Abstract: The present application describes a reagent system for detecting presence of aldehyde in a sample that includes (i) Component A, which includes bisulfite, pararosalinine, and hydrochloric acid; and (ii) Component B, which includes a solution of hydroxide, wherein the Component A has a pH of from about 1.4 to 1.6.

Abstract: A fresh or fermentation food packaging film, a packaging material and a packaging container which use the film, are disclosed. The fresh or fermentation food packaging film whose average pore size is 0.01-2 ?m and whose porosity is 10-80%, wherein the film is manufactured from pure crystalline polymer without addition of inorganic compounds or organic compounds for pore formation, so as to impart microporousness thereto by a dry stretching method which does not use an organic solvent and solvent. The packaging film which can pack fermentation food, such as Kimchi, etc., and fresh food, such as vegetables, etc., in which the packaging film can allow the food some operations, such as breathing and transpiration, etc., but restrain penetration of liquid, such as, water, etc., and can also effectively prevent leakage of smell, such that the food can be kept fresh, through a simple handling process.