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 processing, myofibrils swell laterally taking up water, probably by an entropic mechanism.

The colour of meat is determined by light scattering as well as by absorption. The light scatterers in meat are observed by scanning confocal light microscopy to be smaller than 1 um and concentrated in the A-band regions. It is proposed that light scattering arises from the gaps between myofibrils.

The structures responsible for the toughness of cooked meat have been studied by observing its fracture behaviour. The perimysial connective tissue determines the breaking strength when the meat is pulled apart transversely. In longitudinal tensile tests, the initial event is the debonding of fibre bundles from the perimysium so that they contr ibute independently to load-bearing. At greater extensions. it seems likely that fibre bundles progressively fail leaving perimysial strands as the last structure to break. With aged muscle, the muscle fibres probably fail at smaller extensions and therefore contribute less to the breaking strength.

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