Tag Archives: phenols

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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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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1442–1450 I. Shepelev, R. Galoburda and T. Rakcejeva
Changes in the total phenol content in the industrial potato peel wastes during the storage
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Changes in the total phenol content in the industrial potato peel wastes during the storage

I. Shepelev*, R. Galoburda and T. Rakcejeva

Latvia University of Agriculture, Faculty of Food Technology, St. Liela 2, LV-3001 Jelgava, Latvia
*Correspondence: igor_shepelev@inbox.lv

Abstract:

 As a zero value by-product from the economic point of view, potato (Solanum tuberosum L.) peel is a good source of phenols. As a manufacturing waste, potato peels are stored at the uncontrolled conditions and are exposed to the fermentative, oxidative, and microbial degradation. The aim of the present study was to determine the phenol degradation dynamics in the stored peels so the maximum storage time could be defined to achieve the efficient phenol extraction. Three different types of samples were prepared by abrasion peeling method and stored at room temperature, in open air, up to six days. Phenol extracts were obtained using ethanol-based solvent. Total phenol content was expressed as a gallic acid equivalent; antiradical activity was measured using the 2,2-diphenyl-1-picrylhydrazylradical. Results revealed that total phenols during the storage are more stable in the larger peel samples that can be stored up to two days without significant changes in the total polyphenol content and antiradical activity. Finely shredded peel demonstrated significant decrease in the total phenol amount and in the antiradical activity already on the second day of the storage. This fact indicated that in the finely shredded peel samples phenols are easily accessible to the oxidative and fermentative processes. It is possible, that after peeling there were big amounts of chlorogenic acid in the samples. When total amount of polyphenols decreased, chlorogenic acid degraded and caffeic acid was released in sufficient amount to hold antiradical activity of the extract on the high level.

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