Life Sciences Commons^™

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 …

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 …

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 …

Microstructure And Firmness Of Labneh (High Solids Yoghurt) Made From Cow's, Goat's And Sheep's Milks By A Traditional Method Or By Ultrafiltration, A. Y. Tamime, M. Kalab, G. Davies, H. A. Mahdi

Food Structure

Two types of Labneh (high solids yoghurt) were made from goat's and sheep 's milk: (a) traditional style Labneh was produced by straining yoghurt in a cloth bag, and (b) UF Labneh was made by ultrafiltration (UF) of warm yoghurt. A portion of all products were smoothened by a passage through a lactic curd homogenizer. Irrespective of their origin , the Labneh samples contained 20.5-22.5% total solids (including minerals and un-metabolized lactose), 6.7-8.2% protein, and 7.8- 8.9% fat.

Homogenization markedly decreased firmness of the goat's and sheep's Labnehs and is therefore not re~ commended in industrial production . Firmness of …

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

Food Structure

No abstract provided.

Practical Methods For Identification Of Rice Endosperm Protein Bodies And Fecal Protein Particles In Light Microscopy, D. L. Barber, J. N. A. Lott, D. A. Harris

Food Structure

Indigestible 1-3 ~m protein 'cores', particles that originate from protein bodies of rice endosperm, were examined in bright-field and fluorescence microscopy, using a variety of histological and histochemical procedures. Our application of histological, histochemical and chemical approaches to a study of the feces of aoimals fed rice-containing diets has resulted in the development of methods for routine identification of insoluble rice fecal protein particles. For the specific identification of rice endosperm storage protein, whether protein bodies, cores or fecal protein particles, aqueous eosin Y stain in conjunction with fluorescence microscopy, and a combination of orange G + aniline blue in …

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 …

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 …

Extrusion-Cooking Of Pea Flour: Structural And Immunocytochemical Aspects, Hassane Ben-Hdech, Daniel J. Gallant, Brigitte Bouchet, Jacques Gueguen, Jean-Pierre Melcion

Food Structure

Pea flour was submitted to extrusion-cooking under various conditions. The progressive structural transformation was investigated by light microscopy and immuno- gold transmission electron microscopy. Each of the three major compounds, i.e., starch granules, protein bodies, and cell wall fragments, develop a specific, independent structure. Protein bodies aggregate and fuse giving a protein matrix. Starch granules swell, deform, come into contact with each other, and ultimately also fuse together. The resulting gel expands giving a honeycombed structure. Consequently, the protein matrix is arranged into dense strata, i.e,. protein fibers in cross or longitudinal sections, disrupted by the expanded starch gel. Cell …

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 …

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 …

Textural And Microstructural Properties Of Frozen Fish Mince As Affected By The Addition Of Nonfish Proteins And Sorbitol, K. S. Yoon, C. M. Lee, L. A. Hufnagel

Food Structure

Changes in textural and microstructural properties of washed and unwashed frozen fish mince were studied as affected by the addition of non fish proteins (soy protein isolate, milk protein isolate, egg white, and wheat gluten at 2 , 4 or 6%) and 6% crystalline sorbitol. Soy and milk proteins and sorbitol reduced the hardness of frozen fish mince, while egg white and wheat gluten made the texture firmer without rubberiness developing after frozen storage. All nonfish proteins and sorbitol stabilized the myofibrillar organization by reducing freeze-induced contraction of myofibrils.

The mechanisms of reducing texture hardening appear to be different between …

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 …

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 …

Effects Of Phosphate And Citrate On The Gelation Properties Of Casein Micelles In Renneted Ultra-High Temperature (Uht) Sterilized Concentrated Milk, Donald J. Mcmahon, Paul A. Savello, Rodney J. Brown, Miloslav Kalab

Food Structure

Milk was concentrated to 3X (volume reduction) by ultrafiltration. Disodium phosphate and sodium citrate were added, and the milk concemrates were homogenized. The concentrates were then heated at 135°C for 50 s in a labora· tory ultra-high temperature (UHT) heating system. Rennet gels were made from heated and unheated milk concentrates and their curd firmness measured using a Fonnagraph. Gel microstructures were ex:amined by electron microscopy.

When rennet was added to unhomogenized milk concentrate before UHT heating, the resultant gel consisted of a strong protein network that encapsulated the fat globules. Pockets of milk serum were associated with the fat. …

Influence Of Emulsifier On The Competitive Adsorption Of Whey Proteins In Emulsions, Jean-Luc Courthaudon, Eric Dickinson, Yasuki Matsumura, Andrea Williams

Food Structure

The influence of Tween 20 (polyoxyethylene sorbitan monolaurate) on the composition of adsorbed protein films in hydrocarbon oil-in-water emulsions containing B-lactoglobulin and a-lactalbumin has been investigated at neutral pH. The kinetics of pol ymerization of adsorbed 13-lactoglobulin via sulphydryl-disulphide interchange is little affected by Tween 20. Add ing emulsifier after homogenization leads to slightly greater competitive d i splacement of protein from the interface for emul sions made with pure 8-lactoglobulin than for equivalent emulsions made with 0.-lactalbumin . For emulsions made with the two proteins in a 1 : 1 molar ratio, adding emulsifier after homogeniza t ion leads …

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 …