Food Science Commons^™

A Moving Optical Fibre Technique For Structure Analysis Of Heterogenous Products: Application To The Determination Of The Bubble-Size Distribution In Liquid Foams, C. G. J. Bisperink, J. C. Akkerman, A. Prins, A. D. Ronteltap

Food Structure

The bubble-size distribution in liquid foams measured as a function of time can be used to distinguish between the physical processes that determine the breakdown of foams. A new method based on an optical fibre technique was developed to measure various foam characteristics e.g. the rate of drainage, the rate of foam collapse, the change in gas fraction, interbubble gas diffusion (disproportionation) and the evolution of the bubble - size distribution during the ageing of the foam. The method consists of an optical sensor that can distinguish between phases with distinct refractive indexes as are found in liquid foams.

A Low-Temperature Scanning Electron Microscopy Study Of Ice Cream. I Techniques And General Microstructure, K. B. Caldwell, H. D. Goff, D. W. Stanley

Food Structure

The objective of this study was to investigate techniques suitable for viewing the microstructure of ice cream in the frozen and fully hydrated state using low temperature scanning electron microscopy (L T-SEM), and to examine the microstructure of the frozen product. lee cream bad four distinct structural phases: ice crystals, air bubbles, fat globules and serum. Air bubbles, 10 to 60 ~-tm in diameter, were lined with fat globules, 0.5 to 2.5 J.tnl in diameter. Ice cry stals with a mean di ameter of 40 J.Lffi showed a characteri stic reticulat e structure after sublimation. The appearance of the ice …

Functional Properties And Microstructure Of Chicken Breast Salt Soluble Protein Gels As Influenced By Ph And Temperature, S. F. Wang, D. M. Smith

Food Structure

The effects of different pH's (4 .5 , 5.5, 6.5 and 7.5) and temperatures (30-80 •c) on the functional properties and microstructure of chicken breast salt soluble protein (SSP) in 0.6 M NaCI were investigated. Protein solubility decreased from 98% at pH 6.5 to less than I% at pH 4.3 and below. Salt soluble protein at pH 4.5 produced a discontinuous gel which could not be measured by back extrusion and had an expressible moisture above 80% at all heating temperatures . Aggregated globular microstructures were observed at pH 4.5 by scanning electron microscopy (SEM). Thin-sectioned images as seen by …

Image Analysis To Determine Intramuscular Fat In Muscle, T. Ishii, R. G. Cassens, K. K. Scheller, S. C. Arp, D. M. Schaefer

Food Structure

The area of intramuscular fat in Holstein steer longissimus was determined using an image analyzing system. Slaughter weights of 500, 636 and 773 kg differed (p < 0.05) for intramuscular fat area, marbling score, and ether extractable lipid . Repeated measurements of intramuscular fat area in a given section showed high accuracy . However, comparing two sections from the same sample, there was often a large difference in fat content between the sections. Fat content determined by the imaging system was correlated significantl y with marbling score (r = 0.49) and ether extractable lipid (r = 0.34). Sampling is critical, and in order to obtain a high correlation several samples would be required from each muscle.

Characterization Of The Pore Structure Of Starch Based Food Materials, Z. Hicsasmaz, J. T. Clayton

Food Structure

Macroscopic pore structure parameters (bulk density, true density and porosity) and microscopic pore structure parameters (percentage closed pore volume and pore size distribution) for a highly expanded type (Wonder White Sandwich Bread) and a relatively compact type (Chessmen Butter Cookies) starch based food material were determined and their pore structures were compared. Bulk density determined by solid displacement and true density determined by pycnometry yielded porosity measurement s o f 0.9 for bread and 0.6 for cookies. Percentage closed pore volume calculated by comparing the true density of porous samples of bread and cookies with the true density of !heir …

Influence Of Addition Of Polyols And Food Emulsifiers On The Retrogradation Rate Of Starch, M. Muira, A. Nishimura, K. Katsuta

Food Structure

The influence of polyols and emulsifiers on hardening of non-glutinous rice starch gels has been investigated. The polyols and emulsifiers were added at concentrations of 6% (w/w) and 0.2% (w/w), respectively , to starch gels (starch content, 30%). The hardening rate and the initial viscoelastic values of gels were computed by analyzing static linear viscoelastic parameters (creep compliance) of the gels stored at 0 C for up to 3,000 minutes.

Hardening of gels, i.e., retrogradation of starch, could be described by a first order kinetic equation. Polyols prevented the retrogradation of starch, and formed rigid and stable gel matrices. Emulsifiers …

The Cellular Structure Of Selected Apple Varieties, K. G. Lapsley, F. E. Escher, E. Hoehn

Food Structure

Apple cultivars (Sauergrauech, Klarapfel, James Grieve, Granny Smith, Mcintosh, Robinette) which had different textures based on sensory and instrumental analysis (particularly in firmness and mealiness) were examined by conventional scanning electron microscopy (SEM), cold-stage SEM (cryoSEM) and confocal scanning laser microscopy (CSLM) using various preparative procedures. Advantages, lim itations and artifacts of each technique are discussed.

SEM with glutaraldehyde-fixation and criticalpoint- drying produced minimal tissue distortion and the fracture pattern and appearance of mealy versus non mealy tissue was different. Freeze-drying unfixed tissue caused cell collapse and firm versus soft varieties could not be differentiated. Freeze-fracturing and cryoSEM of apple …

Relating Spectral Observations Of The Agricultural Landscape To Crop Yield, Craig L. Wiegand, Arthur J. Richardson

Food Structure

Remote sensing and microscopy share several common concerns including wavelength and sensor selection, signal processing, and image analysis. For crop yield assessments, multispectral observations are acquired photographically, videographically, or with opticalmechanical scanners from aircraft and spacecraft. Sensors are chosen at wavelengths of high atmospheric transmission and maximum contrast between the soil background and the vegetation growing out of it. Vegetation indices have been developed that maximize the information about the photosynthetic size of the vegetation in the landscape and, hence, about crop stresses and yield . Three such indices that reduce the multispectral observations to a single numerical index are …

Identification Of Proteins And Complex Carbohydrates In Some Commercial Low-Fat Dairy Products By Means Of Immunolocalization Techniques, Barbara L. Armbruster, Nitin Desai

Food Structure

Macromolecular assemblies of proteins and hydrocolloids in low-fat dairy products contribute to the structure and texture of these foods. Immunolocalization techniques were used to identify B-lactoglobulin, casein, bovine whey proteins, and egg albumin in low-fat frozen desserts, reduced fat process cheese, and salad dressings. SimpJesse18 I 00 protein particles were examined and characterized by these methods and compared to naturally occurring protein structures in the low-fat foods. Hydrocolloid identification in low-fat salad dressing was accomplished by complexing cellulase and hemicellulase with colloidal gold and applying the probe as a pre-embedding step, on sections of embedded specimens or on material dried …

Scanning Electron Microscopy Studies Of A Typical Spanish Confectionery Product: "Xixona Turron", M. A. Lluch, M. J. Galotto, A. Chiralt

Food Structure

The microstructure of "Xixona turron" , a typical Spanish confectionery product, made with toasted almonds, sugar and honey, was elucidated, in order to confirm the nature of those physical changes occurring in its manufacturing process, which has not been previously studied. The effect of the major components of "Xixona turron" (oil, proteins and sugar) on its structural c!Jange was established. The initial oil suspension of sugar syrup drops and proteins undergoes a phase inversion , becoming an oil /water emulsion when hot, and a solid-like structure, when the aqueous sugar continuous phase solidifies at room temperature. In order to determine …

Distribution Of Aromatic Compounds In Coastal Bermudagrass Cell Walls Using Ultraviolet Absorption Scanning Microspectrophotometry, Nancy P. Ames, Roy D. Hartley, Danny E. Akin

Food Structure

The distribution of aromatic constituents, including lignin , in the leaf cell walls of "Coastal" hermudagrass (Cynodon dacrylon (L.) Pers.) was investigated using scanning ultraviolet (UV) microspectrophotometry. Leaf blade sections and individual tissue types were scanned at three wavelengths representing the absorbance maxima (318, 287 and 250 nm) of aromatic constituents present in bermudagrass leaves. The measured absorbance data were printed in a geometric arrangement to produce an image of the distribution and amount of aromatic constituents among and within cell wall types which vary in digestibility . Differences in absorbance were observed among cell wall types, among walls of …

Effect Of Chemical Modifications On The Stability, Texture And Microstructure Of Cooked Meat Batters, Andre Gordon, Shai Barbut

Food Structure

The effects of five chemical agents on the stability, texture and microstructure of cooked comminuted meat batters were studied. B-mercaptoethanol (/3-ME), hydrogen peroxide (H20~, ethylenediaminetetraacetic acid (EDT A), urea, and polyoxyetbylene sorbitan monooleate (fween 80) were used. The reduction of disulphide bonds by 8-ME or the oxidation of free sulphydryls by H20 2 prior to cooking did not affect liquid and fat losses during cooking as compared to the control (2.5% NaCI). However, texture profile analysis (fPA) showed that treatment with H20 2 resulted in a harder, more cohesive product than the control and ,8-ME treatments because a more fine-stranded, …

Effect Of Lactose And Protein On The Microstructure Of Dried Milk, V. V. Mistry, H. N. Hassan, D. J. Robison

Food Structure

Skim milk of approximately 3% total protein was ultrafiltered to 16.2% protein and 4.1 % lactose, and then diafiltered to reduce lactose to 2.1% and 0.9%. Total protein con ten t was maintained at approximately 17%. A ponion of the skim milk was condensed in a rising film evaporator to 14.7% protein and 15.7% lactose . All concentrates were spray dried at 120 to 125 °C inlet air temperature and 75 to 80 C outlet temperature using a rotary atomizer in a pilot plant spray dryer . Moisture content of the powders were 4.7 to 6.3% and lactose content ranged …

Cryo-Scanning Electron Microscopy Investigation Of The Texture Of Cooked Potatoes, J. T. Van Marle, A. C.M. Clerkx, A. Boekestein

Food Structure

The texture of steam-cooked potatoes was investigated by examining the fracture planes of four different cultivars, using cryo-scanning electron microscopy (cryo-SEM), which yielded a good preservation of the hydrated structures in potato tissue . For all cultivars , fracturing after steam -cooking took place between cells preferentially alongside the cell walls. However, textural difference appeared from the degree of intercellular contact, the cell shape and the appearance of cell surfaces. Cells in the fracture planes of firm potatoes had large intercellular contacts. In this case, most of the cells were flat and cell surfaces showed folds and cracks . For …

Physicochemical Properties Of Irradiation Modified Starch Extrudates, A. S. Sokhey, R. Chinnaswamy

Food Structure

Corn starch samples containing 0, 25, 50 and 70% amylose irradiated with -y -radiation dosages of 0 (native) , 5 , 10, 20 (containing 0, 2.5 or 5% potassium persulfate , hydrogen peroxide or eerie ammonium nitrate) or 30 kGy were extrusion cooked using a C. W. Brabender single-screw extruder at a barrel temperature of 140 °C, a screw speed of 140 rpm and 18% moisture content. Increasing irradiation dosages from 0 to 30 kGy gave consistently increased expansion ratios from 2.9 to 7.9 for 25% amylose starches and from 6.5 to 14.5 for 50% amylose starches, while the expansion …

Physicochemical And Macromolecular Properties Of Starch-Cellulose Fiber Extrudates, R. Chinnaswamy, M. A. Hanna

Food Structure

Three different pure cellulose fibers (James River Corporation, NJ) with lengths of 22, 60 and 110 pm were used at 1, 2, 4, 6, 8 and 10% concentrations with normal corn starch. The fiber-starch mixtures were extruded (C.W. Brabender Laboratory Extruder) at moisture contents of 14, 18 and 22% (db), 140°C barrel temperature and 140 rpm screw speed. The expansion ratio of the starch-fiber extrudates varied from 5.0 to 13.3. The maximum expansion ratio of 13.3 was obtained with 2%-60 mm fiber and 14% (db) moisture content. Increasing fiber concentration and moisture content generally reduced the expansion volumes. Water solubility …

Structures And Properties Of Stabilized Vitamin And Carotenoid Dry Powders, Victor E. Colombo, Francoise Gerber

Food Structure

The development of special formulated forms of vitamin and carotenoid dry powders solved most of the technical problems encountered in handling the original pure crystalline or oily compounds. Various procedures to obtain stabilized products have been introduced on an industrial scale for feed , food and pharmaceutical purposes. Proven modes of manufacture of formulated dry powders includes the numerous spraying processes for emulsions, dispersions or solutions, and the production of adsorbates of fat-based products.

The objective of this paper is to provide an overview of stabilized vitamin and carotenoid dry powders. This contribution is intended to demonstrate the usefulness of …

Effect Of Chemical Modifications On The Microstructure Of Raw Meat Batters, Andre Gordon, Shai Barbut

Food Structure

The microstructure and stability of raw meat batters treated with five chemical agents were investigated by electron and light microscopy. Six batters were made with NaCI (2.5%). five of which were treated with either hydrogen peroxide (H,O,), B- mercaptoethanol (B-ME), ethylenediamine- tetraacetic acid (EDTA), urea or Tween 80. The Tween 80 treatment produced a highly unstable raw batter with significant (P > 0.05) fat and water losses. None of the other treatments produced an unstable raw batter.

Microstructural examination revealed that, except for Tween 80, the chemically-treated raw batters were stable and showed some similarity to the control in their microstructure …

Structure And Rheology Of Dairy Products: A Compilation Of References With Subject And Author Indexes, David N. Holcomb

Food Structure

No abstract provided.

Structure, Meltability, And Firmness Of Process Cheese Containing White Cheese, Miloslav Kalab, H. Wayne Modler, Marijana Caric, Spasenija Milanovic

Food Structure

White cheese made by coagulating heated milk (90"C) with a 2.5% citric acid solution to pH 5.5 consists of casein particles having a characteristic core-and-shell ultrastructure. The presence of this White cheese in process cheese can be detected by transmission electron microscopy on the basis of the core-and-shell ultrastructure which is stable during cheese processing. White cheese additions may be detected at levels equal to or higher than 8%.

White cheese, which does not melt alone when heated, increases meltability of the process cheese in which it is present as an ingredient. Meltability in creases at all White cheese concentrations …

Effect Of Irradiation And Dielectric Heating On Soybean Ultrastructure, Trypsin Inhibitor, And Lipoxygenase Activities, E. Kovacs, N. D. Lam, J. Beczner, I. Kiss

Food Structure

Scanning electron microscopy ( SEM) was used to observe the protein bodies of soybeans after irradiation (0 - 10 kGy dose range) , dielectric heating and storage . Microbiological changes , lip oxygenase and trypsin inhibit or activities and biological value were also studied after different treatments and storaee . There were no differences in the ultrastructure of control and irradiated ( 3, 6 and 10 kGy) soybeans immediately after irradiation . The effect of storage depended on whether whole or milled soybeans had been stored . There was no direct effect of dielectric he ating on soybeans ultrastruc ture …

Ultrastructural Evidence For Temperature-Dependent Ca2+ Release From Fish Sarcoplasmic Reticulum During Rigor Mortis, Hideki Ushio, Shugo Watabe, Muneaki Iwamoto, Kanehisa Hashimoto

Food Structure

The release or leakage of ca2+ from the sarcoplasmic reticulum (SR) during rigor mortis of fish muscle was investigated by transmission electron microscopy using pyroantimonate and related biochemical changes.

Ca2+ -pyroantimonate deposits were observed in the SR immediately after spiking the fish. At the onset of rigor for fish stored at 0°C, no deposits were found in the SR; however, fish stored for the same period at woe which were still in the pre-rigor state, clearly showed Ca2+ deposits in the SR.

In association with the Ca2+ translocation, ATP degraded faster at 0 c than at 10 °C, probably due …

Distribution Of Amylose And Amylopectin In Potato Starch Pastes: Effects Of Heating And Shearing, K. Svegmark, A. M. Hermansson

Food Structure

The microstructure of potato starch pastes and gels in the concentration range 5-10% (w/w) was studied as a function of shear and heat treatment usi.ng light microscopy. Heating induced extensive swelling of potato starch granules, and the swollen granules filled the whole volume of the starch pastes that were subjected to a minimum of shear. The volume of the aqueous phase outside and in the center of the swollen granules is practically negligible compared to the volume occupied by the walls of the swollen granules. The granules with the lowest gelatinization temperatures swelled quickly without restrictions, so that less water …

Effect Of Extruder Die Temperature On Texture And Microstructure Of Restructured Mechanically Deboned Chicken And Corn Starch, V. B. Alvarez, D. M. Smith, S. Flegler

Food Structure

Proximate composition, textural properties and microstructural changes of mechanically deboned chicken/15% corn starch extrudates were evaluated when restructured at die temperatures of 25, 71, 82, 93 , 104 and ll5°C in a twin-screw extruder. Total sol ids and fat content decreased, whereas protein content increased die temperatures were increased. When die temperature was increased from 71°C to 104°C, apparent stress at failure of extrudates increased by 44 kPa , but decreased at a die temperature of 115°C. Changes in the protein matrix, fat globules and starch granules due to changes i n extruder die temperature were observed by scanning electron …

Application Of Scanning Electron Microscopy And X-Ray Microanalysis To Investigate Corrosion Problems In Plain And Enamelled Three Piece Welded Food Cans, James E. Charbonneau

Food Structure

Scanning Electron Microscopy (SEM) and X-Ray Microanalysis (EDS) have been used to investigate rapid detinning, pitting corrosion and cosmetic corrosion in plain tin plate food cans and pitting corrosion, underenamel corrosion, enamel flaking , sulfide black corrosion and stress corrosion cracking in enamelled food cans.

Through the use of SEM - EDS it was determined that (SnL a /FeK a) Y2 X -ray line intensities arc proportional to the tin coating weight on tinplate. The method was applied to a rapid detinning problem in canned grapefruit sections. The cause of the early corrosion failure was found to be reversed tinplate. …

Magnetic Resonance Imaging Of Cheese Structure, M. Rosenberg, M. J. Mccarthy, R. Kauten

Food Structure

Cheese quality and quality evaluation are important in the production and marketing of cheeses. The commercial value and acceptability of bard and semi-bard cheeses are greatly affected by the cheese structure and body features. This is a feasibility study using magnetic resonance imaging (MRI) techniques to evaluate cheese structure.

The results indicate that MRI is a non-destructive method which can provide high resolution images of the inner structure of cheeses, particularly the presence of air and whey pockets as small as 0.1 x 0.1 x I mm. It may be used to study and evaluate eye structure, size, and distribution …

Relationship Between Microstructure And In Vitro Digestibility Of Starch In Precooked Leguminous Seed Flours, Juscelino Tovar, Alicia De Francisco, Inger Bjorck, Nils-Georg Asp

Food Structure

Precooked flours (PCFs) were prepared by milling boiled and freeze-dried red kidney beans, white beans and lentils. As demonstrated by scanning electron microscopy, PCFs were rich in relatively large particles which contained cell structures filled with starch. In contrast, flours from raw seeds contained a large number of free starch granules. The in vitro a-amylolysis rate ofPCFs was remarkably low, but increased after physical and chemical treatments of the flours. Homogenization resulted in the largest increase of hydrolysis rate. The susceptibility to enzymatic hydrolysis was also enhanced when PCFs were preincubated with pepsin or submitted to additional boiling. These treatments …

Recent Developments In The Application Of X-Ray Microanalysis To The Study Of Food Systems, B. E. Brooker

Food Structure

Low temperature scanning electron microscopy in conjunction with X-ray microanalysis can be used to study not only the internal structure of intact bulk food systems but also the distribution of their constitutive chemical elements. However, the considerable practical problems that are usually encountered when performing X-ray analysis on frozen samples include: a) the controlled deposition of a good quality carbon film to prevent charging, b) producing digital elemental distribution maps of elements whose X-ray spectral energy peaks partially or completely overlap and c) controlling the plane of fracture through the specimen and ensuring that the resulting topography allows meaningful analysis …

Microstructure Of Adzuki Beans (Vigna Angularis Cv. Express), Anup Chilukuri, Barry G. Swanson

Food Structure

Scanning electron microscopy (SEM) was used to study and compare the mic rostructure of adzuki, black and Mexican red bean seeds. The two cotyledons of the beans were separated by a deep fissure. A view of seed coat surface of adzuki beans revealed a characteristic pattern of convolutions and cracks, not observed on the seed coat surfaces of black or red beans. The cro sssection of seed coat of adzuki beans exhibited a thick layer of palisade cells in the epidermal layer followed by underlaid multiple layers of tightly packed parenchyma cells. A sub-epidermal layer comprised of a single layer …

Comparison Of The Effects Of Three Different Grinding Procedures On The Microstructure Of "Old-Fashioned" Non-Stabilized Peanut Butter, Clyde T. Young, William E. Schadel

Food Structure

Three different grinding procedures were utilized to prepare "old-fashioned" non-stabilized peanut butters. A leading commercial brand of stabilized peanut butter was used for comparison. The microstructure of each non-stabilized peanut butter was then evaluated with light microscopy and compared to the microstructure of the commercial brand of stabilized peanut butter. Major findings include: (1) dense spatial relationships of protein bodies, starch grains, and cell and tissue fragments that exist in "old-fashioned " non-stabilized peanut butter as compared to the well-dispersed spatial relationships which exist in commercially prepared stabilized peanut butter; and (2) degree of homogenization in the nonstabilized peanut butters …