Aim of this study is to analyze the effect of chronic administration of beta agonist isoproterenol hydrochloride (60 mg kg
; 30 days) on soleus (a slow type) and extensor digitorum longus (EDL, a fast type) muscles in young mice. Isoproterenol resulted in significant increase in muscle weight to whole body weight ratio with no increase in hypertrophy index in soleus muscle. A significant increase in noncontractile protein collagen is also observed in both muscles but more prominent in soleus muscle. Collagen proliferation is also analyzed on sodium dodecyle sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of pepsin soluble and Cyanogen Bromide (CNBr) treated pepsin insoluble collagen. Isoproterenol remolded the myofibrillar proteins in both muscles but significant increase in myofibrillar ATPase activity occurred only in soleus muscle. It is concluded that growth stimulatory effect of isoproterenol hydrochloride is more prominent in soleus than EDL muscle. Isoproterenol augmented the proliferation of non-contractile protein collagen in soleus and EDL muscles. The transformation in myofibrillar proteins caused by isoproterenol might lead to an enhancement of contractile performance.
Authors:A. Costa, Z. Orosz, P. Apor, N. Csaba, S. Siamilis, Z. Csende, L. Racz and J. Tihanyi
In animal models, unaccustomed eccentric exercise (EE) has been widely related to muscle fiber membrane (sarcolemma) damage. On the contrary, studies in humans reported that sarcolemma was not susceptible to damage following a single bout of EE. We hypothesized that the single bout of EE used by those studies was not sufficient to induce sarcolemma damage, in humans. In this study we examined muscle biopsies from untrained males who either performed six sets of 15 reps of maximum voluntary eccentric contractions (n=9), for six consecutive days, or served as control-group (n=6). Blood and biopsy samples were obtained one week prior to exercise, immediately after bout 3, and 24h after the last training session. In addition to standard haematoxylin-eosin staining, all biopsies were stained immunohistochemically using antibodies specific for fibronectin and desmin antigens. In the exercise-group, no biopsies taken at pre-exercise or post-exercise level showed evidence of sarcolemma damage as stained by anti-fibronectin antibody in eight of nine subjects. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities increased significantly throughout the study despite the lack of sarcolemma damage.We suggest that in humans, repeated bouts of EE do not cause gross sarcolemma damage in the mid-belly of Vastus Lateralis.
Breast muscles from three different birds
were subjected to hydrostatic high-pressure (400 MPa)/temperature (10–75°C)
combinations, and the denaturation-induced effects on the pressurized proteins
monitored by DSC. Comparisons with parallel results from heating-alone processes
were established. Actin was the most labile moiety to pressurization and myosin
together with sarcoplasmic proteins were next in observing pressure-induced
denaturation at low temperatures. Some myosin derivatives (fragments or aggregates)
and collagen remained native-like under pressure at any temperature.
As previously reported, pressure and temperature showed interdependent
and antagonistic-like effects. Hydrostatic high-pressure caused severe proteins
denaturation at non thermal denaturing temperatures. At thermally active conditions,
pressure preserved proteins from subsequent thermal denaturation. This last
effect was lower than in similar but destructured myosystems (batters) because
of the absence of functional salts but presumably also by steric hindrance.
Authors:W. Cortez-Vega, G. Fonseca, B. Zanette and C. Prentice
The appropriate number of washing cycles for obtaining most of the surimi-like materials is not well defined in literature. The aim of this work was to investigate the influence of the number of washing cycles (one, two, or four) on the quality of surimi-like material obtained from mechanically deboned chicken meat (MDCM) using the bleaching method with sodium bicarbonate. The product was evaluated based on its chemical and physical characteristics. The chemical compositions of samples showed an increase in protein (45.7 to 89.9%, dry basis) and decrease in fat (49.1 to 7.0%, dry basis) contents, while the moisture content increased from 69.5 to 79.1% after four washing cycles. Washing diminished yield. Gel prepared with MDCM washed once showed the lowest gel strength (507.1 g.cm). It thereafter increased to 546.0 and 602.7 g.cm after double and quadruple washings, respectively. Higher content of myofibrillar proteins and higher whiteness were also obtained after successive washings. It was concluded that four washing cycles was the most appropriate method for producing surimi-like material from MDCM.
Authors:Y. Hassan, L. Mészáros, A. Simon, E. Tuboly, Cs. Mohácsi-Farkas and J. Farkas
The total viable cell count of bacteria in vacuum-packaged chilled minced beef has been decreased equally, by approx. two log-cycles, as an effect of 1.5-2.0 kGy gamma radiation or 200-300 MPa high hydrostatic pressure (UHP) treatment for 20 min. Coliform bacteria could be eliminated to non-detectable levels by the same treatments. The shelf-life of both untreated and non-thermally pasteurised samples were limited mainly by growth of lactic acid bacteria. At about equal bactericidal effect, more drastic changes of texture and colour occurred in UHP-pasteurized minced beef samples than in the radiation-pasteurized ones. Whereas radiation pasteurisation caused minimal changes in appearance, texture and DSC-thermograms of minced beef, UHP-pasteurisation of the raw samples proved to be strongly discolouring by denaturing the muscle pigments and causing extensive denaturation of the myofibrillar proteins. The water holding capacity of irradiated samples decreased, while that of high pressure treated ones increased as compared to the untreated control. Near infrared spectrometry and electronic nose measurements gave promising results to make distinctions non-destructively on changes of various physical-chemical changes and quality parameters as a function of pasteurising treatments and/or storage.
Authors:B. Csehi, E. Szerdahelyi, K. Pásztor-Huszár, B. Salamon, A. Tóth, I. Zeke, G. Jónás and L. Friedrich
, A. , OLSEN , K. , BOLUMAR , T. , RINNAN, Å. & Ø GENDAL , L.H. , ORLIEN , V. ( 2016 ): The effect of high pressure on the functional properties of pork myofibrillarproteins . Food Chem. , 196 , 1005 – 1015