Food Science Commons^™

Sample Holders For Solid And Viscous Foods Compatible With The Hexland Cryotrans Ct 1000 Assembly, Miloslav Kalab, Paula Allan-Wojtas, Ann Fook Yang

Food Structure

A brass block., 3 .7 mm high and 10 mm in diameter, which has three openings to accommodate rivet-type or plain tubular specimen holders for scanning electron microscopy at low temperature, has been designed to fit the Hexland Cryotrans CT 1000 assembly in place of the original aluminum disc. Viscous food samples are placed in two-piece tubular holders (0.9 mm inner diameter, 1.2 mm outer diameter) made from sterling silver, and rapidly frozen. The holders are inserted into the brass block under 1 iquid nitrogen and tightened with individual setscrews. A handle screwed into the central hole of the block …

The Application Of Cold Stage Scanning Electron Microscopy To Food Research, J. A. Sargent

Food Structure

Host foods and associated microorganisms contain water which in the vacuun of an electron microscope would rapidly evaporate at ambient temperature . In addition constituent fats may melt under the electron beam. Cryopreservation and examination at low temperature avoids these problems. The structure of emulsified or foamed products can be revealed by freeze-fracture techniques. Products such as ice cream which are not stable even under normal pressures at ambient temperature can be prepared rapidly and examined for prolonged periods.

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 …

Effects Of Lignification, Cellulose Crystallinity And Enzyme Accessible Space On The Digestibility Of Plant Cell Wall Carbohydrates By The Ruminant, M. S. Kerley, G. C. Fahey Jr., J. M. Gould, E. L. Iannotti

Food Structure

Intrinsic characteristics of plant cell walls limiting susceptibility of structural carbohydrates to microbial attack in the ruminant's gastrointestinal tract are lignification of the cell wall, covalent bonding of phenolic acids to cell wall polysaccharides, the crystalline structure of cellulose and limited fibrolytic enzyme accessible space. The exact mechanism by which or degree to which each of these characteristics affect rate and/or extent of cell wall polysaccharide hydrolysis by gastrointestinal tract microbes is not well understood. Lignification and limited enzyme accessible space probably affect the extent of cell wall degradation by preventing contact between microbial enzymes and cell wall polysaccharides. Phenolic …

The Microstructure Of Spray-Dried Microcapsules, M. Rosenberg, Y. Talmon, I. J. Kopelman

Food Structure

A newly developed technique for SEM sample preparation has been applied in the study of the effects of process parameters on the microstructure of gum arabic spray-dried microcapsules. The technique, that employs embedding in an apolar resin and partial polymerization makes it possible to simultaneously observe the inner and outer structure of microcapsules. Our results show how the core material is organized in the solid wall matrix, existence of one or more internal voids in the microcapsule, indentation and caps in the exterior of the microcapsules, and how these microstructural features are affected by solids concentration in the sprayed emulsion, …

Changes In The Microstructure Of Saint Paulin Cheese During Manufacture Studied By Scanning Electron Microscopy, Micheline Rousseau

Food Structure

The Saint Paulin cheese used in this study contains 45% fat. Changes in curd structure were followed during syneresis until the end of ripening. Two scanning electron microscopy (SEM) techniques were used: the conventional technique with sample fracture after critical point drying, and cold-stage SEM after rapidly freezing samples at -160 C. The two techniques are complementary since the first leads to satisfactory observation of casein, while the other is more suitable for observing fat globules.

Amino Acid Composition And Structure Of Cheese Baked As A Pizza Ingredient In Conventional And Microwave Ovens, Alenka Paquet, Miloslav Kalab

Food Structure

Amino acid compositions of stirred-curd Mozzarella, stretched Mozzarella, and process Cheddar cheeses were similar and did not change as the result of baking in a conventional oven. D-glutamic acid (D0Glue) and D-phenyl-alanine (D-Phe) were present at low concentrations in all cheese samples, the lowest concentrations having been found in unbaked stirred-curd Mozzarella cheese (2.7% D-Glu of total Glu present and <1.0% D-Phe of total Phe present). The highest concentrations were detected in unbaked stretched Mozzarella cheese (5.6% and 1.2%, respectively). Thechanges were not significant and were not the result of aking, indicating that the heat treatment during baking did n ot cause racemization of the amino acids.

Each cheese had a characteristic structure before baking. The structures of the Mozzarella cheeses were altered by baking in the conventional oven and also in a microwave oven and their original features such as curd granule junction and fat globule …

The Effect Of Processing On Some Microstructural Characteristics Of Fat Spreads, I. Heertje, J. Van Eendenburg, J. M. Cornelissen, A. C. Juriaanse

Food Structure

The processing and the composition of fat spreads determine to a large extent the final product properties such as hardness, spreadability, mouthfeel, emulsion stability and salt release. In establishing the relation between composition, processing and final product properties, microstructural studies play an important role. In this context the influence of some process parameters in the production of shortenings and 80% fat spreads on microstructure and product properties has been investigated. Shear, cooling regime and crystallization conditions influence both the emulsion structure and the fat crystalline matrix. In general, working leads to softer products with a more granular crystalline fat matrix, …

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, …

Characterization Of Hypercontracted Fibers In Skeletal Muscle Of Domestic Turkey (Meleagris Gallopavo), A. Sosnicki, R. G. Cassens, D. R. Mcintyre, R. J. Vimini, M. L. Greaser

Food Structure

Several different muscles from a population of thirty Large White male turkeys were studied by histological and histochemical methods, and a high incidence of hypercontracted fibers was noted . The fibers were characterized in cross-section by an apparent swelling, a rounded rather than polygonal shape and a homogenous appearance. They were eosinophilic, positive to Gomori-trichrome and appeared to have an elevated lipid content. An unusual histochemical profile was noted. It was postulated that the hypercontracted fibers were real , not artifnctual, and resulted from some change occurring in the muscle.

The Effect Of Storage, Processing And Enzyme Treatment On The Microstructure Of Cloudy Spartan Apple Juice Particulate, D. L. Mckenzie, T. Beveridge

Food Structure

The effect of blanching, post-harvest refrigerated (4C) storage and enzyme treatment with poly-galacturonase on the microstructure of Spartan apple juice was examined by thin sectioning and negative staining transmission electron microscopy. Particles were categrized as granules (3-54 nm), spheres (20-368 nm) and aggregates (12-2519 nm). Enzyme treatment with polygalacturonase significantly decreased granule size (P < 0.01). Storage of apples significantly decreased both granule size (p < 0.01) and aggregate length (p < 0.05) and also resulted in a web-like aspect in the microscopic appearance of juice particulate. The web-like aspect of the particulate was removed either through enzyme treatment with polygalacturonase or by blanching. Blanching of puree significantly increased granule (p < 0.05) and sphere size (p < 0.01) while significantly decreasing aggregate length (p < 0.01). In addition, blanching stabilized suspended particulate by what appeared to be the formation of a protective colloid which prevented particle aggregation through electrostatic repulsion.

The Role Of B-Lactoglobulin In The Development Of The Core-And-Lining Structure Of Casein Particles In Acid-Heat-Induced Milk Gels, V. R. Harwalkar, Miloslav Kalab

Food Structure

Acid-heat-induced gels were obtained by coagulating casein micelle dispersions at 90 C using glucono-and-lactone. The casein micelles used were isolated from raw skim milk by centrifugation, washed free of whey proteins and soluble salts, and dispersed in water or a milk dialyzate. The pH values of the gels varied from 4.7 to 6.3. A core-and-lining ultrastructure developed in casein particles coagulated at pH 5.2 to 5.5 from casein micelle dispersions in the milk dialyzate provided that B-lactoglobulin or whey proteins (10 mg/ml) were added to them prior to coagulation. Addition of B-lactoglobulin to aqueous casein micelle dispersions led to the …

Plasmid-Linked Maltose Utilization In Lactobacillus Spp. Isolated From Meat, Mei-Ling Liu

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Five strains of Lactobacillus plantarum and four strains of Lactobacillus species isolated from fresh meat were examined for the presence of plasmid DNA. All strains examined contained between one and five plasmids ranging in molecular mass from 1.3 to 51.6 (Mdal). Plasmid-curing experiments suggest that maltose utilization is associated with a 51 Mdal plasmid in Lactobacillus sp. DB29 and 42 Mdal plasmids in Lactobacillus spp. DB27, DB28, DB31. Southern blot DNA-DNA hybridization showed homology between the maltose plasmid from Lactobacillus sp. DB29 and several plasmids from the other Lactobacillus spp.

Fluoride Content In Home-Canned Fruits In Utah, Sydney Ann Mcdonald

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The purpose of this research was to determine whether or not canning fruit using fluoridated water made a difference in the fluoride contents of the juice and the pulp. Four cities in Utah were chosen. Two cities were fluoridated (Brigham City and Helper) and two cities were not fluoridated (North Ogden and Price). Three homes were chosen within each city, and three jars of canned fruit (one jar each of apricots, cherries, and peaches) were selected from each home. The fruit samples were freeze-dried, and then the fluoride was measured with a fluoride ion electrode. A difference was found in …

The Effect Of Ultrafiltration On Protein Quality Of Skimmilk And Cottage Cheese, Rita Y. Y. Tung

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Protein quality in freeze-dried skimmilk (SM), regular cottage cheese (RCC), retentate (Ret) and cottage cheese made from ultrafiltrated skimmilk (UFCC) were evaluated by chemical (amino acid score) and biological methods. Biological evaluation was at 5, 8 and 11% protein level in growing rats by measuring biological value (BV), net protein utilization (NPU) and nitrogen efficiency for growth (NEG) over a 14-day period. A 28-day protein efficiency ratio (PER) was determined on the same products at 10% protein level. Effects of added lactose on PER of retentate, regular and UFCC were also evaluated. The most limiting amino acids were cystine + …

Cottage Cheese From Ultrafiltered Skimmilk By Direct Acidification, Jorge Ricardo Ocampo-Garcia

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Pasteurized skimmilk at 4°C was acidified to pH 5.8 with 85.5% phosphoric acid (136g H₃PO₄/100 kg skimmilk), then warmed to 54°C and ultrafiltered to a protein concentration 9.1 ± 0.2%. The retentate was heated to 76.5°C for 16 s then cooled to 2°C. Phosphoric acid (85.5%) was added at a rate of 3.41g per kg retentate. The acidified retentate was slowly warmed to 29.5°C (3°C/5 min) when the pH was checked. The pH at this point was no lower than 5.4. Heating was continued until a temperature of 32.2°C was reached. Glucono delta lactone was added …

Factors Affecting Growth Of Proteinase Positive And Proteinase Negative Streptococcus Cremoris Uc310 In Ultrafiltered Milk Retentate, Brent Karl Pope

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Whole milks were adjusted to pH 5.8, 6.2, or 6. 7 with HCl and batch pasteurized at 63°C for 30 min. Each was concentrated 5:1 (40% total solids) through a single tube polysulfone membrane Abcor ultrafiltration unit. Lactose (L), casein hydrolysate (CH), and one of two brands of yeast extract (YE1, YE2) were added into cooled retentates at 0.1, 0.3, 0.5, 0. 7 or 0.9% and equilibrated overnight at 4°C. Five percent proteinase positive (Prt+) Streptococcus cremoris UC 310+ (v/w) milk based culture was added. Unfortified retentate was also inoculated with 0.1, 0.3, 0.5, 0. 7 or 0.9% starter and …

Effect Of Proteolytic Enzymes On Transfection And Transformation Of Streptococcus Lactis Protoplasts And Transformation Of Streptococcus Cremoris, Steven A. Woskow

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The effect of proteolytic enzymes on the transformation and transfection of Streptococcus lactis LM2301 protoplasts was examined in an attempt to eliminate the variability observed. By using both chymotrypsin and mutanolysin to form protoplasts followed by spread plating, consistent frequencies of 104 to 105 transformants per μg of pGB301 DNA, and 105 transfectants per μg of c2 bacteriophage DNA where achieved. Optimum transformation and transfection frequencies were obtained when 16 h cultures were treated simultaneously with 25 U/ml mutanolysin and 1.25 U/ml chymotrypsin for 15 min. Trypsin and pronase in conjunction with mutanolysin also increased transformation frequencies higher than when …

Effects Of Sire, Ration, And Interaction Of Sire With Ration On Reproductive Performance Of Holstein Dairy Cows, Jen-Hon Justin Chen

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

A study was conducted to analyze reproductive data gathered over a ten-year period at the Utah State University Dairy Farm. The study utilized 289 complete first lactations of Holstein cows, including 150 daughters of 10 sires in Trial I and 139 daughters of 8 sires in Trial II. One sire was used in both trials; this was sire 4 in Trial I and sire 18 in Trial II. The study measured ration, season, and sire effects and their interactions on the reproductive performances of dairy cows.

Reproductive traits analyzed were: days from calving to first estrus, days from calving to …

The Effects Of Polysorbate 80 On The Fat Emulsion In Ice Cream Mix: Evidence From Transmission Electron Microscopy Studies, H. D. Goff, M. Liboff, W. K. Jordan, J. E. Kinsella

Food Structure

Emulsifiers are used in ice cream to produce a dry, smooth textured product with desireable melting properties. They function by promoting a partial destabilization of the fat emulsion. Polyoxythylene sorbitan monooleate is used very commonly in the ice cream industry for this purpose. The objective of this research was to examine by transmission electron microscopy the differences in the fat globules in typical ice cream mix emulsions prepared with and without 0.08% polyoxyethylene sorbitan monooleate.

Ice cream mix was combined 3:1 with a 2% solultion of ultralow gelling temperature agarose at 20 degrees C, fixed with 4% glutaraldehyde, postfixed with …

Structural Binding Properties Of Silvercarp (Hypophtalmichthys Molitrix) Muscle Affected By Nacl And Cacl2 Treatments, Ilan Shomer, Zwi G. Weinberg, Roza Vasiliver

Food Structure

The texture of restructured muscle products is well known to be strongly affected by various salts. In the present work the effects of NaCl and CaCl2 on the ultrastructure of both fresh and cooking salted silvercarp (Hypophthalmichthys molitrix) muscle were examined, in order to elucidate the heat-initiated binding phenomenon. Sodium chloride at 0.3 and 1.5% caused swelling and fusion of the myofibrils and loss of arrayed structure. Calcium chloride at all the tested concentrations resulted in shrinkage of myofibrils, The present study demonstrated two main effects of salts on the ultrastructure of fish muscles: (i) swelling of myofibrils which, at …

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 …