During transport, handing and storage, the goods are under the influence of the environment with which they correlate (interact) and consequently undergo biotic changes, of which the most important are:
- Changes due to microorganisms (molds, bacteria, yeasts), which lead to mold growth and rot
- Metabolic processes in the case of organs and organisms, such as respiration, glycolysis, autolysis
- Other biochemical changes, such as rancidity, fermentation, self-heating
- Changes due to animal pests, such as insects (beetles, moths), arachnids (mites) and rodents (rats, mice)
The causal factors are:
- Mechanical influences (throwing, dropping, impacts, jolting), which cause bruises on fruit and vegetables, which in turn act as starting points for microbial attack
- Elevated temperatures
- promote the growth and multiplication of microorganisms to their optimum extent
- encourage animal pests to become active, up to their maximum level of mobility
- additionally activate metabolic processes in goods of vegetable origin
- Relatively low temperatures, which cause chilling damage (chilling) in fruit and vegetables, if the temperature falls below the lower temperature limit admissible for a specific product, e.g. brown spot diseases, loss of ability to ripen
- High water content or high relative humidity, which in particular promotes growth of microorganisms
- Influence of air composition (e.g. atmospheric oxygen, carbon dioxide, ethylene), which affects the respiration and ripening of goods of vegetable origin (allelopathy)
- Air movement, dust and microbe content of air, all of which promote infection by microorganisms
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