Active and Intelligent Food Packaging
Dr. ÇİĞDEM SOYSAL
Food Engineering Department
Active packaging is an innovative concept that can be defined as a type of packaging that changes the condition of the packaging to extend shelf-life or improve safety or sensory properties while maintaining the quality of the food.
Active packages are designed to solve some problems related to food quality and/or food safety. Antimicrobial preservative releasers, antioxidant releasers, and flavoring and aroma emitters are examples of active packaging systems for preservation and shelf life extension of foods or improving their quality.
In the presence of O2, food deterioration is caused by oxidation of food constituents or spoilage by moulds.
By use of an O2-scavenger, which absorbs the residual O2
after packaging, quality changes of O2-sensitive foods can be minimized.
a)iron powder oxidation,
b)ascorbic acid oxidation,
c)photo-sensitive dye oxidation,
d)enzymatic oxidation (e.g. Glucose oxidase and alcohol oxidase),
e)unsaturated fatty acids (e.g. oleic acid or linolenic acid),
f)immobilized yeast on a solid material
Ageless (Mitsubishi Gas Chemical Co., Japan) is the most common O2-scavenging system based on iron oxidation. The sachets are designed to reduce O2-levels to less than 0.01%. A rule of thumb is that 1g of iron will react with 300 cc of O2.
Other iron-based O2-absorbent sachets are:
ATCO O2-absorber (Standa Industrie, France),
Freshilizer Series (Toppan Printing Co., Japan),
Vitalon (Toagosei Chem. Industry Co., Japan),
Sansocut (Finetec Co., Japan) and
Freshpax (Multisorb Technologies Inc., USA)
The sachets can be found in packages of many foods including fresh and pre-cooked pasta, catering, meat products (e.g. smoked ham and salami), bakery products (e.g. bread, pizza crust, pastries, cookies, cakes), cheese, coffee, nuts and potato chips.
An alternative to sachets is the incorporation of the O2-scavenger into the packaging structure itself. Low molecular weight ingredients may be dissolved or dispersed in a plastic or the plastic may be made from a polymeric scavenger.
An example is Oxyguard (Toyo Seikan Kaisha, Japan), an iron-based absorber which can be incorporated into a laminate. The main alternative to dispersal of iron in plastics is organic reactions of plastics themselves.
Oxbar is a system developed by Carnaud-Metal Box (UK) which involves cobalt-catalysed oxidation of a nylon polymer blended especially in PET-bottles for plastic packaging of wine, beer, sauces and other beverages.
Amoco Chemicals (USA) marketed Amosorb, a polymer-based absorber which can be incorporated in various packaging structures including the sidewall or lid of rigid containers, flexible films, and closure liners.
Speed and capacity of O2-scavenging films are considerably lower compared with iron-based O2-scavenger sachets.
b) Ascorbic acid oxidation
The basic reaction of Darex O2-scavenging technology, designed to be incorporated into barrier packaging such as crown caps, plastic or metal closures, is ascorbate oxidizing to dehydroascorbic acid and sulphite to sulphate. The major use is in crown caps to protect beer from oxidation of flavours.
The Pillsbury Co. holds a 1994 patent that also utilizes ascorbic acid as reducing agent. A transition metal, preferably copper, is used to catalyse the oxidation reaction. The product, referred to as Oxysorb can be included inside a pouch or may be incorporated into the packaging.
c) Photo-sensitive dye oxidation
O2-scavenging technique involves sealing of a small coil of an ethyl cellulose film containing a dissolved photosensitive dye and a singlet O2-acceptor in the headspace of a transparent package. Due to illumination of the film with light of the appropriate wavelength, excited dye molecules sensitize O2-molecules, which have diffused into the polymer, to the singlet state. These singlet O2-molecules react with acceptor molecules and are thereby consumed.
Examples of light-activated scavengers, incorporated in the packaging film, are Zero developed by CSIRO and OS1000 developed by Cryovac Sealed Air.