Extreme temperature , humidity , or microoganisms also influence the nutritional value , caloric value and edibility of crops and account for food waste . The `` qualitative losses '' are more difficult to assess than quantitative ones . Losses in the nutritional value , caloric value and edibility of crops , by extremes of temperature , humidity or the action of microorganisms , also account for food waste ; these `` qualitative losses '' are more difficult to assess than quantitative ones .