Kay S. Gregorski

Changes in secondary protein structures during mixing development of high absorption (90%) flour and water mixtures

ABSTRACT Wheat flour and water mixtures at 90% absorption (dry flour basis) prepared at various mixing times were examined using Fourier transform infrared (FT-IR) reflectance spectroscopy. Spectra were obtained using a horizontal attenuated total reflection (ATR) trough plate. The apparent amount of protein and starch on the surface of the dough varied with mixing time but this was likely due to the polyphasic nature of the substrate and the changing particle distributions as the batter matrix was developed. Deconvolution of the Amide I band revealed contributions from alpha helical, β-turn, β-strand, β-sheet, and random conformations. The ratio of β-sheet to nonsheet conformations reached its greatest value about the same time that the mixture was most effectively separated by a laboratory-scale, cold-ethanol-based method but before the peak consistency measured by a microfarinograph.

Atmospheric pyrolysis of carbohydrates with thermogravimetric and mass spectrometric analyses

Abstract The pyrolysis of glucose, maltose, cellobiose, amylose and cellulose was studied by thermogravimetry between 250–400°C at atmospheric pressure in helium. The thermogravimetric analyzer was coupled with a mass spectrometer and the evolving gases were continuously monitored. Between 2.6 and 2.8 moles of water were obtained for every hexose unit. For amylose and cellulose the water formation was in one step; for the other carbohydrates, varying amounts of water formed in two different steps. The scans were evaluated by computer and the concentrations of the possible components were plotted versus temperature. The correlation of these curves with the weight loss curve throws new light on carbohydrate pyrolysis reactions.

Properties of electrospun pollock gelatin/poly(vinyl alcohol) and pollock gelatin/poly(lactic acid) fibers.

Pollock gelatin/poly(vinyl alcohol) (PVA) fibers were electrospun using deionized water as the solvent and pollock gelatin/poly(lactic acid) (PLA) fibers were electrospun using 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) as the solvent. The chemical, thermal, and thermal stability properties were examined for the electrospun samples. The electrospun PVA samples generally had thinner and more uniform fibers than the electrospun PLA samples. For the PVA samples, an increase in total solids content and PVA to gelatin ratio generally resulted in higher average fiber diameter values and wider diameter distributions. Pollock gelatin in both types of electrospun samples remained amorphous. The PVA in electrospun samples had comparable melting temperatures to that of neat PVA, whereas the PLA in electrospun samples had slightly lower melting temperatures than that of neat PLA. Also, the PLA in electrospun samples had crystallization temperatures approximately 30 °C lower than that in neat PLA. This was due to better alignment of PLA chains during electrospinning, which resulted in the chains being more readily crystallized at lower temperatures. In addition, the electrospun PVA samples completely dissolved in water at room temperature after soaking for one day, whereas the electrospun PLA samples remained intact even after soaking for three days.

Physical Characteristics of Genetically Altered Wheat Related to Technological Protein Separation

ABSTRACT Wheat protein is a technologically challenging substrate for food and nonfood applications because of its compositional diversity and susceptibility to denaturation. Genetic modification could be used to create cultivars capable of producing more uniform or focused and novel protein compositions targeted to nonfood uses. These lines could serve as expression systems for specific high-molecular-weight (HMW) protein polymers and would be new crops leading to more diverse agricultural opportunities. However, fundamental changes to the molecular architecture in such wheat seeds could also result in separation and processing issues, such that conventional methods of protein enrichment may need modification or even reinvention. Enriched gluten protein fractions were prepared from Bobwhite lines modified to overproduce HMW glutenin subunits Dx5 and/or Dy10. These lines serve as experimental models to test various approaches that may be taken for protein polymer enrichment. However, conventional wheat gl...

Wheat Flour Exposed to Ethanol Yields Dough with Unexpected Properties

ABSTRACT Exposure of wheat flour to ethanol solutions followed by slow drying of the ethanol in situ alters the subsequent transformation of the flour into dough. Several types of wheat flour were exposed to small amounts of ethanol solutions so as to be “wetted” but without the appearance of a separate liquid phase. The wet sample was then dried in air. Dough was formed from the treated flour, and its rheological parameters were assessed, including time to peak strength (mixograph and farinograph) and gluten index (glutomatic). Untreated and treated flour and the dough prepared therefrom were assayed using 1D SDS-PAGE (reducing and unreducing conditions), capillary zone electrophoresis (CZE) applied to 70% leachates with and without sonication, and differential scanning calorimetry. Both gluten index and time to peak increased as a result of the treatment, and the increase was greater for flour or enriched vital gluten with an initially low gluten index than for flour with a relatively high initial index...

Carbohydrate Pyrolysis. II. Formation of Furfural and Furfuryl Alcohol during the Pyrolysis of Selected Carbohydrates with Acidic and Basic Catalysts

The pyrolysis of five major carbohydrates, glucose, maltose, cellobiose, amylose and cellulose was studied in an inert atmosphere using a thermogravimetric system coupled with a mass spectrometer. The mass spectra of the evolving gaseous mixture were taken at regular intervals and, utilizing a special computerized evaluation program, the composition of the gases was determined as function of time and decomposition temperature. The results obtained with these five carbohydrates showed considerable qualitative and quantitative differences between their pyrolytic decomposition. This confirms that molecular weight and the type of glucosidic coupling greatly affect the pyrolytic reaction mechanism. Acidic catalysts increased the amount of pyrolytic residue at 450° and the composition of the evolving gaseous mixture was simpler. Basic catalysts did not influence considerably the solid residue, but more complex volatile mixtures were obtained. The products contained a wide variety of alcohols, ketones, aldehydes and other oxychemicals in all cases, among them furfural and furfuryl alcohol as the major components.

Carbohydrate pyrolysis: I. A continuous mass spectrometric method for the analysis of the resulting gaseous mixture

Abstract A rapid method has been developed for the analysis of the continuous gaseous streams evolved during the pyrolysis of carbohydrates in a thermogravimetric instrument. The stream was regularly sampled by a mass spectrometer, and the composition was determined by a special computer program which not only evaluated each scan separately, but also correlated the scans with each other to determine the rate of formation of various compounds. This is an important tool to determine the reaction pathways during pyrolysis. The pathways must be known if we want to manipulate the reactions, so that the formation of a desired product can be maximized in the resulting complex mixture.

Thermoanalytical Studies of Carbohydrate Pyrolysis

Reactions of carbohydrates form practically a separate branch of organic chemistry, but the study of the pyrolysis of carbohydrates was neglected for a long time and only a few research groups have been pursuing this research area. Increasing oil prices, however, have created more interest in alternative energy resources. Carbohydrate based biomasses have the best potential to supplement our energy and chemical feedstuff need which is presently derived from fossil fuel. During the past few years, considerable efforts were made on the thermal reactions of various biomasses. Unfortunately, most of the attempts were directed toward developing reactors for special biomasses and not for the basic reactions of those carbohydrates which are the main components of biomasses. For this reason, our knowledge is quite limited on the various simultaneous and consecutive reactions involved in carbohydrate pyrolysis even for such simple compounds as hexoses and pentoses. This paper reports the first step of a mathematical approach to develop more information about these reactions.