Life Sciences Commons^™

Soluble And Insoluble Dietary Fiber In Cooked Common Bean (Phaseolus Vulgaris) Seeds, Joe S. Hughes, Barry G. Swanson

Food Structure

The common bean (Phaseolus vulgaris) requires cooking for extended periods of time prior to consumption. In this investigation both quantitative and microstructural changes in common bean dietary fiber as a result of cooking were examined. Cooking resulted in a slight decrease in soluble dietary fiber and a marked increase in insoluble dietary fiber. The increase in insoluble dietary fiber was responsible for a 15 -30 percent increase in total dietary fiber.

Scanning electron microscopy was used to examine the microstructure of uncooked and cooked bean flours and the insoluble and soluble dietary fiber fractions of these two fl ours. In …

Heat-Set Gels Based On Oil/Water Emulsions: An Application Of Whey Protein Functionality, R. Jost, F. Dannenberg, J. Rosset

Food Structure

The microstructure of portein/lipid gels produced by heat treatment of whey protein stabilized oil-in-water(O/W) emulsions was studied. Scanning electron microscopy as well as transmission electron microscopy was performed on glutaraldehyde/osmium tetroxide fixed, and critical point-dried samples. Microstructure analysis showed that in the case of homogenized O/W emulsions, extensive coating of the fat globule surface with coagulated protein led to a "cauliflower - like" structure. In such gels, uncoated fat globules having smooth surfaces were not present. This specific microstructure was not obtained with protein/lipid gels in which whey protein was added in the continuous phase and mixed with a O/W …

A Method For Light And Scanning Microscopy Of Drought-Induced Damage Of Resting Peanut Seed Tissue, Clyde T. Young, William E. Schadel

Food Structure

Tissue damage creates numerous problems for the microscopic examination of resting peanut (Arachis hypogaea L. cv . Florunner) seed physical structure. This paper presents a method to deal with specific problems encountered in light microscopy (LM) and scanning electron microscopy (SEM) of drought - induced damage of peanut tissue . Major findings include: (1) improved SEM imaging through reduction of charging by increasing coating thickness from 25 nm to 30 nm; (2) improved stain affinity for LM tissue preparations by decreasing osmium tetroxide fixation time from 2 hours to 1 hour; and (3) im proved tissue fixation for LM and …

Rheology And Microstructure Of Strained Yoghurt (Labneh) Made From Cow's Milk By Three Different Methods, A. Y. Tamime, M. Kalab, G. Davies

Food Structure

Labneh is the name for strained yoghurt, i.e., yoghurt made with an elevated solids content, which has originated in the Middle East. For this study , three types of Labneh were made from cow' s milk: (a) "Traditional Labneh" was produced by straining yoghurt in a cloth bag, (b) "UF Labneh" was made by ultrafiltration of warm yoghurt , and , (c) "UF Retentate Labneh" was obtained by culturing homogenised ultrafiltration (UF) milk retentate. A 11 products were passed through a lactic curd homogen is er to smoothen the Labneh curd . Total solids contents of t he products were …

Structural Characteristics Of Pennisetum Americanum (Pearl Millet) Using Scanning Electron And Fluorescence Microscopy, C. M. Mcdonough, L. W. Rooney

Food Structure

Fluorescence bright field and scanning electron microscopy were used to characterize the structure of selected mature pearl millet caryopses from the World Germplasm Collection. Kernel shape (globose, lanceolate, obovate and hexagonal). kernel endosperm color (while. yellow and grey) and external appearance (color) of the samples were documented for 96 varieties. Color of the pearl millet kernel was due to the combined effects of pigmentation in the pericarp. aleurone and endosperm. as well as the pericarp thickness. White kernels had few pigmented areas. yellow kernels had pigments primarily in the epicarp and endosperm. and brown kernels had pigments in the epicarp. …

Influence Of The Extrusion Process On Characteristics And Structure Of Pasta, M. Ambrogina Pagani, Plerpaolo Resmini, Gerardo Dalbon

Food Structure

The effects of the kneading and forming process or pasta quality have been investigated. Using the same blend of wheat flour and keeping mixing and drying conditions constant, three types of spaghetti were produced using the following three kneading and forming processes: A) kneading with a continuous press and forming by pressure-extrusion; B) kneading and forming by sheeting-rolls; C) kneading by hand and forming with sheeting-rolls. These three processes impart different mechanical work on the dough.

The three types of dried spaghetti exhibited differences in cooking requirements and in cooing quality. Spaghetti (A) absorbed water more slowly and showed poor …

Composition And Some Properties Of Spray-Dried Retentates Obtained By The Ultrafiltration Of Milk, Miloslav Kalab, Marijana Caric, Mansour Zaher, V. R. Harwalkar

Food Structure

Retentates containing 20, 27, and 34% total solids, obtained on commercial scale by the ultrafiltration of milk were spray-dried on laboratory scale using centrifugal atomization and single stage drying with the inlet air temperature of 220 C and the outlet air temperature of 90 C.

The protein content in the powders was 31% to 35% compared to 24.8% protein in the control whole-milk powder. Lactose contents were markedly lower in the retentate powders (-10.6%) than in the milk powder (40.4%). Storage of the powders at 37 C resulted in a marked increase in the 5-hydroxmethylfural contents with doubling of this …

Microstructural Changes In Wheat Starch Dispersions During Heating And Cooling, M. Langton, A. M. Hermansson

Food Structure

Microstructural changes in 8-11% wheat starch dispersions during heating, cooling and cold storage have been evaluated by light microscopy and scanning electron microscopy.

Heat treatment of wheat starch dispersions gives rise to two stages of swelling and solubilization. During the first phase of swelling, solubilized amylose was observed ln the centre of the granules and, to some extent, outside the granules. Further swelling deformed the granules and more amylose was released. When the temperature treatment took place under shear, the outer layer of the swo llen granules fra ctured at 94°C and above, and amylopectin fragments were dispersed into the …

The Effects Of Gamma Irradiation And Calcium Treatment On The Ultrastructure Of Apples And Pears, E. Kovacs, A. Keresztes, J. Kovacs

Food Structure

The post-storage quality of fruits depends on the ultrastructure of the outer tissues and on the fruit mineral composition (mostly on calcium). Pectins and their bonds with calcium play a central role in the tissues during ripening.

During senescence the middle lamella disappears from the cell walls, the fruits become soft and cell wall reticulation can be seen. There are changes within the cells too; plasmalemma separates from the wall, tonoplast from the cytoplasm, and plastids, mitochondria and nuclei are disorganized.

The ultrastructure of the skin and flesh of apples and pears were studied as a function of treatments (calcium, …

Lactose Crystallization In Commercial Whey Powders And In Spray-Dried Lactose, Zenichi Saito

Food Structure

Two kinds of whey powder, one containing only amorphous lactose, and the other containing precrystallized lactose, and spray-dried amorphous lactose were examined for particle structure by scanning electron microscopy. Lactose crystallization under 75th relative humidity was studied by X-ray diffraction analysis. Scanning electron microscopy appeared to detect changes due to lactose crystallization on the smooth surface of the particles examined. Lactose crystallization s tarted within 30 minutes after exposure to the humid atmosphere. Both a-lactose hydrate and B-lactose crystals were detected in the s pray- dried amorphous lactose by X -ray diffraction within 40 minutes under the humid conditions. Only …

Application Of Scanning Electron Microscopy And X-Ray Microanalysis To Investigate Corrosion Problems In Plain Tinplate Food Cans And Examine Glass And Glass-Like Particles Found In Canned Food, James E. Charbonneau

Food Structure

Scanning Electron Microscopy (SEM) and X-ray Microanalysis (EDS) have been used to investigate product container interaction problems in plain tinplate metal food containers and to examine glass and glass-like particles that were found in canned food.

Through the use of SEM-EDS, it was determined that: sulfate containing particles from the cannery cooling water reacted with exposed iron or tin-iron alloy on the tinplate surface causing an external rusting problem; sulfur dioxide was responsible for a container discoloration and a pitting corrosion problem in canned fruit nectar; hydrogen sulfide produced from the SO2-tinplate reaction was the cause of an associated off-odor …

The Use Of Transmission Electron Microscopy To Study The Composition Of Pseudomonas Fragi Attachment Material, Paula J. Herald, Edmund A. Zottola

Food Structure

Electron microscopy techniques were used to study the attachment matrix of Pseudomonas fragi used to demonstrate the presence of attachment fibrils of P. fragi adhered to stainless steel. Transmission electron microscopy (TEM) was used to examine thin sectioned cells strained with ruthenium red or alcian blue. Extracellular substances surrounding cells stained with ruthenium red or alcian blue had a mat- or spike-like morphology. This indicated that these substances were acidic mucopolysaccharides that may be involved in the attachment of P. fragi to food contact surfaces.

Scanning Electron Microscopy Of Cellular Structure Of Granny Smith And Red Delicious Apples, Gassinee Trakoontivakorn, Max E. Patterson, Barry G. Swanson

Food Structure

Immature and mature Granny Smith and Red Delicious apples (Malus domestica Borkh . ) were studied with scanning electron microscopy (SEM). Parenchyma cells were observed to form a net-like pattern in sections transverse to the stem-calyx of the apple. Bundles of about six intact cells were connected, creating large intercellular spaces. The intercellular spaces were different in shape from different perspectives to the cut surfaces ; round in stem-calyx transverse sections and elliptical in stem-calyx cross sections. Cell areas, cell lengths and intercellular space areas were determined with image analysis. The patterns of mature apple cell structure of both cultivars …

The Influence Of Ingredients And Processing Variables On The Quality And Microstructure Of Hokkien, Cantonese And Instant Noodles, R. Moss, P. J. Gore, I. C. Murray

Food Structure

Light and scanning electron microscopy have been used as a part of a research program designed to study the influence of flour quality and processing variables on three of the noodle types that are popular in South East Asia . The noodles selected for study were Cantonese, Hokkien and modern instant. They represent the range of cooking and processing variables that are commonly encountered in these products . Flour particle size and the choice of alkaline ingredients influence protein development during the sheeting process . A continuous protein matrix is required in t he raw noodle if it is to …

Seed Microstructure And Its Relationship To Water Uptake In Isogenic Lines And A Cultivar Of Dry Beans (Phaseolus Vulgaris L.), George N. Agbo, George L. Hosfield, Mark A. Uebersax, Karen Klomparens

Food Structure

Comparisons using scanning electron microscopy (SEM) were made among seeds of the isogenic bean strains, 'Nep - 2' and 'San Fernando' and 'Sanilac', a navy bean cultivar, to ascertain interrelationships between seed microstructure and water absorption characteristics. During a 90 min soaking period 1:1 (v /v) tap and distilled water, 'San Fernando' hydrated at the s lowest rate and imbibed water at only 60% and 78% of the percentages of water imbibed by 'Sanilac' and 'Nep-2', respec tively. Among the three bean genotypes, 'Sanilac' hydrated the most rapidly and imbibed the most water (5 2.9% ). 'Nep - 2' was …

Effects Of Drying Techniques On Milk Powders Quality And Microstructure: A Review, Marijana Caric, Miloslav Kalab

Food Structure

The quality of milk powders is markedly affected by the composition and properties of the milk, the manufacturing procedures, thermal processing during manufacture and, in particular, the drying technique itself. A variety of physico-chemical analytical methods, including scanning electron microscopy, has been used to obtain information on the effects of the various factors on the microstructure of the milk powders. Roller-drying, which has recently lost its commercial importance, produces a sheet of dried milk that is powdered in a hammer mill. The resulting powder consists of compact particles with sharp edges. Powders obtained by spray-drying are in the form of …

The Crystallization Of Calcium Phosphate At The Surface Of Mould-Ripened Cheeses, B. E. Brooker

Food Structure

Samples of several different types of mouldripened cheese were examined by light and electron microscopy for evidence of calcium phosphate crystallization near their surfaces , which, it was predicted , should result from the pH changes that take place in the rind during ripening . Transmission electron microscopy showed that characteristic convoluted crystals appeared in the rind as mould growth developed and that there was good evidence that at least some of the crystal nucleation was taking place inside effete hyphae. Light microscopy showed that this coincided with the appearance of birefringent, phosphate-rich crystals in the cheese rind which were …

Influence Of Delignifying Agents On Tissue Structure In Bermudagrass Stems, D. E. Akin, L. L. Rigsby, F. E. Barton, P. Gelfand, D. S. Himmelsbach, W. R. Windham

Food Structure

Permanganate, dioxane, ozone, and hydrogen peroxide, which delignify plant materials, were evaluated for their disruptive action on plant structure, the ir modification of histological reactions for Iignins, and their change in in vitro digestibility by rumen microorganisms of yollng-Tsecond internode from top) and old (fourth and fifth internodes) bermudagrass stems. Epidermis, sclerenchymaring, and vascular tissue (except phloem) gave positive reactions with acid phloroglucinol (AP) or chlorinesulfite (CS) in all samples , whereas cortex and parenchyma in older stems gave a positive reaction with CS. Treatment with delignifying agents reduced the reactions for lignin, with permanganate- treated tissues having the least …

Relationship Between Microstructure And Susceptibility To Syneresis In Yoghurt Made From Reconstituted Nonfat Dry Milk, V. R. Harwalkar, Miloslav Kalab

Food Structure

Increase in the density of protein matrices i n yoghurt samples conta ining 10 to 30% total milk sol ids was studied by scanning electron micros copy and was corr e lated with a decrease in syneresis. Casein particles which formed chains and clusters in the protein matrix were largest in the 10% total solids yoghurt and their dimensions were decreased as the total solids contents were increased. This observation was confirmed by transmission electron microscopy of thin sections. An attempt has been made to explain the discrepancy between results on syneresis obtained by a drainage and a centrifugation method …

Texture And Microstructure Of Soybean Curd (Tofu) As Affected By Different Coagulants, J. M. Deman, L. Deman, S. Gupta

Food Structure

The coagulating properties of five coagulants and the nature of the curd obtained from soymilk was investigated . Viscosity changes during coagulation were studied using a Namctrc Vibrating Sphere Viscometer and texture measurements were made by compression and computer assisted analysis. pH and amount of solids in the whey were determined. The microstructure of the tofu was examined by sca nning electron microscopy. It was observed that CaCI2.2H20 and MgCI2.6H20 coagulaled the milk in stantl y while CaS04 .1/2H20. glucono delta l a~tonc (GOL) and MgS04 .7H20 acted comparatively slowly. The t exture of the curd was greatly influenced by …

Mucilage In Yellow Mustard (Brassica Hirta) Seeds, I. R. Siddiqui, S. H. Yiu, J. D. Jones, M. Kalab

Food Structure

Release of mucilage from yellow mustard (brassica hirta, also known as Sinapis alba) seed coats (hulls) was studied by optical and scanning electron microscopy. Micrographs were obtained of the mucilage which had exuded from briefly moistened seeds and dried subsequently in the form of small droplets on the seed surface.

The mucilage collected from the seed surface and mucilage isolated on a larger scale from seed hulls was hydrolyzed with sulfuric acid and the hydrolyzates were analyzed for sugar composition. Galactose, glucose, and galacturonic acid were found to be major components and mannose, arabinose, xylose, and rhamnose were minor components. …

Ultrastructure Of Cooked Spaghetti, M. A. Pagani, D. J. Gallant, B. Bouchet, P. Resmini

Food Structure

Several electron microscopy (EM) complementary techniques (scanning electron microscopy, freeze-fracturing and thin-sectioning) have been applied in the ultrastructural study of spaghetti.

Experimental spaghetti have been produced starting from two semolinas from the same wheat cultivar and using a low temperature (LT) and very high temperature (VHT) drying schemes.

Cooking quality of these products was not related to the quantity of the main components present in semolina. however, the drying conditions (temperature and humidity) and the nature of the cooking water greatly influenced cooking characteristics.

The three EM techniques were used to detected differences in protein and starch organization in relationship …

Ultrastructure Of Maize Starch Granules. A Review, Daniel J. Gallant, Brigitte Bouchet

Food Structure

History of starch granule ultrastructure and the principal data obtained on maize starch granules are analyzed. New results are developed: i) growth and development of the maize starch granules during maturation depend on the maize varieties and the tissue site in the kernel, especially the horny and flloury endosperms; ii) cytochemical studies of the starch granules differing from their amylose/amylopectin ratio show important differences in the distribution of their crystalline and amorphous zones that explain their behaviour under some hydrolytic treatments; iii) complexing between colloidal gold labelled concanavalin-A and starch (amylopectin) permits new and greater specificity to ultrastructural study of …

Mechanical Properties Of Cheese, Cheese Analogues And Protein Gels In Relation To Composition And Microstructure, M. L. Green, K. R. Langley, R. J. Marshall, B. E. Brooker, A. Willis, J. F. V. Vincent

Food Structure

Samples of commercial Cheddar cheese, experimental Cheddar cheeses made from heated, ultrafiltration-concentrated mllks, processed cheese analogues and whey protein gels of defined composition were examined microscopically and some fracture and deformation properties were determined. Surfaces of cheese prepared by critical point drying and those examined frozen were comparable in microstructure. As the concentration factor of the milk used for experimental c heesemaking increased, the cheese became more resistant to reversible deformation, the work required to cut with a wire or break wf th a hammer increased and the microstructure showed that the protein matrix was coarser. The force to deform …

Structural Characteristics Of Eleusine Corocana (Finger Millet) Using Scanning Electron And Fluorescence Microscopy, C. M. Mcdonough, L. W. Rooney, C. F. Earp

Food Structure

The objective of this study was to document the microstructure of finger millet wlth scanning electron and fluorescence microscopies. Finger millet is an utricle which is spheri ca 1 and about 1 . 5 ITlT1 in diameter. The membranous peri carp of finger millet was loosely associated with the seed at maturity. Beneath the loose pericarp wa s a five-layered testa that varied from red to purple in color. The outer layer was the only testa layer that autofl uoresced, suggesting the presence of phenolic acids, i .e., ferulic acid. The aleurone layer was beneath the testa , and was …

Changes In The Microstructure Of Skipjack Tuna During Frozen Storage And Heat Treatment, L. E. Lampila, W. D. Brown

Food Structure

Samples of fresh, frozen and heat- treated skipjack tuna muscle were observed by scanning electron mieros copy. The photomicrographs were used to assess changes in the microstructure of fish muscle during frozen storage and thermal processing . Differences noted in frozen tissue could be related to the formation of gaps between fibers and the deformation of muscle fibers . No freeze mediated damage to the cell wall was observed at the lower limits, 20,000x, of high resolution scanning electron microscopy. The degree of muscle fiber shrinkage and erosion and the behavior of certain protein fractions was found to be affected …

Freeze Texturation Of Proteins: Effect Of The Alkali, Acid And Freezing Treatments On Texture Formation, Frisco I. Consolacion, Paul Jelen

Food Structure

The effects of alkali extraction, isoelectric precipitation, and rate of ice crystal formation on protein interaction in the freeze texturization process were studied , The protein isolate was obtained from mechanically deboned poultry meat residues by extraction with NaOH at pH 10.5 and precipitation by HCl at pH 5, 0, The presence of large molecular weight subunits in the protein isolate was revealed by SDS-polyacrylamide gel electrophoresis. Scanning electron microscopy demonstrated the nature of the fiber formation and protein cross-linking as affected by freezing at -25'C or -196'C. The transformation of the level of protein organization from the lumpy or …

Microstructure Of Mealy And Vitreous Wheat Endosperms (Triticum Durum L.) With Special Emphasis On Location And Polymorphic Behaviour Of Lipids, A. Al Saleh, D. Marion, D. J. Gallant

Food Structure

Dark inclusions observed in osmiophilic zones, already described in mature wheat endosperm using transmission electron microscopy, were confirmed by freeze-fracture electron microscopy to be lipids. The polar lipids (glycolipids, phospholipids, free fatty acides, monoglycerides) were organized in a liquid crystalline phase. The reversed hexagonal or HII phase should be the main lattice which might arise from the transition of lipids present in membranous structures as a lamellar phase. This transition was caused by dehydration occurring during maturation. It is suggested that the water-dependent lamellar hexagonal phase transitions are of considerable importance in cereal food technology.

Microstructure Of Lentil Seeds (Lens Culinaris), Joe S. Hughes, Barry G. Swanson

Food Structure

Scanning electron microscopy (SEM) was used to investigate the microstructure of five cultivars of lentil seeds (Lens culinaris). Lentil cot yledons contain sphericai starch granules surrounded by protein bodies similar to starch granules and protein bodies observed in cotyledons of other food legumes. Examination of the lentil seed coat in cross - section revealed outer palisade and inner parenchyma layers characteris tic of legumes. The subepidermal layer, however, is comprised of hourglass cells and is found primarily in the area surrounding the hilum and the entire lentil seed coat is thinner than the seed coat s of most other food …

Ultrastructural Study Of Yam Tuber As Related To Postharvest Hardness, L. Sealy, S. Renaudin, D. J. Gallant, B. Bouchet, J. M. Brillouet

Food Structure

Usually, parenchyma cell walls of monocotyledons do not develop secondary walls; however a few days after harvesting, the yam tuber of Dioscorea dumetorum starts to harden. Two or three weeks Iater, hardness is so pronounced that the tubers cannot be eaten, even after a long cooking time.

Cytochemical studies using autofluorescence or some fluorescent dyes, such as phloroglucinol hydrochloride showed that the thin, and flexible cell walls of parenchyma tubers very quickly became fully lignified after harvesting. Ultrastructura 1 stud ies of the hardened ce 11 wa 11 s showed very thick secondary wa 11 s and very deep pit …