摘要:

Catheptic activity was found to be localized in the lysosomal fraction of skeletal muscle of winter flounder(Pseudopleuronectes americanus).The enzyme hydrolyzed hemoglobin, globin, bovine serum albumin and endogenous proteins. The hemoglobin splitting activity of the enzyme under different conditions was determined by gel electrophoresis. An optimum pH of 4.0 was found for both the hemoglobin breakdown and autolytic activity on the endogenous proteins. The enzyme was highly thermostable, dialysis had no effect on its activity, and the enzyme was inhibited by sodium chloride, cysteine, ATP, NAD and phenyl methyl sulfonyl fluoride. Its molecular weight was found to be about 32,000 using sucrose gradient centrifugation.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02716.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The existence of an induction period in the autoxidation of the oil in frozen fish of the speciesPagelus erythrinusheld at –20°C has been shown by the study of its ultraviolet absorption at 232 or 268

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02717.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Fiber dimensions and shear force values were measured in folded, prerigor and rigor stretched semi‐tendinosus and sartorius muscles from unaged adult turkey carcasses. The unheated rigor muscles can be extended in situ but the extent is significantly less than prerigor stretching. Extensibility was detected by increases in sarcomere length. Prerigor and rigor stretching caused significantly smaller fiber diameters. Heat (70°C and 82°C) decreased sarcomere length of stretched muscles, but produced no significant change in folded controls. The stretched muscles had either significantly higher shear force values (semitendinosus) or were not different (sartorius) from the folded controls. All treatments gave reduced fiber diameters on heating. The relevance of this observation to meat tenderness is discussed. Light microscope evidence showed little damage in the rigor‐stretched or heated f

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02718.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The metabolism and histochemical characteristics of muscle from stress‐susceptible and stress‐resistant animals were studied. ATP values were. higher and lactic acid values lower in muscle of stress‐resistant animals than stress‐susceptible animals at the time of exsanguination. Results from oxygen uptake studies revealed that muscle from stress‐susceptible animals had a lower ability for aerobic metabolism or alternatively was more labile to damage during the isolation procedure. Our oxygen uptake values for pig muscle were lower than those reported for muscle from other species. The muscle from stress‐susceptible animals, when incubated under anoxic conditions, produced more lactic acid than did muscle from stress‐resistant pigs under conditions where the muscle from both types of animals had similar CP and ATP levels. Samples for histochemical analysis were examined from restrained and unrestrained muscle strips. There was a trend for the restrained samples to have somewhat smaller fibers. The muscle fiber size from Poland China animals was greater than that from Chester White animals. A large number of intermediate‐type fibers, on the basis of DPNH‐TR and phosphorylase staining, were found in the muscle of stress‐

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02719.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Cooked pork samples were stored at 3°C and analyzed for malonaldehyde (MA). MA increased to a maximum and remained there, typical behavior for a food but contrasting with pure lipid oxidation in which MA increases and then decreases as volatile MA is lost. The failure to lose MA in food products may be attributed to MA binding. Water extracts of cooked pork samples (representing approximately l /3 of the total MA) were fractionated on G‐10 Sephadex and analyzed for MA. With increasing storage time, a definite change in elution pattern from free MA to bound MA took place; the binding was not to protein or amino aci

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02720.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The effect of nitrite concentration on N‐nitrosodimethylamine (DMNA) formation using frankfurter emulsion was investigated. Sodium nitrite was usually added to the emulsion to give levels of 150, 750, 1050, 1500 and 2500 mg/kg of meat. The frankfurters were cooked with light smoke for either 2 or 4 hr. DMNA was determined in all samples by GLC with an alkali flame ionization detector and confirmed by GLC‐MS when sufficient amounts were present. Residual nitrite analysis indicated that about one‐half of the sodium nitrite added was still present after processing. 19 μg DMNA per kg meat was found in frankfurters that contained 2500 mg sodium nitrite per kg of meat and processed for 2 hr. Indications of DMNA in levels of 3–14 μg/kg meat were obtained with frankfurters containing 750–1500 mg sodium nitrite per kg meat and processed for either 2 or 4 hr depending on the nitrite level. There appeared to be some tendency for an increase in DMNA formation on increasing proc

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02721.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Raw protein foods derived from 20 different species of animals of different biological classifications were irradiated with gamma irradiation over a range of doses. The intensity of irradiated flavor developed in each case was determined by an expert panel. Relative flavor sensitivities and threshold doses were estimated.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02722.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

The rate of oxidation of potato chips as a function of oxygen partial pressure, extent of oxidation and equilibrium relative humidity was determined. We used the results to build mathematical models with the rate of oxidation as the dependent variable and the other three factors as independent variables. A mixed approach was used in model building which included incorporation of the knowledge of kinetics of lipid autoxidation mechanisms in food products as well as empirical relations. We developed a relatively simple model with only four constants. Statistical analysis indicates a good fit of this equation to the experimental results and suggests an experimental design allowing evaluation of the constants with less experimentation. The equation developed is useful for package simulation and optimization and storage life prediction, and we expect that the model can be applied to other food products.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02723.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

A mathematical model was developed to describe the deterioration of potato chips, a model of dry food products in flexible packages. In this product, deterioration occurred by two mechanisms acting simultaneously with interaction between them. The mechanisms were: oxidation by atmospheric oxygen and textural changes due to water absorption. We found that the extent of oxidation and the equilibrium relative humidity increase due to water absorption could be predicted as a function of time. The technique can be applied to investigate the storage life of products for different package configurations, initial conditions and environmental conditions.

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02724.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Methods are presented for determination of certain volatile nitrosamines which have been reported to occur in foods. Nitrosamines were removed from foods using a Likens‐Nickerson extractor; 60% of added dimethylnitrosamine and 70% of added diethyl‐nitrosamine were recovered from 10 rig/g aqueous solutions. Potential gas chromatographic (GC) interferences were removed from the extract by a simple acid extraction step and, when needed, by liquid column chromatography. Dilute solutions containing nitrosamines were analyzed directly with a GC solvent stripping technique. Nitrosamines were detected with a Coulson electrolytic conductivity detector operated in the pyrolytic mode and with a flame ionization detector. Sensitivities of these detectors are compared for selected volatile alkyl and heterocyclic nitrosamines of potential significance in foods. The specificity of the Coulson detector is demonstrated for analysis of extracts of smoked fish and a number of processed meats. Additional clean‐up of concentrates from foods is required to insure unambiguous identification of nitrosamines by combined GC‐mass spect

ISSN:0022-1147    

DOI:10.1111/j.1365-2621.1972.tb02725.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY