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An Alternive To Critical Point Drying For Preparing Meat Emulsions For Scanning Electron Microscopy, Edward J. Basgall, Peter J. Bechtel, Floyd K. Mckeith Jan 1983

An Alternive To Critical Point Drying For Preparing Meat Emulsions For Scanning Electron Microscopy, Edward J. Basgall, Peter J. Bechtel, Floyd K. Mckeith

Food Structure

A rapid sample drying technique is described which is useful for the simultaneous preparation of large numbers of samples as an alternative to critical point drying. The cryofractured face of meat emulsions was visualized after appl ying this technique . The fine structure of 1 ipids and proteins were found to be well preser ved in comparison to other reports which used critical point dried meat emulsions. Lipid was readily discerned from the protein matrix by selective fixation of the components in duplicate samples . Stereo imaging was useful in enhancing the texture of the cryofractured surface and as an aid in ...


Myofibrillar Characteristics Of Porcine Stress Syndrome, P. K. Basrur, Sandra Frombach, W. N. Mcdonell, H. D. Geissinger Jan 1983

Myofibrillar Characteristics Of Porcine Stress Syndrome, P. K. Basrur, Sandra Frombach, W. N. Mcdonell, H. D. Geissinger

Food Structure

Porcine Stress Syndrome (PSS) is a genetic trait causing considerable economic loss to the swine industry through stress related death and the poor quality meat known as pale, soft, exudative (PSE) pork . A scanning and transmission electron microscopic examination of muscle biopsies from stress susceptible pigs revealed contracture bands , wide separation of myofibers and focal distortion and dissolution of myofibril s . The changes affecting myofibrillar characteristics and intra and intercellular accumulation of material suspected to be myoplasmic fluid in biopsies of halothane reactors suqqest that the myopathic alterations presaging the carcass deterioration into pale, soft , exudative pork are integrants of ...


Infection Of Oriental Mustard By Nematospora: A Fluorescence And Scanning Electron Microscope Study, Richard A. Holley, Beverley E. Phipps-Todd, Suk H. Yiu Jan 1983

Infection Of Oriental Mustard By Nematospora: A Fluorescence And Scanning Electron Microscope Study, Richard A. Holley, Beverley E. Phipps-Todd, Suk H. Yiu

Food Structure

Fluorescence light microscopy and scanning electron microscopy were used to study penetration by the yeast Nematospora caryli through the seed coat and into the embryonic tissues of oriental mustard seed (Brasslca iuncea).

Infection of the seed was associated with its physical injury; however, it was evident that the yeast was capable of successfully invading healthy plant cells. The pathological process was followed in parallel using both the above types of microscopy. Foci of yeast infection on the seed coat outer surface were characterized by swelling of the infected epidermal cells. Nematospora hyphae were seen in the lumina of the seed ...


Ultrastructure Studies Of Pasta. A Review., P. Resmini, M.A. Pagani Jan 1983

Ultrastructure Studies Of Pasta. A Review., P. Resmini, M.A. Pagani

Food Structure

Freeze-fracturing can be used effectively to study pasta microstructure both in the dry and cooked state. Aft er a walerglycerol soaking. conventional raw wheat pasta shows an uncoagulated protein matrix in which the starch granules are uniformly dispersed. Starch granules appear unswollen with a spherulitic structure. Extensive protein denaturation and starch swelling may occur during processing when a temperature greater than 60°C is attained in drying. Extensive structural transformations take place in cooking. A fibrillar protein network which envelops gelatinized starch is the typical structure observed in cooked durum wheat spaghetti. Whereas. in soft wheat products, there is a ...


The Microscopic Structure And Chemistry Of Rapeseed And Its Products, S. H. Yiu, H. Poon, R. G. Fulcher, I. Altosaar Jan 1982

The Microscopic Structure And Chemistry Of Rapeseed And Its Products, S. H. Yiu, H. Poon, R. G. Fulcher, I. Altosaar

Food Structure

The location and distribution of some of the storage constituents in the structures of rapeseed and its products were investigated. Hand-cut or glycol methacrylate-embedded sections were stained with dyes or fluorochromes of known specificities and examined using fluorescence, bright-field and/or polarizing microscopy. Results obtained from the study were based upon observations of characteristics of the various stainings, birefringence, induced fluorescence and autofluorescence. The effects of enzymatic hydrolysis, solvents and processing on the cellular structures and their affinity for certain dyes/ fluorochromes were also investigated. Major and minor storage constituents were tentatively located in the structure of rapeseed. Lipids and ...


Protein Bodies In Dormant, Imbibed And Germinated Sunflower Cotyledons, R. D. Allen, H. J. Arnott Jan 1982

Protein Bodies In Dormant, Imbibed And Germinated Sunflower Cotyledons, R. D. Allen, H. J. Arnott

Food Structure

Scanning electron microscopy was used to observe the morphology and structure of protein bodies in dormant and imbibed sunflower cotyledons and to document the morphological changes in protein bodies during germination and seedling growth. In order to clearly visualize dormant seed structure, anhydrous fixation techniques were employed. Definite differences in cellular structure are seen in comparisons of dry and imbibed seed tissues. As germination proceeds, protein bodies lose their smooth spherical shape and become indented and pitted. Protein body coalescence and fusion precedes the formation of a central protein vacuole. As protein is hydrolyzed, protein vacuole density decreases, and its ...


Freeze-Induced Fibre Formation In Protein Extracts From Residues Of Mechanically Separated Poultry, R. A. Lawrence, P. Jelen Jan 1982

Freeze-Induced Fibre Formation In Protein Extracts From Residues Of Mechanically Separated Poultry, R. A. Lawrence, P. Jelen

Food Structure

Coagulated protein obtained by alkali extraction and acid precipitation from the bone containing residues discarded after mechanical separation of chicken was textured by freezing in semi-infinite cylinders followed by heat-setting in a microwave oven. Macrophotography was used to illustrate textural differences resulting from pH variations (4.5-6.0) in the precipitated protein, and changes in the ambient temperature used for freezing (-5°C to -32°C). Well identified, permanent fibres were fanned by the process under all conditions studied. The thickness of the fibres decreased and their radial orientation increased with increasing pH and decreasing ambient temperature of freezing. Cross-linkages ...


Freeze-Etch Of Emulsified Cake Batters During Baking, J. D. Cloke, J. Gordon, E. A. Davis Jan 1982

Freeze-Etch Of Emulsified Cake Batters During Baking, J. D. Cloke, J. Gordon, E. A. Davis

Food Structure

Cryofixation, freeze-etch techniques were used to study the structure of cake batters made from a lean cake formulation before heating and after heating to temperatures up to l00-l02°C. Batters were prepared without added emulsifiers and with saturated and unsaturated monoglycerides replacing 5 and l 0% of the oil. Unsaturated monoglyceri des were more effective than saturated monoglycerides in dispersing oil droplets through the batter. Saturated monoglycerides formed liquid crystals during baking. The temperature at which starch granules began to swell was slightly higher for saturated monoglyceride containing cakes. The batter matrix between starch granules was more clearly defined in ...


Electron Microscopy Of Milk And Milk Products: Problems And Possibilities, D. G. Schmidt Jan 1982

Electron Microscopy Of Milk And Milk Products: Problems And Possibilities, D. G. Schmidt

Food Structure

Milk and dairy products have frequently been studied by transmission- and scanning electron microscopy. The specimen preparation procedure may considerably influence the final result, and formation of artefacts is frequently observed. In this respect, formation of ice crystals during cryofixation is a well-known phenomenon. But dehydration, to an extent such as is required for embedding procedures, also appears to be harmful to dairy products. Micrographs of thin sections of plastic- embedded samples of casein submicelles show threadlike material, whereas in freeze-etched specimens only spherical particles are found. Similar observations are made when samples of cheese and of concentrated milk are ...


Detection Of Buttermilk Solids In Meat Binders By Electron Microscopy, Miloslav Kalab, Frederick Comer Jan 1982

Detection Of Buttermilk Solids In Meat Binders By Electron Microscopy, Miloslav Kalab, Frederick Comer

Food Structure

Nonfat dry milk and buttermilk solids used as ingredients in meat binders can be differentiated by transmission electron microscopy. The meat binders are suspended in water and coarser ingredients such as wheat and mustard flours are separated from the milk solids by low-speed centrifugation (415 g for 30 min). The milk solids thus purified are concentrated by ultracentrifugation (8 x 104 g for 90 min) and the resulting pellets are embedded in a resin, thin-sectioned, stained, and examined by transmission electron microscopy. Buttermilk solids are revealed by the presence of fat globule membrane fragments. In the absence of buttermilk solids ...


Fluorescence Microscopy Of Cereals, R. G. Fulcher Jan 1982

Fluorescence Microscopy Of Cereals, R. G. Fulcher

Food Structure

The fluorescence microscope is one of the most sensitive instruments available for morphological and microchemical analysis of biological material, and especially of cereal grains. Recent innovations in illuminating systems, fluorescence chemistry, and specimen preparation have combined to provide significant improvements over conventional bright-field microscopy in both specificity and sensitivity. A variety of relatively specific fluorescent markers has been devised for routine and high resolution detection of all major cereal components. Several examples of useful fluorescent markers are described, including appropriate methods for specimen preparation, fluorescence analysis, and photography.


Correlation Of Microscopic Structure Of Corn Starch Granules With Rheological Properties Of Cooked Pastes, D. D. Christianson, F.L. Baker, A.R. Loffredo, E. B. Bagley Jan 1982

Correlation Of Microscopic Structure Of Corn Starch Granules With Rheological Properties Of Cooked Pastes, D. D. Christianson, F.L. Baker, A.R. Loffredo, E. B. Bagley

Food Structure

The progressive geometric changes that occur in swelling of corn starch granules during heating throughout the range of gelatinization (63-72°C) and at higher temperatures when substantial amount s of soluble starch are released from the granule were observed by scanning electron microscopy (SEM). Corn starch granules begin to swell radially, then undergo radial contraction and random tangential expansion. They form complex geometrical structures at the midpoint range (67-70°C) unlike the more uniform single-dimensional tangential swelling that occurs with lenticular granules of wheat starch . At higher temperatures, when starch begins to solubilize, corn starch granules lose their distinct ridges ...


Light Microscopy Preparation Techniques For Starch And Lipid Containing Snack Foods, F. Olga Flint Jan 1982

Light Microscopy Preparation Techniques For Starch And Lipid Containing Snack Foods, F. Olga Flint

Food Structure

Many processed foods lack the structural integrity associated with biological tissue so that the conventional methods of preparation and staining used in light microscopy may introduce misleading artifacts.

Taking as examples of starch-based processed foods, potato chips (UK potato crisps) and three distinct potato snack foods, methods for preparing and demonstrating the constituents present in cryosections of whole and masticated products are discussed. To show constituents in their true relative locations vapor staining and polarized light are used. Iodine vapor staining indicates the extent of starch gelatinisation in the dry snack and it is also used to show the structural ...


Some Effects Of Lipids On The Structure Of Foods, K. Larsson Jan 1982

Some Effects Of Lipids On The Structure Of Foods, K. Larsson

Food Structure

The functional properties of different lipids in foods are demonstrated and related to the structure of lipid or lipid-water phases. On the basis of new X-ray data on the crystal structure of the B'-form and the a + B' transition in fats, the polymorphic transitions are considered as different lateral arrangements of triglyceride dimers. The physical properties of fat crystals can be explained from the structures, as well as possibilities to influence the polymorphic transitions.

Molecular interaction between polar lipids and proteins or starch is discussed, and the effect of the amylose-lipid inclusion complex on gelatinization temperature and water penetration ...


Structure And Properties Of The Particulate Constituents Of Human Milk. A Review., M. Ruegg, B. Blanc Jan 1982

Structure And Properties Of The Particulate Constituents Of Human Milk. A Review., M. Ruegg, B. Blanc

Food Structure

Milk contains different types of colloidal or coarsely dispersed particles, such as casein micelles, membrane fragments, fat globules and cells. The fat globules are composed of subpopulations of differently sized particles. In contrast to COW 1S milk, the overall average diameter (dys), increases with advancing lactation from about 1.8 ~min colostrum to 4.0 ~min mature milk. Membrane materials originating from the milk fat globule membrane, plasma membrane, secretory vesicles and other sources can be found in milk serum. These particles have also been called lipoprotein particles. Their size ranges from about 10 - 400 nm. New results concerning the ...


Grain Structure And End-Use Properties, Y. Pomeranz Jan 1982

Grain Structure And End-Use Properties, Y. Pomeranz

Food Structure

Practical implications of grain structure relate to every step from grain development and production through market ing to processing, utilization, and consumption . The structure and adherence of the hulls may contribute to protection of grain during germination or malting and protection against insect infestations . Germ retention during threshing and separation during processing depend on the germ structure and location in the kernel. The subaleurone and central endosperm layers differ in cell size, shape, and structure and in composition, especially with regard to protein contents and quality. The main factors in grain hardness are the intrinsic hardness of the main components ...


Scanning Electron Microscopy Of The Pericarp And Testa Of Several Sorghum Varieties, C. F. Earp, L. W. Rooney Jan 1982

Scanning Electron Microscopy Of The Pericarp And Testa Of Several Sorghum Varieties, C. F. Earp, L. W. Rooney

Food Structure

Pericarp thickness (determined by Z gene) varies greatly among sorghum varieties ranging· from very thin (8 ~ m) to very thick (160 ~m ) . Pericarp thickness also varies within an individuual kernel. The areas below the style and near the hilum are the thickest with the sides of the kernel being thinnest . Scanning electron microscopy was used to document differences in pericarp thickness and to explain milling differences . Varieties with a thick pericarp had starch granules in the mesocarp cell layers. Sorghums with a thin pericarp did not have starch granules in the mesocarp except near the hilum and stylar area. U ...


Effect Of High Hydrostatic Pressure On Meat Microstructure, E. A. Elgasim, W. H. Kennick Jan 1982

Effect Of High Hydrostatic Pressure On Meat Microstructure, E. A. Elgasim, W. H. Kennick

Food Structure

Bovine longissimus muscle was prerigor pressure treated at 103.5 MNm- 2 at 37 °C for 2 min and immediately sampled, fixed and examined by light microscopy, scanning and transmission electron microscopy. Parameters like pH, Warner-Bratzler shear force values and sarcomere length were measured and related to the microscopic observations. Pressure treated samples have shorter sarcomere length, lower pH and W-B values. Physical changes include separation of sarcolemmal and endomysial sheath, contraction bands, disruption of myofibrillar structure and increased interfibrillar and intermyofibrillar spaces. At the subcellular levels, disappearance of glycogen granules, appearance of swollen mitochondria, sarcoplasmic reticulum and in some ...


Morphological And Textural Comparisons Of Soybean Mozzarella Cheese Analogs Prepared With Different Hydrocolloids, C. S. Yang, M. V. Taranto Jan 1982

Morphological And Textural Comparisons Of Soybean Mozzarella Cheese Analogs Prepared With Different Hydrocolloids, C. S. Yang, M. V. Taranto

Food Structure

The morphology and texture of mozzarella cheese analogs prepared from soy protein isolate, gelatin, fat and different hydrocolloids (gums) were evaluated and compared. The fracturability, hardness and adhesiveness of the cheese analog gels were found to be proportionally related to the amount of fat and gelatin, and concentration and viscosity of gums. However, the stretchability of the cheese analog progels was not controlled by the viscosity of gums, but by the amount of gum and gelatin in the formulation. Fat content affected the fracturability and hardness, but did not have a significant effect on the other textural parameters or stretchability ...


Microscopy In The Study Of Fats And Emulsions, J. M. Deman Jan 1982

Microscopy In The Study Of Fats And Emulsions, J. M. Deman

Food Structure

Plastic fats consist of a three dimensional network structure of crystals in which liquid oil is trapped. This crystal network is held together by weak attractive forces, the nature of which is nut definitely e stablished. Crystal size is dependent on temperature history and is subject to polymorphic transitions which greatly affect the microstructure of the system. The microstructure of fats has been investigated by using polarized light microscopy, electron microscopy and X-ray diffraction analysis . Recently, a permeametric method has been developed which enables the determination of the specific surface area of the crystals in a fat. This method is ...


Aspects Of Sample Preparation For Freeze-Fracture/Freeze-Etch Studies Of Proteins And Lipids In Food Systems. A Review, Wolfgang Buchheim Jan 1982

Aspects Of Sample Preparation For Freeze-Fracture/Freeze-Etch Studies Of Proteins And Lipids In Food Systems. A Review, Wolfgang Buchheim

Food Structure

To select optimum specimen preparation methods and to correctly interpret freeze-fracture/freezeetch micrographs of food systems a detailed knowledge of the individual steps of preparation -- i.e. chemical fixation of samples, their cryoprotective pretreatment, cryofixation, freeze-fracturing and -etching, and replication -- and of their influence on the appearance of different constituents, especially proteins and lipids, is necessary. Food systems show great variation in composition, structure and especially in their content of water -- e.g. molecular and colloidal solutions, oil-in-water and water-in-oil emulsions, gels suspensions, semi-solid systems such as cheese, dried systems such as milk powders -- thus requiring a careful variation of ...


Ultrastructural Studies Of Milk Digestion In The Suckling Rat, P. B. Berendsen Jan 1982

Ultrastructural Studies Of Milk Digestion In The Suckling Rat, P. B. Berendsen

Food Structure

The structure of milk in the stomach and proximal small intestine of suckling rats at 12 and 24 hours, 5, 10 and 15 days of age was examined by scanning and by transmission electron microscopy. The milk curd in the gastric lumen consisted of chains of casein micelles which entrapped milk fat globules. The appearance was similar to that reported for bovine milk curd and cottage cheese. The gastric milk curd at 12 and 24 hours also contained large masses of granules 4-8 nm in diameter. The relationship of these particles to casein micelles is unknown.

Casein micelles in the ...


Food Microstructure: An Integrative Approach, E. A. Davis, J. Gordon Jan 1982

Food Microstructure: An Integrative Approach, E. A. Davis, J. Gordon

Food Structure

The integration of information at all levels of organization in a food system - atomic and molecular through macroscopic properties is illustrated with cake batters as an example of a formulated food and bovine muscle as an example of a biologically intact, non-formulated food. Direct examples are given using macroscopic data collected in heat and water transport studies followed by integration of microscopical data for interpretive purposes.

The contribution of starch gelatinization to the characteristics of water loss in batter is related to events such as loss of brief ringence as seen by polarizing microscopy , differential heat input as seen by ...


Instrumental And Sensory Analysis Of The Action Of Catheptic Enzymes On Flaked And Formed Beef, S. H. Cohen, R. A. Seagars, A. Cardello, J. Smith, F. M. Robbins Jan 1982

Instrumental And Sensory Analysis Of The Action Of Catheptic Enzymes On Flaked And Formed Beef, S. H. Cohen, R. A. Seagars, A. Cardello, J. Smith, F. M. Robbins

Food Structure

Texture profile analysis, Instron punch and die testing, laser diffraction measurements and scanning electron microscopy (SEM) were used to evaluate the effects of catheptic enzymes on flaked and formed beef. Although salt (NaCl) and sodium tripolyphosphate (TPP) have often been used to improve the textural quality of flaked and formed beef, the catheptic enzymes used in this study were shown to be as effective as NaCl/TPP, and in many cases more effective, in improving the textural characteristics of this product. Instron punch and die and scanning electron photomicrographic analysis showed that the enzyme and NaCl/TPP samples were quite ...