Starch Protein Content Research Articles

Influence of Elevated Potassium Fertilization on Structural and Functional Properties of Sweet Potato Root Tuber Starch

Nine sweet potato varieties with different flesh colors were cultivated under uniform environmental conditions with potassium (K) fertilizer treatments at levels of 0, 22.5, and 45 kg/ha. The structural and functional properties of the starches were subsequently analyzed. The soluble sugar content in the dry root tuber increased, with higher K levels in most varieties. Amylose content decreased in Sushu16 but increased in Ningzishu1, with no significant differences observed in other varieties across different K levels. Elevated K levels had no effect on starch protein content, crystalline type, or gelatinization enthalpy. The impact of K fertilizer on starch thermal and pasting properties varied among the varieties. PLSR and PLS-DA analyses revealed that genotype background was the primary factor influencing starch properties. This research will provide a reference for the improvement of sweet potato production quality and efficiency and a scientific basis for the cultivation and utilization of sweet potato root tubers.

ТЕХНОЛОГІЧНА ЯКІСТЬ КРОХМАЛЮ РІЗНИХ ГІБРИДІВ КУКУРУДЗИ І СОРТІВ СОРГО ЗЕРНОВОГО ЗА ЙОГО БІОХІМІЧНОЮ СКЛАДОВОЮ

The technological quality of starch of different hybrids of corn and varieties of grain sorghum according to its biochemical component is determined. It was founding that the product contains 81.5–83.7% of starch + dextrin. In addition, it contains protein at the level of 1.0–1.1%, dietary fiber – 1.5–1.7%, depending on the maize hybrid. Cornstarch contains vitamins B3 and B4. The technological quality of grain sorghum starch was similar to that of corn. However, sorghum starch contains a higher content of protein and dietary fiber. In terms of moisture and ash content, cornstarch and grain sorghum meet the current requirements. Studies have shown that cornstarch contained polyunsaturated fatty acids (PUFAs), saturated fatty acids (PFA), ash, protein, dietary fiber, water. The main part of it consisted of carbohydrates, represented by starch and dextrin – 82.5–83.7%. The lowest content of polyunsaturated fatty acids (PUFA) – 0.02–0.03%, depending on the hybrid. In addition, the protein content of starch was in the range of 1.0–1.1%, and the content of dietary fiber was 1.5–1.7%, depending on the maize hybrid. The moisture content of starch was 12.1–13.4%, and the ash content was 0.2%, which met the requirements of the standard SSTU 3976–2000 Dry cornstarch. Specifications. Cornstarch contained two B vitamins and 11 mineral elements. Among the vitamins of corn grain in starch, the content of B4 and B3 was determined – 0.4–0.7 mg/kg. Of the mineral elements, sodium contained the most – 25–30 mg/kg of starch. Selenium was the least – 0.002–0.003 mg/kg. The content of copper, zinc and manganese varied from 0.048 to 0.07 mg/kg of starch. Iron content – from 0.43 to 0.48 mg/kg. The content of magnesium and sulfur was in the range of 1.0–2.6 mg/kg. The content of potassium, calcium and phosphorus is 13–20 mg/kg, depending on the maize hybrid. The biochemical component of grain sorghum starch was similar to that of corn. Thus, the starch + dextrin content was at the level of 81.0–83.8% depending on the variety. The content of PUFA was in the range of 0.03–0.04, and the content of NFA was 0.2%. In terms of moisture and ash content, sorghum starch complied with the standards of SSTU 4380: 2005. The starch is modifying. The fat content was 0.8–1.5%; the protein content was 1.8–2.7%, depending on the variety of grain sorghum. It should be noted that the origin of sorghum varieties did not affect the formation of technological quality of starch. Only the content of vitamin B3 – 0.67–1.00 mg/kg was founding in grain sorghum starch. Only nine minerals have been identified. The highest content of phosphorus was 20–28 mg/kg of starch. The content of potassium and sodium was in the range of 20.0–25.0 mg/kg of starch. The copper content was the lowest – 0.003–0.005 mg/kg of product. The manganese content was 0.084–0.098 mg/kg. The content of iron varied from 0.18 to 0.25 mg/kg, magnesium, sulfur and calcium – from two to 6 mg/kg of grain sorghum starch.

Properties of different aged jicama (Pachyrhizus Erozus) plants

Jicama crop potential is very large, the tuber is used as a fresh fruit, ice mix fruit, salad, and can be made into flour, starch and inulin. The nutritional content of yam tubers depends on the age of the harvest, while farmers harvest jicama tubers at the age varying between 4-6 months. The research objective is to analyze the content of proximate fresh tubers and three kinds of flour (flour, starch and starch dregs) by harvesting different age plants. The study was conducted in Malang at a height of 560 m above sea level. Planting was done using plastic mulch with a spacing of 80 cm × 20 cm. Research using complete Randomized block Design with one factor harvesting consisting of 16, 18, 20 and 22 weeks after planting. Jicama tubers were harvested and analyzed the proximate for moisture, ash, fat, protein and carbohydrates in the fresh tubers, flour, starch and jicama flour dregs. The results showed that the late harvest resulted in moisture content, ash content, fiber and fat increase while the protein and carbohydrate decreased. The content of carbohydrates in the flour, starch and starch dregs was almost the same at different harvest time. The protein content of the flour is from 4.22 to 5.87%; while protein content of starch and protein content flour dregs is from 1.05 to 1.90% and 3.95 to 4.84%. Flour fiber content increased with increasing age of plants, while the fiber content of starch decreased but the dregs flour fiber content is almost the same

Comparison of starches separated from different Dioscorea bulbifera Linn. cultivars

AbstractThe physico‐chemical, morphological, thermal, and crystal properties of the starches separated from three different rhizomes of Dioscorea bulbifera Linn. (D.BLH, Hubei; D.BLG1, Guangxitianlin; D.BLG2, Guangxiyulin) were studied and compared. A light microscopic technique was applied in order to quantify the integrity and shape of the starch granules after isolation. Amylose contents of different cultivars were in the range of 12.18–14.34%. Moisture content, ash content, swelling power, solubility, water‐binding capacity, and protein content of starches also differed significantly. The three different D. bulbifera starches all showed a typical C‐type pattern with crystallinity 45.36, 27.10, and 53.04%, corresponding to D.BLH, D.BLG1, and D.BLG2, respectively. The starch separated from the three starches above showed gelatinization range of 10.09, 11.55, and 7.26°C, corresponding to D.BLH, D.BLG1, and D.BLG2. The enthalpy of gelatinization (ΔHgel) ranged from 1.28 to 3.11 J/g. Correlation analysis displayed that amylose content and relative crystallinity values were important in determining thermal starches.

Effect of Drying Temperature and Soaking Conditions on Wet-Milling Characteristics of Amaranth Grain

Amaranth grains (Amaranthus cruentus) were air-dried at 40, 70 and 100 ºC and a moisture range from 29.5 to 10.2, dry basis (d.b.). Dried grains were wet-milled at 53.9ºC in the presence of SO2 aqueous solution in order to obtain fractions of starch, protein and fiber. Effect of drying temperature and SO2 concentration (0.01 – 0.05 w/v %) on fraction yields and protein content of starch were investigated using response surface method (RSM). A factorial design including triplicate of central point was performed. Starch and protein yields decreased as drying temperature increased while fiber yield and protein content in starch fraction shown the opposite behaviour. Protein yield and protein in starch fraction were affected negatively by SO2 concentration. Interaction among studied factors was only appreciable in fiber yield where a synergic effect was observed. The optimum conditions required to maximize starch together with the minimization of protein content in starch fraction included drying temperature of 40°C with amaranth soaking using 0.05 w/v % of SO2. These process conditions lead to 35.1 ± 1.4% of starch yield with a protein content of 1.93 ± 0.015%.

Correlations between wet-milling characteristics of amaranth grain

Relationships of acid wet-milling conditions (soaking temperature and sulfur dioxide concentration) to laboratory wet-milling characteristics (fraction yields, protein content of fractions, and recovery values) of amaranth seeds were determined. Based on correlation coefficients (Pearson matrix), it was found that: (a) starch recovery was significantly correlated to fiber yield ( r = −0.74); (b) the correlations of gluten recovery with protein content of starch ( r = −0.69) and among protein contents of fiber and gluten ( r = −0.63) pointed out the importance to have an efficient fiber isolation to assure satisfactory gluten yield; and (c) the solids in soaking water were correlated with protein contents of wet-milling being fractions being the coefficient value of −0.87 for gluten fraction. Principal component analysis identified three components (named as solids-leaching effect, protein-dispersion effect, and matrix-breakdown effect) that explained 95% of the total variation among wet-milling responses. The needs to recycle the processing water and the greater significance of the fraction quality over the fraction yield were revealed.

Use of commercial protease preparations to reduce protein and lipid content of maize starch

A method was developed to produce pure maize starch from maize flour using a protease processing step, and additional salt washing and sulphite steeping steps. A range of commercial protease enzymes were evaluated for this purpose. The laboratory scale procedure that was developed, using one protease in particular (Promod P25P, thermolysin), produced relatively pure starch (<0.45% protein). Using the same procedure, but applying to starches which had been produced in advance using traditional wet milling, starch protein contents could be reduced further by 25–50% with the lipid content reduced by up to 25%. The amount of starch damage was minimal using this approach (<1%). This procedure could be developed industrially for a ‘greener approach’ to starch extraction – although it may still be necessary to incorporate sulphite steeping stages to facilitate protein solubilisation and extraction.

Effects of steeping conditions on wet‐milling attributes of amaranth

SummaryThe effect of temperature and SO2 concentration on fraction yields (starch, gluten and fibre yields) and protein content of starch during wet milling were investigated using response surface method. Soaking time was adequate to accomplish saturation of the grain. A 32 factorial design including triplicate of central point was performed. The starch and fibre yields decreased with temperature. The effect of SO2 on fraction yields was significant; for gluten, the effect was dependent on the level of temperature. The predicted optimum conditions required to maximise starch and gluten yields together with the minimisation of protein content in starch fraction included steeping at 53.9 °C (1.6 h) with 0.041 w/v% of SO2 concentration. The predicted starch and gluten yields were 45.0% ± 1.35% and 17.5% ± 0.80%, respectively. The predicted protein content for starch fraction was 0.60% ± 0.015%. These predicted values were satisfactorily checked by an experiment at optimal soaking conditions.

Physicochemical Properties of Maize Starch Obtained from Intermittent Milling and Dynamic Steeping (IMDS) Under Various Steeping Conditions

ABSTRACTPhysicochemical properties of maize starch obtained under different steeping conditions by intermittent milling and dynamic steeping process (IMDS) were studied. Brazilian dent maize (hybrid XL 606) was milled using a 2×2×3 factorial experimental design with two lactic acid levels (0.0 and 0.55%, v/v), two SO2 levels (0.05 and 0.1%, w/v), and three temperatures (52, 60, and 68°C). Properties of starch obtained by conventional wet‐milling process (36 hr at 52°C, 0.55% lactic acid, and 0.2% SO2) were used for comparison. Starch protein content and solubility increased with presence of lactic acid, while swelling power decreased. Higher SO2 concentration (0.1%) had the same effect as lactic acid on some properties. Steeping temperatures of 60 and 68°C increased solubility and most of the thermal properties but reduced swelling power, suggesting stronger starch annealing during IMDS at these temperatures. Some thermal changes on starch granules were visualized by scanning electron microscopy (SEM) at 60 and 68°C. Amylose content as well as pasting properties were affected by steeping factors and interactions. Starches from IMDS and conventional wet‐milling processes were similar in most properties, indicating that IMDS provides starch with quality similar to that from conventional milling.

Laboratory Wet-Milling of Grain Sorghum With Abbreviated Steeping to Give Two Products

Short-time and no-time steeping were used in the wet-milling of grain sorghum to give two products, starch in over 78% recovery (starch basis) plus the remaining grain solids. In the wet-milling process 1.5 parts of fresh water were used per part of grain to compensate for drying and transfer losses. Starting with 100 g (dry solids) of commercial No.2 grain sorghum, steep time (1—3 h), steep temperature (25—60 °C), and coarse-grinding speed (7, 500—12, 500 rpm with tip speed of 90.4—150.7 km/h) were varied in a model study; starch recovery, starch lightness (L*), and damaged starch were the responses. Grain sorghum was steeped with twice its weight of process water containing 0.2% sulfur dioxide and the steeped kernels were added to an equal volume of process water and the mixture was ground for 6 min in a Waring blender with blunt blades (d = 3.2 cm). The course-ground material was sieved (opening 1190 μm) to collect the bran/germ, and the throughs were allowed to stand. The sedimented phase was finely ground by one pass through a plate mill, and the fine fiber removed by sieving (opening 73 μm). The slurry was adjusted to a specific gravity of 1.04, and the starch was separated from the protein fraction on a starch table. The protein fraction was combined with the steep-liquor concentrate (54% solids) plus the bran/fiber and the fine-fiber fractions to give the co-product, which contained 70% moisture (wet basis, wb) and 27% protein (dry basis, db). In the surface response study, recovery of starch ranged from 57 to 89%, starch protein content from 0.4 to 0.5%, and lightness (L*) from 90 to 93. Damaged starch content was constant at around 0.4%. Commercial grain sorghum gave the highest starch recovery (90%) after steeping 2 h at 55 °C and coarse-grinding at 10, 500 rpm; whereas a food-grade, a white and a red sorghum gave 85, 84, and 80% recoveries, respectively. The four starches had lightness (L*) values of 93—94 and damaged starch contents of 0.4—0.6%. When the commercial grain sorghum was wet-ground without steeping in 2 parts of water containing 0.2% sulfur dioxide, a 78% recovery of starch was obtained with L* 93.7 and starch damage 0.5%.

Study of a Small‐Scale Laboratory Wet‐Milling Procedure for Wheat

ABSTRACTThe objectives of this research were to study the effects of slurry specific gravity, starch table slope, slurry pumping rate, and their interactions on starch recovery and purity; and to propose a small‐scale laboratory wet‐milling procedure for wheat. First‐order and second‐order response surface regression models were developed to study the effects and interactions of slurry specific gravity, starch table slope, and slurry pumping rate on starch and gluten separation for a 100‐g wheat wet‐milling procedure. The starch and starch protein content data fit the first‐order models (R2 = 0.99 and 0.96) better than the second‐order models (R2 = 0.98 and 0.93). Regression results from the first‐order models indicated that specific gravity, table slope, pumping rate, and their interactions all had a significant effect on starch yield and purity. However, these effects could be simplified as the effect of the resident time of starch and gluten slurry on the starch table and the specific gravity. Starch yield increased as resident time increased and specific gravity decreased. Protein content in starch decreased as the resident time decreased and the specific gravity increased. The separation condition with specific gravity of 3 Bé, table slope of 1.04 cm/m, and pumping rate of 50 mL/min was recommended. Under this condition, starch recovery was 85.6% and protein content of starch was 0.42%, which was similar to the 1.5‐kg laboratory methods in starch recovery. Total solids recovery was 98.1%, which is similar to that from 1.5‐kg laboratory methods. These results indicated that precision of the 100‐g wheat wet‐milling procedure was similar to that of the 1.5‐kg laboratory methods.

Reducing Steep Time by Adding Lactic Acid During Countercurrent Steeping of Corn with Different Initial Moisture Contents

ABSTRACTReducing corn steep time by adding lactic acid instead of relying on in situ fermentation was studied. Corn at two initial moisture levels (15 and 20%) was steeped for 18 hr in a countercurrent steep system. The initial SO2 target concentration in steepwater was 2,000 or 3,000 ppm, while the initial lactic acid concentration in steepwater was 0, 0.28, or 0.55%. Adding lactic acid under all steeping conditions decreased steepwater pH, accelerated SO2 absorption, and increased the amount of solids released from corn. Adding lactic acid during steeping also increased the first grind slurry density and made germ skimming easier than when no lactic acid was added. Starch yields for the hybrid used in this study under all steep conditions were comparable to those from 24‐hr steeping, except when steeping corn with an initial moisture content of 15% in ≈2,000 ppm of SO2 alone. For the 20% moisture corn, adding lactic acid to fresh steepwater significantly improved the starch yield at ≈2,000 ppm of SO2 for 18‐hr steeping. At ≈3,000 ppm of SO2, adding lactic acid did not increase the starch yield for the hybrid used. The protein content in starch was significantly lower when lactic acid was added. Pasting properties of starch were not affected by adding lactic acid. The hybrid used in this study had an initial moisture content of 20% and could be wet‐milled without affecting starch yield, starch protein content, and pasting properties.

Optimum Steeping Process for Wet Milling of Sorghum

ABSTRACTPioneer 8500, a red hard sorghum hybrid, was steeped batchwise using three steeping solutions at 50°C: SO2 solution; SO2 solution containing 1.25% (w/w) of a commercial multiple‐enzyme preparation (Novo SP249); and SO2 solution with the addition of 0.5% (w/w) lactic acid. Novo SP249 contained pectolytic, cellulolytic, hemicellulolytic, and proteolytic activities and small amounts of saccharolytic activities. Three SO2 concentrations (0.1, 0.2, and 0.3% w/v) prepared by dissolving sodium bisulfite in distilled water and three steeping times (24, 36, and 48 hr) were used. Incorporation of multiple enzymes into the SO2 resulted in an increase in starch yield with reduced protein content compared with the SO2 solution alone. The best wet‐milling performance for sorghum resulted from the SO2 solution containing 0.5% lactic acid; it produced the whitest starch with the highest yield and the lowest protein content. Both higher SO2 concentration of the steeping solution and longer steeping time led to higher starch yield, lower protein content in starch, and whiter starch. However, no significant differences in starch yield, protein content in starch, and starch color occurred between SO2 concentrations of 0.2 and 0.3% for all three steeping solutions. The optimum steeping process for wet milling of sorghum was using a 0.2% SO2 solution with 0.5% lactic acid for 36 hr at 50°C. Under these conditions, the starch yield, protein content in starch, and L value of starch color were 60.2% (db), 0.49% (db), and 92.7, respectively, which were not significantly different from the best values from the 48‐hr steeping using the solution with 0.3% SO2 and 0.5% lactic acid.

Yield, Protein Content, and Viscosity of Starch from Wet‐Milled Corn Hybrids as Influenced by Environmentally Induced Changes in Test Weight

ABSTRACTForty‐three yellow dent corn samples of five different hybrids varying in test weight and moisture content were obtained from 14 different locations in 1993. The locations for acquired samples were selected randomly to cover a wide range of test weights based on preliminary data from eight states of the corn belt where 94% of the U.S. corn crop was produced in 1993. Samples were wet‐milled using a 100‐g standard laboratory‐scale wet‐milling procedure. Protein content in starch and starch viscosity were determined. Starch yield, protein content in starch, and starch viscosity were not affected significantly by test weight.

Thermal Properties of Corn Starch Extraction Intermediates by Differential Scanning Calorimetry

ABSTRACTThermal properties of corn starch extraction intermediates from four types of corn were studied using differential scanning calorimetry. Starch at four different stages of extraction, including a standard single‐kernel starch isolation procedure and three starch extraction intermediates, was isolated from mature corn kernels of B73 and Oh43 inbreds and the mutants of waxy (wx) and amylose extender (ae) in an Oh43 background. Differences in thermal properties and moisture and protein contents of starch from the extraction stages were statistically analyzed. Most thermal properties (gelatinization and retrogradation onset temperatures, gelatinization and retrogradation ranges, gelatinization and retrogradation peak temperatures, gelatinization and retrogradation enthalpies, peak height index, and percentage of retrogradation) of starches extracted at stage 3 intermediate (a procedure that did not include a final washing step) were similar to those of starch extracted by the standard single‐kernel isolation procedure. Values for gelatinization peak temperature, gelatinization enthalpy, and peak height index were different between the standard and the stage 3 intermediate. The values obtained from starches extracted at stage 3, however, were consistent and predictable, suggesting that this extraction intermediate might be used in screening programs in which many starch samples are evaluated. By using the stage 3 extraction, samples could be evaluated in three rather than four days and the procedure saved ≈0.5 hr of labor time. The other two starch extraction intermediates, which excluded filtering and washing or filtering, washing, and steeping, produced starch with thermal properties generally significantly different from starch extracted by the standard single‐kernel isolation procedure.

OPTIMIZATION OF SULFUR DIOXIDE AND LACTIC ACID STEEPING CONCENTRATIONS FOR WET-MILLING OF GRAIN SORGHUM

Influence of sulfur dioxide (SO2) and lactic acid (LA) on grain sorghum steeping efficiency in terms of wetmilling characteristics was investigated using response surface analysis. Tested ranges of concentrations in steeping water were 0.050 to 0.278% and 0 to 0.282% for SO2 and LA, respectively. Measured wet-milling variables were steeping solids yield, starch yield, protein yield, fiber/germ yield, starch recovery, protein recovery and protein content of starch. Starch and protein recovery values were highly correlated to each other (r = 0.74). Correlations of these attributes with fiber/germ yield were strongly negative (r = –0.96 and r = –0.70 for starch and protein recovery, respectively). A model comprised of the linear and quadratic terms of SO2 and LA concentrations and the interaction between SO2 and LA was fitted to data for each dependent variable. The model satisfactorily explained starch yield (R2 = 0.84), starch recovery (R2 = 0.85) and fiber/germ yield (R2 = 0.71). Lactic acid was the factor that consistently influenced all significant surfaces (P < 0.01 for starch yield and starch recovery, and P < 0.05 for fiber/germ yield). Maximum stationary points for starch yield and recovery, and a minimum stationary point for fiber/germ yield were observed at similar combinations of SO2 (0.191-0.209%) and LA (1.387-1.415%) concentrations.

Wet Milling Characteristics of Waxy Corn Hybrids Obtained from Different Planting Locations

AbstractStarch yield and residual protein content in starch were determined using a laboratory wet milling procedure for three waxy corn hybrids obtained from up to five planting locations, to investigate the effect of planting location and hybrid on starch yield and purity, and to investigate interactions between planting location and hybrid. Starch yield varied significantly with both hybrid and planting location at the 5% probability level. Residual protein content in starch was not significantly affected by planting location, but was significantly affected by hybrid. Relative rankings of hybrids with respect to starch yield and residual protein content in starch were consistent across planting locations, although starch yield and the residual protein content in starch varied with the planting location. Results indicated that hybrids having high starch yield at one location will likely have high starch yields at other planting locations. The same was found true for starch purity.

Studies on the Steeping Agents for Preparing Corn Starch

A laboratory investigation of corn steeping was performed using several kinds of agents (sodium hydrogen sulfite, sodium thiosulfate, sodium hydrosulfite, sodium carbonate, sulfurous acid, sodium hydroxide and sulphuric acid). 1) No difference between steeping at 30°C and 50°C was found in the water absorption during the steeping and in the yield of starch, but the extraction of protein was increased at 50°C as compared with that at 30°C. On steeping at 50°C, the extraction of protein was in the following order: 0.4% sodium hydrogen sulfite > 0.4 % sulfurous acid >0.2 % sulphuric acid > 0.1 % sodium hydroxide. The yield of starch increased in steeping using sodium hydrogen sulfite and sulfurous acid in comparison with sulphuric acid and sodium hydroxide. 2) The protein contents of starches after steeped at 30°C in sodium hydrogen sulfite and sulfurous acid were 0.40.46/0, but those in sodium hydroxide and sulphuric acid were 0.74-0.84%. 3) The temperatures of gelatinization of starches after steeped at 50°C in 0.2% and 0.4%; sodium hydrogen sulfite were lower than the others, and their maximum viscosities were highest in those starches.