Food manufacturers are working to create products designed for a contemporary lifestyle, a market in which packaging plays an increasingly important role. Yashaswini Premjit, Vedshree Mohanty and Arvind explain different packaging materials and methods for bakery and confectionery products.
The packaging is a method of enveloping or enclosing food items for the sole purpose of protecting commodities from the external environment and their prevention from spoilage. It aids with containment, communication of product information and preservation, while at the same time enhances the shelf life of food products. Packaging technology in bakery products plays a quintessential role in determining the end quality of the product, the shelf life of the product and inevitably, the consumer’s acceptance.
The need for bakery and confectionery packaging
It is a known fact that bakery products are prone to microbial spoilage, particularly mold growth and extending the shelf life with the use of preservatives limited by the development of off-odors and flavors or effects on product quality. Also, there has been a raging trend toward the production of food products that are free of preservatives.
Other factors that significantly reduce the shelf life of bread, which is a principle bakery product, include the complex phenomenon of crust and crumb staling, moisture loss from the product, moisture gain from the surrounding environs, and the oxidative rancidity of fat-rich cookies, crackers and biscuits. While fat bloom is an undesirable surface phenomenon noticed in cookies and chocolate, candies undergo sugar re-crystallization or graining, which occurs primarily due to internal and external graining phenomena. All these defects in bakery and confectionery products can be successfully overcome with the use of proper packaging materials and techniques.
Different materials & methods for bakery packaging
The major objective in the packaging of bakery products has always been to maintain the products in a fresh condition by preventing too rapid drying out, without providing too good a moisture barrier which would promote mold growth on a soggy crust. The most conventional of techniques use LDPE (Low-Density Polyethylene) bags in the form of laminates and films, in which the end is twisted and sealed with a PS tag, which retards moisture gain by the product to a fairly large extent. In certain other speciality bread such as French and Italian, the packaging is done in Oriented Polypropylene (OPP) or Polyethylene (PET) bags that are specifically perforated with small holes that allow moisture to escape and thus retain a crisp crust.
Polymeric materials like ethylene vinyl alcohol (EVOH), polyvinylidene chloride (PVDC) have excellent water vapour and gas resistant properties and they can also be used in laminates to impart good strength, resilience, heat sealability, which is ideal for baked products.
Pagani et al. (2006) investigated variations in the moisture content inside bread loaf during storage and their influence on changes in crumb softness over a period of 48 hours when packaged in perforated OPP films of varying holes diameter and density. It was observed that moisture loss varied from 10% to 25% of the initial moisture content. The best performing film had a mean hole diameter of 0.54 mm and hole density of 21.4 holes cm”2 (corresponding to an open surface of 5%) and allowed both crust crispness and crumb softness to be maintained. This could not have been achieved with the aid of simple paper bags.
The advent of Modified Atmospheric packaging in bakery products
Modified Atmospheric Packaging, which is the enclosure of a food product in a high gas barrier film, in which the gaseous environment has been changed or modified to slow respiration rate, reduce microbiological growth, and retard enzymatic spoilage with the intent of extending shelf life, seems to be a very plausible solution with regard to baked commodities. For instance, Carbon-dioxide enriched atmospheres help to delay staling, lipid degradation or rancidity. As it is well known, oxidative and hydrolytic rancidity results in off-odours and off-flavours and subsequently decrease the shelf life, making the product unpalatable. Another alternate would be to substitute the package atmosphere with 100% Nitrogen (N2), which would also ensure the delay of lipid degradation in low moisture bakery products like cookies and crackers.
In detailed studies with bread and cake stored at 21°C and 27°C and CO2 concentrations of 0%–60%, it was shown that the mold-free shelf life increased with increasing CO2 concentrations, with the effect (not unexpectedly) being greater at lower temperatures. Subsequent studies with mixtures of CO2 and N2 and with 100% CO2 confirmed the need for CO2 in the package headspace, where simply displacing headspace O2 with N2 alone was insufficient to prevent mold growth. (Seiler, 1998)
In a study conducted by Degirmencioglu et al. (2011), potassium sorbate was added to bread dough at concentrations of 0%, 0.15% and 0.30% and the sliced bread were packed in expanded APET-EVOH-LDPE trays sealed with a PA-LDPE film and six different gas concentrations (air, 100% N2, 70:30 N2:CO2, 50:50 N2:CO2, 30:70 N2:CO2 and 100% CO2). The packaged bread samples were stored for 21 days at 20°C and 60% RH. None of the samples showed signs of mold growth after 21 days.
In a review on the use of Modified Atmosphere for the packaging of bakery products, it was concluded that MAP may not be suitable for all types of bakery products and that knowledge of a product’s physical, chemical and microbiological characteristics are critical to the success of this technology. Furthermore, the importance of combining technologies such as O2 absorbers and ethanol vapor generators with the modified atmosphere to increase the shelf life of bakery products was emphasized.
Other Emerging techniques in bakery products packaging
Vacuum packaging is a method of packing a product in a film having high oxygen barrier properties and then removal of air under vacuum. Oxygen in the package headspace is usually <1% and this easily can delay mold growth. It has been shown to prevent mold problems in flatbreads like naan and pita and also in pizza crusts. Gas Packaging is an alternative to vacuum packaging involving the packaging of products in a mixture of desirable concentrations of gases (usually nitrogen and carbon dioxide) in a laminate or film having high gas barrier properties. Continuous or thermal forming gas packaging equipment can be used for gas packaging. It can be used for packaging cakes, doughnuts, pies, and pizzas.
Active packaging is another alternative method for the packaging of baked products, which employs the use of Oxygen Absorbents & Ethanol Vapour Generators. The oxygen level in the packed product depends upon the barrier properties of the laminate, chances of leakage or puncture, and the air trapped inside the product.
In products like bread and cakes, mold spoilage can be delayed by the inclusion of ethanol vapours, by spraying or injecting or depositing it in small amounts directly onto the surface of the product prior to packaging. An alternative method prescribes to the use of ethanol vapour generating sachets.
These sachets made of paper-EVA copolymer contain powdered silica gel (35% w/w) onto which food-grade ethanol (55% w/w) has been absorbed and are placed inside the package prior to sealing. Vanilla can be added to mask the smell of ethanol. They allow the slow release of alcohol vapor, which exerts the preservative effect. The extension in shelf life has been shown by the supplier of the sachets to depend on the ethanol permeability of the packaging material, the integrity of the seals, the water activity of the food and the type of microorganisms present.
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Solutions for packaging of Confectionery products
The two basic factors that control the type of packaging materials required to protect confectionery products from moisture uptake are the water activity of the confection and the RH of the ambient atmosphere.
Confections, sugar candies, boiled sweets, toffees and caramels have almost always been preferred to be wrapped individually, mostly as a hygienic measure, and partly to protect them from atmospheric moisture, and also to prevent them from sticking together. Considerations have been made to avoid the intermingling of the flavors of the different confectionery products. The toffees in the markets generally have both ends of the packaging wrapper sleeve in a twisted fashion, which very conveniently acts a closure and helps keep the contents intact. Waxed papers and plasticized Recycled Cellulose Fibre (RCF) have been used successfully but the use of cast Polypropylene (PP), which holds the twist better than RCF, is evidently more widespread.
While the use of fibrous materials as an alternative for packaging material for confections has been tried and tested, it has been concluded to be unsuitable since they promote adhesion of the wrapper to the sweet.
Suitable packaging for chocolate must provide a good barrier to light, O2, water vapor and foreign odours (Mohas, 2010). The most common material used to package blocks of chocolate used to be unsealed aluminum foil of 0.009 mm thickness. At this thickness it exhibits “dead wrap” characteristics which is a phenomenon in which the material takes on the shape of the product around which it is placed. In warmer climates, a layer of waxed tissue paper was placed inside the foil to prevent fat staining of the outer package; it was also claimed to offer protection against odor penetration (Minifie, 1999).
Chocolate blocks are generally packed in a laminate consisting of aluminum foil and LDPE, making it possible to heat seal the package. These serve as better barriers to water vapor and odour than foil and the foil-paper packages. Such packages may occasionally contain a layer of paper, either between the foil and the LDPE or on the outside of the foil when the latter is laminated directly to the LDPE. In certain other packages, the foil is replaced by PVdC copolymer, which is applied as a thin coat on the LDPE layer.
It was showed that dark chocolate with hazelnuts packaged with an O2 absorber in a barrier packaging material maintained its aroma, taste and nutritional quality substantially longer than other packaging methods. (Mexis et al. 2010). Chocolate was packaged in either PET-LDPE ( or SiOx-coated PET-LDPE) under vacuum or N2 or with an O2 absorber, and stored in the dark at 20°C for 12 months. For samples packaged in PET-LDPE, irrespective of the storage atmosphere, the shelf life was 8–9 months, and for samples packaged in SiOx-coated PET-LDPE, the shelf life was 11 months, irrespective of storage atmosphere. Finally, for samples packaged with an O2 absorber, the shelf life was at least 12 months irrespective of packaging material. (Mexis et al. 2010)
Chocolate-coated confectionery are typically packaged in pearlized Oriented Polypropylene (OPP), which is cold sealed longitudinally and at each end; cold sealants avoid the risk of melting the chocolate during the sealing operation
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While the longevity of a product is a direct result of the processes the product has undergone, it is safe to conclude that the truest determinant of its success in reaching the destined consumer’s palate in its most desirable form depends quite indubitably on the packaging material used to enclose it and the technologies employed in packing it.
- Gordon. L. Robertson 2013. Food Packaging: Principles and practice, 3rd edition, CRC Press, Francis and Group; Page 554-573
Mohas F. 2010. Water activity, shelf life and storage. In: Confectionary and Chocolate Engineering: Principles and Applications. Ames, IA: Wiley-Blackwell, pp. 525–549.
- Pagani M.A., Lucisano M., Mariotti M., Limbo S. 2006. Influence of packaging material on bread characteristics during ageing. Packaging Technology and Science 19: 295–302.
- Seiler D.A.L. 1998. Bakery products. In: Principles and Applications of Modified Atmosphere Packaging of Food, 2nd edn.,
Blakistone B.A. (Ed.). London, U.K.: Blackie Academic & Professional, pp. 135–157.
- Degirmencioglu N., Göcmen D., Inkaya A.N., Aydin E., Guldas M., Gonenc S. 2011. Influence of modified atmosphere packaging and potassium sorbate on microbiological characteristics of sliced bread. Journal of Food Science and Technology 48: 236–241.
- Minifie B.W. 1999. Chocolate, Cocoa and Confectionery: Science and Technology, 3rd edn. Gaithersburg, MD: Aspen Publishers, pp. 709–770.