Distribution of quercetin-3,4′-O-diglucoside,quercetin-4′-O-monoglucoside,and quercetin in different parts of the onion bulb (Allium cepa L.) influenced by genotype

Flavonoids have gained much attention because of their proposed positive effects for human health. Onions are a rich source of flavonoids, consisting mainly of the major flavonols quercetin-3,4′-O-diglucoside (QDG) and quercetin-4′-O-monoglucoside (QMG) in the bulb and the aglycone quercetin in the outer scales. In this study, distribution of these three flavonoids was determined in 16 onion cultivars (Allium cepa) using HPLC–DAD. Three different parts of the onion bulb, the inner layers, the middle layers and the outer scales were analysed. The analysis showed varietal differences in the selected onion cultivars. The cultivars with the highest total flavonoid content were the red skinned ‘Red Baron’ and the yellow skinned cultivars ‘Ailsa Craig’ and ‘Prilep’. The distribution of the total flavonoid content in the different parts of the onion bulb showed the following order: middle layers > outer scales > inner layers. In the inner layers QDG was the major flavonoid, while in the middle layers QDG and QMG were in equal amounts. In the outer scales quercetin was the major flavonoid prior to QMG.     

Flavonoid constituents and their contribution to antioxidant activity in cultivars and hybrids of rabbiteye blueberry (Vaccinium ashei Reade)

Fruit from 42 blueberry (Vaccinium spp.) cultivars, including 36 rabbiteye cultivars (Vaccinium ashei Reade), three V. ashei hybrid derivatives, and three northern highbush (Vaccinium corymbosum L.) standards were evaluated for antioxidant capacity, individual flavonoid content, and the contribution of each identified phenolic compound to total antioxidant activity. Considerable variation was found in flavonoid content, antioxidant activity, and their contribution to total antioxidant activity among cultivars. Among 42 blueberry cultivars, the rabbiteye ‘Early May’ contained the highest amount of chlorogenic acid, myricetin 3-arabinoside, quercetin derivatives, and delphinidin-, cyanidin-, petunidin-, and malvidin-basis anthocyanins. ‘Early May’ cultivar also had the highest antioxidant activity (88.2 μmol TE/g fw). ‘Owen’, ‘Bluegem’, ‘Clara’, Climax’, and ‘Centurion’ were among the other rabbiteye cultivars that also had high levels of flavonoids and antioxidant activities. In contrast, the pink-fruited V. ashei hybrid, ‘Pink Lemonade’, had the lowest content of flavonoids and lowest antioxidant activity. The mean flavonoid content and antioxidant activity of rabbiteye cultivars was higher than those among northern highbush and V. ashei hybrids. The antioxidant activity of V. ashei hybrid derivatives was derived mainly from chlorogenic acid, myricetin, and quercetin, which contributed 62.5% of total antioxidant activity, whereas anthocyanins (malvidin, petunidin, delphinidin, and cyanidin) were the main contributors to the antioxidant activity of rabbiteye cultivars (76.2%) and northern highbush standards (76.8%). Blueberry cultivars identified to have high phenolic content and high antioxidant activity could be used as parents for future blueberry breeding programmes to develop new blueberry cultivars with higher antioxidant activity and further improve human health.     

Improved loquat (Eriobotrya japonica Lindl.) cultivars: Variation of phenolics and antioxidative potential

Leaves and fruits (peel and flesh) of six improved cultivars (‘Mizuho’, ‘Néctar de Cristal’, ‘Mizauto’, ‘Mizumo’, ‘Centenária’ and ‘NE-3’) of loquat (Eriobotrya japonica Lindl.) were studied for their phenolic composition and antioxidant capacity. The analysis by HPLC-DAD-ESI-MS/MS allowed the identification of 18 compounds (8 hydroxycinnamic acid derivatives and 10 flavonoid glycosides). The quantification of the identified compounds revealed distinct profiles amongst the three analysed materials. Loquat leaves exhibited the lowest amounts of phenolics. 3- And 5-caffeoylquinic, and 5-feruloylquinic acids were the major compounds. Generally, ‘Mizauto’ cultivar presented the highest phenolic content. All loquat materials exhibited DDPH scavenging capacity, in a concentration-dependent manner, the leaves being the most active one. This effect seems to be related to the flavonoid content.     

Effect of curing and cooking on flavonols and anthocyanins in traditional varieties of onion bulbs

The stability of the major flavonol glucosides and anthocyanins was studied in two regional varieties of Portuguese onion (a white variety “branca da Póvoa” and a red variety “vermelha da Póvoa”). White and red onions from 2007 and 2008 harvests were subjected to field curing with and without light, but the red cultivar from 2008 was also subjected to typical domestic processing, including chopping and different cooking treatments. Field curing resulted in increases in quercetin content compared to levels at lifting, especially important for all white bulbs (33–40% increase). Flavonol and anthocyanin levels in onions cured in the dark were similar to those obtained in bulbs cured in the light. The treatments chopping followed by refrigerated storage, oven roasting and frying, did practically not contribute to modify the total levels of flavonols. Moderate microwave cooking did not affect to the flavonol content, but intense microwave treatment cause flavonol losses of 16% and 18% for quercetin 3,4′-diglucoside (QdG) and quercetin 4′-glucoside (QmG), respectively. Boiling onions for 30 min leaded losses of quercetin glycosides, which leached to the boiling water without being degraded at 37% and 29% for QdG and QmG, respectively. Boiling for 60 min had more severe effects, since it caused the degradation of quercetin derivatives at 53% and 44% for QdG and QmG, respectively. For anthocyanins, the severity of the cooking treatments was in the following order: frying > boiling > roasting (microwave roasting > oven roasting).     

The flavonoid composition of flavedo and juice from the pummelo cultivar (Citrus grandis (L.) Osbeck) and the grapefruit cultivar (Citrus paradisi) from China

The flavonoid composition of flavedos and juices from four Chinese pummelo cultivars (Citrus grandis ‘Shatianyu’, C. grandis ‘Guanximiyu’, C. grandis ‘Yuhuanyu’, and C. grandis ‘Cuixiangtianyu’) and one grapefruit cultivar (Citrus paradisi ‘Changshanhuyu’), was investigated using high-performance liquid chromatography diode array detection electrospray ionisation mass spectrometry (HPLC-DAD-ESI MS/MS). Twenty-eight flavonoids were identified. Naringin was the predominant flavanone in these pummelo varieties, whereas naringin and neohesperidin were the principal flavanones found in C. paradisi ‘Changshanhuyu’. The four pummelo cultivars had higher levels of flavones when compared with the grapefruit. Based on the flavonoid profiles in flavedos and juices, four pummelo cultivars and one grapefruit cultivar were well separated.     

Phenolic acids and flavonoids in leaf and floral stem of cultivated and wild Cynara cardunculus L. genotypes

Ten genotypes, cultivated and wild of Cynara cardunculus L. were evaluated for their content of phenolic acids, flavonoids and their antioxidant activity. The major compounds present in the leaf were luteolin derivatives in globe artichoke and apigenin derivatives in wild and cultivated cardoon. Apart from ‘Cimiciusa di Mazzarino’ (var. scolymus), caffeoylquinic acids represent the main phenolic compounds in the floral stem. In particular, ‘Sylvestris Creta’ (var. sylvestris) and ‘Violetto di Sicilia’ (var. scolymus) show the highest content of caffeoylquinic acid ∼95% of the total measured polyphenols. The antioxidant capacity, in both leaf and floral stem, was qualitatively and quantitatively dependent on the phenolic acid and flavonoid profile. The phenolic acids and flavonoids in normally uneaten parts of wild and cultivated artichoke could be exploited as sources of natural antioxidants.     

Factors affecting growth of foodborne pathogens on minimally processed apples

Escherichia coli O157:H7, Salmonella and Listeria innocua increased by more than 2 log₁₀ units over a 24 h period on fresh-cut ‘Golden Delicious’ apple plugs stored at 25 and 20 °C. L. innocua reached the same final population level at 10 °C meanwhile E. coli and Salmonella only increased 1.3 log₁₀ units after 6 days. Only L. innocua was able to grow at 5 °C. No significant differences were observed between the growth of foodborne pathogens on fresh-cut ‘Golden Delicious’, ‘Granny Smith’ and ‘Shampion’ apples stored at 25 and 5 °C. The treatment of ‘Golden Delicious’ and ‘Granny Smith’ apple plugs with the antioxidants, ascorbic acid (2%) and NatureSeal^® (6%), did not affect pathogen growth. The effect of passive modified atmosphere packaging (MAP) on the growth of E. coli, Salmonella and L. innocua on ‘Golden Delicious’ apple slices was also tested. There were no significant differences in growth of pathogens in MAP conditions compared with air packaging of ‘Golden Delicious’ apple plugs, but the growth of mesophilic and psychrotrophic microorganisms was inhibited. These results highlight the importance of avoiding contamination of fresh-cut fruit with foodborne pathogens and the maintenance of the cold chain during storage until consumption.     

Antioxidant and radioprotective properties of commercially grown litchi (Litchi chinensis) from India

In an earlier study, radiation treatment (0.5 kGy) and low temperature (4 °C) storage were found to extend the shelf life of litchi fruit var. ‘Shahi’ and ‘China’ from India up to 28 days, while maintaining its physical, biochemical and organoleptic properties. The current study was aimed to elucidate the antioxidant and radioprotective properties of the litchi fruit, and the effect of radiation processing on these properties. The litchi fruit was found to be significantly rich in antioxidant and radioprotective properties, and the antioxidant parameters were found to be well correlated with the phenolic and flavonoid contents. A significant protection to pBR322 plasmid DNA and Escherichia coli cells from radiation induced damage was observed in the presence of litchi juice. Plasmid DNA was well protected even at the dose of 5 kGy, whereas, bacterial cells could be protected up to 0.5 kGy. Neither of these properties was found to be sensitive to radiation processing or low temperature storage.     

Exploring the phytochemical content and the antioxidant potential of Citrus fruits grown in Cyprus

The physicochemical and phytochemical profile as well as the antioxidant properties of the most important Citrus fruits grown in Cyprus [orange (Citrus sinensis, cv. ‘Valencia’), grapefruit (Citrus paradisi, cvs. ‘White Marsh’, ‘Star Ruby’, ‘Rio Red’) and an interspecific hybrid (Citrus reticulata x Citrus sinensis, cv. ‘Mandora’)] were determined. ‘Valencia’ fruit exhibited the highest phenolic, flavonoid and ascorbic acid content, as well as a higher antioxidant potency, followed by ‘Mandora’ fruit and the three grapefruit cultivars. HPLC indicated significant diversity on flavanones among the examined fruits, while LC-MS analysis revealed the presence of hydroxycinnamic acid derivatives, polymethoxyflavones and a furocoumarin. Overall, this study provides supporting evidence for the superiority of ‘Valencia’ orange fruit as an excellent source of bioactive compounds. In addition, to the best of our knowledge, this is the first study thoroughly describing the phytochemical profile of ‘Mandora’ fruit, an interspecific hybrid cultivated in Cyprus.     

Characterisation of onion (Allium cepa L.) by-products as food ingredients with antioxidant and antibrowning properties

Processing and stabilising onion wastes (residues and surpluses of onion) could solve the environmental problem derived from a great onion wastes disposal. Moreover, obtaining stabilised onion by-products as natural antioxidant food ingredients could be advantageous to food industry, not only to improve the use of onion wastes but also to obtain new natural and functional ingredients. The aim of this study was to characterise onion by-products – juice, paste and bagasse – from two Spanish onion cultivars – ‘Figueres’ and ‘Recas’ – that have been stabilised by thermal treatments – freezing, pasteurisation and sterilisation – in order to evaluate the effect of the processing and stabilisation treatment on the bioactive composition, antioxidant activity and polyphenol oxidase (PPO) enzyme inhibition capacity. The results obtained triggered to choose one onion by-product offering better characteristics for its potential development as a food ingredient: source of antioxidant and antibrowning bioactive compounds. In this study it was shown that processing of ‘Recas’ onion wastes to obtain a paste (mixture content) and applying a mild pasteurisation were the best alternatives to obtain an interesting stabilised onion by-product with good antioxidant properties that made useful its use as functional food ingredient.     

Horticultural characteristics and chemical composition of advanced raspberry lines from Quebec and Ontario

Three advanced raspberry (Rubus idaeus L.) lines from the University of Guelph breeding program (‘88-18’, ‘88-117’, ‘88-134’) and one advanced line from the Quebec fruit breeding program (‘SJR942-7’) were tested for their winter hardiness, fruit quality, horticultural characteristics and antioxidant activity compared to four commercially grown cultivars (‘Festival’, ‘Boyne’, ‘Nova’ and ‘Killarney’) recommended for Quebec. Lines ‘88-18’ from Guelph and ‘SJR942-7’ from Quebec had higher antioxidant activity, larger fruit size, better fruit quality and longer shelf life than all other lines and cultivars tested. The ellagic acid content of ‘SJR942-7’ was approximately two times higher than that of the commercial cultivars grown in Quebec.     

Influence of genotype,harvest time and plant part on polyphenolic composition of globe artichoke [Cynara cardunculus L. var. scolymus (L.) Fiori]

Globe artichoke is an ancient herbaceous plant native to the Mediterranean Basin. The edible part of the plant (head) is particularly rich in polyphenols, whose therapeutic properties are well documented. A field experiment was conducted in Sicily (south Italy) to examine the influence of genotype and harvest time on the polyphenol content and profile of different head parts. The concentrations of 19 phenolic compounds were determined by HPLC-DAD-ESI/MSⁿ analysis. It was observed that individual phenolic substances were preferentially accumulated in specific head parts and genotypes. Apigenin 7-O-glucuronide was found to be the major flavonoid, with 6298 mg kg⁻¹ DM in ‘Romanesco clone C3’ receptacle, whereas chlorogenic acid represented the main caffeoylquinic acid, reaching 14841 mg kg⁻¹ DM in the inner bracts of ‘Violetto di Sicilia’. Our findings prove also the influence of climatic conditions on the phenolic profile and thus suggest giving specific consideration to harvest time.     

Profiling and quantifying quercetin glucosides in onion (Allium cepa L.) varieties using capillary zone electrophoresis and high performance liquid chromatography

There is increasing evidence that flavonols demonstrate beneficial properties for human health. Quercetin is the major flavonol present in onion (Allium cepa cv) and is present predominantly as quercetin 3,4′-diglucoside and quercetin 4′-monoglucoside. These compounds are known to be potent free radical scavengers and antioxidants, and are considered to be protective against cardiovascular disease. Analysis for the presence of these compounds has therefore become more important. Robust capillary zone electrophoresis and high performance liquid chromatography procedures were developed for profiling and quantifying the levels of quercetin 3,4′-diglucoside and quercetin 4′-monoglucoside in 70% methanol/water extracts of six different onion varieties available in Victoria, Australia. Quercetin 3,4′-diglucoside, which is not commercially available as a reference standard, was isolated from freeze-dried onion powder by preparative high performance liquid chromatography and used to quantify the levels in the onion extracts. Significant differences in the levels and ratios of the two compounds were seen between red, brown and white onion varieties (e.g. ‘Redwing’; quercetin 3,4′-diglucoside 191 mg/100 g DW, quercetin 4′-monoglucoside 85 mg/100 g DW; ‘Cream Gold’, quercetin 3,4′-diglucoside 153 mg/100 g DW, quercetin 4′-monoglucoside 58 mg/100 g DW, ‘Spanish white’; quercetin 3,4′-diglucoside <1 mg/100 g DW, quercetin 4′-monoglucoside <1 mg/100 g DW).     

Chitin content of cultivated mushrooms Agaricus bisporus, Pleurotus ostreatus and Lentinula edodes

The chitin contents of pileus and stipes of fruit bodies of Agaricus bisporus, Pleurotus ostreatus and Lentinula edodes (shii take) were determined and compared. The fruit bodies of different, common varieties of the cultivated mushroom species were taken from Hungarian and German large-scale farming. The analytical procedure was carried out on the powder of cleaned, dried and milled pileus and stipes. The pileus of A. bisporus variety ‘K-23’ showed a significant decrease (p < 0.05) during the cultivation’s flushes (breaks), 1–3, while the chitin level of stipes seemed to be constant. The other analysed A. bisporus varieties (var. ‘158’, ‘K-7’, ‘Sylvan A-15’, ‘Sylvan 608’, and Le Lion C-9) had practically the same chitin levels. This indicates that the chitin content is a stable characteristic of the species and there are no significant differences between the different varieties. The chitin levels of pileus and stipes were not significantly different (for A. bisporus, 6.68 and 7.25) but showed significant differences for P. ostreatus (p < 0.05) and L. edodes (p < 0.001). In the case of the latter two species, the pileus had the higher and the stipe the lower chitin content. The presented data confirm that a mushroom saprotrophic (A. bisporus) had higher chitin level than had the wood-rotting ones (P. ostreatus, L. edodes).     

Kiwifruit remnants from digestion in vitro have functional attributes of potential importance to health

The physicochemical properties of plant cell walls in the gut are important in modulating processes that influence health. We investigated the physicochemical properties of kiwifruit cell walls digested under gastric and gastroileal conditions in vitro. Soluble and insoluble undigested polymer fractions were measured, the hydration properties of the digested pulp, and the capacity to retard diffusion and mixing in a simulated small intestinal segment. Undigested polymer (dietary fibre) fractions differed little between “Hayward’ (‘Hayward’) and ‘Hort16A’ (gold) kiwifruit cultivars in their relative proportions, although total dietary fibre was greater in ‘Hayward’ than in the ‘Hort16A’. The polysaccharide composition of seed-free digestion-resistant polymer was similar in both cultivars and not affected by in vitro digestion. Indigestible remnants from kiwifruit had strong water retention and swelling capacities, also little affected by digesting, and retarded both glucose diffusion and mixing significantly, especially in the presence of low background viscosity. We conclude that the particulate cell wall remnants of digested kiwifruit retain substantial potential to influence the properties of gut contents.     

Variation of total phenolics, anthocyanins, ellagic acid and radical scavenging capacity in various raspberry (Rubus spp.) cultivars

The aim of this study was to assess the level of some phytochemicals in 19 raspberry cultivars grown in Lithuania. The content of total ellagic acid measured after 20 h acidic hydrolysis of investigated raspberry cultivars, varied from 119.8 (cv. ‘Pokusa’) to 323.5 mg/100 g (cv. ‘Bristol’). The content of total phenolics ranged from 278.6 (cv. ‘Pokusa’) to 714.7 mg/100 g (cv. ‘Bristol’). The total anthocyanins content varied from 2.1 (yellow cv. ‘Beglianka’) to 325.5 mg/100 g (black cv. ‘Bristol’). The radical scavenging capacity of the tested raspberry cultivars highly correlating with their total phenolics and total ellagic acid content (r = 0.90 and 0.92, respectively). The results of this study expand the knowledge about variation in the content of valuable bioactive compounds in raspberries and may help for the selection and validation of the most productive cultivars.     

Evaluation of Penicillium expansum isolates for aggressiveness, growth and patulin accumulation in usual and less common fruit hosts

Experiments were carried out in vivo and in vitro with four isolates of Penicillium expansum (I 1, E 11, C 28 and I 12) to evaluate their aggressiveness, growth and patulin accumulation in both usual (pears and apples) and less common hosts (apricots, peaches, strawberries and kiwifruits) of the pathogen. The 75% of isolates showed the ability to cause blue mould in all tested hosts. In particular, C 28 and I 1 were the most and the least aggressive isolates, respectively (52.9 and 10.6% infection and 20.7 and 15.4 mm lesion diameters). ‘Candonga’ strawberries and ‘Pinkcot’ apricots showed the largest lesion diameters (29.8 and 25.3 mm), followed by ‘Conference’ pears, ‘Spring Crest’ peaches and ‘Abate Fetel’ pears. With the exception of ‘Candonga’ strawberries, the formation of colonies and mycelial growth of P. expansum isolates on fruit puree agar media (PAMs) was stimulated in comparison to a standard growth medium (malt extract agar, MEA). Two of the most aggressive isolates in our assays (I 12 and C 28) showed the greatest accumulation of patulin both in vitro and in vivo, while the least aggressive isolate (I 1) produced patulin only in a few growth media and cvs. Patulin concentration on fruit PAMs was higher than patulin detected in infected fruit tissues. Apple PAMs were the more favorable substrates for patulin accumulation in vitro (maximum concentration 173.1 and 74.1 μg/mL in ‘Pink Lady and ‘Golden Delicious’ PAMs, respectively) and ‘Pink Lady’ apples inoculated with the isolate E 11 showed the greatest accumulation of patulin in the whole in vivo assay (33.9 μg/mL). However, infected tissue of cv Golden Delicious showed lower average accumulation of patulin (1.7 μg/mL) than that of cv Pink Lady (19.1 μg/mL), and no significant differences in patulin concentrations were found among ‘Golden Delicious’ apples and tested cvs of pears, kiwifruits and strawberries. Peaches were highly susceptible to patulin accumulation, showing average concentrations of 27.4 and 18.6 μg/mL in vitro and in vivo, respectively. Apricots were also consistently positive for patulin accumulation, both in vitro (average values of 20.1 μg/mL) and in vivo (average values of 9.4 μg/mL). Our study showed the potential of some less common hosts of P. expansum (in particular peaches and apricots) to support patulin production, indicating that a steady monitoring of patulin contamination should be carried out in fruit substrates other than apples and pears.     

European elderberry (Sambucus nigra L.) rich in sugars,organic acids,anthocyanins and selected polyphenols

Sugars and organic acids in the fruit of two cultivars and three selections of black elderberry (Sambucus nigra L.): ‘Haschberg’, ‘Rubini’, ‘Selection 13’, ‘Selection 14’ and ‘Selection 25’ were quantified. The anthocyanin as well as quercetin profiles of this plant material were also established by the use of HPLC/MS. Significant differences in the concentration of sugars and organic acids were detected between the widely spread cultivar ‘Haschberg’ and all other cultivars/selections; ‘Haschberg’ was the richest in organic acids (6.38 g kg⁻¹ FW), and it contained the least sugar (68.5 g kg⁻¹ FW). The following major cyanidin based anthocyanins were identified in the fruit of black elderberry: cyanidin 3-sambubioside-5-glucoside, cyanidin 3,5-diglucoside, cyanidin 3-sambubioside, cyanidin 3-glucoside and cyanidin 3-rutinoside. The most abundant anthocyanin in elderberry fruit was cyanidin 3-sambubioside, which accounted for more than half of all anthocyanins identified in the berries. The ‘Rubini’ cultivar had the highest amount of the anthocyanins identified (1265 mg/100 g FW) and the lowest amount was measured in berries of the ‘Selection 14’ (603 mg/100 g FW). The ‘Haschberg’ cultivar contained a relatively low amount of anthocyanins in ripe berries (737 mg/100 g FW). From the quercetin group, quercetin, quercetin 3-rutinoside and quercetin 3-glucoside were identified; the latter prevailing in black elderberry fruit. The cultivar with the highest amount of total quercetins was ‘Selection 25’ (73.4 mg/100 g FW), while the ‘Haschberg’ cultivar contained average amounts of quercetins (61.3 mg/100 g FW). The chemical composition of the ‘Haschberg’ cultivar, the most commonly planted, conforms to the standards for sugars, anthocyanins and quercetins and exceeds them in the content levels of organic acids, the most important parameter in fruit processing.