•Selected corn hybrids varied in carotenoid profile and antioxidant activity.•In these commercial hybrids lutein and zeaxanthin showed a wide range of levels.•Antioxidant activity of hexane extracts ...increased with total carotenoid content.•Lutein and β-carotene were primary contributors to TEAC activity.•Lutein, β-cryptoxanthin and β-carotene were primary contributors to TBARS activity.
Carotenoids, which occur naturally in corn grains, have been associated with reduced risk of degenerative diseases. The aim of this research was to measure the carotenoid content of hexane extracts of six commercial high-yield corn hybrids and determine the relationship between carotenoid content and antioxidant activity. Levels of lutein, zeaxanthin, β-cryptoxanthin and β-carotene in hexane extracts were determined using HPLC, and antioxidant activity was assayed using the TEAC system based on the 2,2′-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS+), and the TBARS system based on a linoleic acid emulsion. Corn hybrids varied in carotenoid content and antioxidant activity in both assays. Lutein and zeaxanthin were the predominant carotenoids; their levels were 15-fold higher than those of β-cryptoxanthin and β-carotene. Antioxidant activity in both assays increased linearly with total carotenoid content. Lutein and β-carotene were the primary contributors to TEAC activity, while lutein, β-cryptoxanthin and β-carotene were primary contributors to TBARS activity.
Maize grain starch is the major energy source in animal nutrition, and its high digestion and utilization largely depend on endosperm traits and the structure of the starch-lipoprotein matrix. The ...aim of this work was to determine floury and vitreous endosperm traits and its relation to starch digestibility rate. In total, kernels of 30 hybrids were manually dissected, and amylose, total zein and starch and non-starch lipids were determined in both vitreous and floury endosperm. Starch digestibility of the whole kernel was determined based on glucose released during a two-step in vitro pig model of enzymatic digestion, and starch digestibility rate was calculated according to the first-order kinetics. The vitreous endosperm of tested hybrids had higher contents of amylose (204.6 vs 190.4 g/kg), zein (63.2 vs 40.4 k/kg) and starch lipids (5.6 vs 4.9 g/kg), and lower content of non-starch lipids (7.3 vs 9.6 g/kg) than floury endosperm. Digestibility coefficients varied among hybrids, and starch digestibility rate varied from 0.73 to 1.63 1/h. Lipids in both vitreous and floury endosperm negatively correlated with the most of digestion coefficients, whereas zein correlated in vitreous and amylose in the floury endosperm (P < 0.05). Starch digestibility rate negatively correlated with all traits, except amylose content in vitreous endosperm. As a result, a linear regression model with four variables including contents of zein and starch lipids in vitreous and zein and amylose in floury endosperm can predict more than 65% variability of starch digestibility rate of tested hybrids.
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•Commercial maize hybrids differ in properties of floury and vitreous endosperm.•Starch digestibility rate of the whole kernel (kd) varied broadly among tested hybrids.•Traits of both floury and vitreous endosperm affected kd.•Zein was detrimental in vitreous while amylose in floury endosperm.•Starch and non-starch lipids of both endosperms negatively affected kd.
Fast, simple laboratory methods were used to analyze 22 maize samples varying in kernel vitreousness from 50.23% to 76.41%. Samples were analyzed in terms of zein content (53.86–86.37 g/kg endosperm ...DM), amylose content (190.76–259.77 g/kg endosperm DM), amylose to amylopectin ratio in starch (0.28–0.43), as well as starch granule size (10.95–14.89 μm in equivalent diameter) and starch granule shape (circularity, 0.85–0.94). More vitreous samples had higher zein and amylose content, as well as smaller and less circular starch granules. Nearly all grain traits on their own significantly affected vitreousness, and a multiple regression model to account for their combined effects was able to explain 61.8% of variability in kernel vitreousness. Zein content contributed most to the model, followed by starch granule projected area and circularity. In contrast, the amylose content contributed only 5.1% to the model. These results suggest that starch-protein interactions influence maize kernel vitreousness more strongly than starch molecular properties do.
•Maize vitreousness was related to starch properties and zein content.•More vitreous samples had higher amylose and zein content.•Starch granules were smaller and less circular in more vitreous samples.•A multiple regression model explained 61.8% of variation in kernel vitreousness.•Zein content contributed more to the model than all other variables.
Yolk carotenoid profile reflects the hen diet when corn grain is the only source of carotenoids, but corn origin and processing may affect carotenoid utilization. In the present study, 2 commercial ...dent corn hybrids differing in grain hardness (soft- and hard-type) were dried at low (40°C) and high (85°C) temperature and ground through a 5- and 9-mm sieve to investigate their effects on carotenoid bioavailability in laying hens. With 3 hens per cage, 168 Lohmann Brown laying hens were allocated to 8 dietary treatments (2 hybrids × 2 drying temperatures × 2 grinding sieves) in a completely randomized design (8 treatments × 7 cages). The trial lasted 8 wk, during which eggs were collected for analysis every 3 d until carotenoid content stabilized, and then once a week until the end of the experiment. The carotenoid profile of the experimental diets and yolks was analyzed using an HPLC method and deposition efficiency was calculated based on carotenoid contents, yolk weight, egg production and diet intake. The deposition efficiency for lutein, zeaxanthin, α- and β-cryptoxanthin, and β-carotene averaged 27.37, 18.67, 6.29, 3,32, and 0.94%, respectively. As expected, the tested hybrids highly affected the carotenoid content in egg yolk due to their differences in carotenoid profile. Interestingly, hard- and soft-type hybrids differed in the deposition efficiency for all individual carotenoids but not for the total carotenoids. High grain drying temperature tended to increase the bioavailability of lutein and zeaxanthin in both hybrids. For the hard-type hybrid, the content of β-carotene in egg yolk was higher when grains were dried at a high temperature, while the opposite response was found in the soft-type hybrid. The effect of grinding sieve size was important for the zeaxanthin bioavailability in the soft-type hybrid only. In conclusion, our findings showed that corn hybrid had a primary influence on the carotenoid content in the yolks of laying hens, but grain processing may change the bioavailability of carotenoids.
Maize hybrids with higher vitreousness contain a higher carotenoid content; however, the relationship between the carotenoid profile and the physical and chemical properties related to vitreousness ...has not been investigated. The aim of this study was to investigate the relationship among the physical properties (kernel size, hardness, density and bulk density), macronutrient composition (crude protein and fat, starch, amylose, amylopectin and zein) and carotenoid profile (individual, total, α- and β-branch carotenoids and xanthophylls) in the grain of 15 maize hybrids. The tested hybrids displayed high variability for most analyzed traits. Three hybrids were characterized by the predominance of β-branch over α-branch carotenoids, while others showed a more uniform content of both fractions. The kernel hardness was associated with the bulk density, flotation index, kernel sphericity, crude protein and zein content. Hybrids with a higher kernel hardness and associated traits had a higher content of zeaxanthin and other β-branch carotenoids, as well as the total carotenoids. In contrast, lutein and α-branch carotenoids were related to the crude protein and amylopectin content only. The findings of the present study confirmed that kernel hardness is associated with β-branch carotenoids and provided further insight into the relationship between the carotenoid profile and commonly analyzed grain quality properties in maize hybrids. The production of higher quality maize hybrids implies a higher nutritional value of the grain due to the higher carotenoid content.
Carotenoids in maize grain degrade during storage, but the relationship between their stability and the physicochemical properties of the grain is unclear. Therefore, the carotenoid degradation rate ...in milled grain of three dent hybrids differing in grain hardness was evaluated at various temperatures (-20, 4 and 22 °C). The carotenoid degradation rate was calculated using first-order kinetics based on the content in the samples after 7, 14, 21, 28, 42, 56, 70 and 90 days of storage and related to the physicochemical properties of the grain. The highest grain hardness was found in the hybrid with the highest zein and endosperm lipid concentration, while the lowest grain hardness was found in the hybrid with the highest amylose content and the specific surface area of starch granule (SSA). As expected, carotenoids in milled maize grain were most stable at -20 °C, followed by storage at 4 and 22 °C. Tested hybrids differed in the degradation rate of zeaxanthin, α-cryptoxanthin and β-carotene, and these responses were also temperature-dependent. In contrast, all hybrids showed similar degradation rate for lutein and β-cryptoxanthin regardless of the storage temperature. Averaged over the hybrids, the degradation rate for individual carotenoids ranked as follows: lutein < zeaxanthin < α-cryptoxanthin < β-cryptoxanthin < β-carotene. The lower degradation rate for most carotenoids was mainly associated with a higher content of zein and specific endosperm lipids, with the exception of zeaxanthin, which showed an opposite pattern of response. Degradation rate for lutein and zeaxanthin negatively correlated with SSA, but interestingly, small starch granules were positively associated with higher degradation rate for mostcarotenoids. Dent-type hybrids may differ significantly in carotenoid degradation rate, which was associated with specific physicochemical properties of the maize grain.
This study investigated the effects of supplementing diets consisting of two dent corn hybrids (soft- and hard-type) with different amounts of rapeseed oil (2, 3, and 4%) and with (0.05%) or without ...emulsifier (Lysoforte Extended, Kemin) on the content and deposition of carotenoids in egg yolk. The feeding trial was conducted with 216 Lohmann Brown laying hens which were by 3 located in 72 cages. The cages were randomly assigned to 12 dietary treatments (2 hybrids × 3 rapeseed oil levels × 2 emulsifier levels), resulting in 6 cages (replicates) per each dietary treatment. After depletion, hens were fed treatment diets without added pigment for 7 wk. After stabilization of the carotenoid profile (lutein, zeaxanthin, α- and β-cryptoxanthin and β-carotene and total carotenoids), eggs were collected once a week until the end of the experiment and deposition efficiency was calculated based on carotenoid content in yolk and diets, yolk weight, egg production and diet intake. Corn hybrid and rapeseed oil affected (P < 0.05) the yolk content and deposition efficiency of most carotenoids. Moreover, a significant (P < 0.05) hybrid × rapeseed oil level interaction for all carotenoids indicated hybrid-specific responses to rapeseed oil supplementation. In the soft-type hybrid, the addition of 3% rapeseed oil enhanced the carotenoid content compared to 2% of rapeseed oil, whereas for the hard-type hybrid, 2 and 3% of rapeseed oil resulted in similar contents. Supplementation of 4% rapeseed oil reduced the content regardless of the hybrid. Emulsifier addition positively affected (P < 0.05) the deposition efficiency of all carotenoids except β-carotene. In conclusion, supplementing corn diets with rapeseed oil and emulsifier affected carotenoid utilization and these responses varied in hybrids differing in grain hardness, which should be considered when using corn as the sole source of carotenoids in hen diets.
Commercial high-yielding corn hybrids have not been evaluated for their ability to pigment egg yolk. Therefore, the objective of this research was to investigate the effects of commercial hybrids ...with different carotenoid profiles as the only source of pigments in the diets of hens on yolk color and carotenoid content, as well as the carotenoid deposition efficiency into the yolk. Treatment diets, differing only in one of five corn hybrids, were offered in a completely randomized design in six cages per treatment, each with three hens. Treatment diets and yolks differed in carotenoid profile (contents of lutein, zeaxanthin, β-cryptoxanthin and β-carotene, p < 0.001), with total carotenoid contents ranging from 17.13–13.45 µg/g in diet and 25.99–21.97 µg/g in yolk. The treatments differed (p < 0.001) in yolk color, which was determined by yolk color fan (10.8–9.83) and CIE Lab (redness; range 12.47–10.05). The highest yolk color intensity was achieved by a diet with the highest content of zeaxanthin, β-cryptoxanthin and β-carotene. The deposition efficiency of lutein and zeaxanthin (25.52 and 26.05%, respectively) was higher than that of β-cryptoxanthin and β-carotene (8.30 and 5.65%, respectively), and the deposition efficiency of all carotenoids decreased with increasing dietary content. Commercial corn hybrids provided adequate yolk color and could be the only source of carotenoids in the diets of hens, which could reduce the cost of egg production and increase farmers’ income.
•Maize hybrids varied widely in carotenoid content and L*a*b* color parameters of grain.•Significant relationship existed between certain carotenoids and color measurements.•Scalar and angular color ...sets as predictors estimate carotenoids content with R2 > 0.90.•Carotenoid contents in maize grain can be accurately predicted by the use of simple colorimetry.
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