Enzyme-inactivated meats

Dependence on total fat. For scission of C-C bonds up to about six carbons from the aliphatic end of the chain, the stable hydrocarbon products formed will be the same for most of the fatty acids. Consequently, the yields of such hydrocarbons as pentane and hexane should be independent of the fatty acid composition but dependent solely on the total fat content of the meat sample. This dependence is seen for several low molecular weight hydrocarbons [14, 62] when their normalized yields in four different enzyme-inactivated meats irradiated at -30°C are plotted against fat content, as Figure 15 illustrates for hexane. 

Thayer et al. (26) reported the results of nutritional, genetic, and toxicological studies of enzyme-inactivated, radiation-sterilized chicken meat. The study included four enzyme-inactivated chicken meat products 1) a frozen control, 2) a thermally processed product (llS.b C), 3) a gamma-sterilized product, and 4)... 

That the radiolysis of meats containing similar proteins and comparable fatty acids involves similar primary and secondary processes leading to a common set of radicals stable at -40°C is shown by the ESR spectra in Figure 12 for irradiated, enzyme-inactivated chicken, beef, ham, and pork [3, 62], These spectra reflect the commonality in radicals derived from the muscle proteins, myosin and actin, and fi-om the constituent triglycerides, which have slightly different fatty acid compositions. The minor consequences of this compositional... 

Once ku has been experimentally determined (see section 3.5.2), the curve of reactor operation (X vs t) can be obtained for a certain enzyme concentration (meat)-Eq. 5.69 also allows reactor design (determination of reactor volume), since meat is simply the ratio of enzyme load to reaction volume (Mcat/VR). Simulation of batch bioreactor operation under different scenarios of enzyme inactivation is presented in Fig. 5.16 for simple Michaelis-Menten kinetics (a = 14-K/Si b = -1 c = 0) with Si/K =10. Enzyme load in the reactor was calculated to obtain 90% conversion after 10 h of reaction under no inactivation. The strong impact of enzyme inactivation on bioreactor performance can be easily appreciated. 

Enzyme inactivation or changes in the distribution patterns of enzymes in subcellular particles of a tissue can occur during storage or thermal treatment of food. Since such changes are readily detected by analytical means, enzymes often serve as suitable indicators for revealing such treatment of food. Examples are the detection of pasteurization of milk, beer or honey, and differentiation between fresh and deep frozen meat or fish. 

The main problems with early, irreversible MAOIs were adverse interactions with other drugs (notably sympathomimetics, such as ephedrine, phenylpropanolamine and tricyclic antidepressants) and the infamous "cheese reaction". The cheese reaction is a consequence of accumulation of the dietary and trace amine, tyramine, in noradrenergic neurons when MAO is inhibited. Tyramine, which is found in cheese and certain other foods (particularly fermented food products and dried meats), is normally metabolised by MAO in the gut wall and liver and so little ever reaches the systemic circulation. MAOIs, by inactivating this enzymic shield, enable tyramine to reach the bloodstream and eventually to be taken up by the monoamine transporters on serotonergic and noradrenergic neurons. Fike amphetamine, tyramine reduces the pH gradient across the vesicle membrane which, in turn, causes the vesicular transporter to fail. Transmitter that leaks out of the vesicles into the neuronal cytosol cannot be metabolised because... 

The oranges were washed, chopped in a meat mincer and homogenised by a Fryma mill. Water (0.6 volumes) were added before the slurry was heat treated by steam injection at 100°C for 2 minutes. The enzyme treatment was carried out for 1 hour at 40°C with 10 lU/g slurry of PME and 25 pg enzyme protein/g slurry of the other enzymes for each of the enzymes. The gelated orange slurry were treated at 85°C for 3 minutes to inactivate the enzymes before the strength of the gel was measured by a SMS TeJrture Analyser TA-XT2 (Stable Micro Systems, XT. RA Dimensions, Operations Manual versions) by compression analysis using a flat cylinder (20 mm dia.) with a speed of 2 mm/s. The force to provide a 20% compression was recorded. 

Carrots (Boleo) were peeled by 2% NaOH at 88-96°C for 4 minutes, minced by a meat mincer (2 mm) and homogenised for 2 minutes by an ULTRA-TURRAX T25 homogenizer (from Jahne Kunkel). The carrot mash was preheated to 45°C (20 minutes) before the enzyme preparations, 25 mg enzyme protein/kg mash, were added. The enzymes were dissolved in water to give a dilution of 5% (v/v) of the carrot mash. The mash was incubated at 45°C under stirring (60 rpm) for 2 hours, before the enzymes were inactivated at 86°C for 5 minutes in a microwave oven. Finally the purees were homogenised for 1 minute by ULTRA TURRAX. The viscosity of the puree was measured by a BROOKFIELD viscosimeter Model DV-n + with spindle A from HELIPATH SPINDLE SET at 2.5 rpm thermosta-ted at 50°C. The stability of the puree was measured as the sediment (in %) after centrifugation in 10 ml tube a 1660 x g for 10 minutes. 

Thermal treatment of meat products ensures microbial destruction of microorganisms but also the denaturation of structural proteins, forming a gelled structure, and the inactivation of many endogenous enzymes (see Figure 21.3 above). In precooked products, characteristic color and flavor of the product are also developed during heating. Thermal treatment can be performed in forced convection ovens, both in... 

Extensive proteolysis of a protein often results in the formation of bitter peptides ( ). Therefore, a compromise between high protein yield and low bitterness has to be found when choosing the DH-value at which the hydrolysis reaction should be terminated. For the present process a DH-value of about 10% seems to be a reasonable value. The termination is performed by acid inactivation of the enzyme and the acid used should be chosen in accordance with the desired organoleptic characteristics of the final hydrolysate. A totally non-bitter product can be produced by use of an organic acid like malic or citric acid. Due to the masking effects of such acids, absolutely no bitterness can be detected even when the taste evaluation is performed at neutral pH. Such products are found most suitable for soft drinks. However, when inorganic acids, e.g. hydrochloric or phosphoric acids are used, a slight bitterness may be detected in the pure hydrolysate. However, when evaluated in for instance a meat product, no bitterness at all can be tasted even when the hydrolysate is added up to a proportion of 1 3 of hydrolyzed protein to meat protein. 

Metabolic inactivation, whether taking place in the e,r, or at other sites, is often accidentally inhibited by other drugs. Thus many patients have died as a result of the simultaneous administration of an inhibitor of monoamine oxidase (an enzyme present in mitochondria) and an amine drug which is not toxic on its own. These monoamine oxidase inhibitors, such as tranylcypromine 9,47), are prescribed as mood-elevators in depressive illnesses. Until their synergistic properties were realized, they caused many deaths after usually safe doses of amphetamine, pethidine, and amitriptyline, or after the patient had consumed food rich in pressor amines such as tyramine such foods are red wine, meat-extract, yeast-extract, broad beans, and particularly cheese. These are examples of unfortunate synergism, but many favourable cases are known, examples of which will now be given. 

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