Plant Sciences Doctoral Work

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Black Bean Milling and Flour Functionality
(North Dakota State University, 2020) Fernando, Hettige Supun Sandaru
Dry bean utilization by the food industry can be increased by developing value-added processing applications. The goals of this research were to evaluate (1) the effect of milling method on the physical, chemical and functional properties of whole black bean flour and its fractions and (2) the effect of removing soluble phenolic compounds on the functional and rheological properties of black bean protein isolates. Black bean was milled with five laboratory mills [cyclone mill, hammer mill, stone mill (fine, medium, coarse), disc mill (fine, coarse), and centrifugal mill (10,000 or 12,000 rpm and 250, 500, 1000 μm aperture screen)] and the resulting flours were evaluated for their physical, chemical and flow properties of bulk samples and particle size fractions. Whole black bean flour and cotyledon flour were subjected to phenolic extraction and protein isolation, resulting in protein isolates with and without soluble phenolics. Solubility, wettability, dispersibility, water binding capacity, foam capacity and stability, emulsification capacity, and gelation properties of protein isolates were evaluated. Variation in milling method produced flours with significantly different flour characteristics. Geometric mean size of whole bean flour was negatively correlated with starch damage (r = -0.92), L* (r = -0.94), angle of repose (r = -0.94), and angle of slide (r = -0.80 to -0.90) and positively correlated with moisture (r = 0.72), and loose bulk density (r = 0.72). Milling method and particle size interaction was significant on characteristics of black bean flour fractions. Particle circularity of flour fractions had a negative correlation of r = -0.93, r = -0.81, r ≈ -0.95, and r = -0.94 with L*, angle of repose, angle of slide and compact density, respectively. Particle circularity had a positive correlation of r = 0.93 and r = 0.89 with average minimum particle size and loose bulk density, respectively. The removal of soluble phenolic compounds improved the brightness, solubility, wettability, dispersibility, foaming capacity, foaming stability, emulsion capacity, emulsion stability and gelling properties of protein isolates. These findings will help food manufacturers to process black bean ingredients using different mill settings to achieve different functionalities depending on the consumer requirements.
Causes of Dull Brown Color in Durum and Traditional Semolina Pasta
(North Dakota State University, 2019) Cabas Lühmann, Patricia Alejandra
Bleaching of durum wheat (Triticum turgidum L. ssp. durum [Desf.] Husn.) was evaluated by determining the effect of grain moisture content, temperature, and wet/dry cycles with bulk water and with high relative humidity on the hydration of durum wheat grain and their effect on some physical grain quality parameters. Low initial grain moisture, high temperature, and wet/dry cycles increased water gain. Scanning electron microscopy and light microscopy showed that the germ and ventral surface of grain were important for water absorption. A single exposure to moisture (bulk water or high relative humidity) seems to be enough to cause a decline in grain quality. The effect of the environment on pasta color was evaluated by quantifying the relative importance of environment and genotype effects on pasta color and related traits. The relationship between environmental growing conditions, pasta color and semolina quality traits was determined. The environment had the highest relative proportion of variance for pasta color and related traits. Stepwise multiple linear regression indicated that the number of days with RH ≥ 80% diminished pasta color which could be related to increased speck count in semolina, soluble brown pigment content and an increased in semolina redness. The number of days ≤ 13°C enhanced pasta yellowness and pasta color score. However, why the positive effect occurred was not clear. Milling and processing effects on pasta color were evaluated by determining the effect of milling and pasta processing on polyphenol oxidase (PPO) activity, peroxidase (POD) activity, soluble brown pigment content, and yellow pigment content. Milling caused a reduction in yellow pigment content, soluble brown pigment content, PPO activity and POD activity while pasta processing reduced yellow pigment content, and for some genotypes, increased soluble brown pigment content. Stepwise multiple linear regression indicated that yellow pigment content had a positive effect and protein content, semolina ash content, and speck count had a negative effect on pasta color.
Characteristics of Yam Composite Flour: Properties and Function of Bread and Tortilla Making
(North Dakota State University, 2017) Asiyanbi-Hammed, Tawakalit Tope
Consumer interest in dietary fiber is on the rise as more information about its potential impact on health has become available. Flour from yam (Dioscorea rotundata) could have useful applications in the baking industry, in composite flour blends, because of its high level of dietary fiber and other essential nutrients. Study of the chemical composition, physicochemical characteristics, and pasting properties of unfermented-white yam flour (UYF) and fermented-brown yam flour (FYF) were investigated. Studies show that composite flour from yam has high ash, total starch, and fiber content than refined wheat flour. Thermal studies showed the energy required for composite flour gelatinization is greater than that of refined wheat flour. The firmness of FYF gel significantly increased with increasing number of days unlike UYF where slight hardness in texture was observed. This study revealed that each flour type exhibited different characteristics when compared to refined wheat flour. This necessitates further studies to substitute the yam flour samples with refined wheat flour to create composite flours that could be employed in bakery products. Inclusion of UYF and FYF flour at 5, 10, 15 and 20% levels of substitution with wheat flour affect the dough physicochemical, rheological pasting properties, and the nutritional quality. Proximate analysis of the flours carried out shows composite flours were of lower protein value but had higher fiber content than refined wheat flour. Impact on the gluten quality, gassing power, farinograph parameters was observed. The farinograph water absorption increased significantly (p<0.05) for blends prepared with UYF. Investigation revealed that the end-product quality (oven spring, loaf volume, bread crumb, tortilla weight, flexibility, thickness and color) of bread loaves and tortilla was significantly affected. This study demonstrated that incorporation of up to 10% FYF flour appears to give acceptable dough with good viscoelastic properties and bread with quality traits similar to refined wheat bread. This might be because bread itself is a fermented bakery product. For the tortilla; an unfermented product, 20% UYF inclusion seems to be more suitable to produce tortillas with good extensibility, acceptable thickness and whiteness with no dark spots that will appeal to the consumers.
Characterization of Edible Bean Flours: Properties and Functionality
(North Dakota State University, 2013) Simons, Courtney W.
Consumption of pulses is considered part of a healthy diet. Therefore, the opportunity exists for development of new pulse-based ingredients. However, a better understanding of their properties is necessary. The compositional and functional properties will vary depending on the bean type, their physical form (pre-cooked, raw flour, starch or protein fractionates) and growing location. In this study, edible bean flours (pinto, navy, black and small red) were subjected to extrusion cooking to produce snacks and texturized high-protein flour. The extrudates were studied to determine the effect of extrusion on the physical, physicochemical, chemical, sensory, and digestibility properties. Texturized high-protein flour was used in a bread formulation study. Finally, a preliminary study of location effect on production of grassy compounds, e.g. hexanal and hexanol, in pinto beans was conducted to determine importance of growing environment on flavor development during storage. The results of these studies showed that bean flours generally had excellent extrusion properties (good expansion and texture). However, pre-cooked flours had much lower expansion and textural integrity compared to raw bean flours and starch fractionates. Nutritional content (protein, total starch, fiber and ash) of flours were generally retained after extrusion. Lipids and resistant starch (RS) however were significantly reduced. Significant reduction in RS resulted in snacks having high glycemic index. Extrudates had 20% lower raffinose content suggesting reduced potential for flatulence after extrusion processing. Sensory evaluation of pinto, navy and black bean snacks indicated good overall acceptability. Pinto bean high-starch fraction differed in composition and functionality (viscosity and thermal properties) compared to its raw whole flour and extruded form. Adding 5% texturized pinto bean protein to bread increased its lysine content by 50%; without significantly affecting bread quality. A significant statistical interaction between growing location and storage time on hexanol and hexanal concentrations was observed for pinto beans grown in Forest River, Johnstown and Hatton North Dakota. This Dissertation will help processors understand the potential for beans as a food ingredient. Applications may include use in breads and other baked products, extruded puffed snacks, pasta, and soups. Bean flours can improve nutritional quality and provide unique functionality to food systems.
Evaluation of Pea Protein and Modified Pea Protein as Egg Replacers
(North Dakota State University, 2012) Hoang, Hieu Duy
Native yellow pea (Pisum sativum) protein isolates (PPIs) showed good foaming and emulsifying properties but a poor gelling characteristic. However, this can be corrected by Transglutaminase (TGase) treatment. PPIs were obtained using alkaline extraction method in which extracting pH, precipitating pH, flour–to–water ratio, and extraction time were optimized to obtain maximum yields and least change in protein functionalities. Extraction pH of 10.0, precipitating pH of 4.3, flour–to–water ratio of 1:6, and 30 minute extraction time were found to be optimum values for pea protein extraction. SDS–PAGE gels showed that the PPI had a very similar protein molecular weight profile as its original flour. TGase treatment was applied on PPIs at different pH levels from 4.3 to 7.0. The SDS–PAGE and RVA tests showed that treatment at pH 6.0 provided the best overall functionality. Large molecular weight (MW) proteins (~ 90,000 Da) and medium MW proteins (~50,000 – 80,000 Da) were the main substrates for TGase catalyzed reaction whereas most low MW the proteins (< 45,000 Da) were not involved. RVA results indicated that treatments at pH 6.0 and 7.0 had the highest viscosities but the treatment at pH 6.0 had better stability and consistency. Functionality tests indicated that modified PPIs possessed a better viscosity profile than the native PPIs but no improvement in gelling capacity and only minor impact on foaming and emulsifying properties. PPIs performance greatly depended on their final pHs. The foaming capacity, foaming stability, and emulsion capacity were significantly improved when the final pH of PPIs was adjusted from 4.3 to 7.0. The overall sensory evaluation results suggested that TGase–treated PPIs and PPIs were not yet able to replace egg in the cake system. Only PPI can replace egg in the cookie system. TGase–treated samples had a lower acceptability due to an “off–taste” and a “strange” flavor. Future work, therefore, should study TGase combined with other treatments to further improve PPIs functionalities. Purification should be integrated into extraction process and other food systems should also be included to extent the scope and role of modified PPIs in food industry.
Genetic and Phenotypic Assessment of Iron and Folate Concentration in Lentil (Lens Culinaris Medik.)
(North Dakota State University, 2015) Gupta, Debjyoti Sen
Micronutrients and vitamins are chemical elements required in trace quantities for normal human growth and development. Micronutrients and vitamin deficiency is prevalent throughout the world. The first objective of this research was to determine folate concentration in 10 lentil genotypes and evaluate the effect of environment on folate concentration. Folate concentration ranged from 216 to 290 μg/100 g with a mean of 255 μg/100 g and the concentration differed across years and locations. A significant genotype × environment interaction effect was observed for lentil folate concentration. The second objective was to measure the iron, zinc, copper, calcium and magnesium concentration in 26 cultivated and wild lentils. Significant variation in Fe, Zn, Cu, Ca, and Mg concentration among Lens species and no single genotype had high concentrations of all micronutrients.The third objective was to determine genetic diversity among 29 cultivated and wild lentils using 39 simple sequence repeat markers. Thirteen of 39 SSR markers were polymorphic among the 29 lentil genotypes. Cluster analysis grouped the genotypes into 4 clusters broadly based on the genotyping data and this grouping had correspondence with the pedigree relationships of the genotypes. The fourth objective was to develop expressed sequence tags-simple sequence repeats (EST-SSRs) markers in lentil. Lentil EST sequences (9513) from the NCBI database were assembled into 4053 unigenes. Unigenes were screened for simple sequence repeats and 348 primer pairs were designed. Fifty-seven primer pairs were polymorphic among the 22 lentil genotypes providing additional gene-specific primers for use in lentil breeding. The fifth objective was to develop gene specific molecular markers for iron metabolism related genes in lentil and to study their gene expression in the presence of excess iron. Gene specific markers were developed for Ferritin-1, BHLH-1, and IRT-1 to allow detailed study of the iron metabolic pathway in lentil. Differential gene expression of Ferritin-1 and IRT-1 under excess iron was observed at 2 hours but not at 8 hours and 24 hours. Results of these studies contribute to a broad understanding of the genetic variation, environmental influence on and expression of genes related to micronutrient and vitamin concentration and metabolism in lentil.
Hammer and Roller Milling of Yellow Split Pea
(North Dakota State University, 2019) Kaiser, Amber Christine
Blending nutrient-rich pulses into cereal-based convenience foods could benefit consumers and the cereal and pulse industries but first requires appropriate milling of raw pulses, for which there is no standardized method. Roller milling is the standard method for wheat flour production, but hammer milling is simpler and more cost-effective. Literature documenting pulse flour quality from either system is limited. The goals of this research were to evaluate (1) the effects of hammer mill setup and seed moisture on quality and flowability and (2) the differences between hammer- and roller-milled quality for yellow split pea. For (1), yellow split pea samples at 9 and 11 % moisture were hammer-milled at two rotor speeds (34 and 102 m/s) and with nine mill screen apertures (0.84 to 9.53 mm) and physicochemical properties and flow properties on 6 surfaces were evaluated. For (2), yellow split pea at 11 % moisture was hammer-milled at 102 m/s through a 0.84 mm screen or roller-milled using a two-pass setup, then sieved through a 150 µm screen and evaluated for physicochemical and functional quality. Hammer mill settings had no practical impact on proximate composition, small impact on damaged starch content, and considerable impact on particle size distribution, pasting properties, and flowability. Particle size parameters impacted color, bulk density, pasting properties, and flowability. Flowability was highest on aluminum and lowest on high-density polyethylene. Hammer milling at 102 m/s rotor speed with 0.84 mm screen aperture produced particle sizes closest to that of flour (D10, D50, and D90 of 12, 98, and 348 µm, respectively). Small differences were observed in the D10, starch damage, moisture, peak and final viscosities, and oil binding capacities of hammer- and roller-milled split pea flours. Data from this research supported the viability of hammer milling to produce split pea flour and provided systematic data to support milling, product development, conveying, and storage operations involving split pea and other pulses.
Hard Red Spring Wheat Quality Evaluation with Various Roller Mill Types and Breadmaking Methods
(North Dakota State University, 2016) Baasandorj, Tsogtbayar
Roller mill type and breadmaking methods might be a source of variation in the evaluation of the end-use quality of Hard Red Spring (HRS) wheat. In this study, various roller mill types and baking methods have been used to investigate whether they affect end-use quality evaluation of HRS wheat cultivars. In addition, a quality scoring system has been developed to determine if ranking of the HRS wheat cultivars would change when different roller mills and breadmaking methods were used. Both the roller mill type and breadmaking method had an effect on the end-use quality of HRS wheat cultivars. When using different roller mills for quality evaluation, HRS wheat samples of MN Bolles and ND Glenn from Gulf/Great Lakes (G/GL) region and ND Glenn from Casselton location had overall quality scores of 6.5 or above when averaged across mill types. When using various baking methods and conditions for quality evaluation, ND 817, MN Bolles, ND Glenn cultivars from Pacific Northwest region, and MN Bolles and ND Glenn from G/GL region received overall baking quality scores of 6.5 or above hence these cultivars were considered to have “excellent” baking quality characteristics under different baking conditions. The results in the current research study indicate that although there are differences in the mill type and breadmaking methods on the end-use quality evaluation, the ranking of HRS wheat flours is not affected by the mill type or baking methods and conditions. In other words, cultivars considered to have “fair” quality tend to have low end-use quality, while “excellent” cultivars will have superior end-use quality regardless of the roller mills and/or baking method and processing conditions used. The proposed overall wheat scoring system could assist farmers and breeders in selection of wheat cultivars considering the wheat end-use quality. Development of a comprehensive scoring system will also enable a more detailed scoring system for screening new lines for suitable end-use.
Improvement of the Physicochemical Attributes and Antioxidants Profiles from Pulse Seeds through Germination
(North Dakota State University, 2019) Xu, Minwei
Edible pulse seeds are good sources of food ingredients. Germination has been regarded as an effective process to further improve nutrient digestibility and accessibility of pulse seeds. Our aim was to observe the effect of germination on proximate composition, physicochemical attributes, and phenolic profiles of chickpea (Cicer arietinum L.), lentil (Lens culinaris Merr.), and yellow pea (Pisum sativum L.). In addition, mechanisms of how germination affects the antioxidant activity of phenolic compounds were proposed. Chemical composition, thermal, pasting, and moisture adsorption properties of pulse flours were investigated over 6 days of germination. Protein contents increased by 3 percent points for all pulses over germination. However, lentil had the highest protein content. Lipid contents decreased over germination with chickpea having the greatest decline, from 8.00 to 5.90 g/100g (d.b.). Total starch decreased in lentil and yellow pea during germination. Thermal properties of pulse flours changed slightly, while pasting properties varied among pulses. The highest final viscosities for chickpea, lentil, and yellow pea flours were 1061, 981, and 1052 cP and were observed after 2, 1, and 0 days of germination, respectively. Moisture adsorption isotherms showed improved water adsorption capabilities after germination. Soluble free (SFPs) and polar soluble bound phenolic compounds (PSBPs) were extracted from germinated pulse seeds. Their antioxidant activities were evaluated using both the in vitro system and stripped soybean oil (SSO)-in-water emulsions. Liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry and size-exclusion chromatography with multiangle-light-scattering and refractive-index detection were employed to analyze the phenolic composition and molar mass, respectively. Antioxidant activities of SFPs increased in both in vitro and SSO-in-water emulsion system, however, much lower than those of PSBPs based on SSO-in-water emulsion system. The effect of germination on PSBPs in SSO-in-water emulsion varied between pulses. By virtue of chemometric analysis, nine phenolic compounds were speculated as the pivotal phenolic compounds responsible for the antioxidant activity of PSBPs. In particular, the molar masses of PSBPs had a positive relationship with their antioxidant activity. Protective and co-antioxidative principles were proposed as reasons for the variability of antioxidant activities of PSBPs in oil-in-water emulsions with germination.
Manufacturing Optimization of Non-Traditional Pasta Products
(North Dakota State University, 2015) De La Peña, Elena
A study was conducted to determine the effect of including non-traditional ingredients on the flow and agglomeration properties of flour formulations, the rheological behavior of pasta dough, and the physical and cooked quality of the spaghetti. The effect of including non-traditional ingredients on the chemical changes that occurred in pasta during pasta making and cooking was also investigated. The formulations used were semolina 100% (S), whole wheat flour 100% (WW), semolina-whole wheat flour (49:51) (SWW), semolina-flaxseed flour (90:10), whole wheat flour-flaxseed flour (90:10), and semolina-whole wheat flour-flaxseed flour (39:51:10). Flaxseed flour was incorporated as fine (FF) or coarse (CF) particles. Depending on the experiment, formulations were hydrated to different levels that ranged between 10 and 34%. Study of the flow and agglomeration properties of the formulations indicated that samples containing whole wheat flour and or flaxseed flour were more cohesive and less prone to flow than samples with 100 or 90% semolina. Large agglomerate formation occurred with SFF hydrated beyond 30% moisture; whereas limited large agglomerate formation was detected in whole wheat samples with or without flaxseed flour hydrated up to 34% moisture. Rheological experiments showed that traditional and non-traditional pasta dough behaved like a shear thinning fluid that can be described by the Power Law model. Increased hydration levels and/or presence of flaxseed flour in the dough formulation decreased the apparent viscosity of the dough, which correlated with reduced extrusion pressure, mechanical energy, and specific mechanical energy required to extrude the dough. Better cooked quality was obtained for SWW than for WW, indicating that it is better to have some semolina in the formulation than replacing all the semolina with whole wheat flour. Inclusion of flaxseed flour gave better results when adding the flaxseed to 90% semolina than when adding it to WW or SWW. No chemical interaction was observed between the different ingredients during pasta making and/or cooking. Overall results indicated that the formulation-hydration combinations that optimized the processing and quality of non-traditional pasta products were: 30% for SFF, SCF, SWWFF, and SWWCF, 32% for S, WWFF, and WWCF, 33% for SWW, and 34% for WW.
Metabolite Profiling of Hard Red Spring Wheat (Triticum Aestivum) Inoculated with Fusarium Graminearum Utilizing Ultra High Pressure Liquid Chromatography-Quadrupole Time of Flight / Mass Spectrometry
(North Dakota State University, 2015) Gracia-Gonzalez, Gerardo
Fusarium Head Blight (FHB) of wheat is a fungal disease caused mainly by Fusarium graminearum. It has been a persistent worldwide problem for years causing substantial economic losses. Efforts to breed resistance in wheat cultivars represent a practical way to manage this disease. However, there is still much to contribute on how the infection develops and what events make a cultivar resistant to the infection at a molecular level. A metabolite profiling time course strategy was applied to a wheat near isogenic lines (NIL), with contrasting resistant alleles, and three hard red spring wheat cultivars with various degrees of resistance. The analytical time window where no significant difference occurs from sample extraction to sample analysis was also determined adding robustness to this study. Results indicate a maximum analytical window time of 7:45 hours for a wheat extraction queued in an UHPLC auto-sampler at 25 ¡ãC. Combining UHPLC-QTOF/MS technology with statistical analyses resulted in 61 significant metabolites (p < 0.05; fold change ¡Ý 2). The NIL and wheat cultivars had profiles with common and unique molecules. Tentative identification was performed by using accurate mass search, tandem MS fragmentation data with internal and online databases. Taking into account the restriction of database identifications, results confirm the presence of hydroxycinnamic acid amides (HCAA) which have been shown to induce thickening of cell walls. These compounds were seen in the resistant and susceptible genotypes with no difference in their intensities but can appear as early or late occurring between 0 and 48 hours after inoculation. Compounds classified as resistant related induced and resistant related constitutive were found in the NIL resistant pair at 48hrs. ¡°Susceptibility indicator¡± molecules were also observed in the susceptible NIL pair. This suggest that for the NIL pair, HCAA were a normal part of host reaction, while potentially important metabolites for the host resistance may develop later than 48 hours after inoculation. It was possible to establish an analytical and data mining methodology to perform metabolite profiling in wheat florets utilizing a UPLC-QTOF/MS.
Physicochemical Properties of Commercial Gums and their Effects on Processing and Cooking Quality of Nontraditional Pasta
(North Dakota State University, 2012) Sandhu, Gurleen Kaur
Processing characteristics and quality of pasta made from durum flour and semolina and the physicochemical properties of commercial gums and their effects on processing and cooking quality of nontraditional pasta was investigated. An initial experiment was conducted using semolina and durum flour fortified with nontraditional ingredients (soy flour or oat flour, 10% w/w) and xanthan, guar or locust bean gums (2% w/w). A second set of experiments were conducted to determine the effect of commercial source of food gums on their effect on the processing and cooking quality of nontraditional pasta. Proper hydration of nontraditional ingredient blends was more easily achieved with durum flour than semolina. This was attributed to the smaller particle size of durum flour compared to semolina. Nontraditional ingredients tended to over hydrate semolina resulting in large aggregates that adhered to metal surfaces, all of which made mixing and pasta processing difficult. Initially, dough strength was greater with durum flour than with semolina, but semolina had better dough stability over time. Soy and oat flours reduced dough strength. Xanthan and guar gums increased dough stability, particularly with durum flour. Pasta made with durum flour generally had greater cooking loss and lower cooked firmness than pasta made from semolina. Soy and oat flours reduced cooked firmness and increased cooking loss. Guar and locust bean gums did not affect cooking quality of pasta. Xanthan gum increased cooked firmness of pasta. Samples of each gum were obtained from three different commercial vendors. For each food gum, samples varied in bulk density, molecular weight, viscosity in distilled water and the magnitude of effect on dough strength with commercial source. The effect of xanthan, guar and locust gums on hydration, dough strength, and cooking quality was not affected by commercial source. The magnitude of the increase in dough strength caused by xanthan and guar gums varied among their respective commercial sources.
Prediction of Wort Fermentability in Two-Rowed Barley Genotypes
(North Dakota State University, 2016) Huerta Zurita, Ramon
Fermentability is the parameter that describes the ability of yeast to turn sweet wort into alcohol. As the efficiency of this process is related with alcohol yield, it will regulate the amount of beer produced from a given amount of malt. Considering that fermentation efficiency is influenced by the concentration of fermentable sugars in wort, the diastatic power (DP) of malt has long been associated with fermentability. However, research studies have shown that DP alone can not explain much of the observed variability (R2≤0.50) between malt samples. Some reports suggest that the separate determination of the activity and thermal stability of some of the enzymes contributing to DP and some malt modification parameters can considerably improve prediction (R2=0.91). On the other hand, few studies have focused on measuring fermentability variation in barley breeding. The objective of this study was to determine the effect of standard and non-standard malt quality parameters on the fermentability of different barley breeding lines, and to select the best multi-linear regression model for predicting this trait. Malts of 90 barley genotypes, grown in different locations of North Dakota during two years, were used in this study. Assays of the DP enzymes alpha-amylase, beta-amylase, alpha-glucosidase, and limit dextrinase, as well as their thermal stabilities (determined at 65°C for 10 min), were performed and adapted to a microplate reader format. Fermentability was determined as the real degree of fermentation (RDF) considering that the apparent degree of fermentation (ADF) showed strong alcohol dependence (R2=0.87), which could give false differences when comparing breeding lines in a population with high genetic variability. Results showed that, contrary to other reports, DP and beta-amylase and its thermostability are not highly associated with fermentability when the hot water extract (HWE) is used as the mashing method. Alpha-amylase and limit dextrinase though, had a more significant influence. The malt quality parameters: wort glucose, wort maltose, limit dextrinase, free amino nitrogen, soluble protein, alpha-amylase, and maltotriose, are considered the most significant factors for predicting fermentability as determined by the regression model (R2=0.71).
Structurally Diverse Arabinoxylan Hydrolyzates: Their Activity as Immunomodulators and their Effect on Growth of Bacteroidetes
(North Dakota State University, 2015) Mendis, Mihiri Marini
Arabinoxylan (AX) is a plant polysaccharide which consists of a xylan backbone on which arabinose is substituted. Thirty structurally different wheat arabinoxylan hydrolyzates (AXH) were prepared by means of different combinations of xylanase (Cellvibrio japonicas xylanase (CJX) and Aspergillus niger xylanase (ANX)) and arabinofuranosidase (Bifidobacterium adolescentis arabinofuranosidase (BAF) and Clostridium thermocellum arabinofuranosidase (CAF)). The AXH were analyzed using GC-FID, GC-MS, 1H-NMR and SEC-MALS techniques. In general, the AXH had high proportion of unsubstituted xylose and lesser amount of di- or mono-substituted xylose. The average molecular weights of the AXH varied between 0.78-5.64 million Da. Between the two xylanases, ANX might be an enzyme of choice for the production of arabinoxylan hydrolyzates with simple structural details while the enzyme CJX might be selected for the production of arabinoxylan hydrolyzates with more complex structural features. Addition of BAF followed by CAF was more effective in generating AXH with higher amount of unsubstituted xylose as well as lesser amount of disubstituted xylose. The structural contribution to the immunomodulatory properties of the AXH was also evaluated using LPS induced macrophage cell line. The AXH being tested exhibited both pro- and anti-inflammatory properties. Structure-function relationship of arabinoxylan hydrolyzates as immunomodulators was further assessed using LPS induced colon cancer cell lines: Caco-2 and HT-29. Fine structural details had a strong correlation with the immunological properties of the AXH. The influence of the fine structural details of AXH on the growth of human gut Bacteroides strains was also evaluated. In general, B. cellulosilyticus DSM 14830 had the highest growth while B. eggerthii DSM 20697 had the lowest growth on AXH. Interestingly, B. cellulosilyticus DSM 14830, B. ovatus 3_1_23, B. ovatus ATCC 8483 and B. xylanisolvens XB1A displayed clearly distinguishable phase shifts along the growth curves indicating their ability to tune in their gene expressions to overcome the hindrances to growth exerted by structural details on the substrate polysaccharide. This research confirmed the ability of Bacteroides to utilize structurally diverse arrays of polysaccharides. Overall, the current study indicates that there might be a structure- function relationship between AXH and their immunomodulatory properties as well as prebiotic properties.
Whole Wheat Milling and Baking Studies of Hard Red Spring Wheat
(North Dakota State University, 2016) Khalid, Khairunizah
End product quality of whole wheat bread is affected by many complex parameters. The milling method and chemical composition of bran both affect whole wheat bread quality. When using a centrifugal mill, the combination of low tempering moisture level and high rotor speed produced whole-wheat flour with fine particle size, desirable whole-wheat flour quality, manageable dough, and high loaf volume. Fine bran powder was produced with the combination of low tempering moisture level, low feed rate, and high rotor speed. It was also determined that flour attached to bran affects the bran powder’s temperature, protein content, and starch content. Study of the impact of bran components on whole-wheat bread revealed that fiber (FB) highly impacted gluten quality, farinograph parameters, gassing power, oven spring, loaf volume, and bread crumb protein solubility. FB interacted with other bran components (oils, extractable and hydrolysable phenolics) to increase polymeric protein solubility in bread crumb. Hydrolysable phenolics (HP) improved the farinograph stability. However, the interaction of FB with other components decreased bread loaf volume, especially for the interaction of FB-HP. The baking method and the type of wheat used for whole-wheat bread are also important factors to evaluate whole-wheat bread quality. Sponge-and-dough (SpD), straight dough (StD), and no-time dough (NoD) methods were compared. StD had the highest variation in baking mix time, baked weight, crumb grain score, and symmetry score compared to other baking methods. The StD method was the most sensitive method to distinguish variation in whole-wheat flour samples. Location and cultivar effects were investigated for whole-wheat bread quality. Twenty-one hard red spring wheat cultivars grown at 6 locations across North Dakota were evaluated for whole-wheat bread quality. Location contributed 89% to the variability in whole-wheat baking absorption. Cultivar contributed 47% and 41% to the variability in whole-wheat loaf volume and loaf symmetry, respectively. Loaf volume and crumb color were largely under genetic control, and breeders can aim at high loaf volume in whole wheat bread made from hard spring wheat. Overall, whole-wheat flour and bread quality are greatly affected by: milling method, bran composition, baking method, as well as the environment and genotype.
Whole-Wheat Flour Milling and the Effect of Durum Genotypes and Traits on Whole-Wheat Pasta Quality
(North Dakota State University, 2017) Deng, Lingzhu
An ultra-centrifugal mill was evaluated by determining the effect of mill configuration and seed conditioning on particle size distribution and quality of whole-wheat (WW) flour. Ultra-centrifugal mill configured with rotor speed of 12,000 rpm, screen aperture of 250 μm, and seed conditioning moisture of 9% resulted in a fine WW flour where 82% of particles were <150 μm, starch damage was 5.9%, and flour temperature was below 35°C. The single-pass and multi-pass milling systems were evaluated by comparing the quality of WW flour and the subsequent WW spaghetti they produced. Two single-pass mill configurations for an ultra-centrifugal mill were used (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 grain or to regrind millstreams from roller milling to make WW flour and WW spaghetti. Particle size, starch damage, and pasting properties were similar for direct fine grind WW flour and multi-pass reconstituted flour:fine bran blend and for direct coarse grind WW flour and multi-pass reconstituted semolina:coarse bran blend. Semolna:fine bran or semolina:coarse bran blends made spaghetti with high cooked firmness, while spaghetti made from direct coarse grind or from semolina:fine bran or coarse bran blends had low cooking loss. Nineteen durum wheat (Triticum turgidum L. var. durum) cultivars and 17 breeding lines grown at 19 environments in North Dakota were evaluated for physical and cooking qualities of WW and traditional spaghetti. Of the 36 genotypes evaluated, 21 and 3 genotypes produced good and poor qualities of WW and traditional spaghettis, respectively, while other 12 genotypes produced good traditional spaghetti but produced poor quality WW spaghetti. These data indicate the need to select genotypes specifically for their WW pasta quality. Raw material traits (grain, semolina and WW flour characteristics) were evaluated to identify raw material traits capable of predicting WW spaghetti quality. Grain protein content had significant positive correlation with cooking quality of WW spaghetti. Stepwise multiple regressions showed grain protein content and mixogram break-time and wet gluten were the predominant characteristics in predicting cooking quality of WW spaghetti.

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