Food Science Commons^™

The Stabilisation Of Air In Foods Containing Fat - A Review, B. E. Brooker

Food Structure

Foods containing aqueous solutions of proteins readily foam when air is introduced into them. When fat is also present, interaction between the two components at the air/water interface may produce a stable foam with characteristic bulk properties. In the case of dairy foams (such as whipped cream), bubbles produced in the whipping process are initially stabilised by the adsorption of protein at the air/water interfaces.

Commonly encountered defects in whipping cream arise when large triglyceride crystals, formed in masses of free fat, adsorb to the air/water interface during whipping at the expense of fat globules.

In other food systems , …

Microstructure And Rheological Properties Of Composites Of Potato Starch Granules And Amylose: A Comparison Of Observed And Predicted Structures, K. Svegmark, A.-M. Hermansson

Food Structure

Potato starch granules were gelatinised in amylose solution to study the effect of adding amylose to a highswelling granular starch system. The effects of varying the amount of potato starch from 1-10% , added to a solution of 2% amylose, were studied by means of dynamic viscoelastic measurements and light microscopy.

The granules gelatinised in amylose solution had a lower degree of swelling than those gelatinised in water. The restricted swelling in amylose was reflected in a decrease in the complex shear modulus (G*) at 75'C. GeJatinisation in 2% amylopectin also caused a decrease in G*, but gelatinisation in 2% …

Relationship Between The Starch Granule Structure And The Textural Properties Of Heat-Induced Surimi Gels, V. Verrez-Bagnis, B. Bouchet, D. J. Gallant

Food Structure

Starch, used as a textural additive in heat-induced surimi gel, influences the rigidity of the protein gel matrix and hence the gel strength according to its botanical characteristics. The present study focuses on the correlations existing between the textural properties of heatind uced surimi gels obtained by physical measurements and the characteristics of different commercial starches. The gelatinization temperature of starch was closely related to the expressible moisture, work to fracture, and elongation. Behaviour of starchy components during thermal processing and its relationship to fish protein gel matrix were studied by light and electron microscopy. These studies showed differences in …

Structure-Compressive Stress Relationships In Mixed Dairy Gels, J. M. Aguilera, J. E. Kinsella, M. Liboff

Food Structure

Mixed dairy gels (including a control without fat) of skim milk powder (SMP) and whey protein isolate (WPI) containing fat globules were formed by heating protein emulsions to 90°( and by acid release from glucono- 0-lactone to provide a pH of 4.3-4.4 . Fat globules with artificial protein membranes (FGAPM) were prepared by homogenization of a butter oil /water mixture in the presence of WPI while fat globules without membranes were stabili zed with polyoxyethylene sorbitan monolaurate (Tween 20). Both emulsions were added at a 4% (w/w) leve l to solutions having 3% SMP and 8.3% WPI. The gel contai …

A Tutorial And Comprehensive Bibliography On The Identification Of Foreign Bodies Found In Food, D. F. Lewis

Food Structure

The paper presents a philosophical approach to the investigation of foreign body incidents in food. The suggested procedure has similarities with "key" procedures used for taxonomy. However, the wide diversity of materials encountered and the need to determine something of the history of the offending item demands modifications to this process. The categorisation may be made on instinct or experience, and appropriate confirmatory tests will be applied in the light of the initial categorisation. Cardinal rules are proposed: firstly , the receipt of the items should be well documented; and secondly, the initial observations should be as non-destructive as possible. …

Practical Aspects Of Electron Microscopy In Dairy Research, Miloslav Kalab

Food Structure

Milk products are based mostly on casein micelles, fat globules, and whey proteins. The former two constituents are corpuscular and whey proteins become corpuscular when coagulated. Structural changes in these basic constituents during processing have been studied by electron microscopy. This review discusses the structures of yoghurt, curd, cheeses (hard cheeses, mould-ripened cheeses, cream cheeses, and process cheese), cream, milk powders, and nontraditional dairy products. Defects and deviations from traditional structures of these products are explained where the causes are known. Examples of such causes are foaming of milk, presence of unusual ingredients (bacterial polysaccharides, whey protein concentrates), and alterations …

Fluidization And Its Applications To Food Processing, N. C. Shilton, K. Niranjan

Food Structure

This paper is a comprehensive review of the science behind fluidization of food materials, and its applications in food processing. Fluidization is a process by which a bed of particulate materials exhibts fluid -like behaviour as a result of fluid flowing through it. Fluidization can be carried out by liquids or gases and different forms of fluidization occur depending on the type of fluidizing medium and the properties of the particulate material , this can have an important effect on the type of processes that can be carried out using fluidization.

Typical food processing applications of fluidization include freezing and …

Hydrocolloids As Food Emulsifiers And Stabilizers, Nissim Garti, Dov Reichman

Food Structure

Hydrocolloids are water-soluble biopolymers consisting of high molecular weight polysaccharides known as viscosity builders, gelification agents and stabilizers of food systems.

Several hydrocolloids such as gum arabic (acacia), tragacanth, xanthan and certain modified gums have been mentioned as food additives having special functions such as: "retardation of precipitation of dispersed solid particles and coalescence of oil droplets". The role of these gums as emulsifiers remained somewhat obscure. The present review is an attempt to bring the relevant studies together and to throw some light on the functionalities of the gums as surface active agents and food emulsifiers. In addition, some …

Quality Of Shrimp Available To Consumers In Arkansas, Darlene Gentles, Jimmy D. Bragg

Journal of the Arkansas Academy of Science

No abstract provided.

Regulation Of ΣB Levels And Activity In Bacillus Subtilis, Andrew K. Benson, William G. Haldenwang

Department of Food Science and Technology: Faculty Publications

The sigB operon of Bacilus subtilis encodes (σ^B plus three additional proteins (RsbV, RsbW, and RsbX) that regulate σ^B activity. Using an anti-σ^B monoclonal antibody to monitor the levels of (σ^B protein, P_SPAC to control the expression of the sigB operon, and a ctc-lacZ reporter system to monitor σ^B activity, we observed that the rsbV and rsbW products control (σ^B activity at the ctc promoter independently of their effects on (σ^B levels. In contrast, RsbX was found to have no effect on expression of ctc when the sigB operon was controlled by …

Bacillus Subtilis ΣB Is Regulated By A Binding Protein (Rsbw) That Blocks Its Association With Core Rna Polymerase, Andrew K. Benson, William G. Haldenwang

Department of Food Science and Technology: Faculty Publications

σ^B is a secondary σ factor of Bacillus subtilis. RNA polymerase containing cr transcribes a subset of genes that are expressed after heat shock or the onset of the stationary phase of growth. Three genes (rsbV, rsbW, and rsbX), cotranscribed with the σ^B structural gene (sigB), regulate o dependent gene expression. RsbW is the primary inhibitor of this system with the other gene products acting upstream of RsbW in the σ^B regulatory pathway. Evidence is now presented that RsbW inhibits σ^B-dependent transcription by binding to crB and blocking …

The ΣB-Dependent Promoter Of The Bacillus Subtilis Sigb Operon Is Induced By Heat Shock, Andrew K. Benson, W. G. Haldenwang

Department of Food Science and Technology: Faculty Publications

σ^B, a secondary sigma factor of Bacillus subtilis, was found to increase 5- to 10-fold when cultures were shifted from 37 to 48°C. Western blot (immunoblot) analyses, in which monoclonal antibodies specific for the sigB operon products RsbV, RsbW, and σ^B were used to probe extracts from wild-type and mutant B. subtilis strains, revealed that all three proteins increased coordinately after heat shock and that this increase was dependent on σ^B but not RsbV, a positive regulator normally essential for σ^B-dependent sigB expression. Nuclease protection experiments of RNA synthesized after heat shock supported …