5 research outputs found
Antioxidant content of dark colored berries
Blackberries (Rubus caesius), elderberries (Sambucus nigra L), highbush blueberries
(Vaccinium corymbosum L) and black currants (Ribes nigrum) were selected for research on their
content of phenolic compounds, including anthocyanins and comparing their content in these
berries. Samples were also assayed for ascorbic acid and soluble solid content. The unifying mark
of these fruits is purple-black color, which indicates high content of anthocyanins. Analyses of
these fruits showed that they contain high biological activity components that justify the uses of
these fruits.
The research was done at the Department of Chemistry, Latvia University of Life Sciences and
Technologies, year 2019. Berry samples were bought at the supermarket (highbush blueberries)
or collected from garden in Jelgava, Latvia (blackberries, elderberries and black currants). All
berries were at full maturity. The content of ascorbic acid, total phenols, anthocyanins, flavonoids
as well as soluble solids was determined.
Descending order of ascorbic acid content in berries is: black currants > blackberries
> elderberries > highbush blueberries. Elderberries had the highest content of anthocyanins, total
phenols and flavonoids on average 161.5, 537.9 and 112.6 mg 100 g
-1 FW, respectively. The
content of soluble solids changes from 5.83 Brix (elderberries) to 13.67 Brix (black currants)
Bioactive compounds in herbal infusions
ArticleHerbal 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)
Possibilities of cucumber powdery mildew detection by visible and near-infrared spectroscopy
Received: July 16th, 2021 ; Accepted: November 6th, 2021 ; Published: February 1st, 2022 ; Correspondence: [email protected] are one of the most demanded and widely grown greenhouse vegetables.
Important factors that influence quality and quantity of yield are diseases. Powdery mildew
(caused by Podosphaera xanthii and/or Golovinomyces cichoracearum), is one of the
most harmful cucumber diseases. Early detection of mildew via non-destructive methods can
optimize schemes of fungicide application. The study aimed to find regularities in the reflected
light spectra, indices described in the literature, and severity of mildew. Plants were grown in the
polycarbonate greenhouse under artificial lighting in a 16 h photoperiod with PAR at the tips of
plants 200 ± 30 µmol m-2 s-1. Leaf reflection spectra were obtained using spectroradiometer
RS-3500 (Ltd. Spectral Evolution). Spectral range 350–2,500 nm, bandwidth 1 nm. The severity
of cucumber mildew was evaluated using 10 point scale (0- no symptoms, … 9 - the plant is
dead). The vegetation indices found in the literature have been calculated. The obtained results
show that the calculated indices have different sensitivities. The strongest correlation between the
degree of cucumbers infection with powdery mildew and the light reflectance spectrum was found
in the green range of visible light around 550 nm. Disease-Water Stress Index-2 (DSWI-2),
Structure Intensive Pigment Index (SIPI), and Normalized Difference Vegetation Index (NDVI)
are the most suitable indices for determining powdery mildew in cucumbers. New indices for
detection of powdery mildew have been created. None of the studied indices allows determining
the powdery mildew at the early stages of disease development when powdery mildew severity
is below 10%
Determination of tomato quality with hyperspectral imaging
Received: February 1st, 2023 ; Accepted: July 14th, 2023 ; Published: October 13th, 2023 ; Correspondence: [email protected] (Solanum lycopersicum L.) are a widely used vegetable in the human diet
throughout the year, both fresh and in various processed products. Tomatoes contain compounds
important to human health and are an important source of vitamins, antioxidants, and mineral
elements. Performing biochemical analyses is an expensive, environmentally unfriendly and
time-consuming process; therefore, a way to determine the biochemical composition of tomatoes
using non-destructive methods is being sought. The study includes 45 varieties of tomatoes with
different colors - red, pink, orange, brown, yellow, and bicolor tomato fruits. The content of dry
matter, soluble dry matter, titratable acidity, lycopene, β-carotene, total phenol, and flavonoids
was determined by standard biochemical procedure. Reflectance spectrums of tomato fruits were
obtained with Remote Sensing Portable Spectroradiometer RS-3500 (Ltd. Spectral Evolution,
Haverhill, MA, USA) at the wavelength 350–2,500 nm with a 1 nm interval. In order to determine
the content of various biochemical parameters in tomatoes, the vegetation indices found in the
literature were used, and new ones were developed. The research demonstrated that the developed
vegetative indices allow to detect lycopene and β-carotene content non-destructively. For the
determination of the dry matter, soluble solids and phenolic content, indices designed for
detecting water content can be used, but their correlation coefficients with chemical methods are
moderately high - 0.65, 0.56 and 0.57, respectively. It was found that the best correlation between
biochemically detected parameters and vegetation indices is for lycopene > β-carotene > dry
matter> total phenols = titratable acidity ≥ soluble solids > taste index > flavonoids
Lighting source as cause of changes in cucumbers’ physiology and morphology
The demand of fresh fruits and vegetables is growing. Therefore cultivation of them is
essential all year round. The growth in the dark period of a year is not imaginable without artificial
lighting sources. Therefore the experiments were carried out to investigate the effects of three
different lighting sources on the growth of cucumbers at the early stages of development. Plants
were grown in the polycarbonate greenhouse under three different lighting sources: Led cob Helle
top LED 280, induction lamp and high pressure sodium lamp Helle magna. Cucumbers were
grown in 16h photoperiod with PAR at the tips of plants 200 ± 20 µmol m-2
s
-1
. Plant growth
parameters, specific leaf area, pigments, phenols and flavonoids content in leaves, leaf light
reflection parameters were determined. Results showed that cucumber plants grown under Led
cob Helle top LED 280 in average were smaller, with less chlorophyll, carotenoids and phenols,
but leaves have higher chlorophyll a and b ratio and specific leaf area in comparison with
traditionally used in greenhouses High Presure Sodium Lamps (HPSL). Cucumber plants grown
under Induction lamp in average were shorter, but with larger leaf area, with higher chlorophyll
and carotenoids content, but decreased phenols content in comparison with HPSL. Lichtenthaler
index 1 (LIC1) and NDVI are useful for assessing the physiological state of cucumber plants.
Despite the fact that the plants grow well and develop normally under all lamps, the results show
that sodium lamps are the most suitable for cucumbers. Further research is needed to adjust LED
lighting for cucumber cultivation