摘要:

Pork cuts were stored at relative humidities of 83, 87, 92, 96, and 100% and temperatures of − 6.6°, − 12.2°, − 17.7°, and − 23 °C. for 48 weeks. Visual examination revealed various degrees of surface drying under all conditions, and pronounced methaemoglobin formation at − 6.6 °C. Quantitative colour measurements on both the exposed and internal surfaces of the lean, showed that storage temperature was the primary factor affecting the colour. Temperatures of − 18 °C., or lower, are required to prevent these changes. Samples that had suffered the greatest colour change during storage showed the least change during subsequent exposure.Temperature was also the primary factor affecting the development of rancidity in the fat. Both peroxide oxygen and free fatty acid increased significantly with increase in storage temperature, particularly between − 12.2° and − 6.6 °C., but the actual quantities of free fatty acid were small and of little consequence. Storage temperatures of − 18 °C., or lower, are essential if spoilage of pork fat is to be avoided over storage periods of approximately one year's duration.

ISSN:1923-4287    

DOI:10.1139/cjr41d-004

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

Little or no change due to time or depth was found in the bacterial content of Wiltshire tank pickle during cure. A decided increase in the number of bacteria occurred on the surface of the sides. Settling of bacteria from the pickle was not responsible for this increase. Of the normal commercial practices of salting the sides prior to cure, and washing and wiping after cure, wiping was the most important in reducing the bacterial population of the surface of the meat.The concentration of sodium chloride, nitrate, and nitrite in the curing pickle decreased most rapidly during the first 12 or 24 hr. of cure. Over the remainder of the curing period, the chloride content decreased at a relatively uniform rate and the nitrite content remained constant within the sampling error. Changes in nitrate were generally less than the sampling error. Although stratification of the salts in the tank was evident even after three hours from the beginning of cure, the actual magnitude of the differences was small and would have little detrimental effect on the bacon. There was no apparent relation between bacterial and chemical changes in the pickle during cure.

ISSN:1923-4287    

DOI:10.1139/cjr41d-005

出版商:NRC Research Press    

年代:1941

数据来源: NRC

摘要:

Females of an inbredal c:se ss:eyRmutant strain were crossed with males from a "wild" strain that had been inbred (brother × sister) for more than 60 generations. TheF1males were mated with mutant strain females. The backcross offspring would be expected to appear in eight genotypes with equal frequencies were there no differences in viability. The marker genes permitted the scoring of each fly as to whether it was heterozygous or homozygous for each of the mutant autosomes.The genes used as markers probably had a distinctly negative effect upon both viability and rate of development, but the second pair of autosomes in combination with the other mutant autosomes increased viability, when homozygous, to a greater extent than did a heterozygous mutant-wild type pair. Apparently the possible negative effects of the markersalandcwere more than offset by other genes on this autosome which had positive effects. The negative effects of the homozygous mutant third and fourth chromosomes were severe when in combination.The interactions of the positive second chromosome and the negative third and fourth chromosomes in the eight genotypes were of some geometric order. It was found that the addition of a "positive" or "negative" autosome to any genotype caused a change in viability in the direction of the added autosome, but theamountof change is at present unpredictable and depends upon the particular combination to which the autosome was added.The relation between the different autosomes and the rate of development was quite different from the relation between autosomes and viability. The second chromosome (marked byal c), which gave the only positive contribution to viability, retarded development more than either the third (se ss) or the fourth (eyR). The effects of the three autosomes on rate of development were not strictly additive.It is concluded that there is interaction of the genes for quantitative characters and this interaction is geometric in nature. The significance of the results in their relation to some theories of the inheritance of quantitative characters is discussed.

ISSN:1923-4287    

DOI:10.1139/cjr41d-006

出版商:NRC Research Press    

年代:1941

数据来源: NRC