Food Package

Abstract

This invention relates to food packaging and to methods for its manufacture. It is particularly suited to packaging of perishable foodstuffs which require that oxygen transmission occur across the packaging barrier, but that water vapour transmission be restricted.

1 . A food package comprising:
 (a) a support member comprising a multilayer film comprising:
 (i) at least one starch layer comprising a modified starch; and 
 (ii) at least one other layer having a water vapour permeability coefficient less than 1 g·mm/m 2 ·24 hr·atm measured at 38° C. and 90% relative humidity; and
 wherein the total thickness of the at least one starch layer is greater than 20% of the total thickness of the multilayer film and wherein the modified starch has a degree of substitution less than 1.5; and 
 
   (b) a lidding film wherein the lidding film is sealed to the support member such that a food product is enclosed thereby.   
     
     
         2 . A package according to  claim 1  wherein the water vapour permeability coefficient of the at least one other layer is less than 0.5 g·mm/m 2 ·24 hr·atm, preferably less than 0.2 g·mm/m 2 ·24 hr·atm. 
     
     
         3 . A package according to  claim 1  wherein the total thickness of the at least one starch layer is greater than 30% of the total thickness of the multilayer film, preferably greater than 40% of the total thickness of the multilayer film, more preferably greater than 50% of the total thickness of the multilayer film. 
     
     
         4 . A package according to  claim 1  wherein the at least one other layer comprises a polyolefin, polyethylene terephthalate, nylon, polyvinylchloride and polyvinylidene dichloride or mixtures thereof. 
     
     
         5 . A package according to  claim 4  wherein the polyolefin is selected from the group consisting of ethylene homopolymers, propylene homopolymers, interpolymers of ethylene and propylene and interpolymers of ethylene or propylene with one or more C 4 -C 10  α-olefins, cyclic olefin polymers and copolymers, biaxially orientated polypropylene, chemically modified polyolefins and mixtures thereof. 
     
     
         6 . A package according to  claim 4  wherein the polyolefin is selected from the group consisting of high density polyethylene, low density polyethylene, linear low density polyethylene, polypropylene, biaxially orientated polypropylene and mixtures thereof. 
     
     
         7 . A package according to  claim 1  comprising an inner starch layer and two outer polyolefin layers. 
     
     
         8 . A package according to  claim 1  wherein the at least one starch layer is fixed to the at least one other layer by an adhesive. 
     
     
         9 . A package according to  claim 8  wherein the adhesive comprises a polyurethane and/or polyurethane urea. 
     
     
         10 . A package according to  claim 1  wherein the film has an oxygen permeability coefficient (OPC) less than 0.6 cm 3  mm/m 2 ·24 h·atm at 50% RH, preferably less than 0.3 cm 3  mm/m 2 ·24 h·atm at 50% RH, more preferably less than 0.1 cm 3  mm/m 2 ·24 h·atm at 50% RH, most preferably less than 0.05 cm 3  mm/m 2 ·24 h·atm at 50% RH. 
     
     
         11 . A package according to  claim 1  wherein the total thickness of the multilayer film is between 10 and 1000 micron. 
     
     
         12 . A package according to  claim 1  wherein the at least one starch layer has a total thickness between 100 and 600 micron and the at least one other layer has a total thickness between 10 and 400 micron. 
     
     
         13 . A package according to  claim 1  wherein the at least one starch layer has a total thickness between 10 and 60 micron and the at least one other layer has a total thickness between 5 and 40 micron. 
     
     
         14 . A package according to  claim 1  wherein the modified starch comprises a high amylose starch. 
     
     
         15 . A package according to  claim 1  wherein the modified starch is chemically modified so as to replace hydroxyl functionality with functionality selected from the group consisting of ethers and esters and mixtures thereof. 
     
     
         16 . A package according to  claim 1  wherein the modified starch is chemically modified to include a hydroxyalkyl C 2-6  group or modified by reaction with an anhydride of a carboxylic acid. 
     
     
         17 . A package according to  claim 1  wherein the at least one starch layer further comprises at least one water soluble polymer. 
     
     
         18 . A package according to  claim 17  wherein the at least one water soluble polymer is selected from the group consisting of polyvinyl alcohol and polyvinyl acetate and mixtures thereof. 
     
     
         19 . A package according to  claim 1  wherein the at least one starch layer further comprises at least one plasticiser. 
     
     
         20 . A package according to  claim 19  wherein the at least one plasticiser comprises one or more polyols. 
     
     
         21 . A package according to  claim 1  wherein the lidding film has a higher permeation rate for both moisture and gases than the multilayer film. 
     
     
         22 . A package according to  claim 1  wherein the lidding film has a water vapour permeability coefficient greater than 1 g·mm/m 2 ·24 hr·atm measured at 38° C. and 90% relative humidity. 
     
     
         23 . A package according to  claim 1  wherein the lidding film has an oxygen permeability coefficient (OPC) greater than 0.6 cm 3  mm/m 2 ·24 h·atm at 50% RH. 
     
     
         24 . A method of packaging a food product comprising the steps of:
 a) providing a support member according to  claim 1 ;   b) providing a lidding film;   c) placing a food product on the support member;   d) extending the lidding film above the support member and product; and   e) sealing the lidding film to the support member such that the product is enclosed thereby.   
     
     
         25 . The method of  claim 24 , wherein one or more steps is automated. 
     
     
         26 . The method of  claim 24 , wherein the method comprises at least the step of thermoforming the support member. 
     
     
         27 . The method of  claim 24 , wherein the product is red meat, poultry, fish, cooked vegetables or a prepared meal. 
     
     
         28 . A package according to  claim 1  wherein the at least one starch layer comprises one or more nanomaterials. 
     
     
         29 . A package according to  claim 28  wherein the nanomaterial includes clays and modified clays. 
     
     
         30 . A package according to  claim 29  wherein the modified clay is a hydrophobically modified layered silicate clay. 
     
     
         31 . A package according to  claim 30  wherein the hydrophobically modified layered silicate clay is a clay modified with a surfactant comprising long chain alkyl groups wherein polar substituents are not attached to the long chain alkyl.