Final answer:
The oldest and slowest method of curing meats is air-drying, which dehydrates the meat, preventing microbial growth due to reduced water activity. Smoking meat, while not the oldest, is a traditional preservation method adding flavor and extending shelf life. Filtration is the technique that physically removes microbes without killing them.
Step-by-step explanation:
The oldest and slowest method of curing meats among the options provided is A) Air-drying. This technique has been employed for millennia and is known as desiccation. During the air-drying process, meats are preserved through dehydration, which effectively reduces the water activity within the meat. This reduction in water activity inhibits microbial growth because all cells, including microbes, require water for their metabolism and survival. Desiccation, when augmented with the use of salt or sugar, further decreases water activity, which enhances preservation. Although drying meats controls microbial growth, it does not necessarily kill all microbes.
Regarding the reasons jams and dried meats often do not require refrigeration to prevent spoilage, the answer would be related to the reduction of water activity that prevents microbial growth. Additionally, the smoking of meats, a technique traditionally embraced in the US South, also serves as a means of preservation by imparting flavors that prolong the meat's shelf life and making tougher cuts more palatable. Smoking meat does not remove microbes physically; instead, it helps in preserving the meat through the introduction of smoke, which has antimicrobial properties.
As for the method that removes microbes physically from samples without inhibiting their growth or killing them, the correct answer is A. filtration. Filtration is effective at physically separating microbes from various samples, including air and liquids.