyric acid (10.1 ± 0.3 μg/mL) and peptides/proteins (4210 ± 430 μg/mL). The Trolox equivalent antioxidant capacity of CYW (1.76 ± 0.07 mM) is higher than white wines but lower than red wines.     

Phytonutrient content of Solanum sisymbriifolium Lam. berries

Solanum sisymbriifolium Lam. (Litchi tomato) is grown ornamentally, and in Europe it is used as a trap crop for management of the potato cyst nematode (PCN). Its berries are edible, but little is known about their nutritional content. If more was known about their nutritional value this could provide incentive to grow it as a food crop. Phytonutrient content was characterized in berries from four varieties and four synthetic breeding lines developed to have reduced spininess. Litchi tomatoes contained 6.8–10.4 mg of total phenolics per g dry weight. Antioxidants measured by FRAP ranged from 148 to 242 μmol TE/g DW. HPLC analysis showed chlorogenic acid (1856–4385 μg/g DW) was the most abundant phenylpropanoid. Ascorbic acid ranged from 2042 to 4511 μg/g DW. The yellow/orange flesh color was due to carotenoids, with β-carotene the most abundant (204–633 μg/g DW). Soluble protein in Litchi tomato ranged from 86.9 to 120.9 mg/g. Of the cultivated Litchi tomato varieties analyzed, SS91 had the highest amount of antioxidant activity, ascorbic acid, chlorogenic acid and β-carotene. These results suggest that Litchi tomato fruits can be a good source of phytonutrients, expanding the plant's functionality beyond its use as a PCN trap crop.     

Physicochemical profiles,minerals and bioactive compounds of stingless bee honey (Meliponinae)

This study investigates the physicochemical properties, majority minerals, total phenolic compounds and antioxidant activity of stingless bee honey. Thirty-three samples from ten species were analyzed. The results show moisture as 23.1–43.5% (w/w), the electrical conductivity as 0.150–1.34 mS cm⁻¹, the free acid as 16.2–139 mEq kg⁻¹, the pH as 3.33–6.56, the diastase activity as 4.34–49.6 in Göthe units, the insoluble solids as 55.2–76.1°Brix, the carbohydrates as 48.6–70.5% (w/w) sucrose and the 5-hydroxymethylfurfural (5-HMF) was below the limit of quantitation (LOQ). The most abundant element in the samples was potassium followed by calcium sodium, magnesium and manganese. Stingless bee honeys possess relevant amounts of phenolic compounds and antioxidant activity, suggesting a source of natural antioxidants. The results show that there is great variability in the composition of honey from stingless bees of different species, predominantly flowering and geographical origin. However, it was not possible to identify the real factor influencing its features.     

Determination of folic acid in fortified wheat flours

A reversed-phase high-performance liquid chromatography (HPLC) method with ultraviolet detection to determine folic acid (FA) in fortified wheat flour is described. The method includes FA extraction with tetraborate and trichloroacetic acid buffer solution and purification by solid-phase extraction with strong anion-exchange cartridges. Good results were obtained with respect to repeatability (relative standard deviation ⩽8.8) and recovery (⩾97%). Detection and quantification limits were 0.06 and 0.19 μg g⁻¹, respectively. The comparison between the HPLC method and both microbiological and immunoenzymatic assays revealed similar results. FA determination results on 33 wheat flours samples revealed that 51% of these samples had below 1.50 μg g⁻¹ FA concentration added, the enrichment level established by Brazilian Regulation.     

Characterization of phenolics,betacyanins and antioxidant activities of the seed,leaf, sprout,flower and stalk extracts of three Amaranthus species

Hydrophilic extracts from different parts including leaves, stalks, seeds, flowers and sprouts of 3 Amaranthus species (Amaranthus hypochondriacus, Amaranthus caudatus and Amaranthus cruentus) were characterized for their phytochemical profiles including the phenolics and betacyanins by UHPLC and LC–ESI–MS, and their antioxidant activities by FRAP and ORAC assays. The main betacyanins in Amaranthus samples were identified to be amaranthine and isoamaranthine. Eleven phenolic compounds (gallic acid, protocatechuic acid, chlorogenic acid, gentistic acid, 2,4-dihydroxybenzoic acid, ferulic acid, salicylic acid, rutin, ellagic acid, kaempferol-3-rutinoside and quercetin) were identified in the extracts of different parts of Amaranthus. The total phenolic content (TPC) ranged from 1.04 to 14.94 mg GAE/g DW; the total flavonoid content (TFC) ranged from 0.27 to 11.40 mg CAE/g DW; while the total betalain content (TBC) ranged from 0.07 to 20.93 mg/100 g DW. FRAP values ranged from 0.63 to 62.21 μmol AAE/g DW and ORAC ranged from 30.67 to 451.37 μmol TE/g DW. The leaves of Amaranthus showed the highest TPC, TFC, TBC, FRAP and ORAC values; while the seeds and stalks the lowest. There was a strong correlation between TPC, TBC, TFC and the antioxidant activity. The result suggests that all parts of the Amaranthus plant can be a good source of antioxidants.     

Content of ascorbic acid,quercetin, kaempferol and total phenolics in commercial broccoli

A total of 80 commercial broccoli samples were collected over a two-year period to determine seasonal variation in the levels of ascorbic acid (AA), vitamin C (the sum of AA and dehydroascorbic acid [DHAA]), the predominant flavonoids quercetin and kaempferol, and total phenolics at the consumer level. Levels of AA and vitamin C varied between 13.37–110.30 and 57.35–131.35 mg/100 g fresh weight (FW), respectively. The levels of quercetin and kaempferol ranged from 0.03 to 10.85 and 0.24 to 13.20 mg/100 g FW, respectively. Total phenolic activity ranged from 48.15 to 157.77 mg/100 g FW. Significant seasonal variation and year-to-year variability were observed in the content of all phytochemicals examined. Total phenolic levels correlated positively with levels of vitamin C, quercetin, and kaempferol. Based upon the USDA/ERS 2007 database for consumption based upon sales, and the data reported herein, the daily availability of vitamin C from broccoli was estimated at 8.99 mg; accounting for 15% of Reference Daily Intake (RDI). The average daily availability of quercetin, kaempferol and total phenolics from broccoli was estimated as 0.23, 0.32 and 5.50 mg, respectively.     

Mineral and phenolic concentrations of mungbean [Vigna radiata (L.) R. Wilczek var. radiata] grown in semi-arid tropical India

Mungbean [Vigna radiata (L.) R. Wilczek var. radiata] is an important pulse crop grown in south, east and southeast Asia. Mungbean seed samples harvested from field trials conducted in two environments in Hyderabad, India were utilized to determine genetic variation in the concentrations of minerals Fe, Ca, Mg, Zn, Cu, Mn, Se, Na, K and P and to determine the concentrations of phytic acid (PA) and phenolic compounds. Significant variations in Fe (35–87 mg/kg), Ca (1190–1580 mg/kg), Mg (970–1700 mg/kg), Zn (21–62 mg/kg), Cu (7.5–11.9 mg/kg), Mn (9.8–19.6 mg/kg), Se (0.21–0.91 mg/kg), K (8670–14,100 mg/kg) and P (2760–5170 mg/kg) were recorded in mungbean lines commonly grown in South Asia. The effect of the environment on the concentration of minerals in mungbean lines was observed. The Fe concentration of lines CN 9-5 and Harsha doubled when grown in soil with increased availability of Fe. The low PA concentration (2.6–3.8 g/kg) and the presence of phenolic compounds such as ferulic acid (1540–3400 μg/g) in mungbean may lead to increased bioavailability of micronutrients. Nutrient-rich mungbean should be included in diets to combat micronutrient malnutrition.     

Development of HPLC-DAD method for determination of neonicotinoids in honey

After the EU banned the use of the neonicotinoids in flowering crops that honeybees might visit, there has been an increased interest in determining the neonicotinoid residues in honeybee products such as honey. The aim of this study was to develop and optimize an HPLC-DAD analytical method with dispersive liquid–liquid microextraction (DLLME) and QuEChERS sample preparation procedures for the simultaneous analysis of seven neonicotinoids (dinotefuran, nitenpyram, thiametoxam, clothianidin, imidacloprid, acetamiprid and thiacloprid) in honey samples. The liquid chromatographic conditions were optimized by Response surface methodology with Box–Behnken design and Derringer's desirability. The optimized method was validated to fulfill the requirements of SANCO/12571/2013 standard for both sample pretreatment procedures providing results for accuracy (73.1–118.3%), repeatability (3.28–10.40%) and within-laboratory reproducibility (6.45–17.70%), limits of detection (1.5–2.5 μg kg⁻¹) and quantification (5.0–10.0 μg kg⁻¹) with the use of matrix-matched calibration to compensate the matrix effects. For the first time 104 honey samples from Vojvodina were analyzed. The presence of thiacloprid, imidacloprid and thiametoxam was found in a small number of samples implicating the usefulness of ongoing control of honey. Residues were confirmed by LC–MS/MS.     

Phenolic,alpha-tocopherol,beta-carotene and fatty acid composition of four promising jujube (Ziziphus jujuba Miller) selections

The phenolic, alpha-tocopherol, beta-carotene and fatty acid composition of four jujube selections were investigated in this study. Phenolic compounds, alpha-tocopherol and beta-carotene were analyzed with an HPLC device equipped with a diode array detector, and the fatty acid methyl esters were analyzed with QP 5050 GC/MS equipped with a CP-Wax 52 CB column. Among the jujube selections, considerable differences in phenolic and fatty acid contents were found. Catechin, caffeic acid, p-coumaric acid, ferulic acid, rutin, apigenin-7-glucoside, eriodictyol, quercetin, p-hydroxybenzoic acid, chlorogenic acid and syringic acid were isolated from leaves. Rutin content was very high in the leaves of all the jujube selections, ranging from 269.0 to 367.90 mg/100 g, followed by apigenin-7-glucoside (22.90–49.38 mg/100 g) and eriodictyol (5.06–6.27 mg/100 g). Seven phenolic compounds, catechin, caffeic acid, epicatechin, ferulic acid, rutin, p-hydroxybenzoic acid and chlorogenic acid, were isolated from fruits of jujube selections. Catechin level ranged from 2.46 to 3.74 mg/100 g, and rutin level ranged from 0.88 to 3.60 mg/100 g for fruits. Predominant phenolics were rutin and apigenin-7-glucoside for leaves, and catechin and rutin for fruits. Jujube leaves contained higher amounts of phenolic compounds than jujube fruits. Alpha-tocopherol was only detected in fruits of selections 20-Ç-22 and 20-Ç-52 (0.04 and 0.07 mg/100 g, respectively). Beta-carotene was significantly higher in 20-Ç-22 (35.0 μg/100 g) than in the other selections. Lipid content of the fresh fruits ranged from 0.06% to 0.10% among the four jujube selections. The predominant fatty acids in all jujube selections were oleic acid, linoleic acid, palmitic acid and palmitoleic acid. Unsaturated fatty acids comprised 68.54–72.44% of the total fat in jujube fruit.     

Phenolic and mineral profiles of four Balkan indigenous apple cultivars monitored at two different maturity stages

Some primary and secondary metabolites, as well as mineral nutrients in pulp, peel and juice obtained from four Serbian indigenous apple cultivars (Kožara, Kolačara, Budimka and Šumatovka) collected at two different developmental stages were studied. With advanced maturation soluble solids content, total and reducing sugars increased, while l-ascorbic acid content and titratable acidity decreased. Thirteen phenolic compounds were quantified using LC–MS/MS. The total phenolic content (TPC) ranged from 9.37 to 1440 mg/100 g fw, and 0.83 to 7.84 mg/100 g fw in peel and pulp samples, respectively. Quercetin derivatives were the major detected polyphenolic group. Majority of determined phenolic compounds were influenced by cultivar and the best sources were cultivars Kolačara and Budimka. The content of flavonols (with the exception of quercitrin) varied significantly depending on maturity at harvest. With regard to mineral analysis, K was the most abundant ranging from 104 to 158 mg/100 g fw in peel, 74.4 to 93.3 mg/100 g fw in pulp, and 77.1 to 91.5 mg/100 g fw in juice samples. Obtained results provide detailed information on nutritional potential and chemical composition of tested apple cultivars and thereby could encourage their wider cultivation and consumption.     

Ultra-high-pressure liquid chromatography–solid-phase clean-up for determining aflatoxins in Egyptian food commodities

In this work, we determined the content of regulated aflatoxins (ATs) B1, B2, G1, and G2 in food commodities using solid-phase extraction (SPE) and ultra-high-pressure liquid chromatography with fluorescence detection without derivatization. We extracted ATs from the ground samples by mixing in NaCl and 80% (v/v) methanol. The sample was enriched and cleaned up by SPE technique using Bakerbond^® C18 cartridges. The extract that we obtained was immediately analyzed using isocratic elution with a mobile phase consisting of acetonitrile, methanol and deionized water in a ratio of 64:18:18. Method validation was carried out by determining these ATs in a quality control material consisting of almond T02445QC and with the add-found test. The results provided satisfactory recovery within the range of 89.6–103.3%. Repeatability and intermediate precisions were assessed as RSD (%) which were found in the range of 1.1–11.3% and 1.5–12.0%, respectively. The limit of detection (S/N = 3) was 0.03, 0.02, 0.04, and 0.02 μg kg⁻¹ for B1, B2, G1 and G2, respectively. Finally, the method was successfully applied to determine ATs in raw Egyptian food commodities, namely maize, popcorn, pistachio, corn, peanuts, chilli, wheat, green coffee and almond, and the corresponding RSD did not exceed 11%.     

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.     

Compositional characteristics of commercial beetroot products and beetroot juice prepared from seven beetroot varieties grown in Upper Austria

Beta vulgaris L. (beetroot) contains high amounts of biologically active substances including betalains and inorganic nitrate. We determined the amounts of various compounds (minerals, betalains, oxalic acid, phenolic acids, and sugars) in juice prepared from seven different beetroot varieties cultivated in Upper Austria. Large differences were found between the varieties for some substances (such as nitrate), whereas others showed only minor variation (certain minerals and sugars). The total betalain content was found to range between 0.8 and 1.3 g/L fresh juice (about 60% betacyanins and 40% betaxanthins) that accounted for 70–100% of the total phenolics content. Other detected phenolics were hydroxycinnamic acids, which accounted for up to 2.6% of total phenolics. Nitrate content varied 10-fold between single varieties. Sugar composition was similar in all varieties with an average total content of about 7.7%, consisting of 95% sucrose. Only minor differences in the concentration of oxalic acid (0.3–0.5 g/L fresh juice) were found between the varieties. In addition, 16 commercial juices and four powders were analyzed for their nitrate contents, as its metabolic product nitric oxide has been reported to provide cardiovascular benefits. Large variations of the nitrate levels, ranging from 0.01 to 2.4 g/L, were found.     

Nutritive value,antioxidant activity and phenolic compounds profile of brewer’s spent yeast extract

Spent yeast is the second major by-product from brewing. Mechanical disruption of yeast cell wall can be used to obtain β-glucan rich ingredients and separate inner yeast content, both with potential applications as food and nutraceutical ingredients. In this work, the nutritional composition, including minerals and B-complex vitamins, together with the antioxidant activity and phenolic compounds profile of yeast extract, prepared by mechanic disruption of brewer’s spent yeast and removal of yeast cell wall, was investigated. The lyophilised yeast extract presented 64% of proteins with high proportion of essential amino acids and 4% of RNA; macrominerals (Na, K, Ca, Mg), trace elements such as Zn (11.9 mg/100 g dw), Fe (1.76 mg/100 g dw), and Mn (0.564 mg/100 g dw), and vitamins B3 (77.2 mg/100 mg dw), B6 (55.1 mg/100 g dw) and B9 (3.01 mg/100 g dw). Two phenolic compounds were quantified as free forms, gallic acid and (±) catechin, whereas other bounded phenolic compounds were also quantified. The nutrients content, antioxidant properties and phenolic composition of the lyophilised brewer’s spent yeast extract indicates that it can be an interesting food or nutraceutical ingredient. Thus, its recovery will be beneficial in terms of sustainability and environmental impact.     

Phenolic composition and radical scavenging activity of commercial Greek white wines from Vitis vinifera L. cv. Malagousia

Seven commercial white wine samples of the Malagousia cultivar were investigated for the first time with regard to their phenolic composition and radical scavenging activity. Total phenol content, corrected for ascorbic acid contribution (0–47 mg gallic acid equivalents/L of wine), ranged between 241 and 336 mg gallic acid equivalents/L of wine. On the other hand, the range for total hydroxycinnamates was 51.5–122.4 mg chlorogenic acid equivalents/L of wine and that for total flavanols 19.6–68.8 mg catechin equivalents/L wine. Fifteen phenolic compounds were identified and quantified by gas chromatography/mass spectrometry in the selective ion monitoring and high-performance liquid chromatography coupled with diode array detector. Tyrosol, caftaric, caffeic and 2-S-glutathionyl caffeoyl tartaric (GRP) acids were the major phenolics in all samples with mean concentrations of 12.32, 10.71, 10.17 and 4.79 mg/L wine, respectively. Catechin (3.75 mg/L) and p-coumaric acid (3.04 mg/L) followed in abundance. Variations in the values of GRP/caftaric (0.1–4.6) and caffeic/caftaric (0.4–4.2) acid concentrations, suggested differences in the degree of oxidation on one hand and hydrolytic processes during production and bottling on the other. Despite these variations, the radical scavenging activity of samples examined with DPPH and ABTS⁺ assays (mean value 0.85 and 3.45 mmol Trolox equivalents/L of wine) indicated a high efficiency in comparison to literature data on native and foreign white wines. The present findings can be useful for both technological and nutritional purposes.     

Phenolic acids in potatoes,vegetables, and some of their products

The aim of this study was to determine the distribution and contents of soluble and total phenolic acids in a wide range of vegetables consumed in Finland. The determinations were performed from the pooled samples (14 potato and 45 other vegetable samples). Soluble phenolic acids were extracted with methanolic acetic acid and a tentative quantification was performed by HPLC. The contents of total phenolic acids were determined by HPLC after alkaline and acid hydrolyses. Chlorogenic acid derivatives were the most dominant soluble phenolic acids, while caffeic acid was the most dominant phenolic acid aglycone in the samples studied. Highest contents of soluble phenolic acids were found in raw and cooked potato peels: 23–45 mg/100 g fresh weight calculated as aglycones. In addition, pot-grown lettuces, Chinese cabbage, broccoli, carrot, aubergine, Jerusalem artichoke, peanut and most of the boiled and peeled potato tubers contained more than 5 mg/100 g of soluble phenolic acids calculated as aglycones. Among the best vegetable sources of total phenolic acids were potatoes, with contents varying from 7.9 mg/100 g (cooked and peeled Rosamunda variety) to 52 mg/100 g (cooked peel of Van Gogh variety), and red cabbage, carrot, aubergine, Jerusalem artichoke, broccoli, pot-grown lettuce, spinach, radish and red beet, with contents from 11 mg/100 g (spinach) to 52 mg/100 g (pot-grown lettuce Lollo Rosso). Variation in the phenolic acid contents of the vegetables was either moderate or considerable and needs further research.     

Seasonal variations in antioxidant components of cherry tomatoes (Lycopersicon esculentum cv. Naomi F1)

To evaluate seasonal variations in antioxidant components of greenhouse cherry tomatoes, the compositional profile of fruits (“Pomodoro di Pachino”, cv. Naomi F1) harvested at six different times of the year was compared. Among tomato antioxidants, phenolic compounds (naringenin content ranged from 1.84 to 9.04 mg/100 g, rutin from 1.79 to 6.61 mg/100 g) and α-tocopherol (40–1160 μg/100 g) showed the greatest variability. Ascorbic acid (31–71 mg/100 g), carotenoids (8350–15119 μg/100 g), phenolics and α-tocopherol concentration did not show definite seasonal trends, nor correlation with solar radiation or average temperature. Nevertheless, tomatoes harvested in mid-summer were characterized by lowered lycopene levels. Greenhouse growing conditions induced the accumulation of relatively high level of antioxidants for most of the year: one serving of raw tomatoes (100 g) could provide from 50% to 120% of the recommended daily intake of vitamin C, from 13% to 27% of that of vitamin A, from 0.4% to 12% of that of vitamin E, and from 15% to 35% of the flavonoid daily intake estimated for an Italian diet.