Physical Properties Of Kernels Research Articles

An analysis of the correlations between the hardness index and selected physicochemical properties of wheat grain

The processes of grain grinding and milling are affected by the physical properties of kernels, whereas energy consumption during these processes is influenced mainly by their mechanical properties. Therefore, the main aim of this study was to determine the relationships between selected physicochemical properties of wheat grain classified into different hardness groups. Technological (processing), mechanical and geometric properties of grain were evaluated in 12 wheat cultivars produced in Poland. The cultivars were divided into four grain hardness groups. The results were analyzed using the following statistical modules: descriptive statistics, one-way analysis of variance (ANOVA), correlation analysis, and regression analysis. Kernels of various hardness were found in each of the evaluated wheat cultivars, in particular those classified as medium soft and medium hard. The type and strength of correlations between the analyzed properties of grain were considerably affected by kernel hardness. The greatest differences were observed in comparisons of the following pairs of kernel parameters: length and width, length and relative strain, length and rupture force, and rupture force and relative strain. On average, the strongest correlations were noted between rupture force and rupture energy, and between kernel thickness and mass, whereas the weakest correlation was found between kernel mass and relative strain. The study demonstrated that the mechanical properties of wheat grain were not affected by crude protein content or total ash content. Grain hardness was correlated with kernel length, vitreousness, rupture force, and rupture energy. The hardness index (HI) increased by 110% within the range of average kernel length values (from approx. 5.4 mm to approx. 8.0 mm). The increase in HI values was accompanied by an increase in rupture force (by approx. 90%) and rupture energy (by approx.115%).

Physical properties of kernels from modern maize hybrids used in Croatia

The physical properties of maize are a result of kernel structure, they indicate chemical properties of the kernel, and hence, its nutritive value. This research aimed to explore the physical traits of kernels of 80 commercial maize hybrids from nine seed companies. The grain from investigated hybrids was produced during the same season on the same field under the same agricultural conditions. Moisture content, bulk and real density, Stenvert hardness (time to grind 17mL of grits, height of freshly ground grain, and coarse-to-fine particles ratio, C/F), flotation index, breakage susceptibility, kernel dimensions, and sphericity were determined in maize samples. Test weight was in a range from 70.2 to 82.1 kg/hL, with the majority of hybrids of high nutritive value (>72 kg/hL). Density ranged from 1.159 to 1.301 kg/L and similarly as test weight increased with increasing hardness (C/F; r=0.52 and 0.68, respectively; P<0.001); a trait that is related to breakage and insect resistance, and to decreased starch digestibility. Flotation index was from 8 to 100%, and its value decreased with increasing hardness (r=-0.65; P<0.001). A wide range of values in physical traits of investigated hybrids implies different behavior of grain during postharvest handling and processing and thus variable nutritive value.

Quality Parameters of Masa and Tortillas Produced from Blue Maize (Zea mays sp. mays) Landraces.

There is increasing interest in the production of landrace blue maize varieties for the production of traditional foods and for specialty (noncommodity) products. Most varieties have soft (floury) endosperm and their suitability for thermo-alkaline processing is not known. We examined the physical and functional properties of eight floury varieties with those of three dent and one flint variety for masa and tortilla production. Results revealed high variability in physical properties of kernels. Significant differences (P < 0.05) were observed in kernel, flour, masa, and tortilla color. The softer kernels of blue maize varieties had lower (P < 0.05) cooking times during nixtamalization than those of denser kernels. The results showed variation among varieties (P < 0.05) in the kernel, masa, tortilla hardness, as well as in extensibility of the tortillas. Nixtamalization affected (P < 0.05) masa color, resulting in reduced yellow and reddish tones. The gelatinization temperature was the same (P > 0.05) in all studied landraces for the flour and the masa. The enthalpy was affected (P < 0.05) by the landrace analyzed for starch gelatinization (P > 0.05). The landraces studied showed similar (P > 0.05) starch gelatinization and denaturation temperatures. The storage modulus (G'), loss modulus (G''), and the temperature (TG') of flour and masa-dough were different (P < 0.05) among different varieties. Southwestern floury varieties can be cooked during nixtamalization for shorter periods than flint and dent varieties to obtain comparable tortilla quality. PRACTICAL APPLICATION: Southwestern blue floury maize varieties are suitable for nixtamalized tortilla production. Variation between varieties was observed for quality parameters. Floury varieties require shorter cooking time but it is recommended that nixtamalization parameters be optimized.

Crop management affects dry-milling quality of flint maize kernels

Dry-milling performance of maize ( Zea mays, L.) kernels primarily depends on their hardness. The flint type is harder than the dent and semi-dent maize, yielding a higher proportion of big endosperm pieces in the mill. Nevertheless, crop growing conditions could modify milling properties. The objective of this work was to analyze the effect of different crop environments and management practices on dry-milling quality of flint maize kernels. Two orange-flint hybrids from different eras of breeding differing in flint type expression and grain yield potential were evaluated. They were grown at three different locations of the Argentina's main maize-production area under different sowing dates, plant densities, and fertilization rates during two growing seasons. Crop post-silking growth, grain yield and its components (kernel number and weight), kernel size and hardness-associated properties (test weight, percent floaters and milling ratio), and flaking-grit yield were analyzed. Most of observed differences in physical properties of kernels, particularly for the high-yielding new hybrid with unstable flint expression, were associated with the source–sink ratio established during the post-silking period (explored range from 154 to 617 mg kernel −1). This variable mainly results from changes in crop growth during that period. Increases in weight per kernel improved hardness-associated properties. High crop grain yields together with top dry-milling quality were achieved when the new high-yielding hybrid was cropped with an appropriated crop management.

Physical properties of coriander seeds ( Coriandrum sativum L.)

Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of coriander seeds have been evaluated as a function of seed moisture content, varying from 7.10% to 18.94% (d.b.). In the moisture range, seed length decreased linearly from 4.74 to 4.61 mm, and width, thickness, arithmetic mean diameter, and geometric mean diameter increased linearly from 3.67 to 3.93 mm, 3.39 to 3.54 mm, 3.93 to 4.03 mm and 3.88 to 3.99 mm respectively with increase in moisture content. The sphericity, seed volume, and seed surface area increased nonlinearly from 0.820 to 0.867, 24.97 to 28.52 mm 3, and 42.09 to 45.62 mm 2, respectively. One thousand seed weight increased linearly from 8.72 to 9.71 g. The true density increased nonlinearly with moisture content from 332 to 349 kg/m 3 while bulk density decreased linearly 234.1 to 220.2 kg/m 3 in the range of moisture content between 7.10% and 18.94%, d.b. Also, porosity values of coriander seeds increased nonlinearly from 33.03% to 35.79%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased nonlinearly from 0.435 to 0.877, 0.425 to 0.775, 0.379 to 0.839, 0.364 to 0.781, 0.344 to 0.650, and 0.325 to 0.694 for plywood, polypropylene knitted bag, polyvinyl chloride, galvanized iron, cast polypropylene and stainless steel surfaces, respectively. The angle of repose increased linearly from 24.9° to 30.7° with the increase of moisture content.

Some physical properties of flaxseed (Linum usitatissimum L.)

Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of flaxseeds have been evaluated as a function of seed moisture content, varying from 6.09% to 16.81% (d.b.). In the moisture range, seed length, width, thickness, arithmetic mean diameter, and geometric mean diameter increased linearly from 4.27 to 4.64 mm, 2.22 to 2.38 mm, 0.85 to 0.88mm, 2.45 to 2.63mm and 2.00 to 2.12mm respectively with increase in moisture content. One thousand seed weight increased linearly from 4.79 to 5.32 gr. The true density increased with moisture content from 1000 to 1111kg/m3 while bulk density decreased 726.6 to 555.6kg/m3 in the range of moisture content between 6.09% and 16.81%, d.b. Also, porosity values of flaxseeds increased from 27.34 to 57.44%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.537 to 1.073, 0.515 to 0.933, 0.472 to 0.975, 0.499 to 0.877, 0.544 to 0.862, and 0.472 to 0.824 for plywood, aluminium, stainless steel, galvanized iron, polypropylene knitted bag and kraft paper surfaces, respectively. The angle of repose increased linearly from 21.6° to 33.4° with the increase of moisture content.

Physical properties of popcorn kernels

Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of popcorn kernels have been evaluated as a function of kernel moisture content, varying from 8.95% to 17.12% (db). In the moisture range, kernel length, width, thickness, arithmetic mean diameter, and geometric mean diameter increased linearly from 8.18 to 9.14 mm, 5.71 to 6.32 mm, 3.65 to 4.90 mm, 5.85 to 6.79 mm and 5.54 to 6.55 mm respectively with increase in moisture content from 8.95% to 17.12%. The sphericity, kernel volume, kernel surface area, and thousand seed weight increased linearly from 0.677 to 0.717, 73.24 to 125.14 mm 3, 96.26 to 134.92 mm 2, and 136 to 157 g, respectively. The true density and bulk density decreased linearly from 1.304 to 1.224 g/cm 3 and 0.771 to 0.703 g/cm 3 respectively while porosity increased from 40.87% to 42.56%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.55 to 0.74, 0.47 to 0.62, and 0.46 to 0.61 for plywood, galvanized iron, and aluminium surfaces respectively. The angle of repose increased linearly from 25.3° to 30.8° with the increase of moisture content.