Harry D. Sapirstein

Phenolic content and antioxidant activity of pearled wheat and roller-milled fractions

ABSTRACT Wheat contains phenolic compounds concentrated mainly in bran tissues. This study examined the distribution of phenolics and antioxidant activities in wheat fractions derived from pearling and roller milling. Debranning (pearling) of wheat before milling is becoming increasingly accepted by the milling industry as a means of improving wheat rollermilling performance, making it of interest to determine the concentration of ferulic acid at various degrees of pearling. Eight cultivar samples were used, including five genotypes representing four commercial Canadian wheat classes with different intrinsic qualities. Wheat was pearled incrementally to obtain five fractions, each representing an amount of product equivalent to 5% of initial sample weight. Wheat was also roller milled without debranning. Total phenolic content of fractions was determined using the modified Folin-Ciocalteau method for all pearling fractions, and for bran, shorts, bran flour, and first middlings flour from roller milling. A...

Discrimination of wheat class and variety by digital image analysis of whole grain samples

The application of digital image analysis for objective classification of wheat cultivars according to kernel type and identity was studied. Plan-form spatial shape features and Fourier descriptors of kernel perimeters were automatically determined from computed whole-grain contours. Perfect type classification was obtained for four durum wheat varieties in admixture with ten common wheats representing a broad range of kernel types. Likewise, samples of each of five Canada Western Red Spring (CWRS) wheat varieties were all correctly allocated to the CWRS class. None of 432 kernels of contrasting wheat classes was misclassified as CWRS wheat. Discrimination of Canada Western Red Winter, Canada Western Soft White Spring, Canada Utility and Canada Prairie Spring wheats was less satisfactory. Discrimination of varieties within classes gave inconclusive results with correct classification scores ranging from 15 to 96%.

Intercultivar Variation in the Quantity of Monomeric Proteins, Soluble and Insoluble Glutenin, and Residue Protein in Wheat Flour and Relationships to Breadmaking Quality

ABSTRACT A new fractionation procedure based on differential solubility was applied to wheat flour proteins to evaluate the relationship between protein fractions and functionality for breadmaking. Flour was initially extracted with 50% 1-propanol. Monomeric proteins (mainly gliadins) and soluble glutenin contained in the 50% propanol soluble extract were fractionated by selective precipitation of the glutenin by increasing the concentration of 1-propanol to 70%; monomeric proteins remain in the supernatant. Insoluble glutenin in the 50% propanol insoluble residue was extracted using 50% 1-propanol containing 1% dithiothreitol (DTT) at 60°C. Protein in the final residue was extracted using SDS with or without DTT. It comprised mainly Glu-1D high molecular weight glutenin subunits and nongluten polypeptides. For seven Canadian cultivars of diverse breadmaking quality, there was relatively little variation in the percentage of flour protein corresponding to monomeric proteins (48–52%) and residue protein (1...

An instrumental system for cereal grain classification using digital image analysis

A digital image processing system is described to facilitate objective inspection and classification of cereal grains. Digitized images of whole grain samples of hard red spring wheat, barley, rye and oats were obtained using a charge-coupled device (CCD) video camera interfaced to a custom-built data-acquisition system. Computer programs were written in assembly language for acquisition and preliminary processing of data from the CCD camera. FORTRAN77 programs were developed for image segmentation and feature extraction. Computed grain features include kernel length, width, area, aspect and thinness ratios, contour length and normalized central moments. Size and shape parameters were evaluated with regard to discrimination ability by stepwise discriminant analysis. Canonical discriminant analysis was applied to visualize cereal class differences and a linear discriminant model was derived. Approximately 1% of over 1100 kernels tested were incorrectly classified among wheat, oats, barley and rye in a four-way admixture. The feasibility of the methodology for instrumental determination of foreign material (‘Besatz’) in grain grading is discussed.

Prediction of Bread Crumb Density by Digital Image Analysis

ABSTRACT The cellular structure of bread crumb (crumb grain) is an important factor that contributes to the textural properties of fresh bread. The accuracy of a digital image analysis (DIA) system for crumb grain measurement was evaluated based on its capability to predict bread crumb density from directly computed structural parameters. Bread was prepared from representative flour samples of two different wheat classes, Canada Western Red Spring (CWRS) and Canada Prairie Spring (CPS). Dough mixing and proofing conditions were varied to manipulate loaf volume and crumb density. Sliced bread was subjected to DIA immediately after physical density measurement. Experiments were repeated for the same bread samples after drying to three different moisture contents. Five computed crumb grain parameters were assessed: crumb brightness, cell wall thickness (CWT), void fraction (VF), mean cell area, and crumb fineness (measured as number of cells/cm2). Crumb density ranged from 0.088 to 0.252 g/cm3 depending on p...

Effects of Flour Strength, Baking Absorption, and Processing Conditions on the Structure and Mechanical Properties of Bread Crumb

ABSTRACT The objective of this study was to determine the effects of flour type, baking absorption, variation in sheeting, and dough proofing time on the density, crumb grain (visual texture), and mechanical properties (physical texture) of bread crumb. All response variables were measured on the same bread crumb specimens. Bread loaves were prepared by a short-time bread-making process using four spring wheat flours of varying strength. After crumb density measurement, digital image analysis (DIA) was used to determine crumb grain properties including crumb brightness, cell size, cell wall thickness, and crumb uniformity. Tensile tests were performed on bone-shaped specimens cut from the same bread slices used for DIA to obtain values for Youngs modulus, fracture stress, fracture strain, and fracture energy. Proof time had the most profound influence on the bread with substantial effects on loaf volume, crumb density, crumb brightness, and grain, as well as crumb mechanical properties. Increasing proof ...

Wheat grain colour analysis by digital image processing I. Methodology

A colour digital image processing workstation has been developed to evaluate instrumentally the colour of individual cereal grains and other objects identified within digital images. Digital colour images were acquired by video digitization of the RGB (red, green, blue) signals produced by a Saticon-type video camera. A low-cost microcomputer-frame grabber system was used to control digitization, to perform image segmentation and to extract colour features. The equipment and methodology for colour measurement are described. Colour attributes of cultivars belonging to different wheat classes were examined. In general, significant differences were discerned between varieties of different class (e.g. amber durum and hard red) and some varieties within the same class (e.g. hard red spring varieties Neepawa and Columbus).

Effects of Wheat Bug (Eurygaster maura) Protease on Glutenin Proteins

ABSTRACT Proteolytic degradation of 50% 1-propanol insoluble (50PI) glutenin of six common wheat cultivars by wheat bug (Eurygaster maura) protease was investigated using reversed-phase HPLC. Wheat at the milk-ripe stage was manually infested with adult bugs. After harvest, bug-damaged kernels were blended (2:1, kernel basis) with undamaged grain of the same cultivar. Samples of ground wheat were incubated in distilled water for different times (0, 30, 60, and 120 min). The incubated whole meal samples were subsequently freeze-dried and stored until analysis. The degree of proteolytic degradation of 50PI glutenin was determined based on the quantity of total glutenin subunits (GS), high molecular weight GS (HMW-GS), and low molecular weight GS (LMW-GS). For ground wheat samples incubated for ≥30 min, 50PI glutenin was substantially degraded as evidenced by a >80% decrease on average in total GS, HMW-GS, and LMW-GS. Some cultivars showed different patterns of glutenin proteolysis as revealed by differences...

Wheat grain colour analysis by digital image processing. II: Wheat class discrimination

The extent to which wheat grain colour, objectively measured by video colorimetry, can be used to distinguish kernel type according to wheat class and variety was investigated. Discriminant analyses were performed based on mean red (R), green (G) and blue (B) pixel reflectance (tristimulus) features obtained by colour digital image analysis. Colour data collected from individual kernels of 10 cultivars representing six Canadian wheat classes were used to develop discriminant models. Pairwise discrimination between selected varieties representing the different wheat classes was achieved with considerable success. Over all pairwise trials, 88 % correct varietal classification was achieved on average. In pairwise trials between certain red-grained varieties (cvs), e.g. Neepawa, Norstar or Glenlea and amber durum cv. Wakooma or white spring wheat cv. Owens, correct classification exceeded 96%. A more demanding discrimination problem of correctly classifying grain of single wheat varieties according to official grade class was also posed. Correct classification scores for individual varieties varied from 34 to 90%. Average correct classification scores for the Canada Western Soft White Spring, Amber Durum and Red Spring classes of wheat were 76, 76 and 62 %, respectively. Relatively lower scores of 56 and 34 % were achieved for the Canada Western Hard Red Winter and Canada Prairie Spring wheat classes. The average correct classification for hard red spring type kernels was approximately 90 %.

Genotypic and environmental variation in grain, flour, dough and bread-making characteristics of Western Canadian Spring Wheat

Wheat (Triticum aestivum L.) grain, flour, dough and bread quality characteristics are strongly influencedby growing-season weather conditions. Understanding the impact of genotype, environment, and their interactions on Canadian wheat quality is important for Canada to maintain its high standard for delivery of consistent quality wheat to domestic and international customers. The effects of genotype, environment and genotype by environment (G × E) interaction on numerous grain, flour, dough and bread-making characteristics were assessed. The Canadian Western Red Spring (CWRS) cultivars were AC Barrie, Superb, AC Elsa, and Neepawa; the Canadian Prairie Spring (CPS-white) cultivar was AC Vista; and the Canadian Western Hard White Spring (CWHWS) cultivar was Snowbird. These genotypes were grown at five locations across the Canadian prairies in 2 yr to provide a total of 7 site-years of milling quality wheat for analysis. Genotype, environment and their interactions had significant effects on most parameters...