Food Science Commons^™

Studies On The Microdistribution Of Aerobic Enzymes And Myoglobin In Pork, H. J. Swatland

Food Structure

Techniques were developed to study the microdistribution of aerobic enzymes and myoglobin directly on the surfaces of slices of meat. Despite its solubility, the in vivo distribution of myoglobin was preserved post mortem and, in pork, the distribution of myoglobin followed the distribution of aerobic muscle fibers. Aerobic fibers were grouped centrally in their fasciculi. Differences in oxidative enzyme activity between central and peripheral fibers within fasciculi were detected by staining with methylene blue in an atmosphere with controlled levels of oxygen and nitrogen. Within individual aerobic fibers, there was a radial gradient of SOH (succinate dehydrogenase) activity with more …

X-Ray Microanalysis Of Hollow Heart Potatoes, W. P. Mohr, A. R. Spurr, P. Fenn, H. Timm

Food Structure

Electron microprobe and X-ray fluorescence techniques were used to study elemental gradients associated with the physiological disorder hollow heart i n potato tubers. Gradients were found along the length and across the width of mature tubers. These were not rela ted to the disorder, however . Tubers with advanced symptoms of the disorder had elemental levels and gradients similar to those in healthy, control tubers. The results suggest that if the disorder is initially caused by an elemental deficiency, as has sometimes been proposed , the deficiency is temporary and no longer exists in mature tubers with advanced hollow heart. …

Light And Scanning Electron Microscopy Of Wheat And Rye-Bread Crumb. Interpretation Of Specimens Prepared By Various Methods, Y. Pomeranz, D. Meyer

Food Structure

The crumb of bread baked from wheat flour, rye flour, and rye meal was examined by light( LM ) and scanning electron-microscopy {SEM) . Whereas in the wheat bread the crumb is held together by a matrix of denatured protein, in the rye bread crumb highly expanded starch granules fulfill that r ole . Fractur i ng freeze-dried crumb ~rovided different information than sectioning !Jrior to freeze-drying . In the first case, little damage was caused to components of outer surfaces of vacuoles. In the second case , the protein matrix and starch granules were broken. At the same time, …

Microstructure Of Set-Style Yoghurt Manufactured From Cow's Milk Fortified By Various Methods, A. Y. Tamime, M. Kalab, G. Davies

Food Structure

Five different batches of skim milk were prepared and fortified by the addition of skim milk powder (SMP) or sodium caseinate (Na-cn) or by concentration using a vacuum evaporator (EV), ultrafiltration (UF), or reverse osmosis (RO) to contain similar levels of protein (5.0-5.5%). Yoghurts were made by inoculating the milks with one of 3 commercial yoghurt starter cultures and by incubating the mixes at 42°C for 2.5 h. The following factors were found in this study to affect firmness of the yoghurts: (a) Lactic acid production (acidity) - Yoghurts containing 1.02% of lactic acid or more (pH 4.54 or less) …

Processing Effects On Meat Product Microstructure, Glenn R. Schmidt

Food Structure

Animal species, meat ingredient properties, comminution equipment, mechanical action, product composition, type and level of non-meat ingredients, and thermal processing greatly affect the structural and organoleptic properties of meat products. However, additional research in the area of restructured meat products, meat protein functionality and lipid properties in meat products remains to be done. The interaction of meat proteins with lipids, water and ions should be further investigated. Considerable control of raw materials, mechanical action and heat processing is essential to make research applicable to product and process development.

The Effect Of Salt And Pyrophosphate On The Structure Of Meat, C. A. Voyle, P. D. Jolley, G. W. Offer

Food Structure

Our obective was to determine whether or not salt and pyrophosphate have the same effect on the structure of pieces of meat as they have on isolated myofibrils. Blocks of pig M. longissimus dorsi were incubated in solutions of sodium chloride at pH 5.5 or sodium chloride plus sodium pyrophosphate at pH 5.5 or 8.0. The blocks were obtained from fresh (24h post- mortem) or aged (72h post-mor tem) muscle and incubated for 5 or 24h with minimal agitation. There was considerable uptake of water by the tissue especially at the higher pH and longer times.

Electron microscopy of the …

An Analysis Of Microstructural Factors Which Influence The Use Of Muscle As A Food, R. G. Cassens, C. E. Carpenter, T. J. Eddinger

Food Structure

Study of structure of muscle provides information on the location and arrangement of various components and the changes which may be inflicted upon them. The structura l features of muscle have been descr ibed in detail down to the molecular level, but rega rding its use as a food, special interest centers on the connective tissue component and on myofibri llar proteins . Muscle comprises about 1/3 of the live weight of the a ni mal and is not static , but rather is subject to major changes in properties associated with growth, repair and se nescence. It is apparent …

A Simple Procedure For The Preparation Of Stirred Yoghurt For Scanning Electron Microscopy, Paula Allan-Wojtas, Miloslav Kalab

Food Structure

Stirred yoghurt is aspirated into agar gel tubes having 1.2 mm interior diameter, fixed in glutaraldehyde , dehydrated in ethanol freeze - fractured under liquid nitrogen and critical-point dried. Agar gel encapsulation protects the sample and prevents it from disintegration during the preparative steps. Scanning electron microscopy of the mounted fragments reveals the corpuscular microstructure of this type of yoghurt which develops due to stirring and pumping of the product during manufacture.

Artefacts In Conventional Scanning Electron Microscopy Of Some Milk Products, Miloslav Kalab

Food Structure

Artefacts develop due to changes in the microstructure of the sample under study because of inappropriate preparatory steps and/or due to distortion of the images of properly prepared samples during operation of the microscope. Of a wide variety of possible artefacts. only those occurring mast frequently have been selected and ilustrated with micrographs. In milk powders, the most common artefacts are the recrystallization of lactose in a humid atmosphere, "1 ine" and "dark-area" charging artefacts, and electron beam damage. In moist milk products, artefacts may arise at any preparatory step, such as sampling, fixation, dehydration and critical-point drying or freezing …

Effect Of Environment On The Physical Structure Of The Peanut (Arachis Hypogaea L.), Clyde T. Young, William E. Schadel

Food Structure

Peanuts produced under the drought conditions of 1980 were marred by off-flavors when processed. Several phys ical characteri stics of these peanuts were noted to be related to these flavor problems. This paper deals with the investigation of these physical peculiarities using scanning electron microscopy. Major findings include previously unreported physical abnormalities such as: (1) tissue damage which appears as spotting on the outer surface of the cotyledon which is a result of cracking and fissuring; (2) tissue damage which appears as a narrow band along the inner face of the outer rounded surface and the flattened edge of the …

The Role Of Gap Filaments In Muscle And In Meat, R. H. Locker

Food Structure

The neglected "gap filaments" are now beginning to receive close attention in several centers, in terms of organisation, composition and function. The author's model for their connections gave them a role as cores to A-filaments. This review attempts to weigh the implications of such a role, and relevant evidence, old and new. New ideas arising largely from PAGE*and immunochemkal studies on candidate proteins, and from the developing concept of the cytoskeleton, are considered.

The author's theory of meat tenderness, based on G-filaments, has been tested by PAGE studies on changes in the large structural proteins (particularly titin and nebulin) during …

Mineral Migration In The Wheat Kernel During Mill Conditioning, A. Al Saleh, B. Bouchet, D. J. Gallant

Food Structure

The structure and histology of the kernel govern migration of water during conditioning or drying. Studies by the energy dispersive x-ray system under the SEM have shown that during an increase of water content from 11.5 to 16.5 per cent, soluble elements migrated from the peripheral bran, accumulated in the aleurone cells and passed through its walls to the endosperm of the kernel if the water content was above 14.5 per cent. Results of study were compared with analyses of milling fractions obtained under the same conditions.

Ultrastructure Of Quinoa Fruit (Chenopodium Quinoa Willd), E. Varriano-Marston, Alicia Defrancisco

Food Structure

The structure of quinoa (Chenopodium quinoa) fruit before and after germination was studied using electron microscopy. Protective coverings include a perianth consisting of loosely adhering cell s which are readily removed by washing, a pericarp and two seed coat layers. Starch granules fill the perispenn cells and are arranged in 18 to 20 oblong aggregates. Limited hydrolysis of the starch occurs after 24 hrs of germination, with amylolytic erosion of large granules occurring at the hilum and periphery of the granul es. Ungerminated embryo cells contain protein bodies with phosphorus-containing globoid inclusions. Essentially complete hydrolysis of the embryo protein bodies …

Ultrastructural Studies Of Raw And Processed Tissue Of The Major Cultivated Mushroom, Agaricus Bisporus, E. M. Jasinki, B. Stemberger, R. Walsh, A. Kilara

Food Structure

Commercial mushroom processors currently lose approximately 30 percent of the mushroom weight due to shrinkage during processing (blanching and canning) , resulting in substantial economic losses . Microscopy was used to assess the extent and type of chemical and structural changes induced by processing mushrooms and causing shrinkage. Scanning electron microscopy revealed that the processing operations including vacuum hydration , blanching , and thermal treatment do not damage the integrity of the tissue. Light microscopy revealed that the morphology of the tissue, shape and spacing of cells, appear similar for raw and processed mushroom tissue . However, the intra ce …

Ultrastructural Aspects Of Spun Pea And Fababean Proteins, D. J. Gallant, B. Bouchet, J. Culioli

Food Structure

The ultrastructure of pea and fababean spun proteins has been studied by SEM and TEM as a function of dope pH and washing bath salt concentrations. The textural properties {mechanical resistance, moisture content) and diameter of the fibres have been determined.

Spinning was only possible when dope pH was higher than 11. An increase in dope pH from 11.5 to 13 induced a shear strength increase whereas the moisture content and the diameter of the fibres decreased . The structure of the fibres became more compact and changed from an aggregate of spherical particles to a tridimensional network. When dope …

Morphological Development In Sorghum Grain, C. W. Glennie, N.V.D. W. Liedenberg, H. J. Van Tonder

Food Structure

Immature sorghum grain was harvested at various stages of maturity and its development followed by transmission and scanning electron microscopy . This was done to study the developmental morphology of the sorghum grain. The period immediately following fertilization is a time of rapid development in the sorghum caryopsis. The endosperm expands crush i ng the nucellus and in the nonbirdres i stant sorghums the inner integument is also crushed during this expansion. The cells of the ovary wal 1 expand and elongate to form the peri carp . By the soft dough stage the endosperm has gained most of its …

A Review Of The Muscle Cell Cytoskeleton And Its Possible Relation To Meat Texture And Sarcolemma Emptying, D. W. Stanley

Food Structure

A review of the muscle cytoskeleton is presented. Current evidence leads to the concept of a muscle cell cytoskeleton consisting of at least two elements - gap filaments which are located parallel to the fiber ax~s and provide intracellular elasticity and tensile strength and intermediate filameots found in the zdisc area that function to connect adjacent Z- discs and promote lateral registration. The former constituent consists of the high molecular weight protein connectin (titinl while the latter is composed of the smaller protein desmin (skeletinl. Both proteins exist in filamentous form, are susceptible to proteolysis and are insoluble in physiological …

Image Analysis Of Morphological Changes In Wiener Batters During Chopping And Cooking, A. G. Kempton, S. Trupp

Food Structure

Histological changes in wiener batters during chopping and cooking have often been illustrated with "representative" fields . The practice of selecting representative fields ignores variation and leads to word descriptions that cannot be correlated with numerical scores for functional or sensory tests . If wieners are regarded as a multi-component system, objectivity can be achieved by selecting many fields for each sample according to a rigid sampling plan. Image analysis quantified parameters of both the fat and protein components . The reduction in size of fat globules during chopping of a commercial formulation, for example, was a function of area …

Microstructure Of Winged Beans, K. Saio, Y. Nakano, S. Uemoto

Food Structure

Microstructures of seven plant introductions of winged beans (Psophocarpus tetragonolobus) produced in Okinawa, Japan were investigated. In cotyledonary cells of winged beans, protein bodies plus numerous lipid bodies were distributed in a cytoplasmic network. Starch granules were often found in some introductions but rarely in others. All seven introductions had very thick cell walls. The high protein, fat and hemicellulose contents of winged beans are consistent with the numerous protein bodies, lipid bodies and thick cell walls in the mature cotyledonary cells. The cell walls contained a number of depressions or cavities 1 to 2 lJ m deep which frequently …

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 …

Endosperm Degradation In Barley Kernels That Synthesize Amylase In The Absence Of Embryos And Exogenous Gibberellic Acid, A. W. Macgregor, P. B. Nicholls, L. Dushnicky

Food Structure

During germination at l6°C, whole seeds and distal half-seeds of Klages barley and two types of Clipper barley (Types A and B) were analyzed for a -amylase . Structural changes in the endosperms of these seeds and half-seeds were examined by scanning electron microscopy. In Clipper B half-seeds, Q-amy base activity increased significantly , there was a detectable amount of starch granule hydrolysis and endosperm structure was markedly degraded. No starch hydrolysis and only trace amounts of a-amylase and endosperm degradation were detected i.n Clipper A and Klages halfseeds. The rewns significant a -amylase synthesis, starch hydrolysis and endosperm degradation …

Stranded Structure Development In Thermally Produced Protein Concentrate Gel, T. Beveridge, L. Jones, M. A. Tung

Food Structure

Scanning electron micrographs of thermally induced whey protein concentrate gels were taken. Sample preparation was accomplished by glutaraldehyde fixation, osmium tetroxide post fixation and critical point dehydration. Stranded or beaded gel structures were observed on the external surface of a gas bubble, suggesting that a "string-of-beads" gel microstructure may result from bubble formation during thermal treatment.

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 …

The Effects Of Commercial Processing On The Structure And Microchemical Organization Of Rapeseed, S. H. Yiu, I. Altosaar, R. G. Fulcher

Food Structure

Rapeseed samples collected from different processing stages were obtained from one commercial crushing plant for the present investigation. The samples included (A) whole seeds, (B) flaked seeds, (C) press cakes, (D) solvent extracted meal, (E) desolventized meal and (F) cooled, desolventized meal . Frozen and/or glycol met hacrylate-embedded sections of the samples were examined using the techniques of fluorescence microscopy. Mechanical crushing tended to disrupt cell walls. After cooking and expeller pressing, individual protein bodies fused to form large masses encompassing phytin containing globoids. Storage lipids also coalesced into larger droplets. Most of the oil was removed after solvent extraction …

Morphometry Of Meat By Scanning Light Microscopy, H. J. Swatland

Food Structure

Morphometric data can be collected from meat by using a scanning stage and a photometer, both controlled by a microcomputer. The passive counting of connective tissue boundaries is g1ven as an example to show that enumerative data may be biassed by the ratio of the width of the subject of measurement to the projected diameter of the photometer aperture. In a second example, the scanning stage is actively directed by the observer and is used to map the radial distribution of succinate dehydrogenase (SOH) activity in different histochemical types of muscle fibers. This is accomplished by the arbitrary fitting by …

Effect Of Prerigor Pressurization On Bovine Lysomal Enzyme Activity, E. A. Elgasim, W. H. Kennick, A. F. Anglemier, M. Koohmaraie, E. A. Elkhalifa

Food Structure

Longissimus muscle from 8 dairy cows was prerigor pressure (PRP) treated at different pres sure levels (0, 34.5, 68.9 and 103.5 I·INm- ' ). a-Glucuronidase (indicator of lysosomal enzymes) activity in the unsedimentable (U) and sedimentable (S) fractions was fluorometrically assayed at ! ~ , 24 and 168 hr postmortem. At I ~ and 24 hr postmortem, the specific activity of a-Glucuronidase in the U-fraction from PRP treated samples was significantly (P

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 …

Sensory And Instrumental Texture Properties Of Flaked And Formed Beef, Armand V. Cardello, Ronald A. Segars, John Secrist, Joseph Smith, Sam H. Cohen, Robert Rosenkrans

Food Structure

Four experiments were conducted to assess the sensory textural properties, consumer acceptability and instrumental-sensory correlates of flaked and formed beef steaks. In Experiment 1, the effects of additions of NaCI, TPP and soy isolate on the texture of steaks were examined using a trained texture profile panel, and the texture of these steaks was compared to that of intact muscle (ribeye) steaks. Results showed large differences between the flaked and formed samples and the ribeye steak, as contrasted to small differences among the flaked and formed samples treated with different levels of NaCI, TPP and/or soy isolate.

In Experiments 2 …

Field Spectroscopy In The Food Production Chain, E. J. Brach

Food Structure

This paper reviews the application of field spectroscopy in the food production chain, particularly how field spectroscopy aids research and production of agricultural crops , and helps to understand the process of converting these crops into food.

The review discusses the nondestructive application of field spectroscopy such as ultraviolet, reflective , visible, near infrared and fluorescence techniques using conventional or laser light sources, to determine qualitative and quantitative properties of agricultural crops and produce.

Field spectroscopy can provide data on soil constituents and moisture, crop maturity, crop vigor, crop health, variety, variety within crops , and protein and moisture content …

Composition And Microstructure Of Soft Brine Cheese Made From Instant Whole Milk Powder, Mohamed M. Omar, Wolfgang Buchheim

Food Structure

Comparative studies were made on the composition, microstructure and organoleptic quality of soft brine cheese made from instant whole miIk powder and from raw miIk. The chemical analysis of young and ripened (one and two month) cheese revealed similarity except for a higher salt content in the cheese made from reconstituted milk at the end of ripening . Electron microscopic studies showed distinct differences in the structure of the protein matrices in the ripened cheese samples , i .e . a very homogeneous structure in the cheese made from raw milk compared with a slightly aggregated state of the protein …