Food Preservation Packaging

Abstract

The most important role of food packaging is to provide a total barrier to physical, biological and/or chemical factors that can tender the quality integrity of the packaged food, an ideal food packaging should be rigid and non-reactive to the food enclosed. That is, a packaging material should be safe by and/or for the food. Food and packaging may interact and pose effects, which may affect the quality, integrity and shelf life of the food. This chapter discusses the processes of food packaging interaction such as permeation, migration, sorption and their adverse effects on the food packaging system. Novel packaging systems such as Active packaging (packaging that preserve, communicate and protect quality integrity of the food), Intelligent packaging (packages with improved communication models that help consumers ascertain the quality and the state of the food) and Bio-active packaging (are active packaging with improve compound in them that support stability of the food) were discussed as advanced packaging systems that help in mitigating the food-package interaction as well as give consumer conveniences while extending shelf stability. Scientific models used in studying the extent of food packaging interaction are also discussed which includes the stochastic, mathematical and simulation models.

1. Introduction

Food preservation involves the art and science of extending food quality/integrity or maintaining its nature for a specified period of time [1]. The food preservation techniques includes the use of packaging enclosure to protect food from external factors which may interfere with initial nature or quality of the food. As a food preservation element, food packaging provide enclosure to food and supports the food product against external invasion. It provide an integral role of containment, protection communication and preservation of the inherent quality of the package food [2]. Food packaging provide several advantage in food production that includes; nutrient stability/preservation, information containment and communication including information on ingredients (type and quantity), shelf life and also quality/integrity protection. Therefore, the role of food packaging in food reservation cannot be overemphasized. Food packaging are usually in direct contact with the food, therefore there is direct association which can result to some changes. Some of these changes may render the food unsafe for consumption or may speed up chemical process which may poses organoleptic loss. The advent of food-packaging interaction depends on the nature and quality of the packaging material. Some packaging provide 100% barrier to any external factors why some may allow lite interaction with external system as such can easily pose the food to contamination and or other reactive changes, therefore a packaging selection is critical to the shelf stability of the food and needed to follow stringent process.

An important requirement in selecting packaging systems for foods is the barrier property of the packaging material. To keep a food product crisp and fresh, the package must provide a barrier to moisture. Food changes such as off-flavor and rancidity may occur if the packaging material has a poor barrier to oxygen, allow gas permeation and by allowing passage of light to the food. Original organoleptic properties of a food can be maintained by using a packaging material that offers a good barrier to moisture, gasses and aroma. Thus, properly selected packaging materials are beneficial in extending the shelf-life of foods. A food’s characteristic flavor and aroma are the result of a complex construct of hundreds of individual constituent compounds interacting to produce a recognizable taste and aroma. Therefore, if one or more flavor constituents are altered or diminished, food quality may be reduced. A reduction in food quality may result from the interaction of the food component with external environment or with the internal packaging environment which hinders the ability of the packaging role. The way food package influences the integrity of the packaged food, food under packaging also affect the packaging integrity when it react or possess chemical changes to the packaging films therefore effective packaging system is the one which passes no effect to the food or to the packaging or vice-versa. Plastic and metal packaging usually react if used in direct contact with acidic/corrosive foods therefore needed to be incorporated together with second barer, transparent plastic and glass jars are not advisable to light reacting foods because light can react with food components (such as vitamin and lipid) and speed deteriorative chemical process such as oxidative rancidity. As interaction principle, permeation of volatile aromatic compound into or out of a packaging system causes unbalanced change in flavor profile which changes the sensory properties of the packaged food. Therefore effective packaging that can extend shelf life of a flavored food should provide a total barrier to volatile aromatic compound permeation. Packaging such as aluminum foil are used which provide inert barrier than other polymers/plastic [3]. Plastic packaging such as low-density polyethylene (LDPE), polypropylene (PP), polycarbonate (PC) and polyethylene terephthalate (PET) provide permeation flavor and oxygen as such cannot be used on highly flavored compound or products that are sensitive to oxygen such as fat and oils. The characteristic permeation of oxygen and flavor in LDPE and PP increase linearly while flavor permeation increase with increase in oxygen permeation in PC with increase in flavor absorption in PET with increase in storage duration [4]. Migration on the other hand, causes sensory changes at smaller rate and affect consumer health at a higher rate of occurrence. The effect of migration as interaction may be seen on food as color change, taints and off-flavors [5]. This chapter explored the interaction principles in a food packaging system as well as the preservation effect of the interaction and ways to estimate/ascertain the extent of the interaction, the chapter covers the interaction methods, the effects and included the methodical approach to ascertain the effect of food-packaging interaction.

1.1 Food-packaging interaction

When food products are packaged, the food is in direct contact with the inside surface of the packaging. It is possible for interaction between the food and the packaging to occur and for components of the packaging to be absorbed by, or react with, the food. Food packaging interaction involves mass transfer through which packaging material migrate to food or external environmental factors (such as odor, light or gas) permeate into the packaged food or process that involves sorption through adsorption (by packaging) or absorption (by the food) or combination of all which at end affect the initial quality/integrity of the packaging or the food product. The mass transfer occurs as a result of difference in concentration between the two medium (High and low) which causes migration at a rate equal to the driving force of the specific food component. Different packaging materials allows different mass transfer rate example; metal or glass package approve very low mass transfer if compared with package made up of plastic. The mass movement allows permeation to small molecules of water vapor, volatile gasses, organic vapors, flavors, aroma and additives from food. These movement causes change in the component’s concentration gradient as such more molecule migrated with extended storage which causes quality reduction. Exchange of materials in packaging system offers both positive and negative advantage. Depending on packaging type selected, active package react or changes the packaging environment by interacting with the food enclosed (packaged) thereby extending the food shelf life. The molecular exchange in food packaging can either be through; (i) permeation (ii) migration (iii) sorption/scalping and begin from the moment the package contacts the food during production, and extends throughout the package shelf life and can produce adverse effects on the food, and/or the package. As shown in the Figure 1 below, food-package interaction follows different pattern (permeation, migration, sorption/scalping) and causes varying degree in quality effect on the food (drying, aroma loss, moisture loss/absorption etc.). Different food components follows different exchange pattern with volatile compound mostly adopting to permeation and very low molecule motile compound (such as water molecule) following a migration and permeation sequence. The whole food-packaging interaction methods involves three elements/environment viz. (i) External environment (ii) Internal environment (food) (iii) Packaging. In Permeation pattern molecule of moisture, CO₂, O₂ and other volatile compounds move either from the food or from external environment to the internal packaging environment or to the external surrounding environment through the packaging material [6] this may be due to porosity or less intactness of the packaging film. Example, some nylon packaging can allow moisture to pass thereby causing dissolution of the food packaged. In a case of sachet packs, poor sealing may allow rapid permeation (leakage) which may give rise to moisture loss/absorption, drying (dehydration), de-carbonation, off-flavors and microbial growth (as in Figure 1 below). Leakages on sachets foods can be detected by using vacuum leak test apparatus (VLTA). VLTA machines are made in a way that they absorbed all available gasses around the packaging environment thereby given chance to only permeation of gas from the internal packaging environment that can be physically detected through gas bubble formation (when they escape from the internal packaging environment due to pressure surrounding the external environment formed by vacuum creation) as leakages from the sachets. In the testing process, the sachets are first immersed in a water in the vacuum creation section of the machine, pressure level are then set from the program which will be used to create the vacuum. While permeation covers both external and internal environment of the packaging system, migration on the other hands involves movement of packaging materials from the packaging film to the food. Migration reduce the compactness of the packaging film and can give rise to permeation when the surface packaging materials erodes and migrate to the food which then increase the characteristics porosity of the packaging film as such increase rate of components migration, migration causes sensory quality loss, packaging damage and flavor development. Except the food packaging allows, food-package interaction though inevitable but causes very limited effect to the quality of the food enclosed.

Figure 1.

Food package interaction. Adapted with modification from [6].

1.1.1 Permeation

Caner [6] defines permeation as the movement of gases, vapors or liquids through homogenous packaging materials, and excludes the passage of materials through perforation, cracks, or other related defects. In his own definition, Caner [6] excluded any internal or external defects that allow passage of molecule through packaging as permeation as such defines it as the characteristics of the package that allow such movement therefore; permeation to his own definition is inherent to the packaging materials used. According to Caner [6] permeation involves molecular movement of volatiles and aroma component of gases, moisture and other low molecular weight substances from the outside (external) environment into the food through the packaging materials or vice versa. Permeation process through a packaging film occurs in a three steps:

1. Solution or Absorption: the adsorption involves the dissolution of the food materials on to the surface of the packaging materials. In adsorption process the penetrant disintegrate from the parent food mass and the absorbed to the surface of the packaging. Adsorption process depends on the: (i) particulate nature of the food (ii) condition of the packaging environment e.g. pH, Moisture content, Acidity (iii) the absorptivity of the packaging materials to penetrant. Adsorption principle follows Henry’s rule which states that the amount of gas absorbed by a given volume of a liquid at a given temperature is directly proportional to the partial pressure of the gas therefore the absorptivity of the food depends on the pressure of the internal packaging system which depends on the seallability of the package and the relative condition of the food prior to the initial packaging.

2. Diffusion: Through diffusion, the penetrant passes through the packaging film and are then transferred in or out of the package. Molecules in a diffusion process move from a region/place of high concentration to a region/place of a lower concentration through a permeable membrane (here the membrane is the packaging film). Diffusion principle follows Fick’s law which stated that the quantity of diffusing gas is proportional to concentration and time and inversely proportional to the thickness of the substrate through which it is diffusing.

3. Emergence/desorption: this involves escape of penetrant from opposite surface of the packaging (either from external system or from the internal). Graham’s Law best explain desorption process and states that the velocity of diffusion of a gas is inversely proportional to the square root of the density. Absorption and desorption depend on the solubility of the permeant, and solubility is greatest when penetrant and material have similar properties.

Permeation process as explained in the Figure 2 below follows a concentration gradient because molecules are exchanged from the region where their concentration is high to a region where their concentration is low. Therefore, generally permeation process is affected by the (i) Concentration (ii) Density (iii) Solubility (iii) Internal and External Pressure/Temperature (iv) Permeability of the packaging film (v) Time (vi) Thickness of the packaging film and (vii) Relative humidity. Permeation impact the shelf life of foods, since they gain or lose components, or undergo unwanted chemical reactions with the permeating substances, therefore offers both detrimental and positive advantage. Permeation causes unbalanced flavor profile in a flavored foods, leading to change in sensory properties of the food product therefore packaging selection should ensure packing of food products with packaging material of effective barrier properties that can protect the foods packed in them for longer time not only provide enclosure.

Figure 2.

Permeation principle in a food packaging system. Adapted from [6] with modification.

1.1.2 Migration

There are more than 85,000 chemicals used on consumer products [7] and more than 6000 chemicals are not to be used in food packaging that have direct contact with food [8], and all these chemical compound are prone to cause toxicity hazard if consumed when they migrated into food. Migration or otherwise called diffusion in food packaging is the movement of food substance from a region of higher concentration to a region of a lower concentration through a permeable membrane (packaging film). In food packaging, migration process involves the transfer of packaging materials from the packaging surface to the food product which causes a relative change in the original integrity/quality of the food. According to Abbes et al. [9] migration can either be global (when it involves movement from the packaging itself to the food) or specific (when only specific material moves to the food surface). Ferrara et al. [10] explain migration process in a packaging system in four steps:

1. Diffusion: Movement of the food substance through the packaging film.

2. 1st Desorption: movement of packaging material from the surface of the packaging film.

3. Sorption: movement at the food-packaging interface.

4. 2nd Desorption: movement from the packaging material to the food.

Migration in food packaging is affected by (i) physico-chemical characteristics of the food (ii) Storage time (iii) Temperature (iv) packaging size (v) type of packaging material/coating (vi) type of contact (vii) mobility of the packaging migrant. Depending on the packaging materials, diverse chemical compound migrated from the surface of food packaging and affect the shelf stability of the food. An ideal packaging should be inert (non-reactive) to the food. For inert packaging materials such as stainless steel, ceramics and glass only chemicals from the interior surface of the package migrated to the food and this causes tearing/wearing of the packaging as such affect its strength and its permeation inertness. Migration occurs due to the concentration gradient of the packaging materials and or the food. Migration follows simple Fick’s law which states that; as a steady state, the rate of movement of diffusing compound is proportional to the concentration gradient [9, 11].

However, to determine the extent of migration in food packaging, food simulant are used. The simulant are formulated to have exact physicochemical characteristics of the food to be packaged, they are then packaged into the packaging materials as substitute for the food analyzed for chemical migration after a stipulated length of storage. The simulant differs in types representing different types of foods; hydrophilic (water based), lipophilic (fat based) or amphiphillic foods (food of varying properties). Example, vegetable oil simulant is used to measure migration into oily foods, 10% ethanol or 3% acetic acid are used for a water based drinks, 50% ethanol solution is used as simulant for butter and other amphiphillic foods. Using simulant for the estimation of migration gives only probable estimated values which are close to the actual values. Other processes such as Chemical Risk Assessment (CRA) are conducted to determine the risk of toxicity due to chemical migration into foods; Migration Models (such as Stochastic, Probabilis tic, and Empirical) are also employed to determine the risk and extent of packaging migration.

1.2 Sorption

Sorption or otherwise called scalping involves the mass adsorption or absorption of integral sensory quality components of food such as Favor, Aromas, Lipids and Moisture to the or by the packaging material [12] resulting in the reduction of quality of the packaged products. Sorption in packaging system occurs through both Adsorption and Absorption procedure. Adsorption involves mass transfer from the food to the surface of the packaging material, this resulting to an increased in the concentration of the food components at the interface. Sorption of aromatic components results in degradation of quality. This phenomenon of loss in quality of food product by absorption of flavor from food by polymer or vice versa is known as ‘scalping’ [13]. For scalping to occur, a thermodynamically favorable condition must exist [14]. But the major concern of flavor sorption is that loss in very small amount of flavor has significant effect on quality of the stored food product depending on the component sorbed [14]. A study on packing of orange juice in glass bottles and polyethylene- laminated cardboard packages found that after 24 weeks of storage at 4°C, up to 50% of d-limonene and little aldehydes and alcohols were absorbed into polyethylene-laminated cardboard packages [15]. But, this had little/no effect on the sensory properties of the orange juice [15]. At times, sorption can result in swelling of the packaging material, leading to increased migration and permeation. Further, it can reduce the mechanical properties of the polymer [16, 17, 18]. For instance, the absorption of limonene on LDPE increased the oxygen permeability of the polymer. Flavor absorption depends on characteristics of polymer (polarity, crystallinity, chain stiffness), flavor compounds (concentration, chemical composition, polarity) and environmental and external factors like temperature, relative humidity, duration of storage and composition of food matrix [6]. For liquid foods, sorption is mainly affected by partition coefficient of flavor components, whereas for solid foods, the sorption is affected by solubility and vapor pressure of components in the polymer [19].

Similar to migration, sorption is also a diffusion process. Hence, Fick’s law governs sorption as well [14]. Further, sorption process is also influenced by temperature. In general, sorption and temperature are positively related. Exceptionally, sorption and temperature are negatively correlated in few cases. For instance, sorption of vinyl chloride by dry casein particles was found to reduce with increasing temperature [17, 18]. Pressure on the other hand increases sorption process the way temperature do, the internal pressure of the packaging system reduce the mechanical quality of the packaging at a higher level, high swelling pressure of the packaging film may cause mechanical disintegration of the components of the packaging film thereby making them more available to be sorbed as such increases sorption process. Pressure level with prolonged storage condition increase sorption that is why it is generally required that a packaging material should be inert to external factors. The nature of the sorbing material also affect the rate of sorption process, with chemical (such as coding inks and surface monomers) of high reaction affinity been sorbed faster. In sorption process, the quantity of volatile component sorbed by the polymer can be measured by the parameter ‘solubility’ [20].

1.3 Effect of food-packaging interaction

The interaction of food and packaging possess negative and positive effect to both the food and the packaging materials. When packaging components migrate from the surface of the parent package it causes withering which reduces the compact characteristics of the package. When external environmental factors migrated into the internal packaging system, it causes physical, chemical and microbiological changes to the food. Flavors and other aromatic volatile compound easily migrate out of the package from the surface of food to the external environment through a withered package. The mass movement of vapor from surface of aqueous food causes drying which affect the organoleptic and physical characteristics of the packaged food. Movement of fillers, colorant, inks and other additive from the surface of plastic films causes dangerous toxicity effect. As described in Figure 1 above, food-package interaction possess different adverse effect ranging from:

1. Physical changes (color change, dehydration/drying and packaging damage)

2. Microbial growth (contamination gasses/chemical possess serious health effect)

3. Chemical changes (oxidation of fats, browning, off-favor, decarbonation)

4. Sensory changes (crunches, softness, off-flavor/odor)

Food-packaging interaction as well as Food-packaging and environment interaction plays a major role on quality of the product as well as integrity of the package. These effects may have direct or indirect effect on the sensory attributes of the food product, consumer health and shelf stability of the food thereby causing a direct impact on the market value and the overall acceptability of the product as such affect business good-will. Moreover, Food and Drugs Administration of the United States (FDA) and National Agency of Food and Drugs Administration (NAFDAC, 2022) of Nigeria sets a strict legislations for a ‘zero tolerance’ of carcinogenic migrants, and also considered all migration compounds in food as indirect food additive. Hence, knowledge on factors affecting interaction phenomena and its effect are of high importance. In this section, factors affecting the food-packaging interaction and their possible effects on food quality are discussed.

1.4 Factors affecting packaging interaction

The shelf life of packaged food is dependent on numerous factors such as the intrinsic nature of the food, e.g. acidity (pH), water activity (aw), nutrient content, occurrence of antimicrobial compounds, redox potential, respiration rate and biological structure, and extrinsic factors, e.g. 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 carefully considering all of these factors, it is possible to evaluate existing and developing active packaging technologies and apply them for maintaining the quality and extending the shelf life of different food products.

1.4.1 Food composition

Food is a complex compound containing varying amount of components composing of volatile and non-volatile substance is primarily of protein, lipids, carbohydrate and water [21, 22]. These components of food interact with each other and with the wall of packaging materials [23]. These particulate component of food are held together by a chemical bonding such as (i) hydrogen bond (ii) covalent bond (iii) hydrophobic bond/vander waals (iv) physical binding [24] and they disintegrate/separated at a different petition rate depending on the amount of interaction with micro-molecules in the food matrix. The composition containing fat/oil had major effect on flavor interaction, followed by proteins and polysaccharides and then by disaccharides [4]. Example lipids (fats and oils) determine the physical and sensory characteristics of non-water soluble foods as well as determine their ability to absorbed or loose flavor compounds to or from packaging films. Aqueous and high water foods tend to interact with packaging more than solid or powdered foods therefore very prone to packaging interaction. Increase in food pH also increase the rate of package migration [6], nature and concentration of migrating compound in the food also influences the rate of packaging interaction, example presence of same flavor compound of food on the packaging materials will speed of the rate of scalping process [12]. In nutshell, the selection of packaging for foods should consider the nature of the foods such as; (i) acidity (carbon chain and structure (iii) viscosity (iv) concentration (v) flavor and aroma compound presence (vi) molecular weight of the food (vii) carbon functional group and polarity.

Depending on the food nature, interaction of food with packaging is greatly affected by the food composition, the components of food can either be interactive/migrating (occurs through leaching or volatile system) or non-interactive/non-migration. Migrating compound in food are usually very reactive, loose and less chemically bonded to the food therefore can easily interact with the packaging film. Migrating volatile aromatic compound in dried foods can easily be loss through either diffusion or evaporation, desorption from product or adsorption on to the product without direct contact with the packaging film. For a leaching migrating food system, components of food interact when they are in direct contact with the packaging film, that is the food (such as fat) components diffuse from the food surface, dissolved on the surface of the packaging and the adsorbed by the packaging film, or by its diffusion from the packaging materials, followed by dissolution and dispersion into the food. High fatty foods leach faster than high fiber foods due to their higher affinity and reduced viscosity.

1.4.2 Nature of the packaging material

For an ideal packaging, the packaging material should be; (i) non-reactive to the food (ii) non corrosive (iii) impermeable (iv) sealable (v). Packaging materials such as glass and metal provide total barrier to external factors therefore migration occurs only form the internal contact surfaces. Semipermeable packaging material such as plastics offers limited resistance to permeation and migration therefore used only on properly selected food materials. Porous materials such as paper and paper boards facilitate rapid migration [25]. Interaction rate depends on factors such as (i) molecular weight (ii) density (additive present (iii) temperature (iv) crystallability of the packaging material use. With the increase in use of polymer based packaging materials, over 42% of a the polymers produced are used as packaging materials, and about half are used for food packaging applications [26, 27]. They are usually preferred in food packaging due to their flexibility, low density, strength, ease to mold, cost, controlled hydrophobicity and moldability into different sizes and shape. Several researches shows that there is increase in interaction of food if package in polymer based packaging which can induce undesirable quality changes in packed food. For instance, degree of browning and ascorbic acid degradation of orange and grapefruit juice was found to be high when packed in polyethylene-laminated cartons than in glass [28]. Bott et al. [29] reported that the rate of interaction of LDPE and polystearine decrease by 10 fold with the increase in the molecular weight of the packaging material. Migration rate in polypropylene increases with decrease in the crystallability [30] rate of migration in polyprpyene packaging increase with decrease in crystallability of the polymer.

Interaction of packaging material with the food and the environment plays a major role on quality of the product as well as integrity of the package. These effects have impact on market value, goodwill of the manufacturer, sensory attributes of products and health effect of consumers. Moreover, strict legislations are set for ‘zero tolerance’ of carcinogenic migrants, and also the compounds that migrate into food are considered as indirect food additive by FDA. Hence, knowledge on factors affecting interaction phenomena and its effect are of high importance. The ability of the packaging to absorbed or release light should also be considered in selecting package for oily/fatty foods, example, polyolefins are not advisable for the packaging of lipophilic food [30]. Other than the polymer itself, the nature of additives like colorants, plasticizers, stabilizers, fillers, blowing agents, antioxidants, antimicrobials, slip compounds and printing ink also migrates into the food material, and their characteristics impact the rate of migration [31] which may be toxic if consumed with food. Example, residual ethylene oxide on metal cans is highly toxic [32], concentration of tin lacquer at about 500mgkg⁻¹ can cause gastrointestinal ailments [33] and usually attain acute threshold at about >730 mgkg⁻¹. Lacquers are usually added to reduce interaction of food and packaging as well as with external environment by reducing oxygen scavenging [34] lead coating on beverage containers can cause damage to central nervous system and has negative growth impact, it could also result to mental retardation [35] chemical components of paper packaging such as dioxins, nitrosamines, chlorophenols, chloroanisoles and benzophenone are toxic if found in food [35, 36, 37]. 0.06–1.0% of acetaldehyde was detected in different beverages packaged on PET plastic containers by Lau & Wong [38], acetaldehyde usually impact odors on food especially in cola-type beverages [39] therefore its presence in food is of great significance.

Health related risk assessment from chemical and materials to be used in producing food packaging should be considered and thoroughly studied before used, to prevent contact and potential migration of these chemical/materials into the food which may be carcinogens or caused other ailments. Trace of metal, additives, inks and plastics from the packaging or from environment due to failure of packaging should be eliminated to prevent the food and the consumer health. Hazard related to presence of metals contaminants in foods raised serious health concerns. Acute and chronic symptoms such as dizziness, nausea, diarrhea, loss of appetite, disorders, vomiting and reduced contraception rate has been associated with metal toxicity, and these symptom may results to a serious cardiovascular diseases, suppressed growth, impaired fertility, immune disorders/failure and or neurological ailments which may lead to death [39].

1.4.3 Environmental and storage factors

Environmental factors such as (i) temperature (ii) relative humidity (iii) storage time (iv) moisture content (v) oxygen and other gaseous content. Change in environmental temperature affect the stability of the packaging-food interaction rate by increasing the mobility of interacting material, free volume and the swelling capacity of the packaging film. Storage time also increases the rate of food-packaging interaction with heat processed cans suffering more migration effect than non-heat processed materials [40]. Different packaging material offers different migration rate in relation to change in the environmental relative humidity. Permeation through EVOH packs increase with increase in environmental humidity while there is decrease in permeation in PET and nylon with increase in relative humidity of storage environment.

2. Novel food packaging technology

The world population is on the increase. Currently, there are over 7.8 Billion people living on this planet, this number is expected to reach 9 billion by 2050. With this rise in population and pressure on food, from ancient system of gathering food to modern day food, food production value chains fears that global food production could not meet up with the population growth of animals on earth. This leads to the need to improve people’s access to sufficient, nutritious and value adding food while handling the climate impact on the environment. And as the demand for food increases, peoples also require food access that will meet their personal convenience/need. Novel arose as a result of consumer’s desire for convenient, ready to eat, tasty and mild processed food products with extended shelf life and maintained quality. Recent trend of lifestyle changes with less time for consumers to prepare foods posed a great challenge toward food packaging sector for the evolution of novel and innovative food packaging techniques. The novel food packaging techniques includes; (1) Active packaging (AP) (2) Intelligent packaging (IP) and (3) Bio-active packaging which involve intentional interaction with the food or its surroundings and influence on consumer’s health have been the major innovations in the field of packaging technology. These novel techniques act by prolonging the shelf life, enhancing or maintaining the quality, providing indication and to regulate freshness of food product. The advancement in novel food packaging technologies involves retardation in oxidation, hindered respiratory process, prevention of microbial attack, prevention of moisture infusion, use of CO₂ scavengers/emitters, ethylene scavengers, aroma emitters, time–temperature sensors, ripeness indicators, biosensors and sustained release of antioxidants during storage. The novel food packaging technologies besides the basic function of containment increase the margin of food quality and safety. The novel food packaging techniques thus help in fulfilling the demands throughout the food supply chain by gearing up toward persons own lifestyle (Figure 3).

Figure 3.

Model for packaging function [41].

2.1 Active packaging

Active packaging refers to the integration of certain additives into packaging film or within packaging containers with the aim of preserving and prolonging shelf life [30]. Packaging may be designated active when it accomplishes some desired role in food preservation other than providing barrier to external environments [42, 43]. The primary aim of food packaging is to protect and extend the shelf-life of the packaged foods thereby making it available for later use or extend transport advantage. Active packaging provides such advantage without endangering the quality and safety integrity of the food. By definition, active packaging technology are those packaging technology that provide protection, safety, store as well as maintain food quality integrity without impacting to its original sensory attributes, this is achieved through modification of the food pack condition. It is also a packaging system which provide enclosure to the product and the environment interaction to prolong shelf-life or to enhance safety and/or quality of the food. Active packaging provide packaging protection to all agent of food deterioration; such as Chemical activities (such as lipid oxidation and volatile chemical loss), Physical impact (including protection against impact and compression factors), Moisture invasion (such as sorption and drying), Physiological processes (Such as respiration in root and tubers, Microbiological effect (including spoilage microorganism attack) and Insect/small animal infestation. Active packaging includes additives or freshness enhancers that are capable of scavenging oxygen; adsorbing carbon dioxide, moisture, ethylene and/or flavor/odor taints; releasing ethanol, sorbates, antioxidants and/or other preservatives; and/or preserving temperature control. Table 1 contain list of active packaging and their food application [30, 43].

Active packaging system	Mechanisms	Food application
Preservatives releasers (Usually added on the surface of a packaging that inhibit or slow down some deteriorating activities in or on the package food)	Extract (from spices, herbs & Animal). Antioxidants (e.g. Vitamin E and BHA/BHT) Ethanol capsule Organic Acids Silver zeolite	Meat, Fish, Cheese, Baked products (e.g. bread and snacks), cereal food products, fruits and vegetables
Carbon dioxide Scavenger/Emitters (they are used to increase or reduce the CO2 content in a package thereby inhibiting the surface growth of microorganism [44])	Activated charcoal Iron oxide/hydroxide of calcium Ascorbate/sodium bicarbonate Ferrous carbonate/metal halide	Snack foods and cakes, coffee and tea, nuts, fish-meat and their products.
Ethylene Scavengers	Activated carbon Activated clays/zeolite Potassium permanganate	Fruit and vegetables
Oxygen Scavengers (Used to remove or reduced oxygen in a package of food thereby extending shelf life usually in a Modified atmosphere packaging [45])	Iron based Enzyme based Metal catalyst Metal acids Metal salts	Baked foods (biscuit, breads and cakes), cheese, meat and fish, dried foods, beverage, pasta and cured meat.
Ethanol emitters	Alcohol sprays Encapsulated ethanol	Baked foods (bread, biscuit, etc.), pizza
Moisture Absorbers	PVA blanket Silica gels Activated catalyst	Fish, meat, cereal, dried foods, fruit and vegetables, sandwiches and snacks.
Flavor/ordor absorbers	Cellulose triacetate Acetylated paper Citric acid Ferrous salt/ascorbate Activated carbon/clays/zeolite	Poultry, dairy foods, fruit and fruit juices, fried snacks and cereals
Temperature control package	Non-woven plastics Double walled containers Lime/lime water Ammonium nitrate/water Hydroflourocarbon gas	Meat and meat products, fish, poultry and beverages

Table 1.

Active packaging system and their food application.

2.2 Intelligent packaging

Intelligent packaging is an emerging and existing area of food technology that can provide better food preservation and extra convenience benefits for consumers [46]. Intelligent packaging provides information about the food product enclosed in them prior to provision of the natural packaging properties. They are integrated with a target-specific sensor (TSS), which can store information about the history of a quality attribute, such as freshness, gas leakage, microbial contamination, product demography and footprints, etc., and deliver this information to a consumer. Intelligent or smart packaging refers to a packaging system that senses and informs [30]. They are integrated in a packaging material with a sensing devices that are capable of sensing and providing information about the function and properties of food and assurances of pack integrity, tempering evidence, product safety and quality, and also utilized in authenticating, anti-theft and product traceability [30]. Sensing device in Intelligent packaging system include (i) Time–temperature indicators (TTI), (ii) Gas sensing dyes, (iii) Microbial growth indicators, (iv) Physical shock indicators, and (v) Tracing device such as tamper proof, anti-counterfeiting and anti-theft technologies [30]. Intelligent packaging also provide detailed information about shelf life and quality state of the food in order to ensure consumer satisfaction and safety while potentially improving logistics and minimizing the losses. Other sensing devices in Intelligent Packaging includes biosensors, Radio frequency identification (RFID) tags or electronic tracking tags that stores and wirelessly transmit information about the food packaged and ease traceability.

1. Time–temperature Indicators: In Time–temperatures Indicators, the shelf life of food products or their freshness is determined based on selected indicators, such as vitamins, color or flavor change, enzyme activity, etc. through predictive models which are developed based on accelerated shelf-life tests, usually on meat and meat product, fish and sea foods. TTIs sensors can either be (i) diffusion-based (diffusion of colored esters forms color contrast alongside a reference scale), (ii) Enzymatic (certain enzymatic reaction that can change the environmental conditions, such as pH, which then causes color change), or (iii) Polymer-based (polymerization reaction forms a color contrast with a reference scale) depending on their material of formation. All TTIs commonly require an activation step to start the sensing process at the same time when the product enters the package.

2. Gas Sensors: In Gas sensors packaging, sensitivity to change in gas levels is used as a quality marker inside the package and is used to detect any gas leakage in a Modified Atmosphere Packaging Systems (MAPS). This gas leakage can either be due to microbial contamination, fruit ripening by the formation of aromatic volatiles and degree of fermentation or by the formation of organic acids. Gas sensors works with binding reactions such as redox reactions, pH change, or luminescent dyes to produce color (for easy to interpretation) controlled by the change in the target gas concentrations.

3. Biosensors are used to provide online about microbial contamination, growth, and related biological reactions. Biosensors accomplish their usefulness by detecting and following the development of secondary metabolites, such as volatile nitrogen compounds, sulfide indicators, ethanol, organic acids, etc., due to biological activities (e.g., respiration and fermentation) (Table 2).

Indicator	Principle	Information	Application
Microbial growth Indicators (use both in internal and external package surface).	pH dyes. Metabolite reacting dyes.	Microbial quality of the packaged food.	Perishable goods such as tomato, meat, fish and poultry.
Time–temperature indicators (TTI) (placed externally).	Mechanical. Chemical. Enzymatic.	Storage condition.	For food stored under very low temperature condition (chilled and Frozen).
Carbon dioxide indicators (used internally).	Chemical	Storage condition. Leakage on packs.	Modified and controlled atmosphere packaging.
Pathogen Indicators (internally).	Chemicals that react with microbial released toxins.	Used for pathogen specific bacteria such as E. coli.	For perishable food such as meat, fish and poultry.

Table 2.

Intelligent packaging indicators and their application.

2.3 Bio-active packaging

Bio-active packaging is those packaging materials that employ the use of active biological materials to support/improve shelf stability of package foods. They are novel concept of technologies intended to help in the production of functional foods, whose bioactive principles and actuators are devised to be contained within packaging or coating materials [47]. The bioactive compound is extra nutritional components present in a small amount in foods such as fruits, vegetables, legumes, herbs and spices. They are usually extracted from these foods as probiotics, polyphenos, essential oils, fatty acid or vitamins or as bacteriocin extracted from bacteria.

3. Food-packaging interaction testing

The most important quality of packaging materials is to provide protection to the food by providing enclosure which provide total barrier to external impact. As seen above, food-package interaction follows different pattern and offered several detrimental effect to the food quality/integrity. Packaging testing is necessary step in package selection to ensure that applicable packaging material is used. Quality testing as well as testing to measure the amount of interacting substance in a packaging system is very important for the manufacturer to ensure that standard packaged are employed for enclosure of the food and also to make sure that packaging material has negligible effect on the final product getting the consumer and it does not cause any negative impact on health after consumption of the packed food material. For the detection and analysis of the interacting components in a packaging system the following system are employed (i) simulants (ii) mathematical models (iii) predictive models and (iv) analytical/chromatographic techniques are used.

3.1 Simulation model

Food simulant are compound developed to mimic the natural characteristics of food to be packaged. Food simulant are developed to have the exact physicochemical properties of the food under study. After the development, the simulant are then packaged into the packaging film kept under controlled/studied condition for a stated time to determine the interacting characteristics of the food. Example, vegetable oil simulant is used to measure migration into oily foods, 10% ethanol or 3% acetic acid are used for a water based drinks, 50% ethanol solution is used as simulant for butter and other amphiphillic foods. Using simulant for the estimation of migration gives only probable estimated values which are close to the actual values. The migration quantity is determined by evaporating the simulant and then calculating the weight of the remaining residue. Simulant procedure is limited especially on fatty foods due to their difficulty in vaporization. ASTM standard are put in place for the estimation of odor and taste transfer from a packaging material, the standard employed 0.9 M² test material kept in a required environment for a minimum of 20 hours (Table 3) [49].

Solvent	Simulant	Type of food
Distilled water	Simulant A	Aqueous food (pH > 4.5)
Aqueous acetic acid (3%w/v)	Simulant B	Acidic foods such as fruit juices (pH <4.5)
Aqueous ethanol (15% -50% w/v)	Simulant C	Diary foods and emulsions
Vegetable oils e.g. Sunflower/olive oil	Simulant D	Oily foods, high fat content foods

Table 3.

List of some common simulant used for food-package interaction testing [3, 48].

3.2 Mathematical and predictive models

Mathematical models are predictive equation developed based on a simulation principle to predict the migration in food packaging. The models were developed to determine the diffusion and partition coefficient and explain the interacting substance concentration [50] since it is only when there is partition and when diffusion occurs that packaging materials are said to be loss. Permeation in packaging can also be determine in term of gaseous and moisture transfer rate. Since material permeability depends of the type and characteristics of the packaging film (such as thickness) as well as the condition of the surrounding environment. This is achieved by placing the packaging material in both low and high pressure environment followed by the measurement of pressure difference (both pressure and volume determined) usually expressed as the amount of gas permeated per unit time. Moisture permeation is determined by placing the package in between environment of different humidity rate and estimated by determining the vapor pressure difference in M²day⁻¹ [51].

3.3 Analytical/chromatographic method

Chromatographic techniques were employed to determine trace of metal compound that migrate to food surface. Though there is no standard or direct analytical method for the estimation of packaging migrant in a packaging system, different chromatographic method such as GC–MS and LC-UV. Begley [52] uses LC–MS method to determine interacting component in a packaging system. Although not all migrating compound in a packaging system can be detected using conventional method but the application of chromatographic method prove to be effective.

3.4 Stochastic/predictive models

Stochastic models or predictive models are probabilistic mathematical function that provide a prediction of certain level of migration (food-packaging interaction) of packaging materials in a packaging system [53]. Stochastic models takes account the variability and uncertainty as well as the probability of the occurrence of food-packaging interaction. Latin Hypercube Sampling (LHS) and Monte Carlo Models (MCM) are example of stochastic models that gives numerical values of food migration based on numerical distribution data build through simulation method. Stochastic thermodynamics models measure the thermodynamic changes due to food packaging interaction such as temperature, pressure and moisture changes while molecular models of a stochastic methods measure the rate of molecular changes/interaction of gaseous or chemical molecules arises due to disintegration of either packaging or food components and subsequent molecular interaction [8, 54]. Stochastic models such as Life Cycle Assessment (CA) and High-Throughput Risk-based Screening (HTRS) tools are used to determine extent of migration in plastic packaging while empirical Weibull Model has been used to determine the chemical migration curves in paper packaging [55], Mechanistic Models are used to predict the migration of toxic metals into acidic food [56] while diffusion models are used for the determination of migration in ceramic packaging as well as packaging with low migration risk or plastic additives with low diffusion potentials.

Predictive models are used to generate data and also been associated with statistic functions to develop software programs that simplify the determination methods for food-packaging interaction. The European Flavors, Additives and food Contact materials Exposure Task (FACET) developed a software for the prediction of probabilistic exposure to chemicals from food or packaging contact materials. The software measure the migration, permeation as well as sorption of flavors, moisture, food additives and packaging surface materials in a packaging system using existing probabilistic data in its database [8], the software consist of data that will be able to study over 6000 substances covering metal coatings, paper and paper boards, inks and adhesive, plastic and plastic coverings as well as components of food flavors and additives [8] with over 600 statistics functions all links to packaging use, composition, application, pack size, storage, environmental conditions and food composition/nature. Measurement is achieved through clustering based on chemical, physical properties (polarity and diffusion) [8] and physic-chemical parameters [57] other modeling software includes; MIGRATEST lite 2000/2001 [53], AKTS-SM by Advanced Kinetics Technology Solutions AG Switzerland, SMEWISE (Simulation of Migration Experiments with Swelling Effect), MULTITEMP, MULTIWISE, and SFPP3 by National Institute for Agricultural Research, and FMECAengine (Failure Mode Effect and Critically Analysis) [53, 57]. With the continues rise of artificial intelligence, the future of predictive models is bright and look at possibility of developing robotic system that will simplify the study of food-packaging interaction and its advent.

4. Conclusion

Food-packaging interaction is a systematic procedure that may take long to proliferate, but has direct solid effect to the food integrity, it directly either render the food or the packaging helpless to either external or internal factors which may speed changes that will affect the shelf stability of the food. If the interaction is on the negative side, the food and the packaging losses their initial state of intactness and therefore losses their natural role in packaging system. As evolved from this module, different packaging materials react differently to adverse chemical, physical and environmental factors and that can facilitate to improve or mitigate interaction with food. The compounding effect of food-packaging interaction is critical to selection and even for the preparation of food therefore, critical attention should be made on studying the nature and type of the packaging to be used as well as to the studying the length of storage, condition, the logistic requirement to delivering the product to consumer. Packaging is not only the enclosure of food but part of the food system that can either be detriment or of advantage to the food depending on the type of interaction it has with the food. Novel packaging technologies as new trends brought about solution to reduction of the adverse effect of food-packaging interaction which improve on and reduce to cost of production, shelf stability of food products as well as the environmental impact of packaging. Because it is inevitable, food-packaging interaction can be determine through several methods that are evolving with the continuous evolution of informative computer management system and the artificial intelligence. More work need to be done on the development of better predictive tools for the determination of migration/interaction in paper packaging. Since the science of food is analytical, effort should be made also on the development of fast and precise analytical methods for the determination of food-packaging interaction.

Conflict of interest

The author declares zero conflict of interest and no funding from any person or organization is received in an aim to deliver this chapter. All citation and reference are duly acknowledged.

Notes

I hereby declared that this work was carried out by me, unless where reference is made. I thank my Mom for her immeasurable support throughout the course of delivering this content.