Endosperm Fractions Research Articles

Spatial Distribution and Characteristics of Protein Content and Composition in Japonica Rice Grains: Implications for Sake Quality

The quantity and composition of rice proteins play a crucial role in determining taste quality of sake, Japanese rice wine. However, the spatial distribution of proteins within rice grains, especially in endosperm tissue, and the differences between rice varieties remain unclear. Here, we analyzed the crude protein contents and composition ratios of table (Nipponbare and Koshihikari) and genuine sake rice varieties (Yamadanishiki, Gohyakumangoku, Dewasansan, Dewanosato, and Yumenokaori) to elucidate their spatial distribution within the Japonica rice grain endosperm. Seven sake rice varieties were polished over five harvest years using a brewer’s rice-polishing machine. We obtained fractions at 90–70% (the outermost endosperm fraction), 70–50%, 50–30%, and 30–0% (the central region of the endosperm fraction). Yamadanishiki and Dewanosato exhibited considerably lower crude protein contents than the other cultivars. After applying SDS-PAGE, the protein composition, comprising glutelin/total protein (G/TP), prolamin/TP (P/TP), and G/P ratios of these fractions was determined. In white rice (at a 90% rice-polishing ratio), the average ratio of the major protein composition was G/TP 41%, P/TP 21%, and G/P ratios of 1.97. Gohyakumangoku and Yamadanishiki had higher G/TP ratio, while Dewanosato had a lower value. Despite having lower crude protein contents, Yamadanishiki and Dewanosato exhibited significantly varying G/TP ratios. The G/TP ratio markedly varied among rice varieties, particularly in the rice grains’ central region. The 50–30% fraction had the highest P/TP ratio among all tested rice varieties, suggesting spatial differences in P/TP within rice grains. Koshihikari had the lowest P/TP ratio. In addition, the 50–30% fraction had the lowest G/P ratio among all tested rice varieties, with Gohyakumangoku having the highest G/P ratio. Dewanosato had the lowest G/P value, and this value significantly differed from that of Yamadanishiki in the 30–0% fraction. We found substantial differences in protein composition within distinct spatial regions of rice grains, and larger differences among rice varieties were observed in the rice grain’s central region.

Differences and similarities of albumins from japonica rice bran, japonica, indica, and javanica rice endosperm in the suppressive effect of postprandial blood glucose elevation

AbstractSuppression of rapid increase in blood glucose level using food components can prevent diabetes. To use functional food components from natural resources, information regarding the plant varieties and plant parts where the component exists is important for the effective extraction and the effective use of biological resources. We have previously found that proteins from the albumin fraction of rice endosperm are indigestible and adsorb glucose to suppress postprandial blood glucose elevation in vivo. However, the variety and location of this functional protein remain unknown. We investigated whether water‐soluble fraction from the endosperm of indica and javanica rice and red and middle bran of japonica rice contains functional albumin observed in the endosperm of japonica. Middle bran was found to possess an indigestible albumin with the same molecular weight as that in the endosperm of japonica and adsorb a large amount of glucose. Middle‐bran albumin suppressed postprandial blood glucose elevation after oral glucose loading in animal experiments, as well as the rice‐endosperm albumin. As middle bran is the outer layer of the endosperm, many functional components are distributed. Our study can aid the effective use of middle bran, which is predominantly discarded in the process of making rice wine, as a functional food material for the prevention of diabetes mellitus.

Iron bioavailability of maize (Zea mays L.) after removing the germ fraction.

Maize is a staple food for many communities with high levels of iron deficiency anemia. Enhancing the iron concentrations and iron bioavailability of maize with traditional breeding practices, especially after cooking and processing, could help alleviate iron deficiency in many of these regions. Previous studies on a small number of maize genotypes and maize flour products indicated that degermination (germ fraction removed with processing) could improve the iron bioavailability of maize. This study expanded upon this research by evaluating the iron bioavailability, mineral concentrations, and phytate concentrations of 52 diverse maize genotypes before (whole kernels) and after degermination. Whole and degerminated maize samples were cooked, dried, and milled to produce corn flour. Iron bioavailability was evaluated with an in vitro digestion Caco2 cell bioassay. In 30 of the maize genotypes, bioavailable iron increased when degerminated, thus indicating a higher fractional iron uptake because the iron concentrations decreased by more than 70% after the germ fraction was removed. The remaining 22 genotypes showed no change or a decrease in iron bioavailability after degermination. These results confirm previous research showing that the germ fraction is a strong inhibitory component for many maize varieties. Phytate concentrations in maize flours were greatly reduced with degermination. However, the relationship between phytate concentrations and the iron bioavailability of processed maize flour is complex, acting as either inhibitor or promoter of iron uptake depending on the color of the maize kernels and processing method used to produce flour. Other factors in the maize endosperm fractions are likely involved in the effects of degermination on iron bioavailability, such as vitreous or floury endosperm compositions and the polyphenol content of the bran. This study demonstrates that iron nutrition from maize can be enhanced by selecting genotypes where the inhibitory effect of the bran color and endosperm fraction are relatively low, especially after processing via degermination.

Changes in the physicochemical properties of maize endosperm, endosperm fractions, and isolated starches because of nixtamalization

This work focused on the physicochemical changes undergone by maize endosperm during a thermo-alkaline nixtamalization process for the cooking (0 h) and steeping (8 h) steps. The study was performed on the outermost 10%, subsequent 10%, and the remaining 80% of crude, cooked (0 h), and steeped (8 h) endosperm. Calcium content increased mainly in the outermost layers of the endosperm, while the remaining 80% showed no significant changes. The starch granules showed no external damage during cooking and steeping. X-ray analysis revealed that the hard endosperm contained A-type starch with an orthorhombic crystalline structure. Examination of the isolated starches during nixtamalization showed that there is a fraction that does not undergo physicochemical transformation when in contact with water and heat, and this fraction can be referred to as resistance starch. A new methodology using scanning electron microscopy has shown that the pasting properties are determined by the changes in the morphology of the paste.

Effect of aleurone‐rich fraction on texture and nutritional properties of breads

SummaryAleurone represents a fraction of the outer endosperm in wheat kernels composed of a single‐cell layer containing a variety of nutrients, including dietary fibre (mainly arabinoxylan, β‐glucan, and cellulose), proteins, minerals, vitamins, and antioxidants (ferulic acid). In this study, aleurone‐rich fraction (0%–100%) was added to wheat flour to examine the microstructure of the bread and the crystal structure of the starch after the addition using scanning electron microscopy and X‐ray diffraction. The maximum in vitro hydrolysis rate of bread with 10%–100% aleurone‐rich fraction addition ranged from 35.69% to 65.93%, which was significantly lower than that of white bread (68.76%). Low‐field nuclear magnetic resonance revealed an increase in the amount of bound water in bread after the addition of the aleurone‐rich fraction. Further, bread containing the aleurone‐rich fraction had a higher antioxidant capacity, as evaluated by DPPH• and •OH scavenging activity. Therefore, these results indicate that the aleurone‐rich fraction may be a beneficial ingredient for the manufacture of low‐calorie and high‐fibre foods.

Iron Bioavailability of Maize Is Improved by Degermination for Some but Not All Genotypes: Enhancing Maize Nutrition With Biofortification and Processing

ObjectivesTo evaluate bioavailable Fe, total Fe concentration and phytate concentration of whole and degerminated maize in a diverse panel of 52 genotypes. This work sought to expand upon previous work which identified the germ fraction of the maize kernel as an inhibitory component for Fe bioavailability.MethodsSamples were degerminated manually by scalpel dissection of the germ fraction. Samples were then cooked, lyophilized, and milled to a flour. Iron bioavailability was evaluated with the Caco-2 Cell Bioassay. Iron concentration was measured by ICP-ES. Phytate concentration was determined via a colorimetric assay for total phytate phosphorous (Megazyme Phytate Kit, Megazyme International).ResultsIn 30 of the maize genotypes, bioavailable Fe increased when degerminated, thus indicating a higher fractional Fe uptake as the amount of Fe decreased by more than 70%. The remaining 22 genotypes showed no change or a decrease in Fe bioavailability with degermination. These results confirm previous research showing that the germ fraction is a strong inhibitory component for many maize varieties. Degermination greatly reduced phytate content and phytate:Fe molar ratio; Fe concentrations were positively correlated with phytate, and negatively correlated with phytate:Fe molar ratios for most maize groups. While the high phytate content of the germ fraction likely plays a role, only degerminated yellow maize indicated a significant correlation between Fe bioavailability and phytate concentration, and only pigmented maize indicated a correlation between Fe bioavailability and phytate:Fe molar ratio. Other factors in the maize germ and endosperm fractions are likely relevant to changes in Fe bioavailability.ConclusionsThis study suggests that Fe nutrition from maize can be enhanced by processing (degermination) and or by selecting varieties where the inhibitory effect of the germ fraction is relatively low.Funding SourcesFunded by the United States Department of Agriculture, Agricultural Research Service.

Infrared modification of sorghum to produce a low digestible grain fraction

The present study was aimed to modify sorghum grain by infrared thermal treatment (IRTT) under various moisture regimes and to obtain a modified corneous endosperm (CE) fraction. The CE fraction was studied for starch digestibility, functional, thermal and structural characteristics. The study revealed that the IRTT increased the resistant starch and slowly digestible starch contents in the CE. An increase in storage elasticity modulus (51000–118000 Pa) and peak gelatinization temperature (73.36–76.89 °C) in the modified CE was also observed. The characteristics of starch isolated from modified CE differed from the CE fraction with respect to rheology, oil absorption capacity and starch digestibility. Scanning Electron Microscopy and birefringence micrographs revealed high degree of structural modifications in starch at 30% moisture content. Fourier Transform Infrared spectroscopy revealed that IRTT increased crystallinity at low moisture and it promoted starch retrogradation at high moisture content. Further, the –OH stretching suggested that the starch-protein interaction depended on the moisture content. The IRTT caused structural modifications and hence low starch digestibility. The study indicated that the IRTT could be efficiently used to modify grain starch fraction having low glycemic index with potential in developing functional food formulations.

Struktura skroba u odnosu na fizičke karakteristike zrna kukuruza

The focus of this study is on the physical quality traits and starch composition of various maize kernel genotypes grown in Serbia. Furthermore, the aim was to determine the relationship among these quality traits. Results obtained from the Stenvert hardness test showed great variability among the maize samples. The portion of the hard endosperm fraction (HE) ranged from 53.29% to 76.28%. Test weight (TWt) and 1000-kernel weight (KWt) of 10 different ZP maize genotypes ranged from 782.69 to 907.39 kgm-3 and from 128.40 to 376.50 g, respectively. The specialty maize genotypes had the highest content of amylose (27.8% and 28.9%). Yellow dent genotype, ZP 606, had the lowest amylose content in the kernel (22.3%). The results suggested that the composition of starch granule differed depending on the hardness of the endosperm. The amylose content was highly correlated with the physical traits such as TWt, KWt, density and HE.

The Process of Separation of Husked Soybean in Oblique Airflow

The study concerns an evaluation of the effect of selected parameters on the course of horizontal pneumatic separation of unsorted husked soybean and the process efficiency. The efficiency of the process of isolating endosperm fraction from husks and other impurities was evaluated by determining the separation efficiency indicator η. It was shown that increased moisture content of the mixture results in a significant decrease in the η indicator. For example, with the 2.2% increase of moisture content (from W1 = 10.1% to W2 = 12.3%), the separation efficiency indicator decreased, on average, by 6.8%. The value of the η indicator rose with the increased velocity of the airstream, but the amount of valuable fraction that is picked up by the airstream is higher as well. It was found that, when the air velocity increased from V1 = 7.8 m·s−1 to V2 = 10.5 m·s−1 (for the moisture content W1 = 10.1% and W4 = 15.7%), the increment in the efficiency was the highest and reached 14.9–34.3%. A parametric model of the separation process of fragmented mixtures of biological origin was developed based on the analysis of the obtained results observation undertaken. This model can be used in designing and carrying out operations of separation into particular size fractions and cleaning of various feed mixtures, or in determining parameters of the movement of specific mixture components within pneumatic channels.

Identification of Chemical Compounds from Nipah (Nypa fruticans Wurmb.) Endosperm

The identification of chemical compounds in Nipah (Nypa fruticans Wurmb) endosperm has been done. The extraction of chemical compounds in Nipah endosperm has been done using the maceration method with heating and followed with absorbs-desorbs on active carbon given ethanol fraction. The result obtained was a brownish-yellow fraction. The phytochemical screening test did on endosperm and ethanol fraction. Phytochemical screening results showed that the Nipah endosperm contains phenolic, tannin, flavonoid, and saponin compounds, while the ethanol fraction of Nipah endosperm did not contain alkaloid, flavonoid, steroid, triterpenoid, phenolic, tannin, and saponin compounds. Based on UV-vis, IR, and GCMS spectra, the ethanol fraction contains of furfural compounds.

Karakteristike zrna novih samooplodnih linija u poređenju sa hibridima kukuruza

Grain quality parameters of five new maize inbred lines were investigated and compared with the corresponding properties of two commercial hybrids used in flour production. Kernel of the line L2 had the highest 1000-kernel mass (267.54 g), and line L2 had the highest test mass (844.68 kg m-3 ). The milling response ranged from 9.80 (L2) to 14.03 s (L1). The largest share of the soft fraction of endosperm was determined in L3 (37.13 %), which is slightly lower than in hybrid ZP 633. The highest protein (12.37 %), as well as crude fibre content (2.59 %) was determined in inbred line L4, while the lowest protein was found in the line L2 (9.36 %), and the lowest crude fibre content (1.81 %) was detected in line L3. All tested maize inbred lines were found to be highly prospective for breeding of new hybrids with improved grain quality parameters.

Fizičko-hemijska svojstva zrna žutih i crvenih hibrida kukuruza iz Srbije

Physical traits, kernel structure and chemical composition of five yellow and five red kernel maize hybrids were the subjects of this study. The 1000-kernel weight, a physical indicator of grain quality, ranged from 325.76±7.47 g (ZP 555 red) to 375.63±4.18 g (ZP 606). The hard endosperm fraction content varied between 57.66±0.93% (ZP 4007) and 67.08±0.42% (ZP 366 red). Regarding chemical composition, starch was predominant constituent ranging from 66.80±0.18 (ZP 4007 red) to 72.96±0.37 (ZP 606). The highest protein content was detected in ZP 606 (10.72±0.11) and the lowest in ZP 7007 red hybrid (8.63±0.04%). Milling response was highly influenced by hard endosperm fraction content (0.81**), and starch content was strongly correlated to 1000-kernel weight (0.77**). Whole-grain maize flours produced from yellow and red kernels without removing the germ are naturally gluten-free and can be used as functional food ingredients. All yellow and red kernel maize hybrids investigated in this study showed good quality parameters regarding physical properties and variations in chemical composition which makes them suitable for different industrial uses, primarily for food and feed production.

Hydrothermal treatment of maize: Changes in physical, chemical, and functional properties

The objective of this work was to assess the effects of a traditional parboiling treatment on physical, chemical and functional properties of yellow maize kernels. For this, maize kernels were subjected to the three main stages of a traditional parboiling process (soaking, steaming, and drying) at different moisture contents (15%, 25%, or 35%), and different pressure steaming times (0, 15, or 30 min). Kernels were evaluated for physical and chemical changes, while manually generated endosperm fractions were further evaluated for nutritional and functional changes. The parboiling process negatively altered the maize kernels properties by increasing the number of kernels with burst pericarp and decreasing the total carotenoid content in the endosperm by 42%. However, the most intense conditions (35% moisture and 30 min steam) lowered the number of broken kernels by 41%, and the number of stress cracks by 36%. Results also demonstrated that soaking enhanced the nutritional value of soaked yellow maize by increasing the thiamine content and the bound phenolic content in the endosperm fraction up to 102%. The proper implementation of this hydrothermal treatment could lead to significant enhancements in nutritional and functionality of maize products.

Wheat bran-associated subaleurone and endosperm proteins and their impact on bran-rich bread-making

The functionality of wheat bran-associated subaleurone and endosperm proteins was investigated. The wheat cultivars Apache and Akteur were used as they displayed widely different subaleurone protein contents upon microscopic analysis. Brushing of their roller mill bran yielded a peripheral endosperm- and subaleurone-enriched flour fraction with a protein content of 15.1% and 22.1% for Apache and Akteur, respectively, compared to 10.0% and 12.8% for regular flour. The peripheral endosperm fraction of Akteur, but not Apache, displayed increased glutenin and gliadin contents and increased glutenin subunit crosslinking. Bread-making using bran subjected to heat treatment and particle size reduction indicated that the gluten quantity and quality of the bran-associated tissue, as well as its availability and vitality, significantly affected dough and bread properties. These findings were validated using four commercial bran samples and demonstrate the potential importance of heat stabilization and wheat selection when producing bran for bread-making.

Effect of lutein esterification on the differential distribution of carotenoids in germ and endosperm fractions from tritordeum grains

The effect of lutein esterification on the carotenoid distribution profile in the different fractions of tritordeum grains was studied. Durum wheat, a cereal lacking of lutein esters, was included for comparison in the study. Although carotenoid contents in endosperm and germ were significantly different for both cereals, the pigment distribution showed a marked dependence on the cereal's genetic background. Thus pigment content in durum wheat was 3 times higher in germ (2.52 μg/g fresh weight (fw)) than the endosperm (0.74 μg/g fw). In contrast, carotenoids in tritordeum were distributed more homogeneously (4.16 and 4.59 μg/g fw for germ and endosperm, respectively). Lutein esters were exclusively present in tritordeum fractions, with a 3-fold higher content in the endosperm, which suggests a preferential esterifying activity in this tissue. The fatty acid profile indicated that the presence of lutein esters could be limited by the existence of specific XAT (xanthophyll acyltransferase) enzymes and not by substrate availability. A positive impact of esterification on the even deposition pattern of pigments throughout the tritordeum grain was observed. These data could be useful for optimizing the retention of lutein through the food chain as well as to direct the breeding of crops enriched in lutein esters.

Use of air classification technology to produce protein-enriched barley ingredients

Air classification of an industrial barley endosperm fraction with initial protein content of 8.3% mixed with Aerosil 200F flow aid resulted in protein enrichment up to 28.3% with 21.7% protein separation efficiency. By reducing the classifier wheel speed from 21500 rpm to 8000 rpm, the protein separation efficiency increased to 59.4%, whereas the protein content only decreased to 22.3%. Microstructural analysis showed that small starch granules separated together with protein in the fine fraction and had more continuous protein matrix around them. The protein-enriched fraction obtained at 8000 rpm classifier wheel speed had limited protein solubility of 9.3% at native pH 5.1. Solubility increased in acidic (pH 3, 19.6%) and especially in alkaline (pH 11, 91.9%) conditions. Protein fraction had water and oil binding capacities of 1.2 and 1.1 g/g, respectively. Foaming properties tested at different pH-values revealed best capacity at pH 3. Thermograms showed two melting temperatures, varying from 60.0 to 64.2 °C and from 90.5 to 95.5 °C for all the studied fractions. Cereal side-streams such as the industrial barley endosperm fraction can be utilised as potential plant protein ingredient for various food/feed applications. However, further studies are needed to evaluate the technological, nutritional, and sensory characteristics of this protein enriched fraction.

Distribution of bioactive compounds in maize fractions obtained in two different types of large scale milling processes

Maize kernels contain different bioactive compounds that are important for human health. The aim of this study was to analyze the distribution of the bioactive compounds in maize fractions derived from two industrial dry-milling processes, characterized by a dry-degermination (DD) system and a tempering-degermination (TD) system.The bioactive compounds in maize resulted unevenly distributed in the milling fractions of the kernel. By-products such as the germ and the animal feed flour, had higher total antioxidant capacity (TAC), total polyphenol content (TPC) and total dietary fibre content (TDF) than the whole grains, while xanthophyll and resistant starch resulted to be higher in the fractions derived from the vitreous endosperm. The germ fraction showed also the highest folate content. Results also showed that the type of degermination process influences the bioactive compound contents in the milling fraction, in accordance to the effectiveness of the germ and bran removal from the endosperm fractions. In particular, the animal feed flour obtained by means of TD system resulted in a higher TAC, TPC and TDF than the same fraction obtained by means of the DD system. Conversely, the extraction rate do not affect the recovery of bioactive components in particular fractions.

Performance analysis of a novel cyclone-type pneumatic rice polisher

Energy intensive commercial abrasive-friction rice polishing systems with heavy moving parts induces considerable breakage of rice. Jet polishing, used for metals with high speed air-abrasive particles, could be adopted to develop a simple pneumatic rice polishing system without any moving parts. Its construction is similar to a gas-cyclone system. The effect of four abrasive surfaces, viz., coarse (CR, 483 μm), medium (MD, 254 μm), fine (FN,122 μm) and very fine (VF, 89 μm) on degree of polishing (DP) and broken yield (Br) was studied. Particle-trajectory, particle-abrasive surface interaction, grain rotation pattern and progress of bran removal were also studied. DP and Br increased linearly with number of passes for all the abrasive surfaces. Higher DP (8.49 ± 0.2 and 8.49 ± 0.3%) with CR and MD was attributed to removal of bran layer along with endosperm fractions while FN and VF removed proportionally more bran layer (DP, 6.27 ± 0.3 and 8.31 ± 0.4%) with negligible endosperm fraction. Br was least (24.13 ± 0.5%) with VF and highest (34.0 ± 2.2%) with CR.

Produção e utilização de silagens de grãos úmidos

The high moisture grain silage has emerged as an efficient storage of cereal grains for animal feed at a lower cost and better nutritional value. The improvement in the digestibility of the starch grains with the use of high humidity is caused by reducing interference of the matrix protein in the hydrolysis of the endosperm fraction, since these matrices are not already completely formed and solidified. The use of wet grain silage is an alternative permissible to produce, therefore, provides to the animal a food of high calorific value and better digestibility, which may be stored. Featuring up of raw material quality and workmanship appropriate use is economically feasible to farmer because it allows reducing costs while maintaining production rates.

Distribution of Cadmium, Iron, and Zinc in Millstreams of Hard Winter Wheat (Triticum aestivum L.).

Hard winter wheat (Triticum aestivum L.) is a major crop in the Great Plains of the United States, and our previous work demonstrated that wheat genotypes vary for grain cadmium accumulation with some exceeding the CODEX standard (0.2 mg kg(-1)). Previous reports of cadmium distribution in flour milling fractions have not included high cadmium grain. This study measured the distribution of cadmium, zinc, and iron in flour and bran streams from high cadmium (0.352 mg kg(-1)) grain on a pilot mill that produced 12 flour and four bran streams. Recovery in flour was substantially greater for cadmium (50%) than for zinc (31%) or iron (22%). Cadmium, zinc, and iron in the lowest mineral concentration flour stream, representing the purest endosperm fraction, were 52, 22, and 11%, respectively, of initial grain concentration. Our results indicate that, relative to zinc and iron, a greater proportion of cadmium is stored in the endosperm, the source of white flour.