Burešová, B., Paznocht, L., Jarošová, V., Doskočil, I., Martinek, P. 2023. The Effect of Boiling and in Vitro Digestion on the Carotenoid Content of Colored-grain Wheat. Journal of Food Composition and Analysis. 115. 105002.
The boiling of colored-grain wheat kernels resulted in a more pronounced loss of total carotenoids compared to in vitro digestion (27.3 vs. 12.1%). After both boiling and digestion, the highest carotenoid content was preserved in Citrus and Bona Vita wheats with yellow endosperm (2.34 and 1.88 μg/g), which is more than six times the content retained in the digested material of red and blue varieties. Esterified carotenoids exhibited subaverage heat-resistance, as their content dropped to 58.0% after boiling, while decreasing only slightly due to digestion (to 53.4%). The stability of free zeaxanthin, lutein, and β-carotene differed significantly throughout boiling (92.3 > 72.3 > 27.1%) and subsequent digestion (68.3 > 60.1% > β-carotene was reduced completely). Exposure to high temperatures and other factors in play during digestion (i.e. acidic environment) resulted in lutein E/Z isomerization, mainly reflected by an increase in 9- and 9’-Z-lutein content to 111 and 225%.
Burešová, B., Paznocht, L., Kotíková, Z., Giampaglia, B., Martinek, P., Lachman, J. 2021. Changes in carotenoids and tocols of colored-grain wheat during unleavened bread preparation. Journal of Food Composition and Analysis. 103. 104108.
The content of carotenoids and tocols in the individual steps of technological processing was determined using HPLC-DAD and HPLC-FLD. The dough preparation resulted in a more pronounced loss of the investigated antioxidants (51.5 and 33.0%) compared to baking (22.5 and 9.1%). Carotenoids appear to be markedly less stable than tocols, as only 26.0% compared to 57.9% of the initial flour content was preserved in the final product, accounting for 0.81 and 29.4 mu g/g. In the dough preparation phase, a strong correlation (R = 0.693, p = 0.001) was noted between the tocol content in the flour and the share of retained carotenoids in the dough, indicating a protective effect of tocols on carotenoids. In total, a similar overall retention of carotenoids, as in the leavened bun preparation (27.4%), was found, since the differences in shape of the final product turn out to cause increased carotenoid losses due to high baking temperatures in flatbread.
Paznocht, L., Burešová, B., Kotíková, Z., Martinek, P. 2021. Carotenoid content of extruded and puffed products made of colored-grain wheats. Food Chemistry. 340. 127951.
Wheat is a relevant source not only of essential macronutrients but also of many other health-promoting phytochemicals (carotenoids, anthocyanins, tocols, phenolic acids, etc.). Colored-grain wheats were used for extrusion and kernel puffing. The total content of carotenoids (sum of lutein, zeaxanthin, antheraxanthin, alpha and beta carotene, and xanthophyll esters) decreased significantly due to extrusion (to 25.7%) and puffing (to 31.6%), compared to the content in the raw material. Zeaxanthin was shown to be the most stable among all detected carotenoids (30.8 and 48.7% was preserved). The results of the performed analyses have not confirmed greater stability of xanthophyll esters against higher temperatures (decrease to 29.5 and 22.1%). Both technologies induced E-to Z-isomerization of all-E-lutein and puffing also of all-E-zeaxanthin. Higher concentrations of 13 -Z and 9-Z-zeaxanthin were identified in puffed grains (2x and 37x on average). To preserve more carotenoids, it is appropriate to look for a more suitable food processing technology.
Paznocht, L., Kotíková, Z., Burešová, B., Lachman, J., Martinek, P. 2020. Phenolic acids in kernels of different coloured-grain wheat genotypes. Plant, Soil and Environment. 66.
57-64.
The content of free, conjugated and bound phenolic acids in 12 wheat (Triticum aestivum L.) genotypes of 4 different grain colours (standard red, yellow endosperm, purple pericarp and blue aleurone) from 2-year field trial was analysed in the present study. Significant increase (8%) in the total phenolic acid content was observed in the dryer year 2017. Five phenolic acids (ferulic, sinapic, p-coumaric, vanillic and 4-hydroxybenzoic) and cis-isomers of ferulic and sinapic acid were determined by HPI.C-DAD (high-performance liquid chromatography with a diode-array detector) in grain samples. The total phenolic acid content of coloured wheat groups varied: blue aleurone > purple pericarp > yellow endosperm > red colour (798 > 702 > 693 > 599 mu g/g). The fraction of bound phenolic acids was the major contributor to the total phenolic acid content (91.7%) with ferulic acid predominating (85.2%). Conjugated phenolic acids accounted for 7.9% of the total with sinapic and ferulic acid predominating (47.6% and 19.9%). The composition of individual phenolic acids was similar within these two fractions. The remaining 0.4% was represented by the fraction of free phenolic acids in which the phenolic acid profile varied among the individual coloured groups. Ferulic acid prevailed in red and yellow wheats, vanillic in blue and p-coumaric in purple wheats.
Paznocht, L., Kotíková, Z., Orsák, M., Lachman, J., Martinek, P. 2019. Carotenoid changes of colored-grain wheat flours during bun-making. Food Chemistry. 277. 725-734.
Colored-grain wheat genotypes were used in the preparation of flour, dough, buns, and buns stored for a short period of time. The main carotenoid in all genotypes was lutein, followed by its esters, zeaxanthin, and beta-carotene, while antheraxanthin and alpha-carotene occurred only at negligible levels. The highest carotenoid contents were observed in Yellow- and purple-grained genotypes. After the preparation of dough, total carotenoid content (TCC) decreased significantly by an average of 61.5%. Zeaxanthin was shown to be stable, whereas alpha-carotene was destroyed. In baked buns, the average decrease of TCC and all-E-lutein was lower than in unbaked dough. Greater decreases were recorded for esters, antheraxanthin, and beta-carotene. After storing buns for 24 h at room temperature, approximately one-quarter of TCC observed in the original flour was preserved. Z-Isomers of lutein occurred in minor concentrations, but the degradation of this component, and that of zeaxanthin, was low, suggesting E- to Z-isomerization.
Zrcková, M., Capouchová, I., Eliášová, M., Paznocht, L., Pazderů, K., Dvořák, P., Konvalina, P., Orsák, M., Štěrba, Z. 2018. The effect of genotype, weather conditions and cropping system on antioxidant activity and content of selected antioxidant compounds in wheat with coloured grain. Plant, Soil and Environment. 64. 530-538.
The aim of the study was to evaluate total antioxidant activity (TAA) and total content of carotenoids (TCC), anthocyanins (TAC), phenolics (TPC) and phenolic acids (PAs) in grain of selected pigmented wheat genotypes and traditional control cultivar cultivated under organic and conventional cropping systems in two-year trials. All of the evaluated parameters were significantly affected both by genotype and evaluated environmental factors. While in TPC, PAs and TCC the effect of years prevailed, TAC was affected mainly by genotype. The effect of genotype and year in TAA was comparable. TPC ranged from 581.71 mg/kg (control cv. Annie) to 723.60 mg/kg (cultivar with purple pericarp PS Karkulka), total PAs content from 711.77 mg/kg (cv. PS Karkulka) to 849.47 mg/kg (cv. Skorpion with blue aleurone). TCC varied from 1.56 mg/kg (cv. PS Karkulka) to 5.32 mg/kg (cv. Citrus with yellow endosperm). The highest TAC (63.23 mg/kg) was found in cv. Skorpion, the lowest (12.70 mg/kg) in cv. AF Jumiko with purple pericarp. Anthocyanins were not detected in cvs. Annie and Citrus. TAA varied from 162.68 mg/kg in cv. Annie to 226.71 mg/kg in breeding line KM 53-14 with blue aleurone. Higher TAA and antioxidants contents and lower grain yields were observed in organic cropping system and in drier year 2016.
Paznocht, L., Kotíková, Z., Šulc, M., Lachman, J., Orsák, M., Eliášová, M., Martinek, P. 2018. Free and esterified carotenoids in pigmented wheat, tritordeum and barley grains. Food Chemistry. 240. 670-678.
Carotenoids are important phytonutrients responsible for the yellow endosperm color in cereal grains. Five carotenoids, namely lutein, zeaxanthin, antheraxanthin, a-and alpha-carotene, were quantified by HPLC-DAD-MS in fourteen genotypes of wheat, barley and tritordeum harvested in Czechia in 2014 and 2015. The highest carotenoid contents were found in yellow-grained tritordeum HT 439 (12.16 mu g/g DW), followed by blue-grained wheat V1-131-15 (7.46 mu g/g DW), and yellow-grained wheat TA 4024 (7.04 mu g/g DW). Comparing carotenoid contents, blue varieties had lower whereas purple ones had the same or higher levels than conventional bread wheat. Lutein was the main carotenoid found in wheat and tritordeum while zeaxanthin dominated in barley. The majority of cereals contained considerable levels of esterified forms (up to 61%) of which lutein esters prevailed. It was assessed that cereal genotype determines the proportion of free and esterified forms. High temperatures and drought during the growing season promoted carotenoid biosynthesis.
Eliášová, M., Paznocht, L. 2017. Total phenolic content and antioxidant activity of tritordeum wheat and barley. Agronomy Research. 15(S2). 1287-1294.
Whole grains are a source of numerous antioxidant compounds such as phenolic compounds, anthocyanins, phenolic acids, proanthocyanidins, lignans and others which are able to scavenge free radicals. Thus cereals seem to be very useful in preventing chronic diseases like metabolic syndrome (obesity, high blood pressure, high blood triglyceride and glucose levels), diabetes, neurodegenerative diseases, cancer and chronic inflammatory diseases. Recently, there has been an increased consumer demand for cereal based foods, especially whole cereals. Such demand provides scope for innovations of which an important one is introduction of a completely new cereal cross called tritordeum. This alternative cereal, which is presented as a good source of health beneficial compounds, was assessed in this study and compared with wheat and barley. The total phenolic content (TPC) and related total antioxidant activity (TAA) were investigated via two spectrophotometric methods using a stable 2,2-diphenyl-1-picryhydrazyl radical (DPPH) and Folin-Ciocalteau reagent respectively. Both TPC and related TAA values of tritordeum and wheat were similar but were significantly lower compared to barley. Results have also revealed a close relationship between TAA and TPC (R² = 0.93, p < 0.05), which might suggest that increased antioxidant activity in those grains is caused by phenolic compounds contained in them. Tritordeum seems to represent a new cereal with good prospects; nevertheless more detailed analysis of its health related compounds is required.
