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Changes in the Quality Characteristics of Vacuum-packaged Carabeef During Freezer Storage
Thesis Abstract:
The quality characteristics of vacuum-packed carabeef in frozen state at different freezer temperatures were studied.
Carabeef loin cuts and ground chucks were stored in vacuum-bags at -12.2ºC, -6.7ºC, and at fluctuating temperature (-12.2ºC to 27ºC) for six months and were evaluated through microbiological, chemical, and sensory methods at monthly intervals. At both -12ºC and -6.1ºC, microbial population of all samples considerably reduced. The microbial populations consisted predominantly of the genera Micrococcus, Pseudomonas, and Boclllus. The genus Micrococcus was highly predommant in all instanees. On the other hand, the autolytic process as welI as metabolic activities of the microorganism that survived proceeded, resulting in increased production of basic by-products sufficient to cause quality deterioration. Likewise, production of rancidity by-products continued slowly at different rates, but were insufficient to alter flavor. Nevertheless, regardless of changes in sensory properties, all carabeef samples were still acceptable until the end of the storage period.
After the first month of storage at fluctuating tempernture (-12.2ºC to 21ºC), the microbial populatoon of all samples increased gradually except for coliform count, which continues to decrease until the end of the storage period of the growth of coliform organisms was probably suppressed by Lactobacillus organisms. The microbial populations were highly predominated by members of Lactobacillus, but the proportion of Pseudomonas organisms also continued to increase throughout the storage period. Spoilage ensued owing to the accumulation of acids and basic by-products. Production of rancidity by-products also proceeded slowly at different rates. but again, were insufficient to alter flavor. Despite changes in sensory properties, all carabeef cuts and ground meat samples remained acceptable up to four months of storage. On the fifth month, the sample became unacceptable because of the strong fermented/putrid off-odors, slight greenish discoloration. and slime formation on the surface of the meat.