Effect of Kernel Size,Location, and Type of Damage on Popping Characteristics of Popcorn

Popping characteristics, specifically expansion volume and popping time, were studied for damaged popcorn. A single variety of commercial undamaged yellow popcorn was separated into four size fractions (D < 4.36, 4.36 < D < 5.16, 5.16 < D < 5.95, and D > 5.95 mm) by screening with round-hole sieves. Kernels were damaged using a razor knife by either slicing a 2-mm diameter piece of the endosperm or the germ or by cutting through the pericarp and seed coat into the endosperm or the germ ≈2 mm. A total of five combinations of location and damage were studied (tip cap removed, side cut, side sliced, germ cut, and germ sliced) for each kernel size. A control sample with no damage was also analyzed for each size fraction. All of the damaged kernels (regardless of type of damage) popped, but they had expansion volumes 9.1–47.5% smaller than those of undamaged kernels. The expansion volume of damaged kernels increased by 52.5–85.7%, depending on the damage, when the size of the kernel increased from <4.36 mm to >5.95 mm. Removing the tip cap and slicing through the germ caused less loss of expansion volume than did other types of damage. Damaged popcorn kernels had faster popping times (12.2–24.0 sec) than did undamaged kernels (30.9–34.6 sec). Popping times increased with increasing kernel size for all types of damage.     

Composition and Sensory Evaluation of Popcorn Flake Polymorphisms for a Select Butterfly‐Type Hybrid

The objective of this study was to identify and characterize different popped popcorn flake shapes, or polymorphisms, arising from a yellow butterfly popcorn hybrid (YP‐213), and then to determine the impact of popcorn flake shape on composition and sensory characteristics. Kernels were popped using a microwave oven and visually sorted into three different polymorphisms depending on whether the appendages were expanded unilaterally, bilaterally, or multilaterally. When popped, 9.0 ± 3.1%, 71.2 ± 5.9%, and 12.3 ± 3.8% of kernels were expanded unilaterally, bilaterally, and multilaterally, respectively, while 7.6 ± 1.4% of kernels remained unpopped. Expansion volumes for unilaterally, bilaterally, and multilaterally expanded polymorphisms were 28.6 ± 3.84, 43.0 ± 0.84, and 53.5 ± 2.5 cm³/g, respectively. Unilateral popcorn flakes retained the most fat, saturated fat, and sodium, while multilaterally expanded flakes had the highest levels of protein, total carbohydrate, and popcorn‐like aromatic pyrazines. Sensory evaluation revealed significant differences among polymorphisms for flavor and texture attributes, with the unilaterally expanded polymorphism receiving the highest overall product liking. These data show that different popcorn flake polymorphisms produced from a single hybrid of popcorn affect sensory and compositional profiles. More research is necessary to elucidate the factors that affect popcorn flake polymorphisms and support development of new varieties or techniques to produce the most desirable microwave popcorn.     

Effect of Moisture Content and Tempering Method on the Functional and Sensory Properties of Popped Sorghum

Red and white sorghum were tempered using two methods (direct and indirect) to adjust moisture content (MC) to 12, 14, and 17% and popped using a hot‐air popper. Kernel size, pericarp thickness, bulk density, popped kernel expansion volume and ratio, popped volume, and surface color were recorded. Forty‐six untrained panelists evaluated popped sorghum using a 9‐point hedonic scale and expressed preference using a paired comparison test. Sorghum with thicker pericarp (red) had higher percent popped, expansion ratio, and popped volume. In white sorghum, indirect tempering increased percent popped and tempering to 17% MC increased popped volume. Panelists significantly preferred popcorn in appearance (8.0 ± 1.0) and size (7.9 ± 1.0) to sorghum (6.6 ± 1.7 appearance and 5.6 ± 2.2 size for 12 and 17% MC tempering). Panelists equally preferred the taste of popcorn (7.1 ± 1.5) and popped sorghum tempered to 12% MC (6.4 ± 1.8) and 17% MC (6.9 ± 1.4). Sorghum pops were brighter, vividly whiter, and 5× smaller than popcorn.     

Effects of Storage Temperature and Kernel Physical Condition on Popping Qualities of Popcorn Hybrids

Effect of storage temperature before popping and kernel physical properties on popping characteristics were studied using popcorn (Zea mays L.) hybrids harvested in 1997. Popped volume (PV), unpopped kernel ratio (UPK), and popping times were measured from 250 g of moisture‐adjusted kernels stored at 30, 1, and −29°C for one month. Maximum popped volume (MPV) and minimum unpopped kernel ratio (MUPK) at the corresponding optimum moisture contents (OMC) were mathematically calculated from PV, UPK, and moisture content values. MPV was significantly affected by storage temperature before popping. Hybrid significantly affected MPV and MUPK. Moisture content, storage temperature, and hybrid significantly varied popping time of the popcorn hybrids, with moisture content being the most important. Correlation results showed that MPV was negatively correlated with unsound kernel ratio, UPK, and popping time. Moisture adjustment of intact kernels should be done at different storage conditions; high temperature storage required higher moisture than low temperature storage to give the best outcome.     

Micropycnometer Measurement of Single-Kernel Density of Healthy,Sprouted, and Scab-Damaged Wheats

Samples from four market lots of hard red winter and soft red winter wheat containing sprout- and scab-damaged kernels were used to test a prototype single-kernel density micropycnometer. Fifteen kernels for each damage type and an equal number of healthy kernels were weighed to the nearest 0.01 mg, then measured for volume to the nearest 1.0 μL. Volume measurements for all kernels were performed three consecutive times with the micropycnometer, then kernels were evaluated for weight, size, moisture, and hardness using a Single Kernel Characterization System. The structure of the sampling plan and the goals of the study indicated that a mixed-model statistical analysis was needed. The fixed effects were wheat class and type of kernel, and the random effects included lot, the interaction of lot with class and kernel type, kernels within each lot, and repeated measures of single-kernel density. Results indicated that variability of the three measurements per kernel did not depend on type of kernel or class of wheat. The standard deviation for repeated density measurements was 0.0029 g/cm³. Kernel-to-kernel variability changed depending on the type of kernel; healthy and sprout-damaged kernels showed similar variability in density, whereas scab damaged kernels had a variance about four to five times higher. Type of kernel significantly affected mean density; healthy kernels averaged 1.28 g/cm³, sprout-damaged kernels averaged 1.19 g/cm³, and scab-damaged kernels averaged 1.08 g/cm³. Wheat class did not exert a significant influence on singlekernel density. Attempts to predict single-kernel density using kernel weight, size, moisture, and hardness found no relationships of practical importance.     

Grain and Nutritional Quality Traits of Southwestern U.S. Blue Maize Landraces

Anthocyanin‐rich Southwestern blue maize (Zea mays L.) landraces are receiving interest as functional foods, and commercial production is increasing. We determined variation in kernel color, anthocyanin content, texture, and selected compositional traits of representative varieties. In 2013, eight varieties were grown at four locations in New Mexico. Total kernel anthocyanin content (TAC) and component pigments were measured with spectrophotometry and HPLC, respectively. Oil, protein, starch, and kernel density were determined using NIR spectroscopy and amino acid concentrations using wet chemistry. An average of 49.6 mg/100 g of TAC with a range of 17.6–65.1 mg/100 g was observed. Cyanidin and pelargonidin were major components, and peonidin and succinyl 3‐glucoside were minor components. Low levels of disuccinyl glucoside were detected. Blue kernels were higher in anthocyanin than purple or red kernels. Floury kernels displayed the highest protein and oil contents and the lowest starch content and kernel density. The highest starch and kernel density levels were observed in small flint/dent and pop‐flint/dent kernels. Amino acid content was variable across genotypes and locations.     

微波爆玉米花制备条件的优化研究

探讨物料量、时间和调味料与微波玉米爆开率(Y₁)、膨胀率(Y₂)和感官分数(Y₃)的响应曲面关系，模型Y₁、Y₂、Y₃的失拟性检验不显著（p₁＞0.05、p₂＞0.05和p₃＞0.1），无失拟性因素存在；而模型的显著性检验达显著水平（p₁＜0.05、p₂＜0.01和p₃＜0.01），说明模型较好地拟合玉米爆开率、膨胀率和感官分数与各参试因子之间的关系，R²分别为0.8139、0.8737和0.9160。利用期望函数途径，对响应曲面模型进行模拟预测和验证，得到制备微波玉米的优化条件为物料量1.518水平、微波时间0.518水平、调味料比例1.118水平，玉米爆开率、膨胀率、感官分数同时达到最高，分别为97.5%、11.0和7.2。     

Physicochemical Properties of Wheat Fractionated by Wheat Kernel Thickness and Separated by Kernel Specific Density

Two wheat cultivars, soft white winter wheat Yang‐mai 11 and hard white winter wheat Zheng‐mai 9023, were fractionated by kernel thickness into five sections; the fractionated wheat grains in the 2.7–3.0 mm section were separated sequentially into three fractions according to kernel specific density. Physical properties of unfractionated, fractionated, and separated wheat grains and the physicochemical properties of processed wheat flour were determined. Test weight, relative density, and whiteness of flour in the middle kernel thicknesses were maximal and those properties decreased with increasing or decreasing kernel thickness; they also decreased with decreasing kernel specific density. Extensigraph properties showed the same results. Water absorption of flour and kernel hardness increased with increasing kernel thickness and decreasing kernel specific density. The farinograph properties also were related to kernel thickness and specific density. Pasting viscosity increased with increasing kernel thickness for sections from <2.5 mm to 3.0–3.2 mm, except that the >3.2 mm section was lowest; the kernels with the lightest specific density also were lowest. Thus, the quality of wheat grains with the greatest kernel thickness was not the best, and in fact may be the worst. The quality of wheat grains with small kernel thickness and light kernel specific density generally were worst. Most physicochemical properties of unfractionated and unseparated wheat grains were accurately predicted by the weighted‐average of the different kernel thickness sections and different kernel specific density fractions, except relative density, falling number, dough development time, and pasting temperature.     

Aflatoxin variation among corn samples with varying ratios of Aspergillus flavus-inoculated/noninoculated kernels.

Aflatoxin levels and physical properties of corn kernels inoculated with Aspergillus flavus during development and noninoculated kernels were compared in samples with various proportions of the 2 kernel types. The relationship between mean toxin levels and associated standard deviations of 5 samples demonstrated a linear association from the lowest toxin in noninoculated corn through a mixture of 60% inoculated/40% noninoculated. However, at the highest toxin level in the 100% inoculated material, a reduction in sample variation was observed. Examination of individual kernal weights showed that inoculated kernels were distinctly lighter than noninoculated seed. A uniform grinding procedure of the samples yielded heterogeneous particle sizes based on the starting corn. The large particle fraction (greater than 500 micrometers) decreased from 100% noninoculated kernels through the mixtures to the 100% inoculated seed; particles below 150 micrometers were most abundant in the ground samples from inoculated kernels. In addition, the density of particles within a size category varied; lower densities were observed in samples obtained from A. flavus-inoculated kernels.     

Relationships Among Grain Sorghum Quality Factors

Correlations among grain sorghum quality factors (proximate composition, physical properties, and water absorption properties) were evaluated. Samples of 46 commercial hybrids (24 and 22 from crop years 1993 and 1994) were analyzed for starch, protein, crude free fat, test weight, absolute density, 1,000 kernel weight, percent kernel abraded, water absorption index, initial water absorption rate, and moisture saturation point. Test weight, absolute density, and percent kernel abraded were positively correlated among themselves (r > 0.5). Protein was negatively correlated with both test weight and absolute density (r < -0.5), while moisture saturation point showed negative correlations with test weight, absolute density, 1,000 kernel weight, and percent kernel abraded (r < -0.4). Principal component factor analysis through the covariance matrix explained 95% of the total variation of quality factors among hybrids (two factors), and, through the correlation matrix, 85% of the total variation (five factors). Water absorption rate decreased with increasing starch content of grain sorghum kernels as water absorption rate increased and amount of water for saturation decreased with softening of kernels.     

Effects of Sampling and Wheat Grade on Precision and Accuracy of Kernel Features Determined by Digital Image Analysis

The effect of sampling on the precision and accuracy of digital image analysis of different commercial sample grades of Canada Western Red Spring (CWRS) wheat was investigated. Kernel perimeter, length, width, and area measurements were used to determine mean and dispersion statistics for composite railcar CWRS samples of No. 1, 2, and 3 grades; the numbers of railcars sampled were 27, 40, and 36, respectively. Sample sizes ranged from 10 to 2,000 kernels. Instrumental measurement precision was routinely better than 0.1 mm for macroview images, with a resolution of 0.0054 cm² per pixel. Computed mean kernel feature measurements and dispersion statistics were highly dependent on sample size and grade. Comparative analysis of wheat samples by digital imaging of individual kernels required a sample of no less than 300–500 kernels, depending on sample grade, for accurate representation of the parent sample. This level of sampling resulted in detection of significant differences (P < 0.05) in mean kernel features that, on average, differed by <1%. Except for some samples containing low numbers of kernels, lower grade wheat had more variable kernel features compared with higher grade samples. In relative terms, for comparably sized samples (≥133 kernels), variance in No. 2 grade wheat was 6–11% higher that for No. 1 grade wheat, depending on kernel feature. Similarly, variance in No. 3 grade wheat was 13–23% higher than for No. 2 grade wheat and 20–37% higher than for No. 1 grade wheat, indicating that wheat grading has a predictable effect on and is influenced by the uniformity of kernel characteristics in a sample. The ability of digital image analysis to detect these effects reflects the potential of this technology for use in objective classification of wheat according to grade.     

Mechanical Behaviour of Hazelnut under Compression Loading

Aci Findik, Cakildak, Tombul, and Güney Karasi varieties of hazelnut were loaded between two parallel plates to determine the specific deformation, rupture force, and rupture energy required to initiate shell and kernel rupture. The tests were carried out at two deformation rates of 0·52, and 0·91 mm s⁻¹, four moisture contents of 6, 11, 15, and 18% w.b., and three axes (X,Y,Z). The X-axis is the longitudinal axis through the hilum, while the Y-axis is the transverse axis containing the major dimension at right angles to the longitudinal axis, and the Z-axis is the transverse axis containing the minimum dimension. Physical characteristics of nut and kernel such as mass, dimensions, geometric mean diameter and sphericity were determined. Specific deformation and rupture energy of the shell generally increased in magnitude with an increase in moisture content while rupture force decreased for compression along the X- and Y-axis. The highest nut shell specific deformation, rupture force and rupture energy among the four varieties were obtained for Aci Findik nuts loaded along the Z-axis at a deformation rate of 0·52 mm s⁻¹. The Tombul and Güney Karasi varieties had the highest kernel rupture force and rupture energy, respectively.     

Single-Kernel Characteristics of Hard Winter Wheats in Relation to Milling and Baking Quality

To investigate relationships of wheat single kernel (SK) characteristics with end-use properties, we used 12 hard winter wheat cultivars harvested at six regions in Kansas in 1993. Significant positive correlations occurred among wheat hardness parameters including near-infrared reflectance hardness score, SK hardness index (SK-HI), and SK peak force (SK-PF) obtained by the Single Kernel Characterization System (SKCS). The SKCS characteristics also were significantly correlated to conventional wheat quality parameters such as test weight, kernel density, and kernel sizing. Flour yields were significantly correlated with SK-PF, SK-HI, and SK weight (SK-WT), suggesting the usefulness of SKCS in evaluating milling quality. The negative correlation of milling score with the standard deviation of SK-HI and SK-PF indicated that uniformity of SK hardness is desirable for good milling performance. However, bread loaf volumes had significant negative correlations with SK diameter and SK-WT, mainly due to the inverse relationship between wheat protein contents and kernel weights or sizes. Loaf volume regression values, the changes in loaf volumes per one percentage point of flour protein, also had significant negative correlations with SK-HI, SK-PF, and SK-WT.     

Relationship Between Popcorn Composition and Expansion Volume and Discrimination of Corn Types by Using Zein Properties

The objective of this study was to determine the relationship between the amount and type of lipids, starch composition and structure, and storage proteins on popcorn expansion and to evaluate whether popcorns could be discriminated from other types of corn based on the protein elution parameters. Seven commercial Argentinean popcorn samples were used in the study and significant differences were observed in the popping volume of these popcorns. A significant negative correlation was observed between oleic acid and popping volume and a positive correlation was observed between linoleic acid and popping volume. Popcorn starch properties were significantly different from normal corn but no particular measured attribute of starch correlated with popping volume. α‐Zein proteins and glutelins significantly correlated with popcorn expansion volume with R² = 0.963 and 0.744, respectively. The elution patterns of corn proteins could also be used to discriminate between different types of corn including popcorn, dent, and flint corns.     

Mathematical Modelling of Vacuum Pressure on a Precision Seeder

The purpose of this research was to determine the optimum vacuum pressure of a precision vacuum seeder and to develop mathematical models by using some physical properties of seeds such as one thousand kernel mass, projected area, sphericity and kernel density. Maize, cotton, soya bean, watermelon, melon, cucumber, sugarbeet and onion seeds were used in laboratory tests. One thousand kernel mass, projected area, sphericity and kernel density of seeds varied from 4·3 to 372·5 g, 5–77 mm², 38·4–85·8% and 440–1310 kg m⁻³, respectively. The optimum vacuum pressure was determined as 4·0 kPa for maize I and II; 3·0 kPa for cotton, soya bean and watermelon I; 2·5 kPa for watermelon II, melon and cucumber; 2·0 kPa for sugarbeet; and 1·5 kPa for onion seeds.The vacuum pressure was predicted by mathematical models. According to the results, the final model could satisfactorily describe the vacuum pressure of the precision vacuum seeder with a chi-square of 2·51×10⁻³, root mean square error of 2·74×10⁻² and modelling efficiency of 0·99.     

Effect of Kernel Size and Mill Type on Protein,Milling Yield,and Baking Quality of Hard Red Spring Wheat

Optimization of flour yield and quality is important in the milling industry. The objective of this study was to determine the effect of kernel size and mill type on flour yield and end‐use quality. A hard red spring wheat composite sample was segregated, based on kernel size, into large, medium, and small kernels, as well as unsorted kernels. The four fractions were milled in three roller mills: Brabender Quadrumat Jr., Quadrumat Sr., and Bühler MLU‐202 laboratory mills. Large kernels had consistently higher flour yield than small kernels across mills, with the Quadrumat Jr. mill showing the lowest flour yield. Mill type and kernel size significantly affected variation in flour protein molecular weight distribution. When compared with larger kernels, flour milled from the small‐kernel fraction contained a higher gliadin fraction and SDS‐unextractable high‐molecular‐weight polymeric proteins, which had positive correlations with bread loaf volume (r = 0.61, P < 0.05) and mixograph peak time (r = 0.84, P < 0.001). Overall, small kernels could contribute to enhancing flour breadmaking quality while having a detrimental effect on milling yield.     

Association of Barley Kernel Hardness with Physical Grain Traits and Food Processing Parameters

Kernel hardness is not a well‐characterized food quality trait in barley. Unlike wheat, not much is known about the effect of barley kernel hardness on food processing. Ten barley genotypes differing in single kernel characterization system hardness index (SKCS‐HI) (30.1–91.2) of dehulled kernels were used to determine the association of barley HI with other physical grain traits and food processing parameters. Thousand kernel weight (TKW) values of 10 genotypes were 29.7–38.1 g. Values for bulk density of grains were 721.1–758.9 kg/m³. Crease width and depth values were 0.9–1.3 mm and 0.4–0.7 mm, respectively. Barley HI showed no significant association with TKW, bulk density, or kernel crease dimensions. Kernel loss due to pearling after 325 sec of abrasion was 28.8–38.4% and showed significant negative correlation with HI (r = –0.87, P < 0.01). Proportion of barley flour particles >106 μm had values of 34.5–42.0%, and starch damage values were 1.8–4.5% among those 10 barley genotypes. HI showed significant positive correlations with both proportion of barley flour particles >106 μm (r = 0.93, P < 0.01) and starch damage (r = 0.93, P < 0.01). Water imbibition of barley kernels and cooked kernel hardness did not show significant correlation with HI.     

Factors Affecting the Alkaline Cooking Performance of Selected Corn and Sorghum Hybrids

Dent corn (Zea mays L.) and sorghum (Sorghum bicolor L. Moench) sample sets representative of commonly grown hybrids and diverse physical attributes were analyzed for alkaline cooking performance. The influence of kernel characteristics including hardness, density, starch properties (thermal, pasting, and crystallinity), starch content, protein content, and prolamin content on alkaline cooking performance was also determined. Corn nixtamal moisture content was lower for hard, dense kernels with high protein contents; sorghum nixtamal moisture content was lower for kernels with low moisture contents and low starch relative crystallinities. Statistically significant (P < 0.05) regression equations showed that corn nixtamal moisture content was influenced by TADD (tangential abrasive dehulling device) index, kernel moisture content, starch content, and protein content; sorghum nixtamal moisture content was influenced by starch relative crystallinity, kernel moisture content, and abrasive hardness index. Pericarp removal was not strongly correlated with kernel characterization tests. Location (environmental) and hybrid (genetic) factors influenced most kernel characteristics and nixtamalization processing variables.     

Effect of Moisture Content on the Viscoelastic Properties of Individual Wheat Kernels Evaluated by the Uniaxial Compression Test Under Small Strain

Wheat product quality is related to its physicochemical properties and to the viscoelastic properties of the kernel. The aim of this work was to evaluate the viscoelastic properties of individual wheat kernels using the uniaxial compression test under small strain (3%) to create experimental conditions that allow the use of the elasticity theory to explain the wheat kernel viscoelasticity and its relationships to physicochemical characteristics, such as weight tests, size, and ash and protein contents. The following viscoelastic properties of the kernels of hard and soft wheat cultivars at two different moisture contents (original and tempered at 15%) were evaluated: total work (W_t), elastic work (W_e), plastic work (W_p), and modulus of elasticity (E). There was a significant decrease in W_t as the moisture content increased. In the soft wheat Saturno, W_t decreased 80% (from 0.217 to 0.044 N·mm) as the moisture content increased. Individual wheat kernels at their original moisture content showed higher W_e than under the tempered condition. W_p increased as the moisture content increased. E decreased as the moisture content increased. The soft wheat Saturno showed the highest decline (54.9%) in E (from 14.18 to 6.39 MPa) as the moisture content increased. There were significant negative relationships between the viscoelastic properties and the 1,000‐kernel weight and kernel thickness. The uniaxial compression test under small strain can be applied to evaluate the viscoelastic properties of individual wheat kernels from different classes and cultivars.     

Structure and Physicochemical Properties of Starches from Sieve Fractions of Oat Flour Compared with Whole and Pin-Milled Flour

One oat cultivar grown in Idaho (three field sites) was pin-milled and separated by sieving to investigate whether starch from oat bran differs from the remainder of kernel. Ground oat particles were classified into three sieve fractions: 300–850 μm, 150–300 μm and <150 μm). β-Glucan content in sieve fractions was analyzed and starch was extracted from kernels without milling and from kernels of each sieve fraction. β-Glucan contents of 300–850, 150–300, and <150 μm sieve fractions were 4.2, 2.3, and 0.8%, respectively. Therefore, starch in bran (300–850 μm sieve fraction) and endosperm (<150 μm sieve fraction) were separated. Starch isolated from entire kernels had significantly higher apparent and absolute amylose content than starch from the 300–850 μm sieve fraction. Starch from different sieve fractions was not significantly different in the apparent amylose, absolute amylose, amylopectin molecular weight, gyration radii, starch gelatinization, and amylose-lipid complex thermal transition temperatures. Starch from the 150–300 μm sieve fraction had significantly lower peak, final, and setback viscosity compared with the starch isolated from the 300–850 μm and <150 μm sieve fractions. Starch removed from the oat bran fraction during β-glucan enrichment may have different applications compared with starch obtained from other kernel compartments. Because pin-milling decreased apparent amylose content and shortened amylopectin branch chains, its potential to alter starch structure should be considered.