Tag Archives: flavonoids

892-899 D. Sergejeva, I. Alsina, M. Duma, L. Dubova, I. Augspole, I. Erdberga and K. Berzina
Evaluation of different lighting sources on the growth and chemical composition of lettuce
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Evaluation of different lighting sources on the growth and chemical composition of lettuce

D. Sergejeva¹, I. Alsina¹*, M. Duma², L. Dubova¹, I. Augspole², I. Erdberga¹ and K. Berzina³

¹Latvia University of Life Sciences and Technologies, Faculty of Agriculture, Institute of Plant and Soil Science, Liela street 2, LV-3001 Jelgava, Latvia
²Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Chemistry, Liela street 2, LV-3001 Jelgava, Latvia
³Riga Technical University, Faculty of Power and Electrical Engineering, Kalku street 1, LV-1050 Riga, Latvia
*Correspondence: ina.alsina@llu.lv

Abstract:

Experiment were carried out in Latvia University of Agriculture in plant growth room. Lettuce Lactuca sativa L. var foliosum cv. ‘Dubacek’ and L .sativa L. cv. ‘Michalina’ were grown under 4 types of lights (luminescence lamps, commercial light emitting diodes (LED) lamps (V-TAC premium series – for plant growing) and two different Lumigrow LED strips – dominant wavelength- blue or red with 14 h photoperiod and total photosynthetic active radiation (PAR) 100 μmol m-2 s-1 in all variants. Plant weight, length, amount of leaves were measured. Content of chlorophylls, carotenoids, phenols, flavonoids in lettuce was determined three times per vegetation period. In experiments were found that higher lettuce yield was under commercial LED (V-TAC premium series), but these plants contain less soluble sugars, pigments and phenols. Better plant quality was obtained with luminescence lamps. These lettuces have higher sugar, phenols and flavonoids content. Lettuce growth under blue dominate LED (LEDb) was delayed, but these plants contain higher chlorophylls content. The differences in plant growth, response to light and biochemical content between cultivars were detected.

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1425-1434 G. Krumina–Zemture, I. Beitane and I. Cinkmanis
Flavonoids and total phenolic content in extruded buckwheat products with sweet and salty taste
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Flavonoids and total phenolic content in extruded buckwheat products with sweet and salty taste

G. Krumina–Zemture¹*, I. Beitane¹ and I. Cinkmanis²

¹Latvia University of Agriculture, Faculty of Food Technology, Department of Nutrition, Riga street 22, LV–3004, Jelgava, Latvia
²Latvia University of Agriculture, Faculty of Food Technology, Department of Chemistry, Liela street 2, LV–3001, Jelgava, Latvia
*Correspondence: gita.krumina@llu.lv

Abstract:

The aim of research was to evaluate the effect of added ingredients used for taste improvement on flavonoids and total phenolic content in extruded buckwheat products. The added ingredients were – sugar, vanilla sugar, stevia, agave syrup, cinnamon, caraway, garlic powder, sweet pepper powder and salt. Six extruded buckwheat products were analysed, where an extruded buckwheat product without added ingredients was a control sample, two extruded buckwheat products were with sweet taste and three products with salty taste. Total phenolic content was determined using the modified Folin–Ciocalteu method but flavonoid content according to LC-TOF-MS method.
The highest total phenolic content (p < 0.05) was determined in extruded buckwheat product with vanilla sugar + stevia (91.17 ± 0.67 GAE mg 100g-1DW). It was almost three times higher than in the control sample. The significant differences were observed in extruded buckwheat products with caraway + salt + agave syrup (41.5 ± 0.12 GAE mg 100g-1DW) and sweet pepper powder + salt + agave syrup (42.39 ± 0.80 GAE mg 100g-1DW) comparing to other extruded products (p < 0.05). The highest content of rutin and quercetin (p < 0.05) was established in extruded buckwheat product with garlic powder + salt + agave syrup, whereas the highest content of catechin and epicatechin – in extruded buckwheat product with vanilla sugar + stevia. The extruded buckwheat product with caraway + salt + agave syrup in addition contained luteolin, kaempferol and isoquercitrin. The results of research showed that some added ingredients used for taste improvement can significantly influence the total phenolic content and flavonoid content.

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1322-1330 I. Augšpole, M. Dūma and B. Ozola
Bioactive compounds in herbal infusions
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Bioactive compounds in herbal infusions

I. Augšpole*, M. Dūma and B. Ozola

Latvia University of Life Sciences and Technologies, Faculty of Food Technology, Department of Chemistry, Liela iela 2, LV-3000, Jelgava, Latvia
*Correspondence: ingrida.augspole@llu.lv

Abstract:

Herbal teas are very popular and known as important source of biologically active compounds. Some of popular Latvian herbal teas: Calendula (Calendula officinalis L.), Matricaria chamomilla (Matricaria chamomilla), Lady’s-mantle (Alchemilla vulgaris L.), Jasmine (Jasminum officinale L.), Yarrow (Achillea millefolium L.) and Linden flowers (Tilia spp.) were selected for analysis. This study was carried out with the aim to investigate the effect of extraction time (10, 15, 20 min) on the content of total flavonoids and total phenols as well as antioxidant activity of herbal tea extracts. The infusions were prepared by usual domestic preparation technique using ground air-dried plant materials and boiling deionized water (0.055 μS cm-1) for extraction. Content of total flavonoids, total phenols and antioxidant activity was determined spectrophotometrically. Dry matter content was determined in lyophilized herbal infusions. The obtained results indicated that extraction time did not affected the content of biologically active compounds in the herbal infusions significantly (P > 0.05). The highest level of flavonoids was found in Jasmine and Lady’s-mantle infusions (average 104.98 ± 9.21 mg quercetin equivalent 100 g-1 and 115.28 ± 5.25 QE mg 100 g-1 respectivelly), while the lowest was determined in Matricaria chamomilla extract – (average 70.10 ± 4.68 QE mg 100 g-1). Lady’s-mantle tea contained the largest amount of total phenols (average 4126.62 ± 26.24 mg gallic acid equivalents 100g-1), the lowest – Calendula tea 1828.04 ± 10.37 mg GAE 100 g-1). Data analysis showed a close linear positive correlation between the content of total flavonoids and total phenols in herbal infusions (R2 = 0.872; r = 0.934) with the probability of 99%. In general, all samples tested in this study, demonstrated high level of antioxidant activity (from 75.04 to 91.54 mmol Trolox equivalents 100 g-1). Results of the present experiments demonstrated that content of dry matter in analysed herbal teas was significantly different (P < 0.05).

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1316–1329 L. Klavins, J. Kviesis, M. Klavins
Comparison of methods of extraction of phenolic compounds from American cranberry (Vaccinium macrocarpon L.) press residues
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Comparison of methods of extraction of phenolic compounds from American cranberry (Vaccinium macrocarpon L.) press residues

L. Klavins, J. Kviesis, M. Klavins*

University of Latvia, 19 Raina Blvd., LV–1586, Riga, Latvia
*Correspondence: maris.klavins@lu.lv

Abstract:

American cranberries (Vaccinium macrocarpon L.) contain significant quantities of
various phenolic compounds. Most of these compounds are recovered when berry juice is
produced. However, a considerable part of polyphenols remain in berry press residues and are
discarded as food industry waste. The aim of the study was to compare the methods of extraction
of polyphenols (ultrasound, microwave-assisted, Soxhlet) from press residues of American
cranberry. The impact of main extraction parameters (e.g., extraction time, solid/solvent ratio,
solvent type) on the yield of extracted polyphenols. Ultrasound-assisted extraction showed the
highest potential from all studied methods, given its fast, convenient use and low cost. Aqueous
ethanol and methanol in the presence of acid (anthocyanin extractions should be assisted with
trifluoroacetic acid, polyphenol extractions – with HCl) were assessed as the best solvents for
extraction. The obtained extracts were characterised using the Folin-Ciocaulteu method for
determination of total phenolics and the pH-differential method for determination of total
anthocyanins, and UPLC–PDA was used to determine the content of individual anthocyanins.
Cyanidin-3-O-arabinoside, peonidin-3-O-galactoside, peonidin-3-O-glucoside and peonidin-3-
O-arabinoside were identified as the main anthocyanins in cranberry press residue extracts.

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