Food Science Commons^™

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 …

Proceedings From The 24th Annual Marschall Italian Cheese Seminar, Various Authors

Cheese Industry Conference

No abstract provided.

Influence Of Thresher Cylinder Speed And Grain Moisture At Harvest On Milling Yield Of Rice, R. H. Dilday

Journal of the Arkansas Academy of Science

The percentage of broken rice (Oryza sativa) kernels was determined after threshing the grain at varying cylinder speeds of the thresher and moisture contents of the grain at harvest. Moisture contents of the individual grain samples ranged from 12 to 26% and the two cylinder speeds were 600 and 1000 RPM. Significant differences between germplasm, cylinder speed and moisture content of the grain at harvest on milling yield was observed. For example, Newbonnet had the fewest broken kernels while Leah had the greatest amount of broken kernels. Lemont produced the highest total milling yield; whereas, L202 produced the lowest total …

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 …

Wheat Payments And Protein Content, Department Of Agriculture, Western Australia

Journal of the Department of Agriculture, Western Australia, Series 4

In recent years there has been increasing support from within the Australian wheat industry for the principal of wheat growers recieving payment for their grain according to market value.

Individual loads are now tested for quality characteristics such as hectolitre weight, unmillable material and moisture content.

At present, technology is not sufficiently advanced to enable rapid and accurate analysis of individual loads for all important quality factors.

A more practical system of quality assessment would be one based on allowances for various basic measures (such as hectolitre weight, unmillable material and moisture content), variety (to allow for genetic differences in …

Dairy Herd Recording, R D. Maughan, Frank Treasure

Journal of the Department of Agriculture, Western Australia, Series 4

Fifty-five percent or 320 of Western Australia's daity farmers participate in the dairy herd recording, the highest percentage of dairy farmers who use herd recording in any Australian State.

Herd recording provides the dairy farmer with an accurate measure and record of individual caw and hers performance. Information on milk, fat and protein production, the level of mastitis infection and breeding values assists the dairy farmer with his herd management and selection of cows. The herd recording facility is provided by the Herd Improvement Service and the fees are based on an annual herd fee and a lactation fee for …

Variation In Wheat Protein Content : The Effect Of Environment, G B. Crosbie, Harry Fisher

Journal of the Department of Agriculture, Western Australia, Series 4

Over the past 20 years, the average protein content of WesternAustralian wheat has ranged from 9.3 to 12.0 per cent, with a mean level of 10.4 per cent. At most grain receival points, in any one season, individual loads can often vary in protein content by as much as 5 per cent protein or more. Rainfall and soil fertility account for much of this variation.

Increasing Protein Content Of Wheat By Breeding, B R. Whan, Graham Crosbie

Journal of the Department of Agriculture, Western Australia, Series 4

The most efficient means of increasing protein content of WesternAustralian wheat is by breeding new varieties with higher inherent protein in their grain. But is this possible without sacrificing yeild or other desirable characteristics?

Trends In Wheat Protein/Yield Relationships, G B. Crosbie, Harry Fisher, Bryan Whan

Journal of the Department of Agriculture, Western Australia, Series 4

The major concern of wheat breeders in WesternAustralia has been to increase grain yield while maintaining quality at an acceptable level. There has been no concious effort to select for protein content. It is of interrest, therefore, to compare the relationship between yield and protein of varieties which have been prominent in Western Australia at various times, to see what effects yield increases have had on protein content and the extent of any variation which might exist.

Food Quality And Energy Usage In Foodservice Systems: Convective Thermal Processing Of Turkey Rolls, M. E. Matthews, M. E. Zabik, R. B. Maxcy

Department of Food Science and Technology: Faculty Publications

This study evaluated sensory and nutritional qualities, microbioloqical and chemical safety of turkey rolls and enerqy use durinq convective thermal processing. Turkey rolls were heat processed in home or institutional convection ovens to an internal temperature of 77 to 80°C in the geometric center of the roll. Treatment combinations included three heat-processing temperatures (105, 135, and 165°C) and two holding treatments (not chilled and chilled for 24 hr) and three hot-holding times (0, 60 and 120 min). Sensory studies of white turkey meat roasted at 165°C and reheated showed that juiciness decreased significantly (p<0.05), compared to roasting at 105 or 135°C without reheating. Juiciness was also decreased significantly (p<0.05) as hot-holding progressed (0 to 120 min).

Coagglutination And Enzyme Capture Tests For Detection Of Escherichia Coli Β-Galactosidase, Β-Glucuronidase, And Glutamate Decarboxylase, Charles W. Kaspar, Paul A. Hartman, Andrew K. Benson

Department of Food Science and Technology: Faculty Publications

Polyclonal antibodies to Escherichia coli β-galactosidase, β-glucuronidase, and glutamate decarboxylase were used in coagglutination tests for identification of these three enzymes in cell lysates. Enzyme capture assays were also developed for the detection of E. coli β-galactosidase and β-glucuronidase. The enzymes were released by using a gentle lysis procedure that did not interfere with antibody-enzyme interactions. All three enzymes were detected in 93% (51 of 55) of the E. coli strains tested by coagglutination; two of the three enzymes were identified in the remaining 7%. Of 42 non-E. coli tested by coagglutination, only four nonspecifically agglutinated either two or …

Prevalence Of Sensitivity To Sulfiting Agents In Asthmatic Patients, Robert K. Bush, Steve L. Taylor, Karen Holden, Julie A. Nordlee, William S. Busse

Department of Food Science and Technology: Faculty Publications

Ingestion of sulfiting agents can induce wheezing in some asthmatic patients. However, neither the prevalence of sulfite sensitivity nor the clinical characteristics of the affected asthmatic population are known. In a prospective single-blind screening study, 120 non-steroid-dependent and 83 steroid-dependent asthmatic patients underwent challenge with oral capsules of potassium metabisulfite. Five non-steroid-dependent and 16 steroid-dependent asthmatic patients experienced a greater than 20 percent reduction in their one-second forced expiratory volume within 30 minutes following the oral challenge. Twelve of these sulfite reactors were rechallenged with metabisulfite capsules in a double-blind protocol. Under these conditions, only three of seven steroid-dependent patients …

Phosphotransferase Activity In Clostridium Acetobutylicum From Acidogenic And Solventogenic Phases Of Growth, Robert W. Hutkins, Eva R. Kashket

Department of Food Science and Technology: Faculty Publications

Clostridium acetobutylicum cells, when energized with fructose, transported and phosphorylated the glucose analog 2-deoxyglucose by a phosphoenolpyruvate-dependent phosphotransferase (PT) system. Butanol up to 2% did not inhibit PT activity, although its chaotropic effect on the cell membrane caused cellular phosphoenolpyruvate and the 2-deoxyglucose-6-phosphate to leak out. Cells harvested from the solventogenic phase of batch growth had a significantly lower PT activity than did cells from the acidogenic phase.