Improperly stored foods spoil easily, harming health and wasting money. Common preservation methods include low-temperature storage, high-temperature sterilization, dehydration, increasing osmotic pressure, and raising hydrogen ion concentration. Though these terms may sound unfamiliar, they describe techniques we all use. Let's explore them with 39 Diet Editor.
Food spoilage is common in daily life and causes much frustration. If certain foods could remain fresh indefinitely, we could eat with greater peace of mind. Thus, proper food preservation methods are crucial.
1. Cold Storage
Cold storage inhibits microbial growth and slows spoilage, but it does not completely eliminate microorganisms.When storing at low temperatures, careful temperature control is essential. Generally, the lower the temperature, the longer the food can be preserved.
2. High-Temperature Sterilization
Subjecting food to high temperatures can kill most bacteria and enzymes. When combined with sealing, vacuum packing, and rapid cooling, this method effectively delays spoilage and extends shelf life. Examples include bagged pure milk, beer, and pasteurized milk.
3. Dehydration and Drying
Dehydration reduces moisture content below a threshold where microorganisms struggle to grow and enzymes become inactive. Common household methods include sun-drying, air-drying, heat evaporation, or freeze-drying. Note that while sun-drying is simplest, it causes the greatest vitamin loss.
4. Increasing Osmotic Pressure
Though the term may seem complex, most people have employed this method. Examples include salting or sugar-curing foods. A salt concentration of 8%-10% can inhibit most microbial growth but does not completely eliminate it.To kill microorganisms, salt concentration should be maintained at 15%-20%; for sugar-preserved foods, sugar concentration must reach 60%-65% to inhibit microbial growth. Storage requires airtight containers and moisture protection. Common sugar-preserved foods include dried fruits, candied fruits, and jams.
5. Increasing Hydrogen Ion Concentration
Most bacteria cannot grow normally in environments with a pH below 4.5. Therefore, increasing hydrogen ion concentration can be used for preservation. Vinegar pickling involves adding vinegar to food, a method commonly used for vegetables and fruits like pickled cucumbers, sauerkraut, and pickled bamboo shoots.