Explain two ways by which food industries prevent rancidity.

Rancidity is quality deterioration of fats/oils via oxidation (auto-oxidation forming peroxides, aldehydes) or hydrolysis (lipase activity), causing off-flavors and odors. Two widely used industrial controls:

1. Antioxidants and synergists- Food makers add antioxidants that interrupt free-radical chain reactions. Primary (chain-breaking) antioxidants like BHA, BHT, TBHQ, propyl gallate, tocopherols (vitamin E) donate hydrogen to lipid radicals, forming stable radicals that do not propagate. Secondary antioxidants such as ascorbates, citric acid (a metal chelator), and phosphates reduce pro-oxidant metals or scavenge oxygen/peroxides, enhancing primary antioxidant efficacy. Proper dosing follows legal limits and fat type.
2. Modified atmosphere and protective packaging- Removing or excluding oxygen reduces oxidation. Industry uses nitrogen flushing or vacuum packaging to displace air in headspace, then seals in oxygen-barrier films (e.g., EVOH laminates, metallized films). Opaque or UV-blocking packaging prevents light-induced initiation. Combined with low storage temperature and low moisture, these measures slow radical initiation and enzyme activity. Together, antioxidants plus oxygen/light control dramatically extend shelf life while preserving flavor, color, and nutrition.