Comparison of eggplant landraces and commercial varieties for fruit content of phenolics,minerals, dry matter and protein

Development of eggplant (Solanum melongena) varieties with an improved content in phenolics and nutritionally relevant minerals in the fruit is an increasingly important breeding objective. We analyzed several proximate composition traits (dry matter and protein content), content in phenolics, and eight minerals (P, K, Ca, Mg, Na, Fe, Cu, and Zn) in 31 varieties of eggplant from three different varietal groups (commercial varieties, landraces, and hybrids between the landraces). Considerable differences in the composition among varieties were detected in all the traits studied, with relative differences between the lowest and highest values of 42.9% for dry matter and 156.3% for Ca. Results show that eggplant provides relevant quantities of phenolics, P, K, and Cu to the diet, with global mean values of 48.26 mg/100 g, 26.6 mg/100 g, 198.5 mg/100 g, and 0.062 mg/100 g of fresh weight, respectively. Landraces had, as a mean, higher contents in phenolics (16.4%), P (34.6%), and Zn (30.0%) than commercial varieties. Positive mean heterosis was detected for dry matter content (8.4%) and Na concentration (12.1%), and negative mean heterosis for P (−16.0%), K (−5.5%), and Ca (−38.5%) concentrations. Mean heterosis was not significant for the content in phenolics, although positive values were found for some individual hybrids. Contents in dry matter, protein and the main macrominerals were positively correlated. Also, positive correlations between mid-parent and hybrid values were found for dry matter (r=0.596), P (r=0.658) and K (r=0.599). The results obtained indicate that there is ample variation within eggplant for composition traits and this can be exploited for the selection of varieties with nutritionally improved characteristics. In this respect, we have identified several landraces with high nutritional quality.     

Diversity in composition of scarlet (S. aethiopicum) and gboma (S. macrocarpon) eggplants and of interspecific hybrids between S. aethiopicum and common eggplant (S. melongena)

Scarlet (Solanum aethiopicum) and gboma (S. macrocarpon) eggplants are cultivated vegetable crops native to Africa, for which no comprehensive reports exist on composition and diversity. We have evaluated diversity in composition of three varieties of scarlet eggplant and four varieties of gboma eggplant, as well as of four interspecific hybrids between scarlet and common eggplant (S. melongena) and their respective parents. With the exception of moisture (between 85.8 and 88.3 g/100 g) and pH (between 5.32 and 5.89), there was a wide diversity among varieties within each of the species for the composition traits evaluated, revealing ample possibilities for selection of varieties with improved fruit composition. Scarlet eggplant varieties evaluated presented, on average, lower content than gboma eggplant varieties for carbohydrates (3.60 vs 6.48 g/100 g), starch (3.18 vs 6.15 g/100 g), vitamin C (11.6 vs 18.9 mg/100 g), and total phenolics (24.4 vs 144 mg/100 g) and higher values for soluble sugars content and for the ascorbic/dehydroascorbic acid ratio. Interspecific hybrids between scarlet and gboma eggplants presented moisture content (79.0 g/100 g) and pH (5.15) values below those of any of the parents. For the rest of traits, values were intermediate between both parents, although much more similar to the scarlet eggplant parent.     

Dietary fiber,phytochemical composition and antioxidant activity of Mexican commercial varieties of cactus pear

Cactus pear is one of the most important fruit in Mexican culture; however the phytochemical characterization of the whole cactus pear (pulp, peel and seeds) has not been studied. Therefore, the goal of this research was to evaluate the dietary fiber, vitamin C, total phenolic (TP), flavonoid and betalain concentrations and antioxidant activity (AOX) in the pulp, juice, peel and seeds of four Mexican commercial varieties of cactus pear. Rojo Cenizo and Rojo San Martín pulps presented concentrations of total dietary fiber, vitamin C, TP, betalains, and AOX of 145–166 g, 3–7 g ascorbic acid, 3–6 g gallic acid equivalents (GAE), 500–3444 mg betanin equivalents and 1044–5954 mg indicaxanthin equivalents, and 46–67 mm Trolox equivalents (TE) per kg, respectively. Rojo San Martín peel presented TP content over two times greater than the pulp, whereas AOX levels of Rojo San Martín and Verde Villanueva peels were 4–9 higher than their respective pulp. Cactus pear peel was the most important source of phytochemical compounds and AOX of the fruit, because of that it has to be considered in future applications for the formulation of new health-promoting ingredients and/or foods.     

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.     

The oxalate content of fruit and vegetable juices,nectars and drinks

Fruit and vegetable juices are recommended for the treatment of hypocitraturia in calcium oxalate stone disease as alternatives to drugs containing alkaline citrate. Since dietary oxalate can contribute considerably to urinary oxalate excretion, the oxalate content of vegetable and fruit juices, nectars and drinks was analyzed using a validated HPLC-enzyme-reactor method. The highest oxalate concentrations were found in rhubarb nectar (198.3 mg/100 ml) and beetroot juices (60.1–70.0 mg/100 ml). The oxalate levels of all other beverages were below 10 mg/100 ml. Interestingly, except for carrot juice, the oxalate content of juices containing vegetables from organic farming was higher than from conventional farming. The consumption of even 500 ml/d of certain vegetable juices can contribute to a considerable extent to the daily oxalate intake. Calcium oxalate stone formers should therefore pay attention not only to the oxalate content but also to the ingested amount of these beverages.     

Effect of cultivar and storage temperature on identification and stability of polyphenols in strawberry cloudy juices

The effect of strawberry (Fragaria x ananassa Duchesne) cultivars (cvs) and storage temperature on the stability of polyphenols in cloudy juices was determined. Identification of phenolic compounds by ultra performance liquid chromatography-electrospray ionization/mass spectrometry (UPLC–ESI/MS), as well as quantitative analysis by ultra-performance liquid chromatography–photodiode array–fluorescence (UPLC–PDA–FL), were carried out on fresh and stored products (6 months, 4 °C and 20 °C) from 7 different strawberry cvs. A total of 32 polyphenolic compounds were identified: flavan-3-ols (6), anthocyanins (8), flavonols (4) and flavones (3), hydroxycinnamic acids (4), and ellagic acid derivatives (7). Total polyphenol content ranged from 642.08 mg/L in fresh ‘Florence’ cv. juice to 296.72 mg/L in ‘Honeoye’ cv. juice after 6 months of storage at 20 °C. Anthocyanins (max. 161.40 mg/L in ‘Honeoye’ juice) demonstrated the greatest degree of degradation (31–100%, depending on the molecular structure and temperature). Cyanidin-3-malonylglucoside was less labile than 3-glucoside. In the case of pelargonidin glycosides, 3-glucoside was more stable. The degradation process was the least advanced in ‘Kimberly’ cv. juice (58.53% at 4 °C). Storage conditions also influenced the decrease in p-coumaroyl-hexose, and quercetin-glucuronide content. However, low temperatures limited this process. This was especially noticeable in ‘Florence’ and ‘Honeoye’ cvs. In turn, proanthocyanidins showed the most stability and were the main polyphenols identified in juices (212–434 mg/L). Generally, it was observed that the total content of polyphenols and their stability in juices was dependent on the cultivar, and the duration of storage conditions.     

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.     

The effect of frying on anthocyanin stability and antioxidant activity of crisps from red- and purple-fleshed potatoes (Solanum tuberosum L.)

Red- and purple-fleshed potatoes (Solanum tuberosum L.) are a good source of polyphenols, mainly anthocyanins as one of the most important components. The chemical composition with reducing sugars and the total polyphenol contents were analyzed in four purple potato varieties (Salad Blue, Vitelotte, Valfi, Blue Congo) and three red-fleshed potato varieties (Rosalinde, Herbie 26, Highland Burgundy Red). The anthocyanin composition of raw potato and potato crisps was characterized by high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method. Moreover, the antioxidant activity was measured with the radical scavenging assays using 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as ferric reducing ability of plasma assay (FRAP). In addition, colour parameters in prepared potato crisps were evaluated. Both red and purple-fleshed potato varieties contained high levels of total polyphenols (227–845 mg 100 g⁻¹ dry weight) and anthocyanins (21–109 mg 100 g⁻¹ dry weight). The process of frying caused degradation of anthocyanin compounds (38–70%). The HPLC–MS/MS analysis showed that pelargonidin and malvidin derivates were more stable during frying than petunidin derivatives. Although frying process affected the anthocyanin and polyphenol levels, obtained potato crisps exhibited bright intensive colour and good antioxidant activity.     

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).     

Phenolics and abscisic acid identified in acacia honey comparing different SPE cartridges coupled with HPLC-PDA

The major components of honey are sugar and water, but some phenolic compounds may be responsible for honey quality. We investigated the effects of four reversed-phase (RP) and four reversed-phase and anion-exchange (RP-AE) solid-phase extraction (SPE) cartridges as a pre-concentration technique for honey phenolics. Eleven acacia honey samples were collected from different apiaries of China and their levels of phenolics and abscisic acid were analyzed using high-performance liquid chromatography (HPLC). Our results reveal that RP-AE SPE cartridges are superior to RP SPE cartridges for the pre-concentration of honey phenolics. The improved pre-concentration effect of RP-AE SPE cartridges may be a novel finding of our research. The Strata-X-A cartridge may be used in the concentration of low content phenolics of complex food matrices. We identified cis-trans-abscisic acid and 19 phenolics occurring in acacia honey samples. Seven phenolic compounds and abscisic acid were identified in almost all samples, representing 50% of total phenolics. Abscisic acid possesses the highest average content of 146.0 μg/100 g, and pinobanksin also presented the highest average of 53.1 μg/100 g among all flavonoids. Moreover, we infer that abscisic acid could be the solid ingredient for adulteration identification and quality control of acacia honey.     

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.     

Seasonal and cultivar variations in antioxidant and sensory quality of pomegranate (Punica granatum L.) fruit

Fruits of diverse pomegranate (Punica granatum L.) cultivars were analyzed for soluble phenolics content, antioxidant activity, soluble solid concentration, acidity and internal red color intensity. Analysis was carried out at various dates throughout the harvest season, corresponding to different climatic conditions during fruit ripening. Values obtained varied with cultivar and ripening date. In three cultivars of different sensory properties and harvest season, comparison between late- and early-ripening fruit revealed that arils of fruit ripening later in the season contained more soluble phenolics (1.21–1.71 compared to 0.22–0.88 pyrogallol equivalents, g L^?1) and exhibited a higher antioxidant activity, as measured by the ferric reducing ability (FRAP) assay (1.22–2.37 compared to 0.86–1.95 vitamin C equivalents, g L^?1). The red color intensity of the arils inversely related (R² = 0.89–0.94) to the sum of heat units accumulated during fruit ripening. Multiple linear regression analysis on fruit characteristics in 11 diverse cultivars indicated that juice antioxidative capacity linearly correlated with soluble phenolics content (R² = 0.98), but not with the red color intensity of the arils (R² = 0.38). Also, no significant correlation was established between aril color and either juice pH or total soluble phenolics content. The results imply that pomegranate fruit antioxidant and sensory quality traits can be enhanced by the choice of cultivar and controlled-climate cultivation management.     

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.     

Mineral micronutrient and prebiotic carbohydrate profiles of USA-grown kale (Brassica oleracea L. var. acephala)

Kale (Brassica oleracea L. var. acephala.) is a leafy green brassica vegetable, the production levels of which have increased over the past 10 years due to increased demand by North American consumers. Kale is perceived to be highly nutritious leafy green vegetable even though its nutrient profile has not been well characterized to date. The objective of this study was to determine the nutritional composition (energy, protein, mineral, and prebiotic carbohydrate concentrations) of 25 different kale genotypes grown in Pelion, South Carolina, USA, and assess its potential as a whole food source of daily essential minerals and dietary fiber. The results of this study show a single 100 g serving of fresh kale can provide a significant percentage of the recommended daily intake of mineral micronutrients (188–873 mg K; 35–300 mg Ca; 20–100 mg Mg) identified by the 2015 Dietary Guidelines Advisory Committee as being underconsumed by Americans. This serving of kale can also provide approximately 0.4–6.7 g of prebiotic carbohydrates, including sugar alcohols (45.4–59.8 mg), simple sugars (0.4–3348 mg), and hemicellulose (245–703 mg). Fresh kale is a low calorie food (36–98 kcal/100 g) with moderate levels of protein (1.6–5.9 g/100 g). Among the genotypes studied, ‘Frizzy Lizzy’, ‘Dauro’ and ‘Fizz’ have significantly high levels of essential minerals and prebiotic carbohydrates, moderate protein content, and low caloric value. These data confirm that kale is a whole food that can provide significant quantities of daily essential minerals and prebiotic carbohydrates. By genetic and location sourcing, the nutritional quality of kale could be further enhanced to benefit North American consumers.     

Comparative study of the nutritional and bioactive compounds content of four walnut (Juglans regia L.) cultivars

The proximate and mineral composition, fatty acid profile, total polyphenol, melatonin and serotonin contents were assessed in four walnut (Juglans regia L.) cultivars (cv. Serr, Hartley, Chandler and Howard). The aim was to decide which cultivar is the most suitable from a nutritive, but also commercial, point of view. Proteins and fats accounted for more than 70% of the walnut kernel weight. Due to their content in bioactive compounds such as melatonin, serotonin and total phenols, their high content in magnesium (up to 443 mg 100 g⁻¹ FW) and other minerals, their high contents in polyunsaturated fatty acids (up to 78.0% of total fatty acids) and their favorable n−6/n−3 ratio, among other healthful properties, consumption of all the studied cultivars would be potentially beneficial to health. According to its fatty acid profile, Howard would be the most healthful cultivar, but also it would be theoretically the most sensitive to rancidity, and thus the cultivar with the shortest shelf life. Nonetheless, this cultivar showed the highest content in the antioxidants melatonin and total polyphenols.     

Determination of free quinic acid in food matrices by Hydrophilic Interaction Liquid Chromatography with UV detection

A new method using Hydrophilic Interaction Liquid Chromatography and UV detection was developed for the determination of free quinic acid in fourteen commercial beverages (fruit juices, red wine, coffee, vinegar, and edible mushroom extract). Samples were directly injected into the HPLC system after dilution and centrifugation. All separations were carried out by gradient elution on a ZIC^®-cHILIC column, using an eluent consisting of acetonitrile and aqueous phosphate buffer at pH 6. Quinic acid eluted in 12 min as a symmetric peak well separated from all other peaks in the chromatograms. The total turnaround time per sample was 60 min. The method was validated using cranberry juice as model beverage matrix. Linearity was demonstrated on spiked juice between 200 and 600 μg/mL (r² = 0.999), and precision and accuracy were satisfactory (RSD ≤ 10% and recovery 100 ± 1%, respectively).The method was proven to be suitable for its purpose. Quinic acid levels ranged from undetectable (<15 μg/mL in red grape juice, elderberry juice, and in red wine vinegar) to 740 ± 30 μg/mL (in mushroom extract). The results were discussed in comparison with the previous reports on similar matrices using different HPLC separation modes.     

Thiamin fortification of bread-making flour: Retention in bread and levels in Australian commercial fortified bread varieties

In Australia, thiamin is mandatorily added to bread-making flour with the main purpose of fortification and reducing the prevalence of Wernicke–Korsakoff syndrome. This study aims to measure the retention of added thiamin through laboratory-scale bread processing and provide an update on thiamin contents in commercially fortified bread and flatbread varieties since the introduction of the program in 1991. Even though baking caused degradation loss of thiamin (approximately 16%), the laboratory fortified white bread had a 25% higher thiamin content than its corresponding flour, and laboratory fortified wholemeal bread showed a 16% increase (p < 0.05). Thiamin levels in commercially fortified bread and flat bread varieties ranged between 0.24 and 1.9 mg/100 g (dry weight basis). It can be suggested that most of the bread varieties were made from flour fortified at the minimum mandated level (0.64 mg/100 g flour). Samples of flat bread varieties (white without yeast, wholemeal with yeast and wholemeal without yeast) showed low thiamin levels (0.24–0.49 mg/100 g, dry weight basis). The results suggest that the flat bread varieties were likely made from either commercially under-fortified flour or unfortified general-purpose flour, as only bread-making flour is fortified with thiamin.     

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.     

Nutritional value of tomatoes (Solanum lycopersicum L.) grown in greenhouse by different agronomic techniques

The relevance of agronomic practices on the nutritional quality greenhouse-grown tomatoes has been recognized. We investigated the influence of (1) cultivar: two local (Pera-Girona and Montserrat) and one commercial (Caramba) varieties; (2) nitrogen dose in nutrient solution (low vs. standard N dose); (3) treatment for plant disease control (sulfur vs. Milsana^®) and (4) ripeness (orange vs. full-red color) on levels of carotenoids, phenolic compounds, ascorbic acid and minerals of fruits. Carotenoids and ascorbate were mainly influenced by variety and ripening stage, while N dose slightly affected minerals in fruits; treatments against plant diseases exerted only negligible effects on measured compounds. Local tomato varieties appear more promising as food source of carotenoids, mainly lycopene, and of hydroxycinnamates, such as 5-caffeoylquinic acid and caffeoylquinic derivatives, than commercial variety (total carotenoids: 67.43 mg kg⁻¹ fw vs. 56.34 mg kg⁻¹ fw of Pera-Girona vs. Caramba and total hydroxycinnamates: 90.87 mg kg⁻¹ fw vs. 37.90 mg kg⁻¹ fw of Montserrat vs. Caramba, at full-red color). Tomato variety and harvest maturity of fruit were the main factors affecting nutritional value of tomatoes, while Milsana^® treatment did not result in evident nutritional benefits. However, the use of this elicitor might be appropriate considering the increasing environmentally friendly attitudes of consumers.     

Identification and quantification of phenolic compounds responsible for the antioxidant activity of sweet potatoes with different flesh colours using high performance thin layer chromatography (HPTLC)

The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones.