ABSTRACT:In order to extend product shelf life while preserving the quality scientific attention focused to biopolymers research that are base for edible films and coatings production. Another major advantage of this kind of food packaging is their eco-friendly status because biopolymers do not cause environmental problems as packaging materials derived from non-renewable energy sources do. Objective of this work was to review recently studied edible films and coatings -their sources, properties and possible application. As sources for edible biopolymers were highlighted polysaccharides, proteins and lipids. The most characteristic subgroups from each large group of compounds were selected and described regarding possible physical and mechanical protection; migration, permeation, and barrier functions. The most important biopolymers characteristic is possibility to act as active substance carriers and to provide controlled release. In order to achieve active packaging functions emulsifiers, antioxidants and antimicrobial agents can also be incorporated into film-forming solutions in order to protect food products from oxidation and microbial spoilage, resulting in quality improvement and enhanced safety. The specific application where edible films and coatings have potential to replace some traditional polymer packaging are explained. It can be concluded that edible films and coatings must be chosen for food packaging purpose according to specific applications, the types of food products, and the major mechanisms of quality deterioration.
This study investigated properties of starch-based edible fi lms with oregano and black cumin essential oil addition. Essential oils addition positively affected fi lm swelling (decreased due to essential oil addition), mechanical properties (tensile strength decreased while elongation at break increased), and water vapor barrier properties (decreased along with essential oils addition). Control fi lm did not have any biological activity, which proves the need for essential oils addition in order to obtain active packaging. Oregano oil was more effective in terms of biological activity. Endothermal peak, above 200°C, represents total thermal degradation of edible fi lms. Diffraction pattern of control fi lm showed signifi cant destruction of A-type crystal structure. Addition of essential oils resulted in peak shape change: diffraction peaks became narrower. Principal Component Analysis has been used to assess the effect of essential oils addition on fi nal starch-based edible fi lms characteristics with the aim to reveal directions for the fi lm characteristics improvement, since the next phase will be optimal fi lm application for food packaging.
Osmotic treatment of celery root was studied in two osmotic solutions (sugar beet molasses and a ternary solution of water, sucrose and salt), at three temperatures (20, 35 and 50?C), and three different immersion periods (1, 3 and 5 h), at atmospheric pressure. The aim was to examine the influence of the type of the used hypertonic agent, the temperature and the immersion time on the water loss, solid gain, water activity, dry matter content, antioxidant activity (expressed by DPPH) and colour attributes (described by CIELAB coordinates L*, a* and b*). During the experiments, the antioxidant activity of celery root was increased in sugar beet molasses, while the DPPH value tended to decrease in the ternary solution. The experimental data of osmotic dehydration was used for PCA modelling. The standard scores analysis revealed that the optimum process parameters were gained with an immersion time of 5 h and a temperature of 35?C. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. TR-31055]
In this work, caraway or oregano essential oils were added to the cast
chitosan film in an attempt to design a natural, biodegradable, bioactive
(antioxidant and antimicrobial) packaging film. When the structure of the
tested films was analyzed with Fourier transform infrared spectroscopy, no
significant differences were found between the chitosan film with and without
essential oils of caraway or oregano. The lowest antioxidant activity, based
on the scavenging of the stable DPPH? free radical, was detected for the
chitosan film without oil addition, going from 11.64%, after 2.5 h to 28.96%,
after 24 h. When the caraway essential oil was added to the chitosan film,
the antioxidant activity was increased (p<0.05) to 33.47?4.77%, after 2.5 h
and to 81.08?0.64%, after 24 h. This increase in the antioxidant activity was
even higher in the film with oregano essential oil (p<0.05). After 2.5 h, the
value for the antioxidant activity of the chitosan-oregano film was
87.58?1.71%, and after 4 h and 24 h it was above 90%. The obtained results
for the antimicrobial activity showed that the chitosan film is an effective
antimicrobial agent against Escherichia coli and Staphylococcus aureus. When
caraway essential oil was added in 1% volume concentration to the film, no
increase in the antimicrobial action of chitosan film was detected. On the
other hand, the addition of oregano essential oil promoted chitosan film
antimicrobial activity, which was particularly evident with Escherichia coli.
The results showed that the chitosan film can be successfully applied as a
matrix carrier for essential oils in the active film system.[ Projekat
Ministarstva nauke Republike Srbije, br. TR31032]
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