Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Coated or impregnated woven – knit – or nonwoven fabric which... – Coating or impregnation functions biologically
Patent
1996-12-16
1998-09-29
Morris, Terrel
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Coated or impregnated woven, knit, or nonwoven fabric which...
Coating or impregnation functions biologically
549416, 428 17, 428 22, D04H 158, C07D31500, A01N 300
Patent
active
058145680
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a water-absorbent paper or nonwoven fabric for preventing the discoloration of the cut surface of lettuce stem and a method for preventing the discoloration thereof.
BACKGROUND ART
Various methods have been proposed to retain the freshness of vegetables or fruits or to prevent them from becoming moldy. For example, JP-A-2-303469 discloses a method for packaging a processed "wasabi" (Japanese horseradish) or mustard along with a preservative. JP-A-58-51842 discloses a method for retaining the freshness of vegetables or fruits which comprises applying to the cut surface of their roots or stems, a very small amount of a powder, aqueous solution, glycol solution or alcohol solution obtained by mixing an oxide, peroxide, polysaccharide, gum, metal salt, formaldehyde, urotropin or the like with an organic acid such as malic acid, tartaric acid, citric acid or the like and tightly packaging them respectively in a polystyrene film or the like. JP-A-64-6034 discloses a method for retaining the freshness of vegetables, fruits or cut flowers by packaging them respectively in a plastic sheet (or film) to which 5-hydroxy-2-hydroxymethyl-.gamma.-pyrone is applied.
However, the methods mentioned above are not satisfactory to prevent the cut surface of lettuce stem from discoloring. An object of the present invention is to improve the effects of preventing the discoloration of the cut surface of lettuce stem.
DISCLOSURE OF THE INVENTION
The present inventors have accomplished the present invention as a result of massive research to overcome the drawbacks of the prior art described hereinbefore.
The present invention provides a water-absorbent paper or nonwoven fabric containing 5-hydroxy-2-hydroxymethyl-.gamma.-pyrone for preventing the discoloration of the cut surface of vegetables, fruits and cut flowers and a method for preventing discoloration by the use thereof.
5-Hydroxy-2-hydroxymethyl-.gamma.-pyrone used in the present invention (hereinafter referred to as the pyrone compound) is represented by the following formula (1) and is also called kojic acid. This compound is produced from various carbohydrates by the use of a microorganism and is commercially available. ##STR1##
The water absorption ratio of the water-absorbent paper or nonwoven fabric of the present invention is not less than 60 percent, preferably not less than 80%, as determined by the measurement method described below.
In the present invention, it is necessary that the pyrone compound be impregnated in the water-absorbent paper or nonwoven fabric. The impregnation of the pyrone compound in the water-absorbent paper or nonwoven fabric of the present invention makes it possible to maintain or enhance freshness-retaining effects such as prevention of leaf wilting and rotting and to further prevent the cut surface from discoloring, as compared with the application of the pyrone compound to a plastic film or sheet having less than 60% of water absorption ratio or the direct application of the pyrone compound to lettuce stem. The reason why a discoloration-preventing effect is exhibited is not clear, but it is presumably attributed to the synergism of the antibacterial effects of 5-hydroxy-2-hydroxymethyl-.gamma.-pyrone and the action by the water-absorbent paper or nonwoven fabric of absorbing and removing a browning enzyme.
The content of the pyrone compound in the water-absorbent sheet is preferably less than 8 g/m.sup.2, more preferably 0.05-5 g/m.sup.2.
The nonwoven fabric used in the present invention is composed of short or long fibers of cotton, rayon, acetate, nylon, polyester or the like, but its fiber density and production method are not limited, particularly if its water absorption ratio is within the scope of the present invention.
Referring to the method for impregnating the pyrone compound into the water-absorbent paper or nonwoven fabric, it is preferred to apply it as a solution or dispersion obtained by dissolving or dispersing the pyrone compound in water, an alcohol, an acetic aci
Hishiki Atsushi
Kato Yoshitaka
Asahi Kasei Kogyo Kabushiki Kaisha
Morris Terrel
LandOfFree
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