J. Lachman

Effect of peeling and three cooking methods on the content of selected phytochemicals in potato tubers with various colour of flesh

The impact of peeling and three cooking treatments (boiling, baking and microwaving) on the content of selected phytochemicals in white-, yellow-, red- and purple-fleshed potatoes was investigated. Ascorbic acid and chlorogenic acid contents were determined by HPLC-DAD, total anthocyanin content by pH-differential spectrophotometry, glycoalkaloid, α-chaconine and α-solanine contents by HPLC-ESI/MS/MS. All cooking treatments reduced ascorbic and chlorogenic acid contents, total glycoalkaloids, α-chaconine and α-solanine with the exception of total anthocyanins. The losses of ascorbic and chlorogenic acids were minimised with boiling and total anthocyanin levels retained the highest. Boiling of peeled tubers decreased contents of total glycoalkaloids (α-chaconine and α-solanine) and appeared as the most favourable among the three tested methods. Moreover, due to higher initial levels, red- and purple-fleshed cultivars retained higher amounts of antioxidants (ascorbic acid, chlorogenic acid and total anthocyanin) after boiling and may be healthier as compared with white or yellow cultivars.

Major factors influencing antioxidant contents and antioxidant activity in grapes and wines

Phenolic compounds in wines, especially in red wines, possess strong antioxidant activity, have the largest effect in decreasing atherosclerosis by both hypolipemic and antioxidant mechanisms. The long-term uptake of red wine has a positive impact on antioxidant activity (AA) of blood plasma in rats in vivo and increases AA by 15%–20% compared to a control group. In the article the effect of total phenolics (TP), total anthocyanins (TA), individual anthocyanins, procyanidins and phenolics contained in red grapes, musts, grape seeds and skins and wines on the AA is discussed. Significant impact of varieties, viticultural regions and locations, climate conditions and vintage has been shown. Likewise, the ways and individual stages of the vinification technology process, and storage conditions affect color, TP, TA, and AA and health aspects of produced wines. Resveratrol, another free radical scavenger mainly contained in the skins of grapes, inhibits the risk of cardiovascular diseases. Higher amounts of trans-resveratrol (RES) have been found in wines from cool and wet climate regions and lesser amounts are typical for warm and dry regions. Changes in the TP content and AA affected by grape variety, vineyard location and winemaking process in white and blue varieties from different vineyards of the Czech Republic were studied. Significant differences in TP among varieties were found. Analysis of variance showed statistically high differences among red and white wines and growing locations. Wines differed significantly in TP content and AA increased significantly during the winemaking process. Statistically significant differences in AA values were found among growing areas, wines and varieties. Significant positive correlations between TP and AA were determined. Total antioxidant status (TAS) of white and red wines (white and blue vine varieties) determined by DPPH and ABTS assays revealed significant differences in AA between white and red wines. Moreover, differences were ascertained between individual varieties of red wine. The results obtained supported the assumption that variety plays a considerable role in TAS; the blue vine varieties showed a much higher TAS. Analysis of variance in AA showed statistically high significance between red and white wines. AA increased during the winemaking process, the highest increase was determined during fermentation and maturation stages of red wine.

Immunoanalysis of isoflavonoids in Pisum sativum and Vigna radiata

Abstract Radioimmunoassays (RIAs) combined with liquid chromatography were used for study of isoflavonoids in seeds of pea Pisum sativum and mung bean Vigna radiata. Radioimmunoassays with these specifities were used: (1) daidzein and its 4′-derivatives (e.g. formononetin); (2) daidzein and its 7-derivatives (e.g. daidzin, isoformononetin); (3) genistein and its 4′-derivatives (e.g. biochanin A); and (4) genistein and its 7-derivatives (e.g. genistin, prunetin). Dormant or germinating seeds were extracted with 80% ethanol. Immunoreactivities were measured either in crude extracts or after chromatographic fractionation by HPLC (reversed phase, octadecylsilica). Chromatographic mobilities of immunoreactive fractions were compared to those of daidzein, daidzin, formononetin, isoformononetin, genistein, genistin biochanin A and prunetin standards. Extracts from Vigna radinfa contained daidzein, genistein and their 7- O glucosides, daidzin and genistin, respectively. No immunoreactivity was recorded in HPLC fractions corresponding to glycosides in extracts from P. sativum, but the methods sensitive to 7-derivatives of daidzein and genistein showed peaks with chromatographic mobilities identical to those of the 7-methoxyderivatives, isoformononetin and prunetin, respectively. In additional experiments, the pea extracts were fractionated either by thin layer chromatography (TLC) on silica or by ion-exchange TLC on aminosilica. Identity of the daidzein-7 and genistein-7 immunoreactive entities with isoformononetin and prunetin, respectively, was confirmed by the identical chromatographic behavior in all these different chromatographic systems.

Total phenolic content of yacon (Smallanthus sonchifolius) rhizomes, leaves, and roots affected by genotype

Abstract The content of total polyphenols (TP) in rhizomes, leaves, and tuberous roots of five genotypes of yacon (Smallanthus sonchifolius) from New Zealand, Germany, Ecuador, and Bolivia cultivated on trial field plots of the University of Agriculture in Prague‐Suchdol under field conditions from the 2003 harvest was determined spectrophotometrically by Folin‐Ciocalteau phenol reagent. Obtained results were compared by means of dendrograms according to cluster analyses based on TP and morphological traits. In four genotypes the content of inulin and fructose was also determined. From the obtained results, on the basis of similarity of obtained dendrograms, a very close agreement between TP content in rhizomes and leaves and origin and morphological traits of yacon genotypes was found. Five yacon genotypes were classified into three groups. The genotype from New Zealand with white coloured flesh (NZLw) and genotypes from Ecuador (ECU) and Bolivia (BOL) were distinguished with high TP content in purple coloured rhizomes and leaves; whereas the New Zealand genotype with yellow/orange coloured flesh (NZLy) and the genotype from Germany (DEU) with white coloured rhizomes with purple striations showed lower TP content in rhizomes and leaves. Also, inulin content in genotypes from Ecuador (ECU) and Bolivia (BOL) was higher in comparison to the genotypes from Germany (DEU) and New Zealand (NZLy). Thus, we found that TP and inulin content was dependent on botanical origin, morphological traits and polymorphisms of individual genotypes.

Carotenoid profile and retention in yellow-, purple- and red-fleshed potatoes after thermal processing.

This research aimed to investigate the effect of thermal processing on carotenoid profile, quantity and stability in 22 colour-fleshed potato cultivars grown in the Czech Republic. The total of nine carotenoids was analysed by HPLC using a C30 column and PDA detection. The total carotenoid content for all cultivars ranged from 1.44 to 40.13 μg/g DM. Yellow cultivars showed a much higher average total carotenoid content (26.22 μg/g DM) when compared to red/purple-fleshed potatoes (5.69 μg/g DM). Yellow cultivars were dominated by antheraxanthin, whereas neoxanthin was the main carotenoid in red/purple cultivars. Thermal processing significantly impacted all potato cultivars. Boiling decreased the total carotenoids by 92% compared to baking (88%). Lutein was the most stable carotenoid against thermal processing (decreased by 24-43%) followed by β-carotene (decreased by 78-83%); other carotenoids were degraded nearly completely. Increased formation of (Z)-isomers by thermal processing has not been confirmed.

Identification of potential sources of thymoquinone and related compounds in Asteraceae, Cupressaceae, Lamiaceae, and Ranunculaceae families

AbstractIn this study, forty-seven plant species belonging to seven families were analysed by GC and GC-MS for the contents of pharmacologically effective quinones: dithymoquinone (DTQ), thymohydroquinone (THQ), and thymoquinone (TQ). The results showed that detectable amounts (≥1 mg kg−1) of at least one of these compounds have been found in three species of both Monarda (M. didyma, M. media, and M. menthifolia) and Thymus (T. pulegioides, T. serpyllum, and T. vulgaris) genera, two Satureja (S. hortensis and S. montana) species, and in single representatives of Eupatorium (E. cannabinum), Juniperus (J. communis), and Nigella (N. sativa) genera. The maximum contents of THQ and TQ were found in M. media aerial parts and M. didyma inflorescences (2674 and 3564 mg kg−1 of dried weight, respectively) in amounts significantly exceeding their maximum contents in N. sativa seeds (THQ = 530 mg kg−1 and TQ = 1881 mg kg−1), which are generally considered as the main natural source of both of these compounds. As a conclusion, M. didyma (bergamot) and M. media (purple bergamot) can be recommended as new prospective natural sources of THQ and TQ for pharmaceutical or food industries.

Impact of Phenolic Content on Antioxidant Activity in Yellow and Purple-fleshed Potatoes Grown in the Czech Republic

ABSTRACT Purple-fleshed potatoes cultivars are new on the Czech market. Intensive trials about growing purple-fleshed potato cultivars in the Czech Republic are currently being carried out. Recently many articles deal with phenolic antioxidants and their contribution to the human health; thus the aim of this study was to determine the differences in total phenolic (TP) content and antioxidant activity (AA) between yellow (cvs. Impala, Karin, Dita, Saturna) and purple-fleshed (cvs. Valfi, Violette) potatoes grown in the Czech Republic in 2004 in four locations in field trials. TP content was determined by Folin-Ciocalteau assay and AA by DPPH assay both in freeze-dried tuber matter. Results showed a statistical significant difference in TP content and AA between yellow- and purple-fleshed potatoes. Purple-fleshed cultivars showed 60% higher TP content than yellow-fleshed cultivars and AA content was double in purple-fleshed cultivars. A significant linear correlation between TP and AA was found (r2 = 0.747). Average TP content in yellow-fleshed cultivars was 2.96 GAE (gallic acid mg g−l DM) and in purple-fleshed cultivars 4.68 GAE was found. Average AA in yellow-fleshed cultivars was 11.26 AAE (ascorbic acid equivalent mg 100 g−1 DM) and in purple-fleshed cvs. 24.79 AAE. Purple-fleshed potatoes showed a lower variation among localities (6 % only). The results showed that AA of freeze-dried tuber matter is very low when compared to other plants or sources (wine, tea, chocolate and blueberries) although a high potato intake in humans by Czechs (72 kg capita−1 year−1) is considered.

Potatoes – A crop resistant against input of heavy metals from the metallicaly contaminated soil

abstract The objective of our study was to assess the extent of accumulation of cadmium, lead and zinc in potato tubers depending on the concentration of these heavy metals in soil and to evaluate the resistance of 11 cultivars of potato cultivated in 5 localities of the Slovakia against input of these heavy metals into the consumption part of potato. Contents of Cd (Pb, Zn) in soil were 0.94–2.54 (18.03–24.90, 35.71–72.40) mg/kg in soil extract by aqua regia and 0.030–0.188 (0.149–0.356, 0.052–0.238) mg/kg in soil extract by NH4NO3. The contents of Cd, Pb, and Zn were determined in potatoes in extracts of freeze-dried samples and expressed in mg/kg of fresh matter (FM). Determined contents of heavy metals were in the range of ND–0.058 mg Cd/kg FM, 0.020–0.630 mg Pb/kg FM, 1.836–3.457 mg Zn/kg FM, resp. The statistically significant correlation between heavy metal content in soil and its content in potato tubers were confirmed only: cv. Laura – Spissky Stvrtok (Cd), cv. Red Anna – Odorin (Pb) and Marabel, Red Anna – Odorin, cv. Marabel – Belusa, cv. Volumia – Imel (Zn).

Changes of Polyphenolic Substances in the Anatomical Parts of Buckwheat (Fagopyrum esculentum Moench.) during Its Growth Phases

In this study the changes of total polyphenolics in different anatomical parts (stems, leaves, flowers and seeds) of common buckwheat (Fagopyrum esculentum Moench.) during vegetation period were analysed. The content of total polyphenolics was evaluated in growth phase I (formation of buds), phase II (at the beginning of flowering), phase III (full blossoming) and phase IV (full ripeness). In all growth phases (GP) the stems and leaves were evaluated and statistically significant differences in polyphenolics content between the two parts were confirmed. Statistically significant differences (p < 0.01) in polyphenolics content (in GP II and III) between stems and leaves; and between stems and flowers were found. In flowers an average of 13.8 times higher and in leaves 6 times higher concentration of polyphenolics in comparison with stems was measured. In GP III the content of polyphenolics in common buckwheat was following: flowers > leaves > achene > stems. In flowers an average of 11.9 times higher, in leaves 8.3 times higher and in achenes 5.9 times higher contents of polyphenolics compared with stems were found. In GP III and IV (leaves, achenes, stems) the leaves contained in average 20 times higher and achenes 5.6 times higher polyphenolics than stems.

Tocotrienols and tocopherols in colored-grain wheat, tritordeum and barley

Colored-grain spring and winter wheat, spring tritordeum and barley (blue aleurone, purple pericarp, and yellow endosperm) from the harvests 2014 and 2015 were evaluated for tocol contents by HPLC-FD. Higher content of total tocols was found in spring wheat varieties compared with winter varieties. Four tocols (β-tocotrienol, α-tocotrienol, β-tocopherol, and α-tocopherol) were identified in wheat and tritordeum varieties. Dominant tocols in purple- and blue-grained wheat and yellow-grained tritordeum were α-tocopherol and β-tocotrienol, whereas spring barley varieties differed from wheat and tritordeum by high α-tocotrienol content. Tocol content was significantly affected by genotype and in a lesser extent in some varieties and lines also by rainfall and temperatures during crop year. Higher rainfall and lower temperatures caused in most varieties higher tocol contents. Purple- and blue-grained wheat lines with higher tocol, anthocyanin and phenolic acids with health benefits may be useful for breeding new varieties.