Life Sciences Commons^™

Using Stable Isotope Analysis To Quantify Anthropogenic Foraging In Black Bears, Jerod A. Merkle, Jonathan J. Derbridge, Paul R. Krausman

Human–Wildlife Interactions

Deciding whether to monitor, aversively condition, relocate, or destroy a problem black bear (Ursus americanus) can be difficult for wildlife managers. Understanding the extent of anthropogenic foraging within bear populations can provide insight for management decisions about black bears. An innovative way to estimate opportunistically the amount of anthropogenic food in an individual or a population of bears is through stable isotope analysis (SIA), where hair samples can provide an index of assimilated nutrients (i.e., diet) for the period of hair growth. Our objective was to use SIA to determine whether there was a difference between diets of …

Development Of The Food Microscopist, D. F. Lewis

Food Structure

This paper describes the processes through which the food microscopist develops his/her skills. It is based around a framework of Shakespeare's seven ages of man. The first stage is learning about equipment: how it works and how not to abuse it. Next, attention turns to how to prepare samples for examination whilst maintaining the validity of the observations and avoiding damage to the instrument. The "Lover" is the time at which an understanding of the basic structures of food products is gained and the "Soldier " starts to interpret these structures in terms of the performance of the foodstuff. Next, …

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 …

Changes In The Ultrastructure Of Beef Muscle As Influenced By Acidic Conditions Below The Ultimate Ph, M. V. Rao, N. F. S. Gault, S. Kennedy

Food Structure

Ultrastructural changes in meat incubated with different concentrations of acetic acid were investigated by transmission electron microscopy. Discs of bovine M. longissimus dorsi (48 h postmortem) were incubated at 46 C for 48 h in various acetlc acid solutions, giving discs with pH values ranging from 5.1 to 3.9 . Below pH 4. 5 , the volume of the discs increased markedly due to water absorption.

Discs incubated in 0.01M acetic acid had a pH of 5.1, lower swelling ratios and shorter sarcomeres than control samples at pH 5. 5. Structural studies of the samples at pH 5.1 revealed that …

The Structural Basis Of The Water-Holding, Appearance And Toughness Of Meat And Meat Products, Gerald Offer, Peter Knight, Robin Jeacocke, Richard Almond, Tony Cousins, John Elsey, Nick Parsons, Alan Sharp, Roger Starr, Peter Purslow

Food Structure

A structural approach greatly clarifies which components of meat are responsible for its tenderness, water-holding and appearance, and the events occurring during processing.

In living muscle, water is held in the spaces between the thick and thin filaments. Changes in the content and distribution of water within meat originate from changes in this spacing. Myofibrils shrink laterally post mortem . The fluid expelled accumulates between fibre bundles and between fibres and is drain ed by gravity forming drip. In pale, soft and exudative meat, shrinkage of the myosin heads on denaturation increases myofibrillar shrinkage. In salt solutions used in meat …

Determination Of Internal Color Of Beef Ribeye Steaks Using Digital Image Analysis, K. Unklesbay, N. Unklesbay, J. Keller

Food Structure

Objective measurements of beef ribeye steaks were made to determine the color distribution throughout their interior after heat processing. Steaks from eight animals were grilled to five degrees of doneness according to traditional internal temperature specifications. Images of the interior of these steaks, as seen by a digital image processing system through red, green, and blue filters were analyzed. The mean, standard deviation, skewness, and kurtosis of the histograms of light intensity at all points throughout the surface were determined. The steaks were also analyzed raw and it was determined that little variation in the color of muscle tissue occurred …

Microscopal Observations On The Structure Of Bacon, C. A. Voyle, P. D. Jolley, G. W. Offer

Food Structure

Commercially processed salt-treated pig longissimus dorsi muscle, in the form of bacon slices, sometimes shows localized variations in the light-scattering properties of the tissue. The phenomenon is described as 'tiger-stripe'. A study of areas of tissue showing such variations, using electron microscopy, has revealed differences in the structure at the myofibrillar level. Areas which appear dark when viewed by incident illumination show ordered myofibrillar structure, whereas areas which appear light under similar viewing conditions appear to be disordered.

Early Research On The Fibrous Microstructure Of Meat, H. J. Swatland

Food Structure

The older scientific literature on the histology of skeletal muscle describes the trans verse fragmentation of myofibrils to form sarcomere disks and the attachment of Z lines to the sarcolemma in contracted muscle. These phenomena may now be explained by recent research on the cytoskeletal framework of muscle fibers, particularly desmin and vinculin. The formation of sa rcomere disks might be developed as a simple method to study cytoskeletal integrity in meat. In early research, contraction bands and the disappearance of transverse striations during contraction caused considerable confusion with ordinary light microscopy. These problems were largely resolved by the use …

An Analysis Of Microstructural Factors Which Influence The Use Of Muscle As A Food, R. G. Cassens, C. E. Carpenter, T. J. Eddinger

Food Structure

Study of structure of muscle provides information on the location and arrangement of various components and the changes which may be inflicted upon them. The structura l features of muscle have been descr ibed in detail down to the molecular level, but rega rding its use as a food, special interest centers on the connective tissue component and on myofibri llar proteins . Muscle comprises about 1/3 of the live weight of the a ni mal and is not static , but rather is subject to major changes in properties associated with growth, repair and se nescence. It is apparent …

Processing Effects On Meat Product Microstructure, Glenn R. Schmidt

Food Structure

Animal species, meat ingredient properties, comminution equipment, mechanical action, product composition, type and level of non-meat ingredients, and thermal processing greatly affect the structural and organoleptic properties of meat products. However, additional research in the area of restructured meat products, meat protein functionality and lipid properties in meat products remains to be done. The interaction of meat proteins with lipids, water and ions should be further investigated. Considerable control of raw materials, mechanical action and heat processing is essential to make research applicable to product and process development.

The Effect Of Salt And Pyrophosphate On The Structure Of Meat, C. A. Voyle, P. D. Jolley, G. W. Offer

Food Structure

Our obective was to determine whether or not salt and pyrophosphate have the same effect on the structure of pieces of meat as they have on isolated myofibrils. Blocks of pig M. longissimus dorsi were incubated in solutions of sodium chloride at pH 5.5 or sodium chloride plus sodium pyrophosphate at pH 5.5 or 8.0. The blocks were obtained from fresh (24h post- mortem) or aged (72h post-mor tem) muscle and incubated for 5 or 24h with minimal agitation. There was considerable uptake of water by the tissue especially at the higher pH and longer times.

Electron microscopy of the …

Morphometry Of Meat By Scanning Light Microscopy, H. J. Swatland

Food Structure

Morphometric data can be collected from meat by using a scanning stage and a photometer, both controlled by a microcomputer. The passive counting of connective tissue boundaries is g1ven as an example to show that enumerative data may be biassed by the ratio of the width of the subject of measurement to the projected diameter of the photometer aperture. In a second example, the scanning stage is actively directed by the observer and is used to map the radial distribution of succinate dehydrogenase (SOH) activity in different histochemical types of muscle fibers. This is accomplished by the arbitrary fitting by …

Image Analysis Of Morphological Changes In Wiener Batters During Chopping And Cooking, A. G. Kempton, S. Trupp

Food Structure

Histological changes in wiener batters during chopping and cooking have often been illustrated with "representative" fields . The practice of selecting representative fields ignores variation and leads to word descriptions that cannot be correlated with numerical scores for functional or sensory tests . If wieners are regarded as a multi-component system, objectivity can be achieved by selecting many fields for each sample according to a rigid sampling plan. Image analysis quantified parameters of both the fat and protein components . The reduction in size of fat globules during chopping of a commercial formulation, for example, was a function of area …