Tocopherols and Tocotrienols in Barley Oil Prepared from Germ and Other Fractions from Scarification and Sieving of Hulless Barley

Two cultivars of hulless barley (Doyce and Merlin) were scarified to abrade the outer layers of the kernels (germ, pericarp, and aleurone). The resulting scarification fines fractions were then separated into four particle-size subfractions using sieves. Each of the size subfractions was then extracted with hexane to produce a barley oil, and the levels of free phytosterols, tocopherols, and tocotrienols in the various barley oils were compared. For both cultivars, the fraction with the largest particle size (0.717–1.410 mm) had the highest oil yields (11–12%). Visual examination of this fraction indicated that it consisted almost entirely of small fragments (≈1 mm) of the germ portion of the kernel. The levels of tocopherols were highest in the largest particle-size fraction and their proportion decreased in the fractions with decreasing particle size. In contrast, the levels of tocotrienols were very low in the largest particle-size fraction and increased in the fractions with decreasing particle sizes. Intact germ was also prepared by hand-dissection, extracted, and analyzed. The results indicate that the ≈1 mm germ fragments obtained by scarification-sieving consisted almost entirely of germ fragments, but these fragments represented only 17.5 and 23.7% of the total mass of the germ, from Merlin and Doyce, respectively. These results also suggest that it may be possible to control the concentrations of tocopherols and tocotrienols in barley oil by controlling the particle size of the feedstock used to extract the oil. Germ fragments isolated by such processes could potentially be used as functional food ingredients or extracted to yield oils enriched in health-promoting phytosterols, tocopherols, or tocotrienols.     

Composition and Utilization of Barley Pearling By‐Products for Making Functional Pastas Rich in Dietary Fiber and β‐Glucans

Pearling by‐products and the pearled products of two commercial stocks of hulled barley, pearled according to an industrial process consisting of five consecutive pearling steps, were analyzed for β‐glucans, dietary fiber (total, soluble, and insoluble), protein, lipid, ash, and digestible carbohydrate. The data showed that the pearling flour fractions, abraded in the fourth and fifth hullers, contained interesting amounts of β‐glucans (3.9–5.1% db) from a nutritional point of view. These fractions were subsequently enriched in β‐glucans using a milling‐sieving process to double β‐glucan content (9.1–10.5% db). Functional pastas, enriched with β‐glucans and dietary fiber, were produced by substituting 50% of standard durum wheat semolina with β‐glucan‐enriched barley flour fractions. Although darker than durum wheat pasta, these pastas had good cooking qualities with regard to stickiness, bulkiness, firmness, and total organic matter released in rinsing water. The dietary fiber (13.1–16.1% wb) and β‐glucan (4.3–5.0% wb) contents in the barley pastas were much higher than in the control (4.0 and 0.3% wb, respectively). These values amply meet the FDA requirements of 5 g of dietary fiber and 0.75 g of β‐glucans per serving (56 g in the United States and 80 g in Italy). At present, the FDA has authorized the health claim “may reduce the risk of heart disease” for food containing β‐glucans from oat and psyllium only.     

Milling Performance of North European Hull‐less Barleys and Characterization of Resultant Millstreams

Four hull‐less barley samples were milled on a Bühler MLU 202 laboratory mill and individual and combined milling fractions were characterized. The best milling performance was obtained when the samples were conditioned to 14.3% moisture. Yields were 37–48% for straight‐run flour, 47–56% for shorts, and 5–8% for bran. The β‐glucan contents of the straight‐run white flours were 1.6–2.1%, of which ≈49% was water‐extractable. The arabinoxylan contents were 1.2–1.5%, of which ≈17% was water‐extractable. Shorts and bran fractions contained more β‐glucan (4.2–5.8% and 3.0–4.7%, respectively) and arabinoxylan (6.1–7.7% and 8.1–11.8%, respectively) than the white flours. For those fractions, β‐glucan extractability was high (58.5 and 52.3%, respectively), whereas arabinoxylan extractability was very low (≈6.5 and 2.0%, respectively). The straight‐run white flours had low α‐amylase, β‐glucanase, and endoxylanase activities. The highest α‐amylase activity was found in the shorts fractions and the highest β‐glucanase and endoxylanase activities were generally found in the bran fractions. Endoxylanase inhibitor activities were low in the white flours and highest in the shorts fractions. High flavanoid, tocopherol, and tocotrienol contents were found in bran and shorts fractions.     

Yield and Phytosterol Composition of Oil Extracted from Grain Sorghum and Its Wet‐Milled Fractions

Corn fiber contains an oil with high levels of three potential cholesterol‐lowering phytosterol compounds. Little information is available about the levels and types of phytosterols in sorghum. In this study, phytosterols were evaluated in grain sorhgum and its wet‐milled fractions and were compared with the phytosterols in corn. The study showed that sorghum kernels can provide a significant source of two phytosterol classes, free phytosterols (St) and fatty acyl phytosterol esters (St:E). Most of these phytosterols are concentrated in the wet‐milled fiber fraction followed by the germ fraction. In addition to phytosterols, other lipid classes such as wax esters and an aldehyde (50% C28 and 50% C30) are also present in the sorghum oil. Comparison of sorghum and corn kernels show that corn has 72–93% more phytosterols than sorghum.     

Analysis of Alkylresorcinols in Wheat Germ Oil and Barley Germ Oil via HPLC and Fluorescence Detection: Cochromatography with Tocols

Alkylresorcinols are long‐chain phenolic compounds that have been reported to be localized in the outer layers of the kernels of wheat, rye, barley, and other grains. A sensitive HPLC method with fluorescence detection was recently reported for the quantitative analysis of alkylresorcinols in cereal grains and products. Using this new HPLC method we report for the first time that wheat germ oil contains moderate levels of alkylresorcinols, approximately 800–1,500 µg per gram of oil. We also found that commercial wheat germ oil and some experimental samples of wheat germ oil and barley germ oil also contained three unknown peaks. Upon further evaluation of these peaks it was found that the peaks appeared to be tocopherols (one peak of α‐tocopherol, one peak of δ‐tocopherol, and a peak with the combination of β‐ and γ‐tocopherol), even though the excitation and emission wavelengths for alkylresorcinols (excitation 274 nm and emission 300 nm) are different than those for tocols (excitation 294 nm and emission 326 nm). We also found that with this HPLC system one alkylresorcinol, AR17, had the same retention time (7.6 min) as δ‐tocotrienol and that another alkylresorcinol, AR19, had the same retention time (10.8 min) as α‐tocotrienol.     

Composition of Functional Lipids in Hulled and Hulless Barley in Fractions Obtained by Scarification and in Barley Oil

Two cultivars of hulled barley (Thoroughbred and Nomini) and two cultivars of hulless barley (Doyce and Merlin) were scarified to abrade the outer layers of hull and pericarp. The resulting scarification fines fractions were evaluated as potential sources of functional lipids (phyto‐sterols, tocopherols, and tocotrienols). The levels of total phytosterols and total tocotrienols in the barley scarification fine fractions were probably not high enough to justify their use as functional foods. However, the levels of total phytosterols and total tocotrienols in the oils extracted from both whole kernels and scarified fines were both sufficiently high to make it reasonable to consider their potential use as new functional oils. Indeed, the levels of total tocotrienols in barley oils (2,911–6,126 mg/kg of oil) are several‐fold higher than those reported in two other oils that are being marketed as high in tocotrienols: palm oil (530 mg/kg) and rice bran oil (770 mg/kg). The levels of total phytosterols in barley oils range from 1.20 to 9.60 g/100 g of oil.     

Genotypic Variation in Color and Discoloration Potential of Barley‐Based Food Products

Barley has a variety of potential food uses. However, the dark gray color of the final products negatively affects consumer acceptability. We determined the discoloration potential of barley from different classes and genotypes, and evaluated the relationship of barley composition, total polyphenol content, and polyphenol oxidase (PPO) activity with discoloration potential of barley. Barley grains were abraded, milled into flour, and analyzed for composition, total polyphenol content, and PPO activity. Total polyphenol content of abraded barley, expressed as gallic acid %, was lowest in hulled proanthocyanidin‐free barley (0.02–0.04%), followed by hulled proanthocyanidin‐containing barley (0.11–0.18%), and hull‐less barley (0.19–0.26%). PPO activity of abraded kernels ranged from 62.1 units/g in hulled proanthocyanidin‐containing Baronesse to 116.5 units/g in hulled proanthocyanidin‐free CA803803. Dough sheet brightness (L* value) was the best indicator of discoloration potential of barley. Large variation in L* value of dough sheets was observed among different classes and among genotypes within classes. Brightness of dough sheets measured at 24 hr were significantly higher in hulled (65.3–78.1) than in hull‐less (59.0–63.9) barley, and within hulled barley, higher in proanthocyanidin‐free (72.2–78.1) than in proanthocyanidin‐containing (65.3–69.6) barley. Total polyphenol content significantly correlated with the discoloration potential of barley. Protein content and ash content also had a significant negative correlation with discoloration of dough sheets. The results indicated that polyphenol compounds may play a major role in discoloration potential of barley‐based products.     

Distribution and Structural Variation of Nonstarch Polysaccharides in Milling Fractions of Hull‐less Barley with Variable Amylose Content

Three hull‐less barley genotypes containing starches with variable amylose content (23.8% normal, 4.3% waxy, 41.8% high‐amylose barley) were pearled to 10% and then roller‐milled to produce pearling by‐products (PBP), flour, and fiber‐rich fractions (FRF). PBP were enriched in arabinoxylans, protein, and ash and contained small amounts of starch and β‐glucans. FRF were considerably enriched in β‐glucans and arabinoxylans. The solubility of β‐glucans was higher in PBP than in FRF. The solubility of arabinoxylans was higher in FRF than in PBP. Small amounts of arabinogalactans detected in barley were concentrated in the outer portion of the barley kernel. The content and solubility of nonstarch polysaccharides (NSP) in various milling fractions was also dependent on the type of barley. To obtain more detailed information about the content and molecular structure of NSP, each milling fraction was sequentially extracted with water, alkaline [Ba(OH)₂], again with water, and finally with NaOH. These extractions resulted in four sub‐fractions: WE, Ba(OH)₂, Ba(OH)₂/H₂O, and NaOH. β‐Glucans and arabinoxylans exhibited structural heterogeneity derived from differences in their location within the kernel as well as from the genetic origin of barley. The WE arabinoxylans from FRF and flour had a substantially lower degree of branching than those from PBP. The WE arabinoxylans from FRF of high‐amylose and normal barley contained more unsubstituted Xylp residues but fewer doubly‐substituted and singly‐substituted Xylp at O‐2 than their counterparts from PBP. The WE arabinoxylans from FRF of waxy barley had a relatively high content of doubly‐substituted, but very few singly‐substituted Xylp residues. In all three barley genotypes, the ratio of tri‐ to tetrasaccharides in β‐glucans from PBP was higher than from flour and FRF. Substantial differences in the molecular weight of NSP in different milling fractions were also observed.     

Surface Abrasion of Hulled and Hulless Barley: Physical Characterization of the Milled Fractions

Abrasion techniques were used to remove the hull and pericarp layers of barley kernels to obtain a smaller kernel enriched in endosperm. The objective of this study was to evaluate the fractions produced by two alternative abrading systems on four barley cultivars for potential use in fuel ethanol processes that feature an upstream (of the fermentation) dry fractionation system. Four barley cultivars, two hulled (Thoroughbred and Nomini) and two hulless (Doyce and Merlin), were scarified and whitened at 22 scarification times and three milling degrees (settings 2, 4, and 6), respectively. Three different abrasive surfaces (36, 40, and 50 grit) were used in the scarifier to determine the material removal ratio for each barley cultivar. Material balances and color analyses were conducted for all of the fractions produced. Three fractions were produced with the whitener at each milling degree: broken kernels, fine fractions >323 μm, and fine fractions <323 μm. Setting #2 seems to be the milling level that releases most of the hull in the hulled barley with the whitener. After 50 sec of scarification, rougher surfaces produced more fine material (<1,410 μm diameter) and consequently less coarse material (>1,410 μm diameter). A lower grit (36 grit) abrasive surface induced faster hull removal in hulled barley. Color parameters L* and b* were good indicators of the fine and coarse fractions produced by abrasive methods because they indicate the kernel layer removed and were modeled as a function of the fraction of the material produced. The information obtained in this study has application in designing processes capable of removing and recovering hull and pericarp layers of barley kernels and thereby producing smaller kernels or kernel pieces containing mainly endosperm tissue.     

Tibetan Hull‐less Barley (Hordeum vulgare L.) as a Potential Source of Antioxidants

Tibetan hull‐less barley grows at above 4,000 m altitude. One variety grown in the plain and three varieties grown in Tibet were collected from Tianjin and Lhasa. The barleys were polished into five fractions. Total soluble phenolic content (TSPC), total antioxidant capacity (TAC), and their correlation were investigated. Phenolic compounds were analyzed by HPLC, and TSPC content was evaluated by the Folin–Ciocalteu colorimetric method. TAC was measured using 2,2‐diphenyl‐1‐picrylhydrazyl, 2,2′‐azinobis‐(3‐ethylbenzthiazoline‐6‐sulfonate), and ferric reducing ability of plasma assays. Results showed that TSPC decreased from the outer to the inner fractions, with the outermost layer containing the highest (around 2,803–7,703 μg/g) and inner endosperm the lowest (around 870–1,348 μg/g). TSPC and TAC were highly and positively correlated (r = 0.9583–0.9710). Colored hull‐less barley had higher antioxidant activity than uncolored. TSPC and TAC of Tibetan varieties in the outer layers were more than two‐fold higher than that of Tianjin hull‐less barley. Tibetan hull‐less barley bran extracts are valuable sources of bioactive components with antioxidant activity.     

Functionality of Barley Proteins Extracted and Fractionated by Alkaline and Alcohol Methods

This research optimized the extraction of different protein fractions from barley grains and assessed the physicochemical properties of the fractions obtained. Pearling was first used to remove the grain's outer layers (mainly bran and germ) so that the barley cytoplasmic proteins (albumin and globulin) would be enriched in the pearling flour (PF), while endosperm proteins (hordein and glutelin) would be enriched in the pearled grain flour (PGF). Salt, alcohol, and alkaline solutions were then used to extract different barley protein fractions from PF and PGF. The effects of extraction solvent type, pH, temperature, and extraction time on protein content and extraction efficiency were studied. Aqueous ethanol (55%, v/v) efficiently extracted barley hordein from PGF at 60°C, whereas pH 11.5 alkaline solution was the most efficient for extracting both cytoplasmic and endosperm proteins from barley PF and PGF at 23°C. Subunit molecular weight, amino acid composition, and the functional properties of each isolated barley protein fraction were investigated. Barley glutelin demonstrated superior oil‐binding property and emulsifying stability, whereas barley hordein exhibited good foaming capacity.     

Preparation and Characterization of Films Using Barley and Oat β‐Glucan Extracts

Films for potential food use were prepared from aqueous solutions of β‐glucan extracted from hulled barley, hull‐less barley, and oats. The extracts (75.2–79.3% β‐glucan) also contained proteins, fat, and ash. Glycerol was used as a plasticizer. The films were translucent, smooth, and homogeneous in structure on both sides. Water vapor permeability of films prepared from 4% solutions of β‐glucan extracts were higher than those from 2% solutions, despite similar values for water vapor transmission rate. Mechanical properties were influenced by both β‐glucan source and concentration. The oat β‐glucan films showed higher tensile strength and water solubility, and lower color, opacity, and deformation values than those of barley. Films prepared from hull‐less barley cv. HLB233 remained intact upon immersion in water for 24 hr.     

High‐Speed NIR Segregation of High‐ and Low‐Protein Single Wheat Seeds

Wheat breeders need a nondestructive method to rapidly sort high‐ or low‐protein single kernels from samples for their breeding programs. For this reason, a commercial color sorter equipped with near‐infrared filters was evaluated for its potential to sort high‐ and low‐protein single wheat kernels. Hard red winter and hard white wheat cultivars with protein content >12.5% (classed as high‐protein, 12% moisture basis) or < 11.5% (classed as low‐protein) were blended in proportions of 50:50 and 95:5 (or 5:95) mass. These wheat blends were sorted using five passes that removed 10% of the mass for each pass. The bulk protein content of accepted kernels (accepts) and rejected kernels (rejects) were measured for each pass. For 50:50 blends, the protein in the first‐pass rejects changed as much as 1%. For the accepts, each pass changed the protein content of accepts by ≈0.1%, depending on wheat blends. At most, two re‐sorts of accepts would be required to move 95:5 blends in the direction of the dominant protein content. The 95:5 and 50:50 blends approximate the low‐ and high‐protein mixture range of early generation wheat populations, and thus the sorter has potential to aid breeders in purifying samples for developing high‐ or low‐protein wheat. Results indicate that sorting was partly driven by color and vitreousness differences between high‐ and low‐protein fractions. Development of a new background specific for high‐ or low‐protein and fabrication of better optical filters for protein might help improve the sorter performance.     

Detection of Fragments from Internal Insects in Wheat Samples Using a Laboratory Entoleter

A simple, rapid method that uses a small mechanical rotary device (entoleter) was developed for estimating insect fragment counts in flour caused by hidden, internal‐feeding insects in whole grains of hard red winter and soft red winter wheat. Known counts of preemergent adults, pupae, and larvae of lesser grain borers and rice weevils were blended with 500 g samples of uninfested wheat. The entoleter impeller speed was adjusted based on grain hardness and moisture content to obtain about ≈98% intact and ≈2–2.5% broken kernels in an uninfested sample. The entoleter flung the wheat kernels against a surrounding steel ring. Approximately 70–90% of the insect‐infested kernels, being weaker, released internal insect pieces upon impact. The broken kernels were sieved with number 10 and number 20 sieves to obtain large‐sieved and small‐sieved fractions, respectively. Insect pieces in sieved fractions were counted. The insect piece counts were correlated with the estimated flour fragments (R² = 0.94). The entoleter method can distinguish samples of grain containing 0, 25, or 75 fragments in 50 g of flour, with greater than 95% confidence. The method can be performed in approximately 5 min per 500 g sample and could potentially be a cost‐effective method that grain handlers can use to inspect wheat loads for detecting insect damage and estimating insect fragments in flour.     

Roller Milling of Canadian Hull‐less Barley: Optimization of Roller Milling Conditions and Composition of Mill Streams

Roller milling of hull‐less barley generates mill streams with highly variable β‐glucan and arabinoxylan (AX) content. For high β‐glucan cultivars, yields >20% (whole barley basis) of a fiber‐rich fraction (FRF) with β‐glucan contents >15% can be readily obtained with a simple short mill flow. Hull‐less barley cultivars with high β‐glucan content require higher power consumption during roller milling than normal β‐glucan barley. Recovery of flour from high β‐glucan cultivars was greatly expedited by impact passages after grinding, particularly after reduction roll passages. Pearling before roller milling reduces flour yield and FRF yield on a whole unpearled barley basis, but flour brightness is improved and concentration of β‐glucan in fiber‐rich fractions increases. Pearling by‐products are rich in AX. Pearling to 15–20% is the best compromise between flour and FRF yield and flour brightness and pearling by‐products AX content. Increasing conditioning moisture from 12.5 to 14.5% strongly improved flour brightness with only a moderate loss of flour yield on a whole unpearled barley basis. As moisture content was increased to 16.5%, flour yield declined without a compensating improvement in brightness, but the yield of fiber‐rich fraction continued to increase and concentration of β‐glucan in FRF also increased.     

Sources and composition of soil organic matter fractions between and within soil aggregates

It is generally accepted that particulate organic matter derives from plants. In contrast, the enriched labile fraction is thought by many to derive from microbes, especially fungi. However, no detailed chemical characterization of these fractions has been done. In this study, we wanted to assess the sources (plants or microbes; fungi or bacteria) and degree of microbial alteration of (i) three particulate organic matter fractions – namely the free light fraction (1.85 g cm^?3), the coarse (250–2000 μm) and the fine (53–250 μm) intra‐aggregate particulate organic matter fractions – and of (ii) three density fractions of fine‐silt associated carbon – namely < 2.0, 2.0–2.2 (i.e. enriched labile fraction) and > 2.2 g cm^?3– by analysing the amino sugars, by CuO oxidation analyses, and by ¹³C‐, ¹H‐ and ³¹P‐NMR analyses. Macroaggregates (250–2000 μm) were separated by wet‐sieving from a former grassland soil now under a no‐tillage arable regime. The three particulate organic matter fractions and the three density fractions were isolated from the macroaggregates by a combination of density flotation, sonication and sieving techniques. Proton NMR spectroscopy on alkaline extracts showed that the enriched labile fraction is not of microbial origin but is strongly degraded plant material that is enriched in aliphatic moieties partly bound to aromatics. In addition, the enriched labile fraction had a glucosamine content less than the whole soil, indicating that it is not enriched in carbon derived from fungi. Decreasing yields of phenolic CuO oxidation products and increasing side‐chain oxidation in the order coarse intra‐aggregate particulate organic matter < fine inter‐aggregate particulate organic matter < fine‐silt fractions indicate progressive alteration of lignin as particle size decreases. The light fraction was more decomposed than the coarse inter‐aggregate particulate organic matter, as indicated by (i) its larger ratio of acid‐to‐aldehyde of the vanillyl units released by CuO oxidation, (ii) the smaller contribution of H in carbohydrates to total extractable H as estimated by ¹H‐NMR spectroscopy, and (iii) a larger contribution of monoester P to total extractable P in the ³¹P‐NMR spectra. In conclusion, the four fractions are derived predominantly from plants, but microbial alteration increased as follows: coarse inter‐aggregate particulate organic matter < light fraction ≈ fine inter‐aggregate particulate organic matter < enriched labile fraction.     

Isolation and Characterization of Water‐Extractable Arabinoxylan from Hull‐less Barley Flours

A new procedure was developed for the isolation of highly purified water‐extractable arabinoxylan (WE‐AX) from hull‐less barley flour. It included inactivation of endogenous enzymes, removal of proteins with silica gel, and removing β‐glucans, arabinogalactan‐peptides, and starch fragments by enzyme or solvent precipitation steps. WE‐AX recovered by this isolation procedure represented, on average, 47% of all WE‐AX present in hull‐less barley flour. Purified WE‐AX from flour of different hull‐less European barley cultivars contained 84.9–91.8% AX and showed small structural differences. The apparent peak molecular weight of the purified WE‐AX was 730,000–250,000, and the arabinose‐to‐xylose ratio was 0.55–0.63. Proton nuclear magnetic resonance spectroscopy showed that the levels of un‐, O‐2 mono‐, O‐3 mono‐, and O‐2,O‐3 disubstituted xylose residues were 59.1–64.7%, 8.2–10.0%, 5.7–10.6%, and 17.6– 23.1%, respectively, and the ratio of di‐ to monosubstituted xylose was 0.90–1.54. Both O‐3 mono‐ and disubstituted xylose residues occurred isolated or next to disubstituted xylose residues in the WE‐AX chain.     

Differences in Carbohydrate Composition and Digestion In Vitro of Selected Barley Cultivars as Influenced by Pearling and Cooking

Among common cereals, barley is a low glycemic index food. In an attempt to better understand this character, the nutritional properties of glycemic carbohydrates and dietary fiber concentrations of nine cultivars were evaluated. The cultivars were selected based on botanical variations and commercial value to investigate the impact of pearling and cooking on nutritional properties. Each cultivar was pearled into four fractions ranging from hull removal only to hull, bran, germ, and crease removal. The study showed that botanical class and degree of pearling significantly affect the carbohydrate composition and digestion indices of barley. Waxy starch cultivars had less total starch and more rapidly digestible starch (RDS), rapidly available glucose (RAG), and β‐glucan than the other nonwaxy cultivars. Regardless of the barley type, the less pearled kernels had significantly lower total starch and higher total low molecular weight sugars, insoluble, and total fiber. However, β‐glucan content was fairly comparable in the whole grain and pearled fractions. Cooking had a significant effect on nutritional properties of Celebrity and AC Klinck cultivars. The only consistent significant difference between raw and cooked barley was resistant starch (RS), which increased after cooking regardless of cultivar or fraction. The study showed that barley cultivar and carbohydrate composition significantly affected starch digestion with some cultivar fractions holding a promise for the development of low glycemic index foods.     

Dry‐Milling and Fractionation of Transgenic Maize Seed Tissues with Green Fluorescent Protein as a Tissue Marker

The efficiency of fractionating cereal grains (e.g., dry corn milling) can be evaluated and monitored by quantifying the proportions of seed tissues in each of the recovered fractions. The quantities of individual tissues are typically estimated using indirect methods such as quantifying fiber or ash to indicate pericarp and tip cap contents, and oil to indicate germ content. More direct and reliable methods are possible with tissue‐specific markers. We used two transgenic maize lines, one containing the fluorescent protein green fluorescent protein (GFP) variant S65T expressed in endosperm, and the other containing GFP expressed in germ to determine the fate of each tissue in the dry‐milling fractionation process. The two lines were dry‐milled to produce three fractions (bran‐, endosperm‐, and germ‐rich fractions) and GFP fluorescence was quantified in each fraction to estimate the tissue composition. Using a simplified laboratory dry‐milling procedure and our GFP‐containing grain, we determined that the endosperm‐rich fraction contained 4% germ tissue, the germ‐rich fraction contained 28% germ, 20% endosperm, and 52% nonendosperm and nonembryo tissues, and the bran‐rich fraction contained 44% endosperm, 13% germ, and 43% nonendosperm and nonembryo tissues. GFP‐containing grain can be used to optimize existing fractionation methods and to develop improved processing strategies.     

Laboratory Measurement of Yield and Composition of Dry‐Milled Corn Fractions Using a Shortened,Single‐Stage Tempering Procedure

The objective was to describe a laboratory‐scale dry‐milling procedure that used single‐stage tempering and determine the effect of hybrid on yields and fraction compositions in milled corn. Samples of 11 commercially available hybrids were processed through a laboratory dry‐milling procedure that used 1 kg samples of corn to produce milling fractions of large grits, small grits, fines, germ, and pericarp. Compositions of milling fractions (protein, neutral detergent fiber, ash, and crude fat) were determined. The procedure used a single‐stage tempering step that increased corn moisture from 15 to 23.5% wb during an 18‐min tempering period. Germ were separated from endosperm particles using a roller mill followed by screening over a sieve with 1.68‐mm openings. Coefficients of variability were small, indicating acceptable repeatability. Overall yield means were 39.2, 25.3, 13.8, 78.2, 14.3, and 6.8 g/100 g (db) for large grits, small grits, fines, total endosperm, germ, and pericarp, respectively. There were effects due to hybrid (P < 0.05) on fraction yields and compositions of milling fractions. Correlations (r) among endosperm fractions (large grits, small grits, and fines) ranged from 0.54 to |–0.92|. Correlations among endosperm fractions and germ and pericarp were <0.68. The developed dry‐milling method estimated milling yields among hybrids with low standard deviations relative to the means and should be a useful tool for research and industry in measuring dry‐milling characteristics.