By Prof. J Mitra*
Introduction
The basic concept of packaging is to contain the food, provide physical, chemical, or microbial contaminant free food to consumer and nonetheless to communicate the product composition and properties.Of late,the growing consumer demand for increased shelf life, minimally processed food has compelled the food scientists and packaging industries to develop innovative solutions to address the changing demands of the consumers. These resulted in active and intelligent packaging.Active packaging is used to increase protection function of package by enhancing mechanical, barrier, optical and most commonly antimicrobial property. However, intelligent packaging is an extension of communication function of the package.
Food is a highly perishable and readily interact with the ambience. Intrinsic factors affecting the food quality include pH, water activity (aw), nutrients, presence of antimicrobial compounds, respiration rate, and the biological structure, initial microbial load; whereas, extrinsic factors include storage temperature, relative humidity (RH), and the surrounding gas composition.
Active Packaging
Active packaging interacts with the food or with the headspace gas composition to add certain functionality to the package.These are optical barrier, oxygen scavengers, ethylene scavengers, liquid and moisture absorbers, flavour and odour absorbers or releasers, antimicrobials, and very recently nanocomposites etc.Nanostructures immobilize enzymes, kill/inactivate microbes, act as biosensors etc.
Table 1: Common active packaging systems:
|
Active Packaging systems |
Mechanism/compounds |
Commercial names |
|
Oxygen Scavengers |
Iron, iron salts,photosensitive colouring matter,Ascorbic acid, unsaturated fatty acids (oleic, linoleic), Enzymes (glucose oxidase/catalase, alcohol oxidase), Mechanism: Get oxidised and control the oxygen concentration inside the package. |
Independent systems: Ageless®, ATCO® oxygen scavengers, FreshPax®, FreshMax®,FreshCard®,Freshilizer®, O-BUSTER. Integrated systems: SHELFPLUS® O2, OxyguardTM,OxbarTM, CryovacOS,valOR ActivBloc100, Amosorb series, ZERO2, Bioka Oxygen Scavenging Film Laminate, and ActiTUF® |
|
Ethylene Scavengers |
|
Ethylene Control Power Pellet sachets and Retarder®, Bio-fresh packaging system, Ethysorb, Evert-Fresh Green Bags®, PEAKfresh®,Profresh. |
|
Moisture Absorbers |
Silica gel, montmorillonite, molecularsieves, carbohydrates, minerals, calcium oxide, cellulose fibres, polyacrylate salts and polypropylene glycol. |
ADPTM, Dri-FreshTM, InflexTM, ToppanTM, Crisp-itTM, Dri-FreshTM Resolve, Eat-FreshTM, Dri-Loc®, Lite-Loc® Plus, Humidipak, Luquasorb® FP 800, Luquasorb® P 1480, NatraSorb®, ATCO Pad, and Pichit. |
|
Flavour and Odour Absorber/Releaser |
eliminate, undesirable compounds/odour releasingdesirable compounds
|
Releaser: Aroma-Can® and Compel Aroma®. ABSCENTS, Aroma-Can®, ATCO® oxygen scavengers, Compel Aroma®, ODORLESS D, and Sincera® Absorber: Minipax, Natrasorb, 2-in-1 Pak® are multipurpose absorbent. BHM powder (EKA Noble), ABSCENTS Deodorizing powders
|
|
Antimicrobials |
Ethanol, carbon dioxide, silver ions,chelators, etc. chlorine dioxide, antibiotics, organic acids, essential oils, spices, and allyl isothiocyanate etc. bacteriocins such as nisin,lacticin, and pediocin. Chitosan. |
CO2 releasing: Ageless® G, FreshPax, and Freshilizer®. Agion® Antimicrobial: microbeguard®, food touchTM and Ciba® irgaguard
|
|
Antioxidants |
vitamin E, phenolic compounds, terpenes, cyclodextrins |
|
Oxygen Scavengers
The deteriorative reactions in many foods accelerate by oxygen,produceoff-flavours, change colours, degrade vitamins (vitamins A, C, E), causes rancidity (oils, nuts, and fatty foods), and induces microbial growth.This can be controlled by oxygenscavengersto as low as 0.01% oxygen.
Ethylene Scavengers
Ethylenecauses ripening, tissues oftening, chlorophylls degradation, and consequently deterioration of fresh fruits and vegetables specially in climacteric fruits and vegetables such as apples, kiwis, bananas, mangos, tomatoes, onions, carrots, and asparagus.
Moisture Absorbers
High moisture causes softening of dry and crunchy products (snacks, biscuits, pasta, cookies), initiate microbial growth, and causes caking in milk or coffee powders.moisture absorbers are selected based onintrinsic and extrinsic factors.
Flavour Releaser/Odour Absorber
Release of artificial flavour/aromas during storage are controlled by temp, pH, RHetc. Gradual release of flavours can offset the natural loss of taste or smell of products with long shelflife.
Antimicrobials
Volatile antimicrobials of package can penetrate most of the food matrix and offer antimicrobial effect. High carbon dioxide concentration is desired for fresh and processed fish, meats, cheeses, and baked goods, to retain the organoleptic properties of the products and to impart bacteriostatic effect.
Antioxidants
Oxidation of lipids, nuts, butter, fresh meat, meat derivatives, bakery products, fruits and vegetables leads to reduction in shelf-life due to changes in taste, odour, nutritional quality, texture and functionality of muscle foods.Radical scavengers eliminate free radicals as soon as they are formed.
Intelligent Packaging
Intelligent packaging sense, detect and inform the consumer about the quality of the product.This quality changes can cause due to temperature fluctuations during transfer and storage, microbiological contamination of food, physical damage, tearing etc.Intelligent packaging includes time-temperature indicators, gas detectors, and freshness and/or ripening indicators.
Table 2: Common intelligent packaging systems:
|
Intelligent Packaging systems |
Mechanism |
Commercial names |
|
Time-Temperature Indicators (TTI) |
Based on enzymatic reactions, polymerization, or chemical diffusion. |
Ovum and Novus Ice, Monitor MarkTM, Warm Mark Time-Temp Tags, Check Point, Cold SNAP, Fresh-Check®, Log-ic®, ThermRF tag, Coldmark, ThermRF Logger, and ThermRF Tag. Log-ic® RFID and VarioSens® |
|
Freshness Ripening Indicators |
Indirect detection: colour indicators (pH). Direct detection: biosensors Detect genetic modification, and food safety, presence of Salmonella sp., Campylobacter sp., Listeria sp., Escherichia coli, etc. |
FreshTags®, (Eo)®, Timestrip®, ripeSense®, SensorQTM Food Sentinel SystemTM (detect food pathogens) Toxin Guard™ |
|
Integrity indicators |
Chemical or enzymatic reactions based. Redox dyes (methylene blue, 2, 6-dichoroindophenol) for O2 intelligentink detects presence of oxygen by changing its color |
O2 indicator:Ageless Eye®, Wondersensor O2 absorber:Wonderkeep
|
Time-Temperature Indicators (TTI)
Temperature fluctuation during storage and transportation induce chemical, biochemical and microbial changes to perishable foods; hence, the shelf life deviates from the designed one. TTI are strictly irreversible. They arevisual indicators and radio frequency identification (RFID) tags.The RFID tag uses RF electromagnetic fields to store and communicate real-time information of the product.RFID tag (inbuilt microchip connected to a tiny antenna)remotely monitor multiple items at a time and store it.
Integrity indicators
The headspace gas composition, moisture and temperature may change due to leaks/tear of the package.Chemical or enzymatic reactions causes colour change in most of the indicators when it reaches the critical limit.
Freshness and/or Ripening Indicators
Freshness indicators (FI)indicate the quality by measuring the concentration changes of metabolites(glucose, organic acids, ethanol, carbon dioxide, biogenic amines, volatile nitrogenous or sulphuric compounds) during storage which signify microbial growth for meat, fish etc., and diacetyl, amines, carbon dioxide, ammonia and hydrogen sulfide, produced during aging of foods.
Other systems
Scavenger antibodyoffers a higher sensitivity towards atoxic substance.Nanocomposites retain freshness, show high barrier and antimicrobialproperty, thermal buffering, and deliver nutrients also. Nanofibers and microfibers encapsulate bioactive moleculesmay dictate the future packaging strategies using biosensors. Nanosensors detect the antigens-antibodies binding, enzymes and substrate/cofactor, through a physical and/or electromechanical signal and detect chemical contaminants, toxins and antibiotic residues in food.
Conclusion
The primary objectives of packaging i.e., protection and communication have come across a huge transformation as active and intelligent packaging systems, which truly offers exciting opportunities for food industries. Oxygen scavengers and moisture absorbers are by far the most commercially important sub-categories of active packaging followed by TTIs.
The upcoming change in food packaging using nanotechnology and electronic devices is inevitable and will significantly reduce the food losses in future. However, the scientist and food industry people should tactfully deal with the technological issues as well as cost-economics for large-scale implementation of active and intelligent packaging.
* Author is an Assistant Professor, AgFE Department, Indian Institute of Technology Kharagpur Contact: Email: jayeeta.mitra@agfe.iitkgp.ac.in
