Characteristics of Granular Cold‐Water Gelling Starches of Cereal Grains and Legumes Prepared Using Liquid Ammonia and Ethanol

Starches of wheat, corn, smooth and wrinkled peas, and chickpeas were modified to a free‐flowing powder of granular cold‐water gelling (GCWG) starch using liquid ammonia and ethanol at 23°C and atmospheric pressure. Amylose content of starches was 26.3% in wheat, 27.1% in corn, 35.4% in chickpeas, 43.2% in smooth peas, and 79.9% in wrinkled peas. The modified starches remained in granular form with an increased number of grooves and fissures on the surface of the granules compared with native starch, while the crystallinity was mostly lost, as shown by X‐ray diffractograms and DSC endothermic enthalpies. Pasting viscosity of modified starches at 23°C was 171 BU and 305 BU in wheat and corn, respectively, and much higher in legume starches, ranging from 545 BU to 814 BU. Viscosities of modified legume starches at 23°C were at least twice as high as those of native starches determined at 92.5°C. Swelling power of modified starches at 23°C ranged from 8.7 g/g to 15.3 g/g, while swelling power of native starches heated to 92.5°C ranged from 4.8 g/g to 16.0 g/g. GCWG starches exhibited higher dextrose equivalent (DE) values of enzymatic hydrolysis, ranging from 25.2 to 27.0 compared with native starches (1.5–2.9). Modified starches from wheat, corn, smooth peas, and chickpeas formed weak gels without heat treatment and experienced no changes in gel hardness during storage, while native starch gels formed by heat treatment showed an increase in hardness by 1.1–7.5 N during 96 hr of storage at 4°C.     

Significance of Amylose Content of Wheat Starch on Processing and Textural Properties of Instant Noodles

The effect of amylose content of starch on processing and textural properties of instant noodles was determined using waxy, partial waxy, and regular wheat flours and reconstituted flours with starches of various amylose content (3.0–26.5). Optimum water absorption of instant noodle dough increased with the decrease of amylose content. Instant noodles prepared from waxy and reconstituted wheat flours with ≤12.4% amylose content exhibited thicker strands and higher free lipids content than wheat flours with ≥17.1% amylose content. Instant noodles of ≤12.4% amylose content of starch exhibited numerous bubbles on the surface and stuck together during frying. Lightness of instant noodles increased from 77.3 to 81.4 with the increase of amylose content of starch in reconstituted flours. Cooking time of instant noodles was 4.0–8.0 min in wheat flours and 6.0–12.0 min in reconstituted flours, and constantly increased with the increase in amylose content of starch. Hardness of cooked instant noodles positively correlated with amylose content of starch. Reconstituted flours with ≤12.4% amylose content of starch were higher in cohesiveness than those of wheat flours of wild‐type and partial waxy starches and reconstituted flours with ≥17.1% amylose content. Instant fried noodles prepared from double null partial waxy wheat flour exhibited shorter cooking time, softer texture, and higher fat absorption (1.2%) but similar color and appearance compared with noodles prepared from wheat flour of wild‐type starch.     

Paste Particle and Bean Size as Related to Sweetened Azuki Paste Quality

Influences of the amount of sugar, particle size of unsweetened paste, and bean size on sweetened paste quality were evaluated in two types of azuki. Increased sugar resulted in darker, less red, and less yellow sweetened paste and decreased hardness, adhesiveness, and chewiness of sweetened paste. Sweetened paste produced from larger particles was less red and less yellow than that from smaller ones. Paste particle size, as determined by sedimentation tests, was correlated with graininess of sweetened paste (r = 0.930**), indicating that the larger the paste particle, the grainier the sweetened paste produced. Protein content ranged from 22.3% in small beans to 26.1% in large beans in Azuki cv. Erimo and from 22.4% in medium size beans to 23.5% in large beans in Azuki WSU 262. Proportion of unsweetened paste particles that were <106 μm was 71.5% in small beans but only 39.3% in large beans in Erimo, and 38.7% in medium size beans, and 23.8% in large beans in WSU 262. Sweetened paste produced from larger beans was less red and lower in hardness, adhesiveness, and chewiness than that from smaller beans.     

Characteristics of French Bread Baked from Wheat Flours of Reduced Starch Amylose Content

Wheat genotypes of wild type, partial waxy, and waxy starch were used to determine the influence of starch amylose content on French bread making quality of wheat flour. Starch amylose content and protein content of flours were 25.0–25.4% and 14.3–16.9% for wild type; 21.2 and 14.9% for single null partial waxy; 15.4–17.1% and 13.2–17.6% for double null partial waxy; and 1.8 and 19.3% for waxy starch, respectively. Wheat flours of double null partial waxy starch produced smaller or comparable loaf volume of bread than wheat flours of wild type and single null partial waxy starch. Waxy wheat flour, despite its high protein content, generally produced smaller volume of bread with highly porous, glutinous, and weak crumb than wheat flours of wild type and partial waxy starch. French bread baked from a flour of double null partial waxy starch using the sponge-and-dough method maintained greater crumb moisture content for 24 hr and softer crumb texture for 48 hr of storage compared with bread baked from a flour of wild type starch. In French bread baked using the straight-dough method, double null partial waxy wheat flours with protein content >14.3% exhibited comparable or greater moisture content of bread crumb during 48 hr of storage than wheat flours of wild type starch. While the crumb firmness of bread stored for 48 hr was >11.4 N in wheat flours of wild type starch, it was <10.6 N in single or double null partial waxy flours. Wheat flours of reduced starch amylose content could be desirable for production of French bread with better retained crumb moisture and softness during storage.     

Recovery and Purity of Isolated Barley Starch and Protein as Affected by Fractionation Water Temperature

Wet fractionation of barley flours was conducted to identify appropriate fractionation water temperature considering the recovery and purity of starch and protein. In abraded hulless regular barley, yield of starch fraction, starch recovery, and purity of the protein fraction increased from 43.3 to 45.7%, from 61.7 to 64.8%, and from 37.6 to 65.2% when water temperature in fractionation was increased from 23 to 60°C. In abraded hulless waxy barley, recovery of starch with 40°C water was much greater (67.7%) than that at other temperatures (<61.7%). Starch recovery and protein purity of regular barley cultivars were higher than those of waxy barley cultivars with fractionation water of 60°C. In whole hulless barley flours fractionated with 60°C water, waxy barley flours showed similar to or higher protein purity (44.8–48.9%) than regular barley flours (42.8– 44.6%), while regular barley flours exhibited higher starch recovery (>60.6%) than waxy barley flours (<57.3%). The purity of isolated starch was >97.7%, regardless of water temperature and barley type. Considering yield and recovery of the isolated starch, and purity of the isolated protein, 60°C water for hulless regular barley and 40°C for hulless waxy barley seem to be appropriate for fractionation of barley flour for isolation of starch and protein.     

Phenolic compounds of barley grain and their implication in food product discoloration

Barley grains contain significant amounts of phenolic compounds that may play a major role in the discoloration of food products. Phenolic acid and proanthocyanidin (PA) composition of 11 barley genotypes were determined, using high-performance liquid chromatography and liquid chromatography-mass spectrometry, and their significance on food discoloration was evaluated. Abraded grains contained 146-410 microg/g of phenolic acids (caffeic, p-coumaric, and ferulic) in hulled barley and 182-282 microg/g in hulless barley. Hulled PA-containing and PA-free genotypes had comparable phenolic acid contents. Catechin and six major barley PAs, including dimeric prodelphinidin B3 and procyandin B3, and four trimers were quantified. PAs were quantified as catechin equivalents (CE). The catechin content was higher in hulless (48-71 microg/g) than in hulled (32-37 microg/g) genotypes. The total PA content of abraded barley grains ranged from 169 to 395microg CE/g in PA-containing hulled and hulless genotypes. Major PAs were prodelphinidin B3 (39-109 microg CE/g) and procyanidin B3 (40-99 microg CE/g). The contents of trimeric PAs including procyanidin C2 ranged from 53 to 151 g CE/g. Discoloration of barley flour dough correlated with the catechin content of abraded grains (r = -0.932, P < 0.001), but not with the content of individual phenolic acids and PAs. Discoloration of barley flour dough was, however, intensified when total PA extracts and catechin or dimeric PA fractions were added into PA-free barley flour. The brightness of dough also decreased when the total PA extract or trimeric PA fraction was added into heat-treated PA-free barley flour. Despite its low concentration, catechin appears to exert the largest influence on the discoloration of barley flour dough among phenolic compounds.     

Influence of Bran Particle Size on Bread‐Baking Quality of Whole Grain Wheat Flour and Starch Retrogradation

The influence of bran particle size on bread‐baking quality of whole grain wheat flour (WWF) and starch retrogradation was studied. Higher water absorption of dough prepared from WWF with added gluten to attain 18% protein was observed for WWFs of fine bran than those of coarse bran, whereas no significant difference in dough mixing time was detected for WWFs of varying bran particle size. The effects of bran particle size on loaf volume of WWF bread and crumb firmness during storage were more evident in hard white wheat than in hard red wheat. A greater degree of starch retrogradation in bread crumb stored for seven days at 4°C was observed in WWFs of fine bran than those of coarse bran. The gels prepared from starch–fine bran blends were harder than those prepared from starch–unground bran blends when stored for one and seven days at 4°C. Furthermore, a greater degree of starch retrogradation was observed in gelatinized starch containing fine bran than that containing unground bran after storage for seven days at 4°C. It is probable that finely ground bran takes away more water from gelatinized starch than coarsely ground bran, increasing the extent of starch retrogradation in bread and gels during storage.     

Starch Characteristics Influencing Resistant Starch Content of Cooked Buckwheat Groats

Cooked buckwheat groats are suggested to contain a greater amount of resistant starch (RS) than cereal grains. High RS content, in addition to dietary fibers present in groats, contributes to the low‐calorie, high‐fiber food status of buckwheat. Six buckwheat genotypes exhibiting high, medium, and low RS content of cooked groats were selected, and starches were isolated to determine their functional properties to explore the possible cause of high RS content of cooked buckwheat groats. Apparent and actual amylose contents were 27.4 and 31.6–34.5% in high, 27.4–28.6 and 32.5–33.7% in medium, and 21.4–25.6 and 24.5–32.0% in low RS genotypes, respectively. Genotypes of high RS content exhibited greater amylose leaching based on total starch content during cooking than genotypes of low RS content, mainly because of higher amylose content in the former than latter. Genotypes of low RS content exhibited a relatively high content of amylose‐lipid complexes, as determined with a differential scanning calorimeter (DSC). Gelatinization enthalpy and degree of amylopectin retrogradation determined with a DSC were not related to RS content. An evident relationship was observed between RS content of cooked groats and amylose retrogradation determined by gel hardness (r = 0.91, P < 0.05), cohesiveness (r = 0.89, P < 0.05), and syneresis (r = 0.88, P < 0.05). Increases in starch amylose content, amylose leaching capacity, and amylose retrogradation, as well as a decrease in the amount of amylose‐lipid complexes all appear to be related to high RS content of cooked buckwheat groats.     

Physicochemical and Thermal Characteristics of Starch Isolated from a Waxy Wheat Genotype Exhibiting Partial Expression of Wx Proteins

A unique wheat genotype carrying waxy‐type allelic composition at the Wx loci, Gunji‐1, was developed, and its starch properties were evaluated in comparison to parental waxy and wild‐type wheat varieties. Gunji‐1 was null in all three of the Wx genes but exhibited a lower level of Wx proteins than the wild‐type. Starch amylose content and cold water retention capacity were 10.1 and 70.5% for Gunji‐1, 4.2 and 76.6% for waxy, and 27.9 and 65.0% for wild‐type, respectively. No significant differences were observed in microstructure, granule size distribution, and X‐ray diffractograms of the starch granules isolated from Gunji‐1 compared with those of waxy and wild‐type wheat varieties. Starch pasting peak, breakdown, and setback viscosities and peak temperature of Gunji‐1 were intermediate between waxy and wild‐type wheat. In starch gel hardness, Gunji‐1 (1.1 N) was more similar to waxy wheat (0.5 N) than to the wild‐type variety (17.6 N). Swelling power, swelling volume, paste transmittance during storage, and gelatinization enthalpy of Gunji‐1 were lower than those of waxy wheat but greater than those of wild‐type wheat. Retrogradation of starch stored for one week at 4°C expressed with DSC endothermic enthalpy was absent in the waxy wheat variety, whereas Gunji‐1 exhibited both retrogradation of amylopectin and amylose‐lipid complex melting similar to the wild‐type parent, even though enthalpies of Gunji‐1 were much smaller than the wild‐type parent.     

Functional and Nutritional Characteristics of Wheat Grown in Organic and Conventional Cropping Systems

The effects of organic versus conventional farming practices on wheat functional and nutritional characteristics were compared. Soft white winter wheat and hard red spring wheat were obtained from multiyear replicated field plots near Pullman, Washington, and Bozeman, Montana. Test weight, kernel weight, and kernel diameter tended to be greater in both soft and hard organic wheat than in conventional wheat in the Pullman studies. Phenolic content and total antioxidant capacity tended to be lower in organic than in conventional wheat. Flour ash, P, and Mg contents in whole wheat flour varied in parallel among cropping systems, but levels were not consistently associated with either organic or conventional cropping systems. Protein contents of whole wheat and refined flours were similar in organic and conventional wheat from Pullman when fertility levels were similar. Higher fertility was associated with higher protein content in both organic and conventional cropping systems. Soft wheat flour from a low‐fertility organic cropping system had lower sodium carbonate, lactic acid, and sucrose solvent retention capacities, lower protein content, and greater cookie diameter and cake volume than soft wheat flour from the higher fertility organic and conventional cropping systems; the change in end‐product quality was significant in one out of two crop years. In the Bozeman hard wheat studies, higher fertility in both organic and conventional cropping systems tended to increase protein content and bread loaf volume. Results indicated that neither organic nor conventional cropping systems were associated with substantially improved mineral and antioxidant nutritional properties, and end‐use quality of wheat was more strongly associated with fertility level than with organic versus conventional cropping systems.