Active PackagingActive PackagingFood Packaging

Definition of Active Definition of Active PackagingPackagingActive packaging the incorporation of

certain additives into packaging film or within packaging containers with the aim of maintaining and extending product shelf life

Packaging may be termed active when it performs some desired role in food preservation other than providing an inert barrier to external conditions (Rooney, 1995; Hotchkiss, 1994)

Active packaging includes additives or freshness enhancers that are capable of scavenging oxygen; adsorbing carbon dioxide, moisture, ethylene and/or flavour/odour taints; releasing ethanol, sorbates, antioxidants and/or other preservatives; and/or maintaining temperature control.

Applying Active PackagingApplying Active Packaging All food products have a unique deterioration

mechanism that must be understood before applying active packaging

The shelf life of packaged food is dependent on numerous factors such as ◦ Intrinsic nature of the food acidity (pH), water

activity (aw), nutrient content, occurrence of antimicrobial compounds, redox potential, respiration rate and biological structure

◦ Extrinsic factors temperature, relative humidity (RH) and the surrounding gaseous composition

These factors will directly influence the chemical, biochemical, physical and microbiological spoilage mechanisms of individual food products and their achievable shelf lives By considering all of these factors, it is possible to choose and apply active packaging for maintaining the quality and extending the shelf life of different food products (Day, 1989)

Table 1. Examples of active packaging systems Table 1. Examples of active packaging systems (cont.)(cont.)

Table 1. Examples of active packaging Table 1. Examples of active packaging systems (cont.)systems (cont.)

Active Packaging ≠ Intelligent Active Packaging ≠ Intelligent PackagingPackagingIntelligent or smart packaging packaging

that senses and informs about : ◦ The function and properties of packaged food◦ Provide assurances of pack integrity, tamper

evidence, product safety and quality, and are being utilised in applications such as product authenticity, anti-theft and product traceability

Intelligent packaging devices include time-temperature indicators, gas sensing dyes, microbial growth indicators, physical shock indicators, and numerous examples of tamper proof, anti-counterfeiting and anti-theft technologies.

Oxygen Scavengers 1Oxygen Scavengers 1Oxygen have considerable detrimental

effects on foods Oxygen scavengers can maintain food

product quality by : ◦ Decreasing food metabolism,◦ Reducing oxidative rancidity◦ Inhibiting undesirable oxidation of labile

pigments and vitamins◦ Controlling enzymic discolouration ◦ Inhibiting the growth of aerobic

microorganismsOxygen scavengers now is the most

commercially important sub-category of active packaging

Oxygen Scavengers 2Oxygen Scavengers 2The type of oxygen scavengers :

◦Iron based powder with catalyst Most well known oxygen scavanger Separated from the food by keeping it in a small,

highly oxygen permeable sachet that is labelled Do not eat

Mechanism : often react with water supplied by the food to produce a reactive hydrated metallic reducing agent that scavenges oxygen within the food package and irreversibly converts it to a stable oxide

Advantage : capable of reducing oxygen levels to less than 0.01% (much lower than the typical 0.3–3.0% residual oxygen levels achievable by MAP)

Can be used alone or in combination with MAP. Their use alone eliminates the need for MAP machinery and can increase packaging speeds

Oxygen Scavengers 3Oxygen Scavengers 3 Non-metallic oxygen scavengers have also been

developed to alleviate the potential for metallic taints being imparted to food products.

The problem of inadvertently setting off in-line metal detectors is also alleviated even though some modern detectors can now be tuned to phase out the scavenger signal whilst retaining high sensitivity for ferrous and non-ferrous metallic contaminants

Non-metallic scavengers include those that use organic reducing agents such as ascorbic acid, ascorbate salts or catechol. They also include enzymic oxygen scavenger systems using either glucose oxidase or ethanol oxidase which could be incorporated into sachets, adhesive labels or immobilised onto packaging film surfaces

COCO22 Scavengers / Emitters Scavengers / Emitters 1 1 The use of carbon dioxide scavengers

for fresh roasted or ground coffees that produce significant volumes of carbon dioxide

Fresh roasted or ground coffees cannot be left unpackaged (will absorb moisture and oxygen and lose desirable volatile aromas and flavours), however, if coffee is hermetically sealed in packs directly after roasting, the carbon dioxide released will build up within the packs and eventually cause them to burst

COCO22 Scavengers / Emitters Scavengers / Emitters 22Two solutions :

◦Use packaging with patented one-way valves that will allow excess carbon dioxide to escape

◦Use a carbon dioxide scavenger or a dual-action oxygen and carbon dioxide scavenger system

Dual-action sachets typically contain ◦ Iron powder scavenging oxygen◦Calcium hydroxide scavenges carbon

dioxide when it is converted to calcium carbonate under sufficiently high humidity conditions

COCO22 Scavengers / Emitters Scavengers / Emitters 33CO2 emitting sachet can either be

used : ◦Alone example : used for extending the

shelf life of fresh meats and fish using MAP package containing CO2 emitting sachet (sodium bicarbonate/ascorbate)

Combined with an oxygen usually contain ferrous carbonate and a metal halide catalyst scavenger used for snack food products, e.g. nuts and sponge cakes

Preservatives ReleasersPreservatives ReleasersPackaging film with potential of :

◦Antimicrobial Organic acids, e.g. propionate, benzoate and

sorbate, bacteriocins, e.g. nisin, spice and herb extracts, e.g. from rosemary, cloves, horseradish, mustard, cinnamon and thyme, enzymes, e.g peroxidase, lysozyme and glucose oxidase, chelating agents, e.g. EDTA, inorganic acids, e.g. sulphur dioxide and chlorine dioxide and antifungal agents, e.g. imazalil and benomyl

Applications : meats, fish, bread, cheese, fruit and vegetables

◦Antioxidant Usually used : BHT, BHA, vitamin E Vitamin E natural and safer than the synthetic

ones

Moisture AbsorbersMoisture AbsorbersExcess moisture is a major cause of food

spoilageSoaking up moisture by using various

absorbers or desiccants is very effective in maintaining food quality and extending shelf life by inhibiting microbial growth and moisture related degradation of texture and flavour

Usually, moisture absorbers in the form of sachets, pads, sheets or blankets

For packaged dried food applications, desiccants such as silica gel, calcium oxide and activated clays and minerals are typically contained within

Sachets may also contain ◦ Activated carbon for odour adsorption ◦ Iron powder for oxygen scavenging

Flavor / Odor AbsorbersFlavor / Odor Absorbers Interaction of packaging with food flavours

and aromas undesirable flavour scalping of desirable food components

Commercially, very few active packaging techniques have been used to selectively remove undesirable flavours and taints, but many potential opportunities exist

Example the debittering of pasteurised orange juices. Some varieties of orange, such as Navel, are particularly prone to bitter flavours caused by limonin, a tetraterpenoid which is liberated into the juice after orange pressing and subsequent pasteurisation limonin adsorbers (e.g. cellulose triacetate or acetylated paper)

Temperature Control Temperature Control PackagingPackagingTemperature control active packaging

includes :◦ Innovative insulating materials to guard

against undue temperature abuse during storage and distribution of chilled foods increase the thermal mass of the food package so that it is capable of withstanding temperature rises

◦ Self-heating cans and containers self-heating aluminium and steel cans and containers for sake, coffee, tea and ready meals are heated by an exothermic reaction which occurs when lime and water positioned in the base are mixed

◦ Self-cooling cans endothermic dissolution of ammonium nitrate and chloride in water is used to cool the product

Food SafetyFood SafetyAt least four types of food safety and regulatory

issues related to active packaging of foods : ◦ Any need for food contact approval must be

established before any form of active packaging is used

◦ It is important to consider environmental regulations covering active-packaging materials

◦ A need for labelling in cases where active packaging may give rise to consumer confusion

◦ It is important to consider the effects of active packaging on the microbial ecology and safety of foods

All of these issues are addressed in an EC funded Actipack project to evaluate the safety, effectiveness, economic and environmental impact and consumer acceptance of active and intelligent packaging

Consumer AcceptabilityConsumer AcceptabilityIn the USA, Japan and Australia, active

packaging concepts are already being successfully applied

In Europe, the development and application of active packaging is limited because of legislative restrictions, fear of consumer resistance, lack of knowledge about effectiveness and economic and environmental impact of concepts

In Finland, a consumer survey conducted in order to determine consumer attitudes towards oxygen scavengers revealed that the new concepts would be accepted if consumers are well informed by using reliable information channels

Modified Atmosphere Modified Atmosphere PackagingPackagingFood Packaging

IntroductionIntroductionMany foods spoil rapidly in air due to

moisture loss or uptake, reaction with oxygen and the growth of aerobic microorganisms, i.e. bacteria and moulds

Microbial growth results in changes in texture, colour, flavour and nutritional value of the food render food unpalatable and potentially unsafe for human consumption

Storage of foods in a modified gaseous atmosphere can maintain quality and extend product shelf life◦ by slowing chemical and biochemical

deteriorative reactions ◦ by slowing preventing the growth of spoilage

organisms

Definition of MAPDefinition of MAPModified atmosphere packaging (MAP) is

defined as ‘the packaging of a perishable product in an atmosphere which has been modified so that its composition is other than that of air’

The gaseous composition of fresh MAP foods is constantly changing due to chemical reactions, microbial activity, and gas exchange between the pack headspace and the external environment

Controlled atmosphere storage (CAS) involves maintaining a fixed concentration of gases surrounding the product by careful monitoring and addition of gases

Gases Used in MAPGases Used in MAPThe choice of gas is totally

dependent upon the food product being packed

The three main gases used in MAP O2, CO2 and N2

Used singly or in combination, these gases are commonly used to balance safe shelf life extension with optimal organoleptic properties of the food

Noble or inert gases such as argon are in commercial use for products such as coffee and snack products

Carbon DioxideCarbon DioxideCO2 is a colourless gas with a slight pungent

odour at very high concentrations. It is an asphyxiant and slightly corrosive in the presence of moisture

CO2 dissolves readily in water (1.57gkg−1 at 100kPa, 20°C) to produce carbonic acid (H2 CO3) that increases the acidity of the solution and reduces the pH

The solubility of CO2 increases with decreasing temperature antimicrobial activity of CO2 is markedly greater at temperatures below 10°C than at 15°C or higher

OxygenOxygen O2 is a colourless, odourless gas that is highly

reactive and supports combustion Oxygen promotes several types of deteriorative

reactions in foods including fat oxidation, browning reactions and pigment oxidation. Most of the common spoilage bacteria and fungi require O2 for growth to increase the shelf life of foods, the pack atmosphere should contain a low concentration of residual O2

It should be noted that in some foods a low concentration of O2 can result in quality and safety problems (for example, unfavourable colour changes in red meat pigments, growth of food poisoning bacteria), and this must be taken into account when selecting the gaseous composition for a packaged food

NitrogenNitrogen N2 is a relatively un-reactive gas with no

odour, taste or colour, has a lower density than air, non-flammable and has a low solubility in water and other food constituents

Nitrogen does not support the growth of aerobic microbes and therefore inhibits the growth of aerobic spoilage but does not prevent the growth of anaerobic bacteria

The low solubility of N2 in foods can be used to prevent pack collapse by including sufficient N2 in the gas mix to balance the volume decrease due to CO2 going into solution

Carbon MonoxideCarbon MonoxideCO is a colourless, tasteless and

odourless gas that is highly reactive and very flammable, has a low solubility in water but is relatively soluble in some organic solvents

CO has been studied in the MAP of meat and has been licensed for use in the USA to prevent browning in packed lettuce

Commercial application has been limited because of its toxicity and the formation of potentially explosive mixtures with air

Noble GasesNoble GasesThe noble gases are a family of

elements characterised by their lack of reactivity helium (He), argon (Ar), xenon (Xe) and neon (Ne)

These gases are being used in a number of food applications now, e.g. potato-based snack products