Due to the recent increase in ecological consciousness, research has turned toward finding edible materials. Viable edible films and coatings have been produced using milk proteins. These films and coatings may retard moisture loss, are good oxygen barriers, show good tensile strength and moderate elongation, are flexible, and generally have no flavor or taste. Incorporation of lipids in protein films, either in an emulsion or as a coating, improve their properties as barriers to moisture vapor. Interactions between chemical, structural properties, as well as film-forming conditions and functional properties of edible milk films are elucidated. Some potential uses of milk protein packaging, which are hinged on film properties, are described with examples.

Milk Proteins for Edible Films and Coatings

Food packaging, although an integral part of the food chain, has a major drawback in that, often, the packaging material interacts with the flavor constituents of the food, causing either a selective or an extensive loss of desirable food flavors or absorption of undesirable off-flavors from the packaging material, thereby resulting in an eventual loss of quality of the packaged food item. The process is called “scalping” and is of great concern to the food industry, which is always looking out for new avenues in “packaging solutions” for its final product quality needs. The review highlights the various attributes of the scalping process, explores approaches to the reduction of the manifested undesirable effects, and covers other relevant aspects.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2007.00014.x

Scalping of Flavors in Packaged Foods

The gas barrier properties of ethylene vinyl alcohol copolymer (EVOH) against oxygen, carbon dioxide and water vapor have been widely investigated in relation to different material characteristics,...

https://tandfonline.com/doi/pdf/10.1080/15583724.2017.1394323

Recent Updates on the Barrier Properties of Ethylene Vinyl Alcohol Copolymer (EVOH): A Review

Active packaging is an emerging food technology to improve the quality and safety of food products. Many works have been developed to study the antimicrobial activity of essential oils. Essential oils have been traditionally used as flavorings in food, so they have an important odor impact but they have as well antimicrobial properties that could be used to protect the food. Recent developments in antimicrobial active packaging showed the efficiency of essential oils versus bread and bakery products among other applications. However, one of the main problems to face is the odor and taste they could provide to the packaged food. Using some aromas to mask the odor could be a good approach. That is why the main objective of this paper is to develop an antimicrobial packaging material based on the combination of the most active compounds of essential oils (hydrocinnamaldehyde, oregano essential oil, cinnamaldehyde, thymol, and carvacrol) together with some aromas commonly used in the food industry. A study of the concentration required to get the antimicrobial properties, the organoleptic compatibility with typical aroma present in many food systems (vanilla, banana, and strawberry), and the right combination of both systems has been carried out. Antimicrobial tests of both the mentioned aromas, the main components of some essential oils, and the combination of both groups were carried out against bacteria (Enterococcus faecalis, Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella choleraesuis, Yersinia enterocolitica, Escherichia coli), yeasts (Candida albicans, Debaryomyces hansenii, Zygosaccharomyces rouxii), and molds (Botrytis cinerae, Aspergillus flavus, Penicillium roqueforti, Eurotium repens, Penicillium islandicum, Penicillium commune, Penicillium nalgiovensis). The sensory properties of the combinations were evaluated with a triangular test and classification was by an order test; the odor threshold of the aroma compounds was also studied. The results reveal that none of the aromas had antimicrobial properties. The most antimicrobial compounds are thymol, carvacrol, and cinnamaldehyde, but none of them could be combined with banana aroma, whereas only thymol with strawberry aroma gave the right combined organoleptic profile. All of the antimicrobials under study could be combined with vanilla aroma, providing both antimicrobial property and the odor expected.

Effect of mixed antimicrobial agents and flavors in active packaging films.

barrier properties and improved thermomechanical resistance DTU Orbit (10/03/2019) Hybrid poly(lactic acid)/nanocellulose/nanoclay composites with synergistically enhanced barrier properties and improved thermomechanical resistance Poly(lactic acid) (PLA)‐based hybrid nanocomposites (PLA, nanoclay and nanocellulose) were prepared by reinforcing neat PLA with commercially available nanoclay (Cloisite C30B) and nanocellulose, in the form of either partially acetylated cellulose nanofibres (CNFs) or nanocrystalline cellulose. Composites with 1 or 5 wt% of nanocellulose, in combination with 1, 3 and 5 wt% of nanoclay, were prepared, and their barrier properties were investigated. It was found that the combination of clay and nanocellulose clearly resulted in synergistic behaviour in terms of the oxygen transmission rate (OTR) through a reduction of up to 90% in OTR and a further reduction in the water vapour transmission rate of up to 76%. In addition, the nanocomposite films showed improved thermomechanical resistance and improved crystallisation kinetics while maintaining high film transparency. This makes the hybrid PLA/CNF/C30B nanocomposites a very promising material for food packaging applications. © 2016 Society of Chemical Industry

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Hybrid poly(lactic acid)/nanocellulose/nanoclay composites with synergistically enhanced barrier properties and improved thermomechanical resistance

The sorption of some aroma components from tomato juice by polyethylene terephthalate (PET) was shown to be less than the sorption of the same components by polyethylene (PE) and wet ethylene/vinylalcohol copolymer (EvOH) polymers. Furthermore, sorption by PET was less influenced by pH than sorption by the PE and EvOH polymers. The amounts of aroma compounds extracted from the polymers varied with type of polymer, type of aroma compound, pH and time of storage.

The sorption of aroma components from tomato juice by food-contact polymers

In this study, the effect of a vegetable oil on the oxygen barrier properties of different polymer packaging materials [i.e. amorphous polyethylene terephtalate (APET), polypropylene (PP) and high density polyethylene (HDPE)] was investigated. The influence of both relative humidity and the combination of relative humidity and sorbed oil on the oxygen transmission rate (OTR) was studied. Regardless of the relative humidity, the APET film remained an excellent oxygen barrier even after storage in rapeseed oil for 40 days. An increased OTR was observed in both the PP and HDPE films stored for 40 days in rapeseed oil. The OTR of the HDPE films was altered to a much greater extent than the OTR of the PP film. The OTR of the HDPE film was also significantly increased for films stored for 20 days in rapeseed oil. The increase in OTR of an HDPE film stored for 40 days in rapeseed oil was between 36 and 44%, depending on the relative humidity, compared to the OTR through the virginal polymer. The amount of oil sorbed by the polymer films used decreased in the following order: HDPE ≫ APET > PP.

Influence of sorbed vegetable oil and relative humidity on the oxygen transmission rate through various polymer packaging films

The effectiveness of five polymer films as aroma barriers at 5° C, 25° C and 75° C was investigated by determining their permeability, diffusion, and solubility coefficients for aldehyde vapours. Ethylvinyl acetatelaminated polyethene was not a better aldehyde barrier than its unlaminated counterpart. Polyvinyl chloride was found to be an inferior aldehyde barrier at 5° C compared to the other investigated polymers.

Polymer films as aroma barriers at different temperatures

Extraction with supercritical carbon dioxide was used to quantity the amounts of seven different aroma vapours sorbed in polyethene films. The method was found to completely extract all aroma compounds from the films. The solution of aroma compounds in the polymer films decreased with increasing polymer density. Monoterpenes were always completely sorbed in the films, whereas aldehydes and ketones had a much lower affinity for the films. The sulphur-containing compound, thiophene, was difficult to analyse due to its adsorption on metal surfaces.

Anders Leufvén

Papers

The sorption of aroma components from tomato juice by food-contact polymers

Influence of sorbed vegetable oil and relative humidity on the oxygen transmission rate through various polymer packaging films

Polymer films as aroma barriers at different temperatures

Quantification of aroma vapours sorbed in polyethene films using supercritical carbon dioxide