Major preservation techniques include:
*Reduction in water activity
*Vacuum and modified atmosphere packaging
*Physical preservation technologies
*Use of preservatives
Preservatives are to keep food fresh and to prevent spoilage. This is important, as in modern lifestyle; food is rarely eaten at the time or place it is produced.
Preservatives serve as either anti-microbials or antioxidants - or both. As anti-microbials, they prevent the growth of mould, yeasts and bacteria.
As antioxidants, they keep foods from becoming rancid, browning or developing black spots. Rancid foods may not make the people sick, but they smell and taste bad.
Most of the effective and widely used preservatives are acids, for example, the weak lipophilic organic acids such as sorbate, benzoate, and propionate, or the inorganic ones such as sulfite or nitride, all of which are most effective at pH value lower than 5.5.
The use of chemical preservatives in foods allowed the industry to provide microbiological safe, extended shelf-life foods that were convenient; good examples being cured meats, sausage and marinated fish.
Food additives as food preservatives