Food Science Commons^™

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 …

An Electron Spin Resonance Study Of Stearic Acid Interactions In Model Wheat Starch And Gluten Systems, L. E. Pearce, E. A. Davis, J. Gordon, W. G. Miller

Food Structure

Electron spin resonance (ESR) was used to examine interactions of 16- Doxyl stearic acid in wheat starch-water (starch:water "'1: 1), vital wheat gluten-water and glut en-starch-water model systems, Immobilization of the 16-Doxyl stearic acid, shown by broadIine ESR powder patterns , occurred in wheat starch model systems. In contrast to the starch systems, 16-Doxylstearic acid in gluten-water systems did not display broad line powder patterns. Broadened 3- line ESR spectra were recorded for the gluten-water-16- 0oxyl stearic acid, Th is result was probably due to s pin probe which was bound, and spin probe which was bound in different water …

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 …

Scanning Electron Microscopy Studies Of The Cellular Changes In Raw, Fermented And Dried Cocoa Beans, A. S. Lopez, P. S. Dimick, R. M. Walsh

Food Structure

Cocoa beans are submitted to a curing process of fermentation and drying to develop flavor precursors . The beans must have reached maturity; otherwise, no amount of processing can produce the desired flavor . Early work with cacao cell cultures showed that only when the cells have "matured" co uld a chocolate or cocoa flavor result from further processing. Fermentation is therefore required because unfermented beans may develop little chocolate flavor when roasted . likewise , the outcome of excessive fermentation may also result in unwanted flavor . Thus , the first major post - harvesting phase t o have …

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 …

The Size Distribution And Shape Of Curd Granules In Traditional Swiss Hard And Semi-Hard Cheeses, M. Ruegg, U. Moor

Food Structure

Curd granule junction patterns in hard (Emmentaler, Gruyere, Sbrinz) and semi-hard cheeses (Appenzeller , Tilsiter, Raclette) were visualized on slices and examined using light microscopy and digital image analysis. Horizontal and vertical sections were cut in different zones of the loaves, in order to obtain information on the orientation of the flattened curd granules.

The frequency histograms of the cross section areas could in most cases adequately be described as a log-normal distribution. The median values ranged from 0.97 to 1.15 mm2 and, from 1.31 to 1.68 mm2 for hard and semi-hard cheeses, respectively.

An elliptical form factor was used …

Effect Of Ionizing Irradiation And Storage On Mushroom Ultrastructure Ii. The Stipe And The Upper Part Of The Cap Of Agaricus Bisporus (Lge. Imbach), A. Keresztes, E. Kovacs

Food Structure

After having investigated t he ultra structural effects of ionizing irradiation used for shelf -life extension , on the gills of Agaricus bisporus and Pleurotus ostreatus previously , it was of interest to examine how other parts of the fruit body were affected by t he same treatment . Samples were taken from the lower and upper parts of the stipe and from the upper part of t he cap of the control , stored , and irradiate d (2.5 kGy ) t he n stored A. bisporus fruit bodies. Transmission electron microscopy sh owed that irradiated samples generally retained …

Microstructural Studies Of Texturized Vegetable Protein Products: Effects Of Oil Addition And Transformation Of Raw Materials In Various Sections Of A Twin Screw Extruder, S. Gwiazda, A. Noguchi, K. Saio

Food Structure

In high-temperature short- time extrusion cooking with a twin screw extruder , effects of oil addition to defatted soybean flour and microstructural transformation of full - fat soybean flour during cooking , were investigated by use of a light microscope. At levels up to 15% , soybean oil was distributed in the protein and carbohydrate matrix as small, spherical drops under the experimental conditions used in this study. However , oil contents above 15% significantly prevented formation of well-aligned fibrous structures in the extrudates . During extrusion cooking , the starting materials began to break down by shearing and kneading …

Fluorescence And Light Microscopic Analysis Of Digested Oat Bran, S. H. Yiu, R. Mongeau

Food Structure

The Structural and chemical compositions of digested oat bran were analyzed by fluorescence and other types of light microscopy. The digestion of oat bran was carried out under two conditions - in vitro, by incubation with human saliva, and in vivo, by feeding rats with an oat-bran supplemented diet. Comparison of the digestive breakdown among different structural components of oat bran was conducted by microscopically examining samples obtained from the tents of the large intestine (LIC) of the rats. Results of the examinations revealed that the (1-3) (1-4) - B - D - glucan - rich cell wall of the …

Effect Of Clotting In Stomachs Of Infants On Protein Digestibility Of Milk, S. Nakai, E. Li-Chan

Food Structure

Differences in clotting between human and cow's milk in the stomachs of infants are discussed. Gastric pH, after ingesting milk, of an infant up to 6 months of age stays at a pH range of 4-5, near the isoelectric point of casein, and never reaches the value of 2, which is found in adults. Pepsin C (or gastricsin) can hydrolyze proteins at this pH range. Gastric emptying time is shorter with human milk than with cow's milk which appears to be correlated to the smaller size of human milk clots. Elimination of a readily coagulable fraction of casein from cow's …

Textural Properties And Microstructure Of Process Cheese Food Rework, Miloslav Kalab, Joseph Yun, Suk Hing Yiu

Food Structure

Process cheese food was made using sodium citrate (2.7%) or trisodium phosphate (TSP, 2.7%) as emulsifying agents. No precooked cheese (rework) was used in some samples whereas in others the rework (20%) consisted of a cheese blend emulsified with sodium citrate (2.7%) and (a) briefly heated to 82 degrees C, (b) heated to 82 degrees C for 1 h, (c) heated to 82 degrees C for 5 h, and (d) heated to 82 degrees C for 5 h, frozen at -10 degrees C for 24 h, and thawed at +4 degrees C. Heating for extended periods of time produced so-called …

Internal Porosity Of Corn Extrudate Air Cell Wall, Samuel H. Cohen, Charles A. Voyle

Food Structure

Transmission electron microscopy was used to observe structures within the air cell wall of a corn-based extrudate. Modified fixation and embedding techniques were employed to obtain optimum thin sections. Photomicrographs from these sections showed minute air cells measuring approximately 5 um or less. The size of air cells might impose a limiting factor on the infusion of particulate materials throughout the extrudate matrix.

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 …

Product Morphology Of Fatty Products, I. Heertje, M. Leunis, W. J.M. Van Zeyl, E. Berends

Food Structure

In order to relate composition, processing and product properties of fat spreads, a proper description of the microstructure of these products is required . A technique for the observation of the three-dimensional product structure has been developed which allows free observation of the solid crystalline matrix by removing the liquid oil phase from a fat spread with a solvent system. To perform the different preparation steps required in a reproducible and efficient way, a special sample holder was constructed. Application of preformed sintered bronze elements allows free penetration of the organic solvents. In general, reproducible results are obtained with retention …

Textural Properties And Structure Of Starch-Reinforced Surimi Gels As Affected By Heat-Setting, J. M. Kim, C. M. Lee, L. A. Hufnagel

Food Structure

The gel forming behavior of red hake (Urophycis chuss) surimi with and without starch and its relationship to the structure of the gel matrix were studied. For surimi gels without starch, a combination of preheat- setting at 40 C and cooking at 90 C resulted in significantly greater gel strength than cooking alone. However, preheat - setting of gels containing wheat or potato starch had no significant effect on gel strength demonstrating an opposite trend in gel strength due to the differences in swelling power, water holding ability and gelatinization temperature between potato and wheat starches. This difference in gel …

Confocal Scanning Laser Microscopy In Food Research: Some Observations, I. Heertje, P. Van Der Vlist, J. C. G. Blonk, H. A. C. M. Hendrickx, G. J. Brakenhoff

Food Structure

Confocal Scanning Laser Microscopy (CSLM) has advantages over conventional light microscopy and electron microscopy. In particular the possibility to perform optical sectioning, allowing the disturbance free observation of the three-dimensional internal structure, offers new possibilities in microstructural studies of food systems. The technique is further considered to be very valuable in the study of dynamic processes and transport phenomena. Preliminary results are discussed of an investigation into the microstructure of fat spreads, mayonnaise, cheese and rising dough using this CSLM technique.

The Morphology Of Black Tea Cream, R. D. Bee, M. J. Izzard, R. S. Harbron, J. M. Stubbs

Food Structure

The colloidal precipitate known as tea cream, which separates when a hot aqueous infusion of black tea is cooled, is investigated by electron microscopic (EM) techniques of shadowing, sectioning, freeze-etching and scanning and also by optical microscopy. These indicate tea cream to be an association colloid, the morphology of which depends on overall solids concentration. Dilute infusions (0.1% w/w) produce macromolecular aggregates of about 50 run, but at higher tea solids concentrations secondary aggregation of the initial particles results in ill-defined clusters of approximately 1 um in diameter. At 5% w/w, clear , spherical liquid droplets, typically 1-2 um in …

The Microstructure And Rehydration Properties Of The Phoenix Oyster Mushroom (Pleurotus Sajor Caju) Dried By Three Alternative Processes, Brigitte Li-Shing-Tat, Pavel Jelen

Food Structure

The aim of this investigation was to observe the effects of three drying methods on the microstructure and rehydration properties of the Phoenix Oyster mushroom. Mushrooms were dried at 55C by air-, freeze- and vacuum-drying pilot plant processes. At the microstructural level, the hyphae of the air-dried samples were more flattened and collapsed than the vacuum - and freeze dried samples. The Basidia were distorted by all three treatments to a certain extent, but there seemed to be less damage on the gill surface of the vacuum-dried samples. Appearance, rehydration time and capacity were similar for freeze- and vacuum-dried mushrooms; …

Cellular Rupture And Release Of Protoplasm And Protein Bodies From Bean And Pea Cotyledons During Imbibition, Stephen C. Spaeth, Joe S. Hughes

Food Structure

Imbibition is a critical phase in germination and processing of legume seeds because cellular disruption during imbibition may influence seedling vigor and processing quality Cellular disruption of cotyledonary surfaces of beans (Phaseolus vulgaris L.) and peas (Pisum sacivum L.) and the cellular contents released during imbibition were examined with scanning electron microscopy. Two types of c e llular disruption we r e observed during imbibition: ruptures and fractures. Individual cells and small groups of cells on t he surfnces of cotyledons ruptured after immersion in water. Ruptured cells had flaps of cell walls which remained attached to intact portions of …

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 …

Microbial Cell Division And Separation: Effect Of Citrate On The Growth Of Group N Streptococci, S. Ito, T. Kobayashi, K. Ozaki, T. Morichi, M. Saitoh

Food Structure

In the presence of citrate, some strains of lactic streptococci grow as long chains of innumerable cells. The results with citrate-negative and citrate-resistant variants suggest that citrate is involved in the cell separation system of the streptococci. Observations of the long chains under scanning and transmission electron microscopes suggest that citrate inhibits a certain step near the final cell separation, or that citrate can stimulate initiation of cell division at multiple sites, thereby leading to the cells in long chains.

Physical And Molecular Properties Of Lipid Polymorphs - A Review, K. Sato

Food Structure

The physical and molecular properties of the polymorphism of stearic acid, oleic acid and SOS (1.3-distearoyl-2-oleoyl glycerol) are comparatively discussed. Temperature dependence of Gibbs energy (G-T relation) of three polymorphs of stearic acid; A, B and C, revealed close relationships to each other. The molecular structures subtly differed in these polymorphs. In contrast, three plymorphs of oleic acid, b , and y exhibited remarkably different characteristics. G-T relation showed more diversified features: in particular, the melting points of 9 and B differ by 3 C. An order-disorder transformation occured between 9 and y, as a result of conformational disordering the …

Determination Of Internal Color Of Beef Ribeye Steaks Using Digital Image Analysis, K. Unklesbay, N. Unklesbay, J. Keller

Food Structure

Objective measurements of beef ribeye steaks were made to determine the color distribution throughout their interior after heat processing. Steaks from eight animals were grilled to five degrees of doneness according to traditional internal temperature specifications. Images of the interior of these steaks, as seen by a digital image processing system through red, green, and blue filters were analyzed. The mean, standard deviation, skewness, and kurtosis of the histograms of light intensity at all points throughout the surface were determined. The steaks were also analyzed raw and it was determined that little variation in the color of muscle tissue occurred …

Comparative Microscopy And Morphometry Of Skeletal Muscle Fibers In Poultry, Carol S. Williams, John W. Williams, Ronald A. Chung

Food Structure

Two experiments comparing microscopic analyses were performed using two cooking methods an:t two different muscles from both chickens and turkeys. In the first experiment, breast (pectoralis) and thigh (quadriceps) muscle taken from male and female Rhode Island Red chickens at three ages (10 weeks, 25 weeks and 52 weeks) were cooked in a microwave oven . Samples were collected for observation with brightfield, phase contrast, interference contrast (Nomarski) and transmission electron microscopy. Samples from the same muscle areas were provided for taste pane l evaluation . In the second experiment, breast and thigh samples were collected from 10-week old male …

Effects Of Processing And Cooking On The Structural And Microchemical Composition Of Oats, S. H. Yiu

Food Structure

Fluorescence microscopy was used to analyze the structural and microchemical organization of oat constituents in cooked and uncooked products of whole grain and three commercial ly available rolled oats. Results of the microscopic examination indicated that proteins and lipids in the endosperm tissue were most susceptible to processing. Instead of being individually packaged in distinct structural units like those found in unprocessed groats, both proteins and lipids appeared as aggregated masses after processing. Cooking induced further aggregation. Starch grains in the uncooked rolled oat samples still retained their granular. polygonal structures. although some compound grains were broken up into individual …

The Microstructure Of The Hen's Egg Shell - A Short Review, R. M. G. Hamilton

Food Structure

The structure of the hen's egg shell can be divided into five separate layers . The Innermost layer consists of two distinct membranes known as the inner and outer shell membranes. These membranes are compos ed of networks of protein/polysaccharide fibres and are =70 mm thick. Attached to the outer fibres of the outer membrane are polycrystals of calcite (calcium carbonate) which extend outward in an inverse conical manner until the cones from several sites of crystal i nit iation fuse together. The fibre/ crystal attachment sites, known as basal caps, and the cones form the mammillary knobs layer which …

Electron Dense Granules In Yoghurt: Characterization By X-Ray Microanalysis, Estelle M. Parnell-Clunies, Yukio Kakuda, Richard Humphrey

Food Structure

A study was undertaken to investigate the influence of buffer composition, pH and glutaraldehyde fixation time on the appearance of electron dense granules in yoghurt. Yoghurt particles were fixed in 3.5% glutaraldehyde and postfixed in 2% osmium tetroxide in verona! acetate or phosphate buffer. Thin sections were examined unstained with an electron microscope equipped with a scanning transmission electron microscope module and energy dispersive X- ray analyser.

Electron dense granules appeared whenever glutaraldehyde and osmium tetroxide were utilized sequentially, irrespective of the type of buffer, pH (5.0 vs 6.75), or glutaraldehyde fixation time (2 or 24 h). Granules were absent …

Accuracy And Utility Of Sarcomere Length Assessment By Laser Diffraction, Peter A. Koolmees, Frank Korteknie, Frans J.M. Smulders

Food Structure

In two experiments the computation of sarcomere length from laser diffraction patterns was tested for accuracy against phase-contrast microscopy . Particular attention was paid to methodological factors such as sampling location and computation formulae. Correlation coefficients between the laser diffraction technique and the microscopical method were high (r= 0.96) in both experiments. However, when computed from a simplified formula, the sarcomere length values, determined by laser diffraction patterns tended to be approximately 0. 10 lJm lower. It is recommended to use the correct formula in computing the laser diffraction data and to investigate a limited number of fibres (3) in …

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 …

Fluorescence Characterization Of The Mature Caryopsis Of Sorghum Bicolor (L.) Moench, C. F. Earp, L. W. Rooney

Food Structure

Fluorescence microscopy was used to characterize the mature car yaps is of Sorghum bicolor (L.) Moench . Acid Fuchsin, a protein specific dye used in bright field microscopy, caused protein bodies and matrix in the sorghum endosperm to fluoresce. ANS (8-ani lino-1- naphthal e ne sulfonic acid) also caused the protein bodi es and matrix in the endosperm to fluoresce. Varietal differences in endosperm protein dist r ibution were evident when viewed after sta · ning with Acid Fuchsin . Nile Blue A caused fl uorescence in neutral lipids such as those in :he lipid bodies in the aleurone and …