Why does bacon change colour in the shops?

Bacon changes color in shops due to the curing process and the presence of nitrates or nitrites used in preserving it. These chemicals react with the meat's myoglobin, giving bacon its characteristic pink hue. Additionally, exposure to oxygen can cause the meat to appear brighter or duller, depending on how long it's been displayed. Over time, bacon may also take on a brownish tint as it oxidizes and ages.