There is no single answer to this question. Much depends on the type of food and the type of process to which the food is subjected. In general I would say that the same rules apply to both processed and non-processed foods, i.e. storage temperatures, exposure to light and air. In processed foods it is important to block the growth and development of microorganisms for long preservation with physical or chemical treatments, other times it is important to reduce the water content and exposure to light to prevent oxidative phenomena. So a lot depends on the type of food and also on the type of treatment that the food undergoes during the transformation phase.

Spoilage of processed food depends on nature of raw materials and hygienic condition under taken during anyfood processing operations. It might be intrinsic( properties of raw ingredients) and extrinsic (environmental) factors. Moisture content,oxygen, biological materials, water activity,PH, Temperature and Relative humidity are among common spoilage factors in processed food.

Depending on the nature of the food, there may be different factors. These include, enzymatic activities, storage time and sterilization and packing conditions, presence of spolage microbes

Much depends on the consumer/user practices. Very few processed foods are sterile and consumers typically understand the signals of spoilage.

Improper handling, processing and packing may cause contamination by Anaerobic spore forming bacteria which are the most important spoilage agents.

The major contributing factors that may cause spoilage in processed foods include:

1. Microbial contamination: Introduction of bacteria, yeast, mold, or other microorganisms during processing, packaging, or storage can lead to spoilage.

2. Oxygen exposure: Oxidation of fats and oils can lead to rancidity, while exposure to air can cause enzymatic browning in fruits and vegetables.

3. Moisture content: High moisture levels can promote microbial growth and enzymatic reactions, leading to spoilage.

4. pH levels: Foods with an improper pH level may be susceptible to microbial growth and spoilage.

5. Temperature abuse: Improper temperature control during processing, transportation, or storage can accelerate spoilage by allowing microbial growth and enzymatic reactions.

6. Contaminants: Chemical, physical, or biological contaminants introduced during processing or packaging can lead to spoilage.

7. Packaging: Ineffective or damaged packaging can lead to moisture loss, air exposure, or contamination, accelerating spoilage.

8. Enzymes: Enzymatic activity can cause changes in color, flavor, and texture, leading to spoilage in processed foods.