https://docs.google.com/document/d/e/2PACX-1vScdv9wJdLISxpXNpqsQYzd3osoU-OSFEJHGiSO4xV7C9csv1j8oeWZO2MEIkTi4CdMCyl0_dBbkGqK/pub
Chapter 6: Flavor-release food and beverage packaging
Abstract:
6.1 Introduction
6.2 Mechanism of flavor release from package to food
6.3 Impact of diffusion in the packaging material on flavor release kinetics
6.4 Practical applications and commercial examples
6.5 Safety issues
n Abstract:
The scientific principles and practical applications of flavor-release food and beverage packaging are presented in this chapter. Flavor-release from packaging materials to the foods they contain is achieved through diffusion of active ingredients (volatile or non-volatile) inside the packaging materials and desorption at package/liquid and/or package/headspace interfaces. In indirect contact systems, adsorption of flavor compounds from the headspace onto food may also be involved. All systems may affect the perceived quality of the packaged food products. An encapsulation technology with appropriate triggering mechanism is often applied to control the time and place of the lavor-release. Safety and ethical concerns should be properly addressed in the development of lavor-release packaging so that this technology is not used to disguise bad products or spoiled foods.
Key words
aroma
diffusion
trigger
encapsulation
safety
6.1 Introduction
The flavor profile is one of the most important sensory attributes of a food product and plays a major role in determining consumer acceptability. The term 'flavor' encompasses both aroma and taste, which relate to people's perception of food products by the nose and by the tongue. Traditional flavoring techniques (e.g. direct addition of flavorants to food formulations) have been used to achieve products that are stable and attractive to consumers. In this chapter, lavor-release packaging, an innovative technology, is introduced as a method for the addition of lavors into foods using packaging.
Flavor-release packaging is a packaging system which incorporates and delivers extraneous flavor to food products to enhance their flavor profiles and improve consumer acceptability. The uniqueness of this technology is that the delivery of lavor is controlled by the packaging and some external factors. It can replenish lavor or compensate for a lack of lavor compounds in the food thus enhancing the lavor proile at the point of consumption. Flavor-release packaging can be used for the delivery of both volatile and non-volatile lavor compounds, but the major emphasis is on volatile compounds (i.e. aromas). Flavor-release packaging is available in various physical forms (e.g. films, rigid containers) and is produced by different processing methods (e.g. extrusion, coating).
6.2 Mechanism of flavor release from package to food
The means by which lavor compounds are released from the package and reach the food vary. In this section two major categories are crudely distinguished: (1) indirect contact between package and food, and (2) direct contact between package and food.
6.2.2 Indirect contact system
This system only applies to the release of aroma compounds into solid food products. Figure 6.1 presents a general situation where there is a large package headspace, aroma compounds are embedded in the packaging material and are released into the headspace. Three steps are involved:
FIG. 6.1 Aroma release in an indirect contact system.
➊ diffusion of aroma compounds inside the packaging material (usually a polymer),
➋ desorption of aroma compounds at the package/headspace interface, and
➌ adsorption of aroma compounds into the food. One example of an indirect contact system is PolylFF® from International Flavor & Fragrances Inc.
6.2.2 Direct contact system
This system applies to both aroma and non-volatile lavor compounds released from packages into foods that mostly are beverage products. In fact, the direct and indirect contact systems often function simultaneously since there is usually some headspace between the package and food and this is what is described in this section. Figure 6.2 illustrates the situation of a beverage product involving both direct and indirect contact. There are ive main steps:
FIG. 6.2 Flavor release from a direct contact system.
➊ diffusion of aroma/non-volatile lavor compounds inside the packaging material;
➋a. dissolution of aroma/non-volatile lavor compounds at the package/ liquid interface or
➋b. desorption of aroma/non-volatile flavor compounds at the package/headspace interface;
➌ dispersion or diffusion of aroma/non-volatile flavor compounds in the liquid;
➍ desorption of aroma/non-volatile flavor compounds at the liquid/head-space interface; and
➎ dispersion of aroma/non-volatile flavor compounds in the headspace.
One example of a direct contact system is the chocolate-flavored milk bottle from AddMaster.
6.3 Impact of diffusion in the packaging material on flavor release kinetics
In both indirect and direct contact systems, diffusion in the packaging material is an important step determining the release kinetics of lavor compounds (usually the rate determining step). Diffusivity, a quantifiable parameter, is always used to describe diffusion processes. By manipulating design variables to change the diffusivity of the lavor compound, the desired release proile can be provided. The diffusivity of a lavor compound is dependent on the polymer matrix, temperature, humidity, etc. Complicated mechanisms such as encapsulation and complex formations can be used to obtain the desired diffusivity.
An intelligent flavor-release packaging designed by Chalier et al. (2009) exploits the dependence of carvacrol diffusivity on temperature and humidity for a volatile antimicrobial packaging system. Even though volatile carvacrol was used for antimicrobial purposes in their system, the proposed concept can also be applied to any volatile lavor-release system. In their packaging system, carvacrol was incorporated into soy protein isolate (SPI) which was coated on the paper: SPI was used to incorporate and release carvacrol and paper provided the physical support for the packaging system. The release of carvacrol could be attained through its diffusivity increase with temperature and relative humidity (RH) (Table 6.1). Moisture uptake of SPI from the package internal environment led to a glass transition temperature shift to lower temperatures and higher mobility of carvacrol. This system has meaningful practical application for high RH food products since the release of lavor compound is slow during storage of packaging materials before use in packaging the foods (low temperature and low RH, when not in contact with foods) and fast after it is used for packing products such as fresh produce and meat.
Table 6.1
Diffusivity of carvacrol as function of temperature and RH
Summarized from Chalier et al. (2009).
As mentioned above, the diffusivity of flavor compounds is a critical parameter controlling their release profile and thus understanding the dif-fusivity as function of different control variables is a key step for developing and designing flavor-release packaging. Therefore we have compiled diffusivity values under many different conditions from the literature. Table 6.2 provides a summary of the diffusivity values of various flavor compounds in food packaging polymers under different environmental conditions. The information on flavor diffusivity for the given polymer and storage conditions will enable packaging engineers to predict the time-dependent release of flavor compounds from packages of varying thickness and initial loadings. The same flavor compound has a wide variability in diffusivity in different polymers. While temperature is an important variable increasing the diffusivity (see those for allyl isothiocyanate in polyvinylidene chloride/polyvinyl chloride (PVDC/PVC) copolymer in Table 6.2), surface contact conditions can also greatly affect the diffusivity (see diffusivity of limonene in LDPE for air and water contact by Cava et al., 2005). High humidity is an effective accelerator of diffusion in hydrophilic polymer like nylon and ethylene vinyl alcohol (EVOH). These environmental conditions can be employed to control flavor-release in food storage and food service.
Table 6.2
Summary of literature data of diffusivities in food packaging polymers
*Abbreviations: EVOH = ethylene vinyl alcohol; PE = polyethylene; LDPE = low density polyethylene; PET = polyethylene terephthalate; PVC = polyvinyl chloride; PVDC = polyvinylidene chloride.
6.4 Practical applications and commercial examples
Various commercial designs for flavor-release packaging have been developed to achieve particular objectives. The release mechanisms in the different designs vary to suit specific requirements. For example, as aroma compounds are volatile, they are susceptible to heat and other unfavorable environmental conditions. To prevent their loss during processing and storage, they are commonly encapsulated, but then need to be released from the encapsulating material at the right place and time; therefore the release mechanism needs to be sophisticated. Steps of triggering and diffusion are commonly involved.
Trigger systems such as heat and physical force are applied to start the release of aroma or flavor compounds at the right time. The release mechanisms are complicated since they must remain dormant until the system is triggered, and the release must be controlled by properly adjusting the dif-fusivity. No matter how sophisticated the system is, though, the basic steps of diffusion, dissolution, desorption and dispersion are always involved in the release. Interactions among the variables come into play for timely, smart release. Figure 6.3 presents some typical examples of trigger systems of flavor release, which will be described below. Table 6.3 also presents some commercially available flavor-release package systems. Some non-food applications are also listed for reference. Detailed information can be found on the developers' webpage.
Table 6.3
Commercially available flavor-release packaging system
Developer
Packaging system
Target product
AddMaster
Chocolate-flavored
masterbatch for polyethylene
Chocolate-flavored milk-based drink
ScentSational
Encapsulated aroma release (CompelAromaTM)
Not specified
International Flavors & Fragrances Inc.
Aroma blended masterbatch (PolyIFF®)
Not specified
Membrana/Accurel Systems
Polymer resins in microporous structure which acts like sponge to absorb flavor compounds (Accurel® MP)
Not specified
Ball Packaging Europe
Widget technology: packaging system that generates nitrogen to form foam head
Milk, yoghurt, milk-based drinks with and without alcohol, coffee based drinks
UnistrawTM
Flavor coated straw (Sipahh™ milk flavoring straws)
Milk products
Süd-Chemie
Canisters that incorporate lemon, orange, vanilla, mint or chocolate (Aroma-Can®)
Nutritional and pharmaceutical products
Polyvel Inc.
Fragrances incorporated masterbatch (PolyScentTM)
Toys, film products, odor maskants and other applications
Ampacet
Fragrances incorporated masterbatch
Not specified
Well Plastics Limited
Fragrances incorporated packaging system
Nappy sacks, point of sale bags, hospital waste sacks, fridge fresheners
FIG. 6.3 Some examples of commercial flavor-release packaging systems.
6.4.1 Heat trigger
Heat or temperature is a very useful variable that impacts polymer structure, phase changes and molecular mobility inside a packaging material or food. Thus heat can be applied to trigger the release of aroma compounds, an example of which is aroma releasing package for microwave food products. Aromas do not develop in microwaved food as they would do in food cooked in a conventional oven, due to the different heating mechanism employed. To overcome this shortcoming, an aroma release system reacting to heat can be incorporated into the food packaging. The system is ruptured by the heat generated during microwave heating, releasing the aroma compounds into the headspace of packaging (Fig. 6.3(a)). Upon opening the heated package to consume the product, consumers perceive an aroma profile similar to that of conventionally cooked food. One microwave-heat triggered system embeds a comestible aroma into an encapsulation system inside the packaging material containing two elements: materials to prevent aroma release before the cooking and materials which cause aroma release (Parliment et al., 1989). Lipids such as lard, tallow, butter and mono-, di- and triglycerides are used to prevent aroma release at low temperature but melt upon heating in a microwave oven. For the materials causing aroma release, ferrites and magnetites are used since they are susceptible to microwave heating and transfer heat easily to the lipid layer to melt it, facilitating the release of the aroma. In another similar system, the aroma releasing substrate includes aroma compounds and sealant polymers (Prasad and Willey, 2000). Sealant polymers here make the system heat sensitive, protecting the aroma from being released at low temperatures, but enabling it to be released at high temperatures. Some examples of suitable sealants are amorphous polyethylene tetraphlate (APET)-based, ethylene vinyl acetate (EVA)-based or acrylic-based pressure sensitive sealants. The aroma-releasing substrate can be employed in the form of a label attached to the package or a direct coating on the package. Results of packaging headspace analysis confirmed greater increase in chicken flavor compound with the release label system compared to the instant flavor spray (Table 6.4).
Table 6.4
Headspace content of hexanal and 2,4-decadienal (chicken flavor compound) expressed in gas chromatograph peak area
Samples
Hexanal
2,4-decadienal
Control (no flavor added)
1,979
7,409
Instant spray of dried flavor
24,942
9,246
Flavor-release label
1,489,017
53,809
Modified from Prasad and Willey (2000).
6.4.2 Force trigger
Because flavor perception by consumers occurs when the package is opened, mechanical force on opening the cap can be used to release aroma locked in the capsule structure (Fig. 6.3(b)). In a bottle cap design, aroma compounds are encapsulated inside capsules incorporated in the screws of the cap, which are broken down and release the aroma compounds when consumers open the bottle (Sun et al.,2000).
For packaged liquid foods sold with straws attached, consumption is achieved by liquid flow through the straw. The UnistrawTM delivery system uses the liquid flow through the straw to deliver the flavor to the beverage product itself. It consists of three parts: a transparent straw, beads (called UniBeads) which flavor compounds are coated onto and which are positioned inside the straw wall (Fig. 6.3(c)) and two filters at both ends that block the movement of UniBeads to prevent consumers from consuming them. When liquid passes through the straw, the compounds in the Uni-Beads are released into the liquid to add flavor to the product. Flavors can be delivered to the consumers without manipulating food formulation. The system is currently applied in milk and coffee with flavors such as chocolate, vanilla and mint.
Widget technology has been developed mainly for forming foamy heads in beverages, including both alcoholic and non-alcoholic products (Ball-Packaging-Europe, 2011). Beverage cans employing this technology often have a base incorporating capsules which release nitrogen upon opening. Some of the successful applications are beer and coffee drinks. Even though ball- or rocket-shaped widgets currently release only pressurized gas and not flavors or aromas, the concept could be adapted for the release of flavor and aroma compounds.
In the tobacco industry, cigarette packets that function as a flavor-release system have been developed. The flavor compounds are encapsulated in the inside side wall of the lid of the packet (Dennen, 2002). Upon opening, the capsules on the side wall are ruptured by friction between the lid and the rest of the packet and the flavor compounds are released (Fig. 6.3(d)). This concept has been commercially launched in the cigarette industry and used to incorporate a candy-like flavor into the packet but also raised some concerns associated with its appeal to youth (Carpenter et al., 2005).
6.4.3 Other systems
There are also some packaging systems that aim to emphasize the inherent aroma of a product. For example, the AROMA-Can is a packaging design of a beer or wine can that has two openings: one is for consumption and one for delivering the aroma of beer or wine (Anon, 2011).
There are concerns that flavor-release systems may be used to mask off-flavor compounds which are indicators of food degradation, either chemical or microbial. Without doubt, this is not what flavor-release technology is intended to achieve. Some ethical norms should be adhered to when using flavor-release packaging in the food industry. The technology is mostly applicable to foods that are shelf-stable and are not a risk from the point of view of microbial and chemical safety. In fact, many food and beverages of this type are packaged in plastic containers and lose their flavor/aroma through scalping processes, reducing their quality (Licciardello et al., 2009). Even if those aroma compounds are present in very low concentrations, they play a very important role in the perceived sensory quality of the product. Therefore by activating the reverse-scalping process of flavor-release packaging, the flavor balance can be maintained throughout the required shelf life. Also the flavor of packaged foods that are re-heated or cooked may be enhanced by the release of flavors just before consumption.
6.6 References
Anon, Background ofthe AROMA-Can Available from. 2011. http://www.arom.a-can.com/background [(accessed July 2, 2011)].
Ball-Packaging-Europe. Success story: widget technology for Kenco Ice Cappio. Available from http://www.ball-europe.com/382_711_ENG_PHP.html, 2011. [(accessed July 2, 2011)].
Carpenter, C.M., Wayne, G.F., Pauly, J.L., Koh, H.K., Connolly, G.N. New cigarette brands with flavors that appeal to youth: tobacco marketing strategies. Health Affairs. 2005; 24(6):1601–1610.
Cava, D., Lagarón, J.M., López-Rubio, A., Catala, R., Gavara, R. On the applicability of FT-IR spectroscopy to test aroma transport properties in polymer films. Polymer Testing. 2004; 23(5):551–557.
Cava, D., Catala, R., Gavara, R., Lagaron, J.M. Testing limonene diffusion through food contact polyethylene by FT-IR spectroscopy: film thickness, permeant concentration and outer medium effects. Polymer Testing. 2005; 24(4):483. [189].
Chalier, P., Arfa, A.B., Guillard, V., Gontard, N. Moisture and temperature triggered release of a volatile active agent from soy protein coated paper: effect of glass transition phenomena on carvacrol diffusion coefficient. Journal of Agricultural and Food Chemistry. 2009; 57(2):658–665.
Dennen, R.P. Flip open package with microencapsulated flavor-release. US Patent 6612429. 2002.
Gallo, J.A.Q., Debeaufort, F., Voilley, A. Interactions between aroma and edible films. 1. Permeability of methylcellulose and low-density polyethylene films to methyl ketones. Journal of Agricultural and Food Chemistry. 1998; 47(1):108–113.
Licciardello, F., Del Nobile, M.A., Spagna, G., Muratore, G. Scalping of ethyloc-tanoate and linalool from a model wine into plastic films. LWT-Food Science and Technology. 2009; 42(6):1065–1069.
Lim, L.-T., Tung, M.A. Vapor pressure of allyl isothiocyanate and its transport in PVDC/PVC copolymer packaging film. Journal of Food Science. 1997; 62(5):1061–1062.
Lopez-Carballo, G., Cava, D., Lagaron, J.M., Catala, R., Gavara, R. Characterization of the interaction between two food aroma components, alpha-pinene and ethyl butyrate, and ethylene vinyl alcohol copolymer (EVOH) packaging films as a function of environmental humidity. Journal of Agricultural and Food Chemistry. 2005; 53(18):7212–7216.
Matsui, T., Ono, A., Shimoda, M., Osajima, Y. Thermodynamic elucidation of depression mechanism on sorption of flavor compounds into electron beam irradiated LDPE and EVA films. Journal of Agricultural and Food Chemistry. 1992; 40(3):479–483.
Paik, J.S. Comparison of sorption in orange flavor components by packaging films using the headspace technique. Journal of Agricultural and Food Chemistry. 1992; 40(10):1822–1825.
Parliment, T.H., Cipriano, J.J., Scarpellino, R. Aroma release during microwave cooking. US Patent 4857340. 1989.
Prasad, N., Willey, J. Aromatized food package. US Patent 6066347. 2000.
Simko, P., Simon, P., Khunova, V. Removal of polycyclic aromatic hydrocarbons from water by migration into polyethylene. Food Chemistry. 1999; 64(2):157–161.
Sun, R., Quintus-Bosz, H., Given, P., Pineiro, R., Morrison, A. Aroma release bottle and cap. US Patent 6102224. 2000.
Zhang, Z., Lim, L.-T., Tung, M.A. Limonene transport and mechanical properties of EVOH and nylon 6,6 films as influenced by RH. Journal of Applied Polymer Science. 2001; 79(11):1949–1957.
Chapter 6: Flavor-release food and beverage packaging
Abstract:
6.1 Introduction
6.2 Mechanism of flavor release from package to food
6.3 Impact of diffusion in the packaging material on flavor release kinetics
6.4 Practical applications and commercial examples
6.5 Safety issues
n Abstract:
The scientific principles and practical applications of flavor-release food and beverage packaging are presented in this chapter. Flavor-release from packaging materials to the foods they contain is achieved through diffusion of active ingredients (volatile or non-volatile) inside the packaging materials and desorption at package/liquid and/or package/headspace interfaces. In indirect contact systems, adsorption of flavor compounds from the headspace onto food may also be involved. All systems may affect the perceived quality of the packaged food products. An encapsulation technology with appropriate triggering mechanism is often applied to control the time and place of the lavor-release. Safety and ethical concerns should be properly addressed in the development of lavor-release packaging so that this technology is not used to disguise bad products or spoiled foods.
Key words
aroma
diffusion
trigger
encapsulation
safety
6.1 Introduction
The flavor profile is one of the most important sensory attributes of a food product and plays a major role in determining consumer acceptability. The term 'flavor' encompasses both aroma and taste, which relate to people's perception of food products by the nose and by the tongue. Traditional flavoring techniques (e.g. direct addition of flavorants to food formulations) have been used to achieve products that are stable and attractive to consumers. In this chapter, lavor-release packaging, an innovative technology, is introduced as a method for the addition of lavors into foods using packaging.
Flavor-release packaging is a packaging system which incorporates and delivers extraneous flavor to food products to enhance their flavor profiles and improve consumer acceptability. The uniqueness of this technology is that the delivery of lavor is controlled by the packaging and some external factors. It can replenish lavor or compensate for a lack of lavor compounds in the food thus enhancing the lavor proile at the point of consumption. Flavor-release packaging can be used for the delivery of both volatile and non-volatile lavor compounds, but the major emphasis is on volatile compounds (i.e. aromas). Flavor-release packaging is available in various physical forms (e.g. films, rigid containers) and is produced by different processing methods (e.g. extrusion, coating).
6.2 Mechanism of flavor release from package to food
The means by which lavor compounds are released from the package and reach the food vary. In this section two major categories are crudely distinguished: (1) indirect contact between package and food, and (2) direct contact between package and food.
6.2.2 Indirect contact system
This system only applies to the release of aroma compounds into solid food products. Figure 6.1 presents a general situation where there is a large package headspace, aroma compounds are embedded in the packaging material and are released into the headspace. Three steps are involved:
FIG. 6.1 Aroma release in an indirect contact system.
➊ diffusion of aroma compounds inside the packaging material (usually a polymer),
➋ desorption of aroma compounds at the package/headspace interface, and
➌ adsorption of aroma compounds into the food. One example of an indirect contact system is PolylFF® from International Flavor & Fragrances Inc.
6.2.2 Direct contact system
This system applies to both aroma and non-volatile lavor compounds released from packages into foods that mostly are beverage products. In fact, the direct and indirect contact systems often function simultaneously since there is usually some headspace between the package and food and this is what is described in this section. Figure 6.2 illustrates the situation of a beverage product involving both direct and indirect contact. There are ive main steps:
FIG. 6.2 Flavor release from a direct contact system.
➊ diffusion of aroma/non-volatile lavor compounds inside the packaging material;
➋a. dissolution of aroma/non-volatile lavor compounds at the package/ liquid interface or
➋b. desorption of aroma/non-volatile flavor compounds at the package/headspace interface;
➌ dispersion or diffusion of aroma/non-volatile flavor compounds in the liquid;
➍ desorption of aroma/non-volatile flavor compounds at the liquid/head-space interface; and
➎ dispersion of aroma/non-volatile flavor compounds in the headspace.
One example of a direct contact system is the chocolate-flavored milk bottle from AddMaster.
6.3 Impact of diffusion in the packaging material on flavor release kinetics
In both indirect and direct contact systems, diffusion in the packaging material is an important step determining the release kinetics of lavor compounds (usually the rate determining step). Diffusivity, a quantifiable parameter, is always used to describe diffusion processes. By manipulating design variables to change the diffusivity of the lavor compound, the desired release proile can be provided. The diffusivity of a lavor compound is dependent on the polymer matrix, temperature, humidity, etc. Complicated mechanisms such as encapsulation and complex formations can be used to obtain the desired diffusivity.
An intelligent flavor-release packaging designed by Chalier et al. (2009) exploits the dependence of carvacrol diffusivity on temperature and humidity for a volatile antimicrobial packaging system. Even though volatile carvacrol was used for antimicrobial purposes in their system, the proposed concept can also be applied to any volatile lavor-release system. In their packaging system, carvacrol was incorporated into soy protein isolate (SPI) which was coated on the paper: SPI was used to incorporate and release carvacrol and paper provided the physical support for the packaging system. The release of carvacrol could be attained through its diffusivity increase with temperature and relative humidity (RH) (Table 6.1). Moisture uptake of SPI from the package internal environment led to a glass transition temperature shift to lower temperatures and higher mobility of carvacrol. This system has meaningful practical application for high RH food products since the release of lavor compound is slow during storage of packaging materials before use in packaging the foods (low temperature and low RH, when not in contact with foods) and fast after it is used for packing products such as fresh produce and meat.
Table 6.1
Diffusivity of carvacrol as function of temperature and RH
Summarized from Chalier et al. (2009).
As mentioned above, the diffusivity of flavor compounds is a critical parameter controlling their release profile and thus understanding the dif-fusivity as function of different control variables is a key step for developing and designing flavor-release packaging. Therefore we have compiled diffusivity values under many different conditions from the literature. Table 6.2 provides a summary of the diffusivity values of various flavor compounds in food packaging polymers under different environmental conditions. The information on flavor diffusivity for the given polymer and storage conditions will enable packaging engineers to predict the time-dependent release of flavor compounds from packages of varying thickness and initial loadings. The same flavor compound has a wide variability in diffusivity in different polymers. While temperature is an important variable increasing the diffusivity (see those for allyl isothiocyanate in polyvinylidene chloride/polyvinyl chloride (PVDC/PVC) copolymer in Table 6.2), surface contact conditions can also greatly affect the diffusivity (see diffusivity of limonene in LDPE for air and water contact by Cava et al., 2005). High humidity is an effective accelerator of diffusion in hydrophilic polymer like nylon and ethylene vinyl alcohol (EVOH). These environmental conditions can be employed to control flavor-release in food storage and food service.
Table 6.2
Summary of literature data of diffusivities in food packaging polymers
*Abbreviations: EVOH = ethylene vinyl alcohol; PE = polyethylene; LDPE = low density polyethylene; PET = polyethylene terephthalate; PVC = polyvinyl chloride; PVDC = polyvinylidene chloride.
6.4 Practical applications and commercial examples
Various commercial designs for flavor-release packaging have been developed to achieve particular objectives. The release mechanisms in the different designs vary to suit specific requirements. For example, as aroma compounds are volatile, they are susceptible to heat and other unfavorable environmental conditions. To prevent their loss during processing and storage, they are commonly encapsulated, but then need to be released from the encapsulating material at the right place and time; therefore the release mechanism needs to be sophisticated. Steps of triggering and diffusion are commonly involved.
Trigger systems such as heat and physical force are applied to start the release of aroma or flavor compounds at the right time. The release mechanisms are complicated since they must remain dormant until the system is triggered, and the release must be controlled by properly adjusting the dif-fusivity. No matter how sophisticated the system is, though, the basic steps of diffusion, dissolution, desorption and dispersion are always involved in the release. Interactions among the variables come into play for timely, smart release. Figure 6.3 presents some typical examples of trigger systems of flavor release, which will be described below. Table 6.3 also presents some commercially available flavor-release package systems. Some non-food applications are also listed for reference. Detailed information can be found on the developers' webpage.
Table 6.3
Commercially available flavor-release packaging system
Developer
Packaging system
Target product
AddMaster
Chocolate-flavored
masterbatch for polyethylene
Chocolate-flavored milk-based drink
ScentSational
Encapsulated aroma release (CompelAromaTM)
Not specified
International Flavors & Fragrances Inc.
Aroma blended masterbatch (PolyIFF®)
Not specified
Membrana/Accurel Systems
Polymer resins in microporous structure which acts like sponge to absorb flavor compounds (Accurel® MP)
Not specified
Ball Packaging Europe
Widget technology: packaging system that generates nitrogen to form foam head
Milk, yoghurt, milk-based drinks with and without alcohol, coffee based drinks
UnistrawTM
Flavor coated straw (Sipahh™ milk flavoring straws)
Milk products
Süd-Chemie
Canisters that incorporate lemon, orange, vanilla, mint or chocolate (Aroma-Can®)
Nutritional and pharmaceutical products
Polyvel Inc.
Fragrances incorporated masterbatch (PolyScentTM)
Toys, film products, odor maskants and other applications
Ampacet
Fragrances incorporated masterbatch
Not specified
Well Plastics Limited
Fragrances incorporated packaging system
Nappy sacks, point of sale bags, hospital waste sacks, fridge fresheners
FIG. 6.3 Some examples of commercial flavor-release packaging systems.
6.4.1 Heat trigger
Heat or temperature is a very useful variable that impacts polymer structure, phase changes and molecular mobility inside a packaging material or food. Thus heat can be applied to trigger the release of aroma compounds, an example of which is aroma releasing package for microwave food products. Aromas do not develop in microwaved food as they would do in food cooked in a conventional oven, due to the different heating mechanism employed. To overcome this shortcoming, an aroma release system reacting to heat can be incorporated into the food packaging. The system is ruptured by the heat generated during microwave heating, releasing the aroma compounds into the headspace of packaging (Fig. 6.3(a)). Upon opening the heated package to consume the product, consumers perceive an aroma profile similar to that of conventionally cooked food. One microwave-heat triggered system embeds a comestible aroma into an encapsulation system inside the packaging material containing two elements: materials to prevent aroma release before the cooking and materials which cause aroma release (Parliment et al., 1989). Lipids such as lard, tallow, butter and mono-, di- and triglycerides are used to prevent aroma release at low temperature but melt upon heating in a microwave oven. For the materials causing aroma release, ferrites and magnetites are used since they are susceptible to microwave heating and transfer heat easily to the lipid layer to melt it, facilitating the release of the aroma. In another similar system, the aroma releasing substrate includes aroma compounds and sealant polymers (Prasad and Willey, 2000). Sealant polymers here make the system heat sensitive, protecting the aroma from being released at low temperatures, but enabling it to be released at high temperatures. Some examples of suitable sealants are amorphous polyethylene tetraphlate (APET)-based, ethylene vinyl acetate (EVA)-based or acrylic-based pressure sensitive sealants. The aroma-releasing substrate can be employed in the form of a label attached to the package or a direct coating on the package. Results of packaging headspace analysis confirmed greater increase in chicken flavor compound with the release label system compared to the instant flavor spray (Table 6.4).
Table 6.4
Headspace content of hexanal and 2,4-decadienal (chicken flavor compound) expressed in gas chromatograph peak area
Samples
Hexanal
2,4-decadienal
Control (no flavor added)
1,979
7,409
Instant spray of dried flavor
24,942
9,246
Flavor-release label
1,489,017
53,809
Modified from Prasad and Willey (2000).
6.4.2 Force trigger
Because flavor perception by consumers occurs when the package is opened, mechanical force on opening the cap can be used to release aroma locked in the capsule structure (Fig. 6.3(b)). In a bottle cap design, aroma compounds are encapsulated inside capsules incorporated in the screws of the cap, which are broken down and release the aroma compounds when consumers open the bottle (Sun et al.,2000).
For packaged liquid foods sold with straws attached, consumption is achieved by liquid flow through the straw. The UnistrawTM delivery system uses the liquid flow through the straw to deliver the flavor to the beverage product itself. It consists of three parts: a transparent straw, beads (called UniBeads) which flavor compounds are coated onto and which are positioned inside the straw wall (Fig. 6.3(c)) and two filters at both ends that block the movement of UniBeads to prevent consumers from consuming them. When liquid passes through the straw, the compounds in the Uni-Beads are released into the liquid to add flavor to the product. Flavors can be delivered to the consumers without manipulating food formulation. The system is currently applied in milk and coffee with flavors such as chocolate, vanilla and mint.
Widget technology has been developed mainly for forming foamy heads in beverages, including both alcoholic and non-alcoholic products (Ball-Packaging-Europe, 2011). Beverage cans employing this technology often have a base incorporating capsules which release nitrogen upon opening. Some of the successful applications are beer and coffee drinks. Even though ball- or rocket-shaped widgets currently release only pressurized gas and not flavors or aromas, the concept could be adapted for the release of flavor and aroma compounds.
In the tobacco industry, cigarette packets that function as a flavor-release system have been developed. The flavor compounds are encapsulated in the inside side wall of the lid of the packet (Dennen, 2002). Upon opening, the capsules on the side wall are ruptured by friction between the lid and the rest of the packet and the flavor compounds are released (Fig. 6.3(d)). This concept has been commercially launched in the cigarette industry and used to incorporate a candy-like flavor into the packet but also raised some concerns associated with its appeal to youth (Carpenter et al., 2005).
6.4.3 Other systems
There are also some packaging systems that aim to emphasize the inherent aroma of a product. For example, the AROMA-Can is a packaging design of a beer or wine can that has two openings: one is for consumption and one for delivering the aroma of beer or wine (Anon, 2011).
There are concerns that flavor-release systems may be used to mask off-flavor compounds which are indicators of food degradation, either chemical or microbial. Without doubt, this is not what flavor-release technology is intended to achieve. Some ethical norms should be adhered to when using flavor-release packaging in the food industry. The technology is mostly applicable to foods that are shelf-stable and are not a risk from the point of view of microbial and chemical safety. In fact, many food and beverages of this type are packaged in plastic containers and lose their flavor/aroma through scalping processes, reducing their quality (Licciardello et al., 2009). Even if those aroma compounds are present in very low concentrations, they play a very important role in the perceived sensory quality of the product. Therefore by activating the reverse-scalping process of flavor-release packaging, the flavor balance can be maintained throughout the required shelf life. Also the flavor of packaged foods that are re-heated or cooked may be enhanced by the release of flavors just before consumption.
6.6 References
Anon, Background ofthe AROMA-Can Available from. 2011. http://www.arom.a-can.com/background [(accessed July 2, 2011)].
Ball-Packaging-Europe. Success story: widget technology for Kenco Ice Cappio. Available from http://www.ball-europe.com/382_711_ENG_PHP.html, 2011. [(accessed July 2, 2011)].
Carpenter, C.M., Wayne, G.F., Pauly, J.L., Koh, H.K., Connolly, G.N. New cigarette brands with flavors that appeal to youth: tobacco marketing strategies. Health Affairs. 2005; 24(6):1601–1610.
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Dennen, R.P. Flip open package with microencapsulated flavor-release. US Patent 6612429. 2002.
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Licciardello, F., Del Nobile, M.A., Spagna, G., Muratore, G. Scalping of ethyloc-tanoate and linalool from a model wine into plastic films. LWT-Food Science and Technology. 2009; 42(6):1065–1069.
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Paik, J.S. Comparison of sorption in orange flavor components by packaging films using the headspace technique. Journal of Agricultural and Food Chemistry. 1992; 40(10):1822–1825.
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Sun, R., Quintus-Bosz, H., Given, P., Pineiro, R., Morrison, A. Aroma release bottle and cap. US Patent 6102224. 2000.
Zhang, Z., Lim, L.-T., Tung, M.A. Limonene transport and mechanical properties of EVOH and nylon 6,6 films as influenced by RH. Journal of Applied Polymer Science. 2001; 79(11):1949–1957.
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