The interest in study of resistant starch in the pig nutrition is increasing. This experiment was done to evaluate resistant starch content in maize/corn by using an in vitro method. A total of 27 varieties of corn were used in this trial to determine the evaluation of in vitro resistant starch (RS); in vitro non-resistant starch (NRS); in vitro total starch (TS); dry matter (DM); ash and organic matter (OM). All treatments of corn samples were carried out in triplicates. In vitro determination of RS, NRS and TS were determined directly before the spectrophotometer reading with a wavelength of 510 nm. In vitro RS, NRS and TS ranged from 0.56 – 1.98%, 22.11 – 52.33% and 22.69 – 54.27% respectively; DM, Ash and OM ranged from 85.71 – 95.34%, 1.1 – 1.85% and 98.15 – 98.9% respectively. In RS, 424L and 5660 (P/≤/0.05); in NRS, 652N and MC 4050 (P/≤/0.01; in TS, 652N, MC 4050 and 424L (P/≤/0.01, 0.01 and 0.05 respectively); and in DM, 590 (P/≤/0.05). Results indicated that varieties of corn used may be low in amylose content because the RS values were negligible (≤ 1%) giving MC 5800 and 652N as the lowest RS values suitable for growing pigs. Further work is needed to validate these results. Keywords: In vitro; Resistant starch; Corn samples; Non-resistant starch; Total starch; Spectrophotometer

Two tannin sorghums, (high-tannin, black with tannin), high anthocyanin sorghum (black), and non-tannin sorghum (white) were used to investigate the effects of sorghum phenolic compounds on in vitro starch digestibility, estimated glycemic indices (EGI) and resistant starch contents (RS) of porridges. Sorghum varieties were chosen to have a wide range of total phenols (3-23 mg/g gallic acid) and tannin contents (0-34 mg catechin eq./g). Normal corn starch, enzyme resistant high amylose corn starch, and whole sorghum grains were cooked with the aqueous fraction of sorghum bran extracts obtained with 70% aqueous acetone. Endosperms of soft and hard sorghum varieties were mixed with sorghum brans and cooked into porridges with distilled water. Hi-tannin, black and black with tannin sorghum bran extracts significantly (p<0.05) decreased starch digestibility and estimated glycemic index (EGI) while they increased resistant starch (RS) contents of normal corn starch, enzyme resistant high amylose corn starch, and whole sorghum grain porridges. The highest reduction in starch digestibility of the porridges occurred with hi-tannin sorghum bran extracts, followed by black with tannin and black sorghum bran extracts. Double cooked corn starch porridges, which were cooked with these bran extracts had EGI values of 49-67 and RS contents of 9.1-57.7%. These RS values are higher than foods such as legumes, whole pasta and whole grain cereals which are considered health foods with low EGI (36-71) and high RS contents (2.9-6.8). Only brans of condensed tannin-containing sorghum varieties (tannin, black with tannin sorghums) significantly (p<0.05) decreased starch digestibility, and EGI, and increased RS contents of the endosperm porridges. When tannin sorghum bran extracts were cooked with zein added to corn starch porridges, starch digestibility of the porridges significantly (p<0.05) increased, while RS significantly (p<0.05) decreased because the zein reacted preferentially with the tannins. The cooking trials indicated that sorghums with tannins significantly reduced the activity of digestive enzymes, reduced EGI, and increased RS contents of porridges. Thus, specialty sorghum varieties have a potential to lower EGI and increase RS contents of starchy foods. Their aqueous bran extracts have potential use to reduce risk factors for type II diabetes and obesity.

Master of Science / Department of Grain Science and Industry / Yong Cheng Shi / Resistant starch (RS) is notable for having several health benefits in humans, including glucose control and intestinal well-being. Pullulanase is able to debranch amylopectin and result in higher RS content. Different levels of pullulanase have been used to debranch waxy maize starch in the literature, but the changes of structure during debranching are well documented. In this study, waxy maize starch was cooked and debranched by pullulanase with 80, 160 and 240 New Pullulanase Unit Novo (NPUN)/g starch pullulanase. One NPUN was defined as the amount of enzyme, which, under standard conditions, hydrolyzes pullulan, liberating reducing carbohydrate with reducing power equivalent to 1 µmole glucose per minute. The structure of waxy maize starch during debranching was investigated and the digestibility of the debranched products was measured. When pullulanase was increased from 80 to 240 NPUN/g, more amylopectin was debranched in the same debranching time, and the degree of crystallinity and the RS content increased. After the debranched starches were crystallized at 25°C for 24 hours, the RS contents were greater than 63%. When heated and recrystallized under highly regulated conditions, the linear material formed crystallites of a range of geometries, including spherulites of a highly organized structure. Debranched waxy maize starches were used to produce crystalline structure under four conditions: spherulites formed by adding ethanol and crystallized at 4°C (ES4); spherulites formed in water (WS4) at 4°C; particles formed at 50°C (WS50); and spherulites formed at 50°C then further precipitated at 4°C (WS50-4). Spherulites formed at 50°C (WS50) had a higher proportion of smaller molecules than existed in the parent starch (Rh<15nm). ES4 and WS4 were B-type crystalline structure; whereasWS50 and WS50-4 were A-type crystalline structure. ES4 had a larger proportion of molecules with a low degree of polymerization and the RS content was also the lowest of the four samples. With cooling from 50°C to 4°C (WS50-4), the RS content was increased from 60% to 73%. ES4 and WS50-4 contained particles with spherical symmetry and WS4 had partial radial symmetry with some distortions, whereas WS50 displayed oblate particles with a parallel crystal structure.

Master of Science / Department of Grain Science and Industry / Yong-Cheng Shi / Sorghum flour is a gluten-free ingredient and can be used to prepare foods for celiac patients. In addition, sorghum flour is a good source of fiber in the form of resistant starch. The objectives of this research were to develop an effective process to increase resistant starch content of sorghum flour and investigate the effects of sorghum protein matrix on starch digestibility. Samples of white sorghum flour (28.9% amylose content) with different moisture contents (0%, 12.5%, 20%, and 30%) were treated at different temperatures (100, 120, and 140 [degrees]C) for different times (1, 2, and 4 h). Samples after heat treatments were tested for starch digestibility, protein digestibility, differential scanning calorimetry (DSC), size-exclusion chromatography (SEC), and X-ray diffraction. The sample treated with 20% moisture at 100[degrees]C for 4 h had high resistant starch (RS) content (22.1% compared with 5.6% of the native sample) and low protein digestibility (8.4% compared with 68.3% of the native sample). The same heat-moisture treatment on isolated sorghum starch showed no significant change in RS content. DSC showed a very low degree of gelatinization for samples treated at moisture contents 20% and below. X-ray diffraction also suggested minimal change in starch crystallinity after heat treatment at low moisture contents (20% and below). Sorghum protein solubility after heat treatment was reduced, suggesting that protein structure was altered during the heat treatments. In conclusion, heat-moisture treatments were successful in increasing resistant starch content of sorghum flour by altering sorghum protein without gelatinizing the starch to retain starch functionality in food product applications. Sorghum flour with increased resistant starch content after heat treatment was evaluated and compared with normal sorghum flour for starch digestibility using the Integrated Total Dietary Fiber method, and for food applications in tortillas.

Carbohydrates and fats are the main fuel sources for energy production during exercise. Consumption of low glycemic index foods slows digestion and absorption in the small intestine. The slow digestibility of resistant starch containing foods contributes to the slow and sustained release of glucose into the bloodstream, minimizing occurrence of hyperinsulinemia-induced suppression of lipolysis. The objectives of this study were to determine the consumption of resistant starch (RS) by regular exercisers (Blacksburg and San Jose (SJ)); and to analyze the eating and exercise habits of the subjects. Subjects were recruited at gyms in SJ (n=27) and Blacksburg (n=26). Participants kept 3-day food records and completed a questionnaire on eating habits and physical activity. Mean body mass index for the subjects was similar (SJ: 23.06 Kg/m² ± 2.55; Blacksburg: 23.53 Kg/m² ± 3.09). Average exercise time was 12 hours/week, and > 50% engaged in weight training in addition to aerobic type exercise. Percentage contribution of carbohydrates to the total energy intake was significantly higher for SJ males (53.53% ± 8.06%) compared to Blacksburg males (48.39% ± 6.33%; alpha=0.10). Prominent RS food sources in both groups were pasta, potatoes, bananas, and corn. Rice and various legumes were more frequent in the SJ group. It appears that consumption of RS is higher among SJ subjects. Consumption of RS prior to prolonged exercise could cause stable glycemic and insulinemic responses that may help delay the onset of fatigue during exercise. / Master of Science

This study aimed to quantify resistant starch (RS) beta-glucans (BG) and fructo-oligosaccharides (FOS) in Indian and Canadian wheat varieties and in chapaties made from these; and to assess the effects of soy flour on the levels of these components and its effects on the sensory and functional properties of the wheat-soy chapaties. Seven wheat varieties (Indian / Canadian) were milled into flour; supplemented with 0 % (control), 10 %, 20 % or 30 % defatted soy flour and made into chapaties. Flours and chapaties (freeze-dried, pulverized) were assayed for BG, FOS, RS and simple sugars (glucose / sucrose). Sensory evaluation was carried out by (9 point) hedonic rating of chapaties by 20 untrained Indian panelists. Flour water-holding capacity and water absorption indices (WAI) were determined. RS content of flours ranged from 7.1 g/100 g to 12.6 g/100g, but decreased when made into chapaties, (< 1 g/100 g), and decreased further with soy flour addition. BG content in flours ranged from 0.8 g/100 g to 1.4 g/100 g, while FOS content ranged from 1.3 g/100 g to 2.3 g/100 g. Minimal changes were observed in BG and FOS content when made into chapaties. Simple sugars were minimal in flours and chapaties. WAI of wheat flour was increased with addition of soy bean flour. Addition of up to 30 % soybean flour elevated the sensory acceptability of chapaties. While there is a decrease in RS with chapati making, the levels of BG and FOS are largely unchanged with processing. / Master of Science

Master of Science / Department of Human Nutrition / Mark D. Haub / Purpose: Physical activity (PA) and resistant starch (RS) beneficially affect metabolic health. However, their combined effects on gut health are poorly understood. The purpose of this thesis was to investigate the combined effects of PA and RS via breath hydrogen production and blood glucose responses and directly learn about the research process. Methods: Twenty subjects with no reported symptoms of metabolic diseases participated in this thesis project. Subjects wore accelerometers to determine PA status, and were then stratified into two groups: less active or more active. Once enrolled and stratified into groups based on PA assessment, subjects came to the laboratory on two more occasions to eat a standardized energy dense test meal with a lemonade beverage. The beverage contained different doses (5 g or 25 g) of RS type 4. On each test day, breath hydrogen was collected at baseline through the sixth hour at hour intervals through the fourth hour. Between hours four and six, the breath samples were collected every 30 minutes. Blood glucose samples were collected at baseline before the meal and then 15, 30, 45, 60, 90, and 120 minutes after beginning to eat the meal. Results: The incremental areas under the curve for glucose were not different between PA groups or RS dose (p>0.05). The area under the curve values for breath hydrogen were not different (p>0.05) between groups or doses of PA and RS, respectively. Conclusion: These results indicate that acute assessments of gut fermentation in generally healthy participants, as assessed by postprandial breath hydrogen production, requires more than six hours of assessment to determine differences between treatments and levels of physical activity.

Doctor of Philosophy / Department of Human Nutrition / Mark D. Haub / Objective: The objective was to compare the postprandial glycemic and insulinemic responses to nutrition bars containing either cross-linked RS type 4 (RS4[subscript]XL) or standard wheat starch in normoglycemic adults (n=13; age= 27±5 yr; BMI=25±3 kg/m²). Methods: Volunteers completed three trials during which they consumed a glucose beverage (GLU), a puffed wheat control bar (PWB), and a bar containing RS4[subscript]XL matched for available carbohydrate content. Serial blood samples were collected over two hours and glucose and insulin concentrations were determined and the incremental area under the curve (iAUC) was calculated. Results: The RS4[subscript]XL peak glucose and insulin concentrations were lower than the GLU and PWB (p<0.05). The iAUC for glucose and insulin were lower following ingestion of RS4[subscript]XL compared with the GLU and PWB trials. Conclusions: These data illustrate, for the first time, that directly substituting standard starch with RS4[subscript]XL, while matched for available carbohydrates, attenuated postprandial glucose and insulin levels in humans. It remains to be determined whether this response was due to the dietary fiber and/or resistant starch aspects of the RS4[subscript]XL bar. Keywords: insulin sensitivity, diabetes, dietary fiber, prebiotic, glycemic index

Doctor of Philosophy / Department of Grain Science and Industry / Yong-Cheng Shi / Wheat bran is high in dietary fiber. Resistant starch (RS) is considered a source of dietary fiber. Wheat bran and RS have different functional properties and may not have the same nutritional properties. This dissertation covers two areas of importance in cereal chemistry and human nutrition: wheat bran and RS. Wheat bran chemical and physical influence of nutritional components Wheat bran has become a hot topic due to positive nutritional correlations, and industrial /humanitarian needs for healthy ingredients. Evolving wheat bran into a demanded product would impact the industry in a positive way. The overall aim of this research was to understand chemical and structural composition, to provide avenues for wheat bran development as a healthy food ingredient. To achieve this goal, antioxidant properties in dry wheat milling fractions were examined, effects of wheat bran particle size on phytochemical extractability and properties were measured, and substrate fermentation was investigated. It was noted that mixed mill streams, such as mill feed, have antioxidant properties (0.78 mg FAE/g; 1.28 mg/g total antioxidant capacity; 75.21% DPPH inhibition; 278.97 [mu]mol FeSO[subscript]4/g) originating from the bran and germ fractions. Additionally, extraction of reduced particle size whole wheat bran increased measured values for several assays (185.96 [mu]g catechin/g; 36.6 [mu]g/g; 425 [mu]M TE), but did not increase volatile fatty acid production during in vitro rumen fermentation over unmilled bran. RS digestion, glycemic response and human fermentation In vitro action of enzymes on digestion of maize starches differing in amylose contents were studied. The objectives of this study were to investigate the exact role of [alpha]-amylase and amyloglucosidase in determining the digestibility of starch and to understand the mechanism of enzymatic actions on starch granules. Starch digestibility differed (30-60%) without combination of enzymes during in vitro assay. Further investigations utilized human glycemic response and fermentation with consumption of a type 3 RS without dietary fiber (AOAC method 991.43). Blood glucose response provided lower postprandial curves (glycemic index value of 21) and breath hydrogen curves displayed low incidences fermentation (40%) with consumption of the type 3 RS, due to the structure of starch and digestion by enzymatic action.

Unripe banana flour (UBF) production employs bananas not submitted to maturation process, is an interesting alternative to minimize the fruit loss reduction related to inappropriate handling or fast ripening. The UBF is considered as a functional ingredient improving glycemic and plasma insulin levels in blood, have also shown efficacy on the control of satiety, insulin resistance. The aim of this work was to study the drying process of unripe banana slabs (Musa cavendishii, Nanicão) developing a transient drying model through mathematical modeling with simultaneous moisture and heat transfer. The raw material characterization was performed and afterwards the drying process was conducted at 40 ºC, 50 ºC e 60 ºC, the product temperature was recorded using thermocouples, the air velocity inside the chamber was 4 m·s-1. With the experimental data was possible to validate the diffusion model based on the Fick\'s second law and Fourier. For this purpose, the sorption isotherms were measured and fitted to the GAB model estimating the equilibrium moisture content (Xe), 1.76 [g H2O/100g d.b.] at 60 ºC and 10 % of relative humidity (RH), the thermophysical properties (k, Cp, ?) were also measured to be used in the model. Five cases were contemplated: i) Constant thermophysical properties; ii) Variable properties; iii) Mass (hm), heat transfer (h) coefficient and effective diffusivity (De) estimation 134 W·m-2·K-1, 4.91x10-5 m-2·s-1 and 3.278?10-10 m·s-2 at 60 ºC, respectively; iv) Variable De, it presented a third order polynomial behavior as function of moisture content; v) The shrinkage had an effect on the mathematical model, especially in the 3 first hours of process, the thickness experienced a contraction of about (30.34 ± 1.29) % out of the initial thickness, finding two decreasing drying rate periods (DDR I and DDR II), 3.28x10-10 m·s-2 and 1.77x10-10 m·s-2, respectively. COMSOL Multiphysics simulations were possible to perform through the heat and mass transfer coefficient estimated by the mathematical modeling. / A farinha de banana verde (UBF) produzida de bananas não submetidas ao processo de maturação é uma alternativa interessante para minimizar as perdas dos frutos relacionadas ao manejo inadequado e a alta perecibilidade do produto. A UBF pode ser considerada um ingrediente funcional em formulações alimentícias, pois pode reduzir o índice glicêmico e o nível de insulina plasmática no sangue, demonstrando eficácia no controle da saciedade e da resistência à insulina. O objetivo deste trabalho foi estudar o processo de secagem de fatias de banana verde (Musa cavendishii, Nanicão) e desenvolver um modelo de secagem transiente através da modelagem matemática com transferência de massa e energia simultânea. Inicialmente, foi realizada a caraterização físico-química da matéria prima que foi submetida ao processo de secagem em escala piloto, a 40 ºC, 50 ºC e 60 ºC, com termopares inseridos no produto monitorando sua temperatura, a velocidade do ar de secagem foi de 4 mos-1. Com a cinética de secagem e a temperatura interna da fatia foi possível validar o modelo de difusão baseado na 2a Lei de Fick e Fourier. Para este propósito, foram medidas durante o processo: as isotermas de sorção ajustadas ao modelo do GAB permitindo estimar a umidade de equilíbrio (Xe), 1.76 [g H2O/100g d.b.] a 60 ºC e 10 % de umidade relativa (RH) e as propriedades físicas e termofísicas (k, Cp, ?) para serem inseridas no modelo. Consideraram-se cinco casos: i) Propriedades termofísicas constantes; ii) Variáveis; iii) Estimativa do coeficiente de transferência de massa (hm) de calor (h) e difusividade efetiva (De) parâmetros importantes que controlam a taxa de secagem, 134 Wom-2oK-1, 4.91x10-5 m-2os-1 e 3.278x10-10 mos-2 para uma temperatura de 60 ºC, respectivamente; iv) Estimativa do De como função do teor de umidade (M) apresentando um comportamento polinomial de terceira ordem; v) O encolhimento teve influência no modelo matemático, em especial nas primeiras três horas de secagem, a espessura da banana verde experimentou uma redução de (30.34 ± 1.29) %, encontrando dois períodos de taxa de secagem decrescentes (DDR I e DDR II), os De estimados para estes dois períodos foram 3.28x10-10 mos-2 e 1.77x10-10 mos-2, respectivamente. As simulações no COMSOL Multiphysics foram possíveis de serem realizadas através dos dados estimados pelo modelo matemático.