Rheological and Sensory Evaluation of Wheat Flour Tortillas During Storage

Texture of wheat flour tortillas over 15 days at room temperature was evaluated using an expert sensory panel, consumer panels, subjective rollability test, large deformation rheological methods (i.e., bending, extensibility [1‐D and 2‐D], and puncture tests), and stress relaxation method. Most of the changes in texture occurred during the initial 8 days of storage, while texture of tortillas changed slowly thereafter. Differences in texture between fresh and 1‐day‐old tortillas were detected by many objective rheological methods but not by either sensory panel. The expert sensory panel observed a rapid decrease in tortilla extensibility and an increase in staleness between 1 and 8 days of storage and smaller changes in sensory scores after 8 days of storage. Most objective rheological parameters changed rapidly between 0 and 5 days, and slowly after 5 days of storage. Significant correlations and factor analysis reveal that changes occurring in flour tortillas during staling are estimated better by subjective rollability, sensory evaluation (expert and consumer panels), and 2‐dimensional extensibility test than by other methods. Hence, some rheological methods are useful to estimate sensory properties of flour tortillas.     

Enhanced Lipid Stability in Whole Wheat Flour by Lipase Inactivation and Antioxidant Retention

The purpose of this study was to determine the effectiveness of dry heat, steam, and microwave treatments in decreasing lipase activity, while retaining antioxidant activity, to stabilize whole wheat flour against lipid degradation during storage. Bran was heat‐treated in 230‐g batches using four levels (exposure times) for each of the three treatment methods. Lipase activity and antioxidant activity were quantified for all treatment combinations. None of the treatments significantly decreased antioxidant activity; the levels determined to be optimal, inasmuch as further heating did not significantly decrease lipase activity, were 25 min of dry heat, 60 sec of microwave (1000W), and 60 sec of steam. These treatments effectively decreased lipase activity by 74, 93, and 96%, respectively. Optimum treatments were evaluated for acceptance using a consumer sensory panel during a 12‐month storage period. No significant differences in acceptance were found between the control and any of the samples either at baseline or after storage. This suggests that whole wheat flour can be stabilized against lipolysis by utilizing the treatments described in this study without decreasing antioxidant activity, and that manufacturers may utilize these treatments without risking decreased consumer acceptance.     

Whole Grain Wheat Flour Production Using an Ultracentrifugal Mill

Interest has been growing in whole grain products. However, information regarding the influence of the ultracentrifugal mill on whole grain flour quality has been limited. An experiment was conducted to produce whole wheat flour with hard red spring (HRS) wheat using an ultracentrifugal mill. This study determined the effect of centrifugal mill parameters as well as grain moisture (10–16%) on producing whole wheat flour and its final products. Mill parameters studied were rotor speed (6,000–15,000 rpm) and feed rate (12.5–44.5 g/min). Results showed that fine particle size (<150 µm) was favored by low seed moisture content (10–12%) and high rotor speed (12,000–15,000 rpm). Flour moisture content was positively related to seed moisture content. Wheat grain with low seed moisture content (10–12%) milled with high rotor speeds (12,000–15,000 rpm) produced desirable whole grain wheat flour quality, with 70–90% of fine particle size portion and low damaged starch (less than 11%). This whole wheat flour produced uniform and machinable dough that had low stickiness and formed bread with high loaf volume.     

Laboratory Milling Method for Whole Grain Soft Wheat Flour Evaluation

Whole grain wheat products are a growing portion of the foods marketed in North America, yet few standard methods exist to evaluate whole grain wheat flour. This study evaluated two flour milling systems to produce whole grain soft wheat flour for a wire‐cut cookie, a standard soft wheat product. A short‐flow experimental milling system combined with bran grinding in a Quadro Comil produced a whole grain soft wheat flour that made larger diameter wire‐cut cookies than whole grain flour from a long‐flow experimental milling system. Average cookie diameter of samples milled on the short‐flow mill was greater than samples milled on the long‐flow system by 1 cm/two cookies (standard error 0.09 cm). The long‐flow milling system resulted in more starch damage in the flour milling than did the short‐flow system. The short‐flow milling system produced flours that were useful for discriminating among wheat cultivars and is an accessible tool for evaluating whole grain soft wheat quality.     

Relationship Between Grain,Semolina, and Whole Wheat Flour Properties and the Physical and Cooking Qualities of Whole Wheat Spaghetti

Durum breeding programs need to identify raw material traits capable of predicting whole wheat spaghetti quality. Nineteen durum wheat (Triticum turgidum L. var. durum ) cultivars and 17 breeding lines were collected from 19 different environments in North Dakota and were evaluated for physical and cooking qualities of whole wheat spaghetti. Raw material traits evaluated included grain, semolina, and whole wheat flour characteristics. Similar to traditional spaghetti, grain protein content had a significant positive correlation with cooking quality of whole wheat spaghetti. Stepwise multiple regressions showed grain protein content, mixogram break time, and wet gluten were the predominant characteristics in predicting cooked firmness of whole wheat spaghetti.     

Effect of Single‐Pass and Multipass Milling Systems on Whole Wheat Durum Flour and Whole Wheat Pasta Quality

Single‐pass and multipass milling systems were evaluated for the quality of whole wheat durum flour (WWF) and the subsequent whole wheat (WW) spaghetti they produced. The multipass system used a roller mill with two purifiers to produce semolina and bran/germ and shorts (bran fraction). The single‐pass system used an ultracentrifugal mill with two configurations (fine grind, 15,000 rpm with 250 μm mill screen aperture; and coarse grind, 12,000 rpm with 1,000 μm mill screen aperture) to direct grind durum wheat grain into WWF or to regrind the bran fraction, which was blended with semolina to produce a reconstituted WWF. Particle size, starch damage, and pasting properties were similar for direct finely ground WWF and multipass reconstituted durum flour/fine bran blend and for direct coarsely ground WWF and multipass reconstituted semolina/coarse bran blend. The semolina/fine bran blend had low starch damage and had desirable pasting properties for pasta cooking. WW spaghetti was better when made with WWF produced using the multipass than single‐pass milling system. Mechanical strength was greatest with spaghetti made from the semolina/fine bran or durum flour/fine bran blends. The semolina/fine bran and semolina/coarse bran blends made spaghetti with high cooked firmness and low cooking loss.     

Effect of Wheat Grain Steaming and Washing on Lipase Activity in Whole Grain Flour

During whole grain flour (WGF) storage, lipase activity causes partial loss of its functionality and the sensory acceptability of products produced from it. The objective of this research was to evaluate the effect of steaming and washing on lipase activity in (fractions of) wheat. Steam treatment conditions were optimized for wheat grains and their bran, shorts, and flour fractions. Lipase activities were determined colorimetrically, as were peroxidase, endoxylanase, and α‐amylase activities. Steaming grains for 180 s effectively inactivated lipase, peroxidase, endoxylanase, and part of the α‐amylase without gelatinizing starch. The work further demonstrated that lipase is mainly, if not only, located in the bran fraction. Separate bran treatment holds promise for obtaining WGF with reduced lipase activity but without altered functional properties. Washing grains did not reduce WGF lipase activity.     

Bran Characteristics and Bread‐Baking Quality of Whole Grain Wheat Flour

Variations in physical and compositional bran characteristics among different sources and classes of wheat and their association with bread‐baking quality of whole grain wheat flour (WWF) were investigated with bran obtained from Quadrumat milling of 12 U.S. wheat varieties and Bühler milling of six Korean wheat varieties. Bran was characterized for composition including protein, fat, ash, dietary fiber, phenolics, and phytate. U.S. soft and club wheat brans were lower in insoluble dietary fiber (IDF) and phytate content (40.7–44.7% and 10.3–17.1 mg of phytate/g of bran, respectively) compared with U.S. hard wheat bran (46.0–51.3% and 16.5–22.2 mg of phytate/g of bran, respectively). Bran of various wheat varieties was blended with a hard red spring wheat flour at a ratio of 1:4 to prepare WWFs for determination of dough properties and bread‐baking quality. WWFs with U.S. hard wheat bran generally exhibited higher dough water absorption and longer dough mixing time, and they produced smaller loaf volume of bread than WWFs of U.S. soft and club wheat bran. WWFs of two U.S. hard wheat varieties (ID3735 and Scarlet) produced much smaller loaves of bread (<573 mL) than those of other U.S. hard wheat varieties (>625 mL). IDF content, phytate content, and water retention capacity of bran exhibited significant relationships with loaf volume of WWF bread, whereas no relationship was observed between protein content of bran and loaf volume of bread. It appears that U.S. soft and club wheat bran, probably owing to relatively low IDF and phytate contents, has smaller negative effects on mixing properties of WWF dough and loaf volume of bread than U.S. hard wheat bran.     

Effect of Storage on Fat Acidity and Pasting Characteristics of Wheat Flour

Two cultivars of wheat (Triticum aestivum L.), Sunco and Sunsoft, were used to study the influence of storage time and temperature on the formation of starch-lipid complexes in flour pastes. Untreated and fat-reduced whole meal flours were stored separately for up to 12 months at 4, 20, and 30°C. The stored samples were analyzed for fat acidity, pasting properties, and iodine binding values. Fat acidity increased significantly in the untreated flour samples stored at 30 and 20°C compared with 4°C. Starch pasting properties, as measured using a Rapid Visco Analyser (RVA) indicated that the final viscosity of untreated flour samples of both cultivars increased significantly with storage time and elevated temperature, and correlated positively with increased fat acidity. Iodine binding values of the RVA pastes decreased with storage time and elevated temperature, and correlated negatively with fat acidity and final viscosity. The fat-reduced Sunco and Sunsoft flours showed less pronounced changes compared with untreated flours, whereas small changes in the RVA parameters were noted in grains stored over 12 months. The results indicate that free fatty acids are released during storage and that they increase the potential for starch-lipid complex formation when stored whole meal wheat flours are pasted in the RVA. These changes were evident after two to three months of storage at 20 and 30°C.     

Mixing Properties,Baking Potential,and Functionality Changes in Storage Proteins During Dough Development of Triticale‐Wheat Flour Blends

Flours from advanced lines or cultivars of six triticales and two prime hard wheats, along with triticale‐wheat blends, were investigated for mixing, extension (excluding blends), and baking properties using microscale testing. Percentage total polymeric protein (PPP) and percentage unextractable polymeric protein (UPP) of flours and doughs, including blends, mixed to optimal dough development were estimated using size‐exclusion HPLC to determine the changes in protein solubility and association with blend composition (BC), mixing properties, and loaf height. Each triticale was blended with flours of each of the two wheat cultivars (Hartog and Sunco) at 0, 30, 40, 50, 60, 70, and 100% of wheat flour. Nonlinear relationships between BC and mixograph parameters (mixing time [MT], bandwidth at peak resistance [BWPR], and resistance breakdown [RBD]) were observed. A linear relationship between BC and peak resistance (PR) was predominant. PPP of triticale flours was mostly higher than PPP of wheat cultivars. UPP of all triticales was significantly lower than wheat cultivars. PPP of freeze‐dried doughs was mostly nonsignificant across the blends and showed a curvilinear relationship with BC. The deviations from linearity of MT and PPP were higher in triticale‐Sunco blends than in triticale‐Hartog blends. UPP of blends was closer to or lower than the lower component in the blend. The deviations from linearity for MT and UPP were greater in triticale‐Hartog blends than triticale‐Sunco blends. A highly significant correlation (P < 0.001) was observed between BWPR and loaf height. This suggested that BWPR in triticale‐wheat flour blends could be successfully used for the prediction of loaf height. Triticale flour could be substituted for wheat flour up to 50% in the blend without drastically affecting bread quality. Dough properties of triticale‐wheat flour blends were highly cultivar specific and dependent on blend composition. This strongly suggested that any flour blend must be tested at the desired blend composition.     

Quantitative Characterization of Polar Lipids from Wheat Whole Meal,Flour, and Starch

Lipids constitute only a minor proportion of total flour components but the composition and structure of wheat flour polar lipids influence the end‐use quality of bread. So it is important to determine which specific lipid class and molecular species are present in wheat. Lipid profiling is the targeted, systematic characterization and analysis of lipids. The use of lipid profiling techniques to analyze grain‐based food has the potential to provide new insight into the functional relationships between a specific lipid species and its functionality. The objective of this study was to utilize lipid profiling techniques to quantitatively determine the polar lipid species present in whole wheat meal, flour, and starch. Two commonly grown wheat cultivars, Alpowa and Overley, were used in this study. Direct infusion electrospray ionization tandem mass spectrometry was used to identify and quantitatively determine 146 polar lipid species in wheat. The predominant polar lipid classes were digalactosyldiglycerols, monogalactosyldiglycerols, phosphatidylcholine, and lysophosphatidylcholine. ANOVA results concluded that the wheat fraction contributed a greater source of variation than did cultivar on total polar, total phospholipid, and total galactolipid contents. Wheat whole meal, flour, and surface starch contained greater concentrations of total galactolipids, whereas internal starch lipids contained greater concentrations of monoacyl phospholipids. This research provides evidence that lipid profiling will provide the ability to determine the functional relationships between specific lipid species and the impact on end‐use quality.     

Fate of Dwarf Bunt Fungus Teliospores During Milling of Wheat into Flour

Wheat contaminated with teliospores of Tilletia controversa Kühn (TCK) was mixed with uncontaminated wheat and processed through the Kansas State University pilot mill. Two 50-bu lots of the contaminated mixture were cleaned, tempered, and milled. Approximately 500 samples of wheat, cleanings, and mill fractions were collected and examined for the presence of intact and broken TCK teliospores. Whole wheat samples (50 g) were washed, sieved through a 60-μm nylon sieve, and pelleted by centrifugation. Contents of the pellet were examined microscopically for the presence of TCK spores. The procedure was modified as needed to accommodate cleanings and mill fractions. Levels of spore contamination in whole wheat samples decreased at each step during the handling process, and large numbers of spores were found in materials that were sieved or aspirated from the grain. Very few spores were found in bran, germ, and shorts; none were detected in red dog or straight-grade flour. The results showed that a high percentage of spores can be removed from wheat by mechanical cleaning but that it is not feasible to remove all of them.     

Stability and Dietary Contribution of Vitamin E Added to Bread

Daily intake levels of vitamin E in the range of 200–800 IU are now recommended for its antioxidant effect. However, only vitamin E supplements or fortified foods may provide these high intake levels. As a fortified food, breads were prepared containing 200, 400, 800, or 1,600 IU of added vitamin E (dl‐α‐tocopheryl acetate) per pound loaf. These levels of fortification exerted no adverse effects on bread quality. However, only about two‐thirds of the added vitamin E was retained (recovered) in the breads, with retention values showing no further significant change during the seven‐day shelf‐life of the product. In fresh breads, vitamin E retention values were nearly the same (range 66.3–68.5%, average 67.2%) at all levels of vitamin E tested; this may hold true for levels not tested. Factoring in an average retention value of 67.2%, and actual potency (81.8%) of the vitamin E source used, a 50‐g serving of bread fortified with 1,600 IU of vitamin E per loaf would provide nearly one‐fourth of a suggested daily intake of 400 IU.     

Effect of Saline Organic Acid Solutions Applied During Wheat Tempering on Flour Functionality

Previously, we showed that tempering with saline organic acid solutions can reduce the aerobic plate count of wheat by as much as 4.3 log CFU/g. The purpose of this study was to evaluate the impact of these tempering solutions on the functional properties of resulting whole grain (WGF) and straight‐grade (SGF) flours. Wheat was tempered to 15.5% moisture by tempering with sterile distilled water (control) or solutions containing NaCl (26% [w/v]) together with organic acid (acetic or lactic 2.5 and 5.0% [v/v]). After milling, fractions were collected and recombined as needed to obtain WGF or SGF. The acid content in WGF was higher than in SGF, indicating limited penetration of the organic acids into the endosperm of the grain. In WGF, the saline organic acid treatments caused a decrease in paste viscosity and bread crumb cell sizes in breads. In SGF, the saline organic acid treatments caused significant changes in paste viscosity and some Mixograph parameters; however, principal components analysis indicated that the treatments did not substantially affect SGF functionality. Thus, WGF was altered by the saline organic acid solutions, whereas SGF functionality was minimally affected by tempering treatments, perhaps because of acids only partially penetrating into the endosperm.     

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.     

Alkylation of Free Thiol Groups During Extraction: Effects on the Osborne Fractions of Wheat Flour

Wheat proteins are classified according to solubility into the so‐called Osborne fractions. Because wheat flour contains both free thiol and disulfide groups, thiol–disulfide interchange reactions are possible during extraction. Osborne fractionation of 12 different wheat flour samples was performed in the presence of N‐ethylmaleinimide (NEMI) to alkylate free thiol groups and without addition of NEMI (control). The addition of NEMI during extraction tended to decrease the content of gliadins (predominantly α‐gliadins) and caused an increase of the content of glutenins in most flour samples. Thus, alkylation of free thiol groups during extraction led to a decline of the gliadin/glutenin ratio from 2 (control) to approximately 1.5 (NEMI). NEMI and control gliadins were separated by gel‐permeation HPLC into an oligomeric subfraction (high‐molecular‐weight [HMW] gliadins) and two monomeric subfractions. In most flours (8 of 12), the addition of NEMI led to a significant increase of the content of HMW gliadins. HMW gliadins from cultivar Akteur wheat were preparatively isolated from NEMI and control gliadins and characterized by HPLC, sodium dodecyl sulfate polyacrylamide gel electrophoresis, and N‐terminal sequencing. HMW gliadin isolated in the presence of NEMI had a significantly higher content of low‐molecular‐weight glutenin subunits and disulfide‐bound cysteine as well as a lower content of α‐gliadins and disulfide‐bound glutathione compared with the control.     

Effects of Extraction Rates of Wheat Flour on Phyllo (Yufka) Properties at Different Storage Temperatures

Phyllo sheets were produced with flour obtained at different extraction rates (53, 58, or 67%), and stored at 4 and 25°C. Physical, chemical, and sensory properties of fresh and stored phyllo were researched. Fresh phyllo samples from wheat flour at 53% extraction rate were thinner (0.4 mm) and had whiter color (L* = 87.6). Textural properties and overall sensory acceptability of phyllo samples significantly decreased (P ≤ 0.01) with increased extraction rates and storage times. At the end of four days, toughness and extensibility decreased from 0.88 N and 10.9 mm to 0.65 N and 6.7 mm at 4°C and to 0.45 N and 5.6 mm at 25°C. The 53% extraction rate was more suitable for producing phyllo. The shelf life of phyllo samples for preparing borek was determined four days at 4°C and two days at 25°C according to acid contents and sensory properties.     

Effects of Inorganic Phosphates on the Thermodynamic,Pasting, and Asian Noodle‐Making Properties of Whole Wheat Flour

The effects of four inorganic phosphates on the thermodynamic and pasting properties of whole wheat flour as well as color, cooking quality, textural properties, and structural characteristics of whole wheat noodles were studied. The addition of phosphates increased the gelatinization temperature and enthalpy of melting of starch in whole wheat flour. Rapid visco analysis showed that all phosphates significantly increased whole wheat flour peak viscosity and final viscosity. Moreover, the whole wheat noodles prepared with disodium phosphate, trisodium phosphate, and sodium tripolyphosphate (STPP) exhibited brighter appearance, and the use of STPP and sodium hexametaphosphate reduced the cooking loss of whole wheat noodles. Texture profile analysis of cooked noodles revealed that the addition of phosphates significantly decreased the hardness and slightly increased the springiness, cohesiveness, and resilience. The microstructure of whole wheat noodles showed a larger degree of connectivity of the protein network and coverage of starch granules in the presence of inorganic phosphates. The results suggested that inorganic phosphates exhibited substantial effects on improving the quality of whole wheat noodles. Of the four phosphates studied, STPP appeared to be the most effective one in improving the overall properties of whole wheat noodles when they were normalized to constant phosphate content.