Stepwise mass spectrometry-based approach for confirming the presence of benzoxazinoids in herbs and vegetables.

INTRODUCTION: Benzoxazinoids (BXs) are plant phytochemicals that have both defensive properties in plants and therapeutic effects in humans. The presence of BXs has been largely studied in the Poaceae family (monocots). To study the presence or absence of BXs in dicotyledons and monocotyledons outside the Poaceae family, parts of 24 plant species at several growth stages were selected for analysis, some of which were already known to contain BXs. OBJECTIVES: To devise a stepwise mass spectrometry-based approach for confirming the presence of BXs in plant samples, and to use the method to explore the status of BXs in selected plant species. EXPERIMENTAL: Plant samples were extracted using accelerated solvent extraction and analysed using triple-quadrupole liquid chromatography-mass spectrometry. RESULTS: The use of different columns, double mass transitions, and ion ratios proved to be a robust tool for confirming the presence of BXs in different plant species. By this method, the presence of BXs was confirmed in three of the 24 species. Double-hexose forms of BXs, which have not been reported before in dicotyledons, were confirmed to be present in the dicotyledon plants Acanthus mollis and Lamium galeobdolon, and the presence of BXs in the seeds of Consolida orientalis is reported for the first time here. High concentrations of BXs were found in the aerial parts of Acanthus mollis and Lamium galeobdolon, at 20 and 32 µmol/g plant dry weight, respectively. CONCLUSIONS: The stepwise approach described in this work confirmed the presence of BXs in new samples.

Root isolations of Metarhizium spp. from crops reflect diversity in the soil and indicate no plant specificity.

Metarhizium spp. have recently been shown to be associated with the roots of different plants. Here we evaluated which Metarhizium species were associated with roots of oat (Avena sativa), rye (Secale cereale) and cabbage (Brassica oleracea), common crop plants in Denmark. Thirty-six root samples from each of the three crops were collected within an area of approximately 3ha. The roots were rinsed with sterile water, homogenized and the homogenate plated onto selective media. A subset of 126 Metarhizium isolates were identified to species by sequencing of the 5' end of the gene translation elongation factor 1-alpha and characterized by simple sequence repeat (SSR) analysis of 14 different loci. Metarhizium brunneum was the most common species isolated from plant roots (84.1% of all isolates), while M. robertsii (11.1%) and M. majus (4.8%) comprised the remainder. The SSR analysis revealed that six multilocus genotypes (MLGs) were present among the M. brunneum and M. robertsii isolates, respectively. A single MLG of M. brunneum represented 66.7%, 79.1% and 79.2% of the total isolates obtained from oat, rye and cabbage, respectively. The isolation of Metarhizium spp. and their MLGs from roots revealed a comparable community composition as previously reported from the same agroecosystem when insect baiting of soil samples was used as isolating technique. No specific MLG association with a certain crop was found. This study highlights the diversity of Metarhizium spp. found in the rhizosphere of different crops within a single agroecosystem and suggests that plants either recruit fungal associates from the surrounding soil environment or even govern the composition of Metarhizium populations.

Quality of carrots as affected by pre- and postharvest factors and processing.

The aim of this review is to provide an update on factors contributing to quality of carrots, with special focus on the role of pre- and postharvest factors and processing. The genetic factor shows the highest impact on quality variables in carrots, causing a 7-11-fold difference between varieties in content of terpenes, ß-carotene, magnesium, iron and phenolics as well as a 1-4-fold difference in falcarindiol, bitter taste and sweet taste. Climate-related factors may cause a difference of up to 20-fold for terpenes, 82% for total sugars and 30-40% for ß-carotene, sweet taste and bitter taste. Organic farming in comparison with conventional farming has shown 70% higher levels for magnesium and 10% for iron. Low nitrogen fertilisation level may cause up to 100% increase in terpene content, minor increase in dry matter (+4 to +6%) and magnesium (+8%) and reduction in ß-carotene content (-8 to -11%). Retail storage at room temperature causes the highest reduction in ß-carotene (-70%) and ascorbic acid (-70%). Heat processing by boiling reduces shear force (-300 to -1000%) and crispiness (-67%) as well as content of phenolics (-150%), terpenes (-85%) and total carotenes (-20%) and increases the risk of furan accumulation. Sensory and chemical quality parameters of carrots are determined mainly by genetic and climate-related factors and to a minor extent by cultivation method. Retail temperature and storage atmosphere as well as heating procedure in processing have the highest impact in quality reduction.

Impact of organic and conventional carrots on intestinal and peripheral immunity.

BACKGROUND: Studies on health effects of organic (ORG) products are still limited and often contradictory. We have investigated the impact of ORG and conventional (CV) carrots from two consecutive harvest years on mouse peripheral and intestinal immunity. RESULTS: Danish carrots (Bolero variety) were grown in three ORG (O1, O2 and O3) and one CV cropping system (D-CV). Italian carrots (Maestro and Excelso varieties) were grown in one ORG and one CV field for each variety. Immune phenotypes of blood, spleen and intestinal lymphocytes, and cytokine serum levels were analyzed in mice fed the different carrots for 30 days. Principal component analysis (PCA) was performed in mice fed the Danish carrots. The consumption of the 'more organic' O2 and O3 carrots induced some changes in lymphocyte populations, including an increase in regulatory T cells. In Italian carrots more differences between ORG and CV were observed in the first as compared to the second year. No relevant differences were observed in cytokine secretion. PCA showed a clear separation among mice fed the O1, O2, O3 and D-CV carrots. CONCLUSIONS: Although a great variability was observed between the two years, an immune stimulation was found after the ORG carrot consumption.

Multi-method comparison of carrot quality from a conventional and three organic cropping systems with increasing levels of nutrient recycling.

BACKGROUND: There is a need to advance the study of the effects of organic and conventional systems on product quality. In particular, little is known about the importance of different farming practices concerning nutrient cycling and the use of external inputs within organic farming for the quality characteristics of the products. In this study the quality characteristics of carrot grown under different farming practices (conventional and three organic cropping systems) over a two-year period were analysed with the aim of discriminating between organic and conventional and investigating the effect of different organic farming practices concerning nutrient recycling and use of external nutrient input. RESULTS: All quality characteristics measured did not give a clear differentiation between the carrots from the different growing systems, even when multivariate statistical evaluation (principal component analysis) was applied, because of the significance of the differences between the field replicates within each management system and of the seasonality. Only some tendencies were emphasised over the two years that could be related to the fertilisation practices and the external inputs used. CONCLUSION: The results indicated that it was not possible to discriminate over the years between carrots from conventional and different organic cropping systems even though controlled conditions and a multi-method approach of analysis were adopted.

Nitrogen split dose fertilization, plant age and frost effects on phytochemical content and sensory properties of curly kale (Brassica oleracea L. var. sabellica).

We investigated how concentrations of sensory relevant compounds: glucosinolates (GLSs), flavonoid glycosides, hydroxycinnamic acid derivatives and sugars in kale responded to split dose and reduced nitrogen (N) fertilization, plant age and controlled frost exposure. In addition, frost effects on sensory properties combined with N supply were assessed. Seventeen week old kale plants showed decreased aliphatic GLSs at split dose N fertilization; whereas reduced N increased aliphatic and total GLSs. Ontogenetic effects were demonstrated for all compounds: sugars, aliphatic and total GLSs increased throughout plant development, whereas kaempferol and total flavonoid glycosides showed higher concentrations in 13 week old plants. Controlled frost exposure altered sugar composition slightly, but not GLSs or flavonoid glycosides. Reduced N supply resulted in less bitterness, astringency and pungent aroma, whereas frost exposure mainly influenced aroma and texture. N treatment explained most of the sensory variation. Producers should not rely on frost only to obtain altered sensory properties.

Eating Quality of Carrots (Daucus carota L.) Grown in One Conventional and Three Organic Cropping Systems over Three Years.

The eating quality of carrots (Daucus carota L.) was investigated to evaluate the impact of cropping systems (one conventional and three organic systems) and growing years (2007, 2008, and 2009) on root size, chemical composition, and sensory quality. The content of dry matter, sugars, polyacetylenes, and terpenes as well as the sensory quality and root size were related to the climate during the three growing years. A higher global radiation and a higher temperature sum in 2009 as compared to 2007 and 2008 resulted in larger roots, higher contents of dry matter, sucrose, total sugars, and total polyacetylenes, and lower contents of terpenes, fructose, and glucose. No differences were found between conventional and organic carrots with regard to the investigated parameters. This result shows that organically grown carrots have the same eating quality as conventionally grown carrots, while being produced in a more sustainable way.

Increase of vitamin D(2) by UV-B exposure during the growth phase of white button mushroom (Agaricus bisporus).

BACKGROUND: Mushrooms are the only non-animal food source of vitamin D. Wild mushrooms have naturally high vitamin D(2) content, and cultivated mushrooms produce vitamin D(2) from ergosterol when exposed to supplementary UV-B during the post-harvest phase. OBJECTIVES: This study investigated the effects of providing supplementary UV-B during the growth phase on vitamin D(2) formation and the interactions with growth of mushrooms, as compared to supplementary UV-B during the post-harvest phase or exposure to sunlight for both cultivated and wild mushrooms. METHODS: Experiments were carried out with exposure to supplementary UV-B just prior to harvest in the range of 0-2,400 mJ cm(-2). Mushrooms grew for 2 days with or without repeated UV-B exposure each day. Vitamin D(2) and growth rate were determined. In addition, some mushrooms were post-harvest treated by exposure at 200 mJ cm(-2) supplementary UV-B or natural sunlight, prior to vitamin D(2) determination. RESULTS: The content of vitamin D(2) was 0.2-164 µg 100 g(-1) fresh weight, and there was a linear relationship between UV-dose up to 1,000 mJ cm(-2) and vitamin D(2) content. The fast growth rate of the mushrooms diluted the vitamin D(2) from 24 to 3 µg 100 g(-1) within 2 days of exposure at 200 mJ cm(-2). Following repeated UV-B exposure, vitamin D(2) increased to 33 µg vitamin D(2) 100 g(-1). Growth was unaffected by UV-B. Post-harvest exposure to supplementary UV-B resulted in a higher vitamin D(2) content of 32 µg 100 g(-1) compared to the 24 µg 100 g(-1) obtained from exposure to UV-B during the growth phase. In contrast, wild and cultivated mushrooms with and without exposure to sunlight had vitamin D(2) content in the range of 0.2-1.5 µg vitamin D(2) 100 g(-1). CONCLUSIONS: This study showed that mushrooms with a well-defined content of vitamin D(2) can be obtained by exposure to supplementary UV-B just prior to harvest.

Effect of differential N and S competition in inter- and sole cropping of Brassica species and lettuce on glucosinolate concentration.

Field and greenhouse pot experiments were conducted to evaluate the potential to use intercropping as an alternative method to increase glucosinolates in Brassicas by manipulating nitrogen (N) and sulfur (S) balance by intercropping with lettuce (Lactuca sativa L. var. capitata). In both experiments, four combinations of N and S fertilization were used. In the field experiment no effect of intercropping on the total glucosinolate concentration was found as the growing lettuce was strongly inhibited by the presence of broccoli (Brassica oleracea L. var. italic). In contrast to this, in the pot experiment both total and individual glucosinolate concentrations in red leaf mustard (Brassica juncea L.) increased by intercropping. Fertilization treatments influenced glucosinolate concentrations in both experiments, and an interaction between N and S fertilization was noticed.