Vera Lazić

Lipid oxidative changes in chitosan-oregano coated traditional dry fermented sausage Petrovská klobása

The effect of a chitosan coating with added essential oil of oregano (Origanum vulgare) on lipid oxidation of dry fermented sausage (Petrovská klobása) was investigated. Fatty acid profile, aldehyde contents and sensory analysis of odor and flavor were determined after drying and during seven months of storage. Between coated and control sausage, a difference was observed after two months storage in fatty acid profiles (myristic, oleic and linoleic acids), but after seven months storage there was no difference. Decrease in polyunsaturated acid content was observed (from 17.25% to 15.70%), as well as an increase in total aldehydes (from 4.54 μg/g to 31.80 μg/g), due to lipid oxidation during storage. After seven months storage, the content of most aldehydes was significantly lower in coated sausage than in the control. Sensory characteristics of odor and flavor were better for coated sausage, after seven months of storage. Results suggest that chitosan-oregano coating can be successfully applied to protect dry fermented sausages from lipid oxidation.

Edible films and coatings: Sources, properties and application

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.

Characterization of Starch Edible Films with Different Essential Oils Addition

Abstract This study investigated properties of starch-based edible films with oregano and black cumin essential oil addition. Essential oils addition positively affected film 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 film 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 films. Diffraction pattern of control film showed significant 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 final starch-based edible films characteristics with the aim to reveal directions for the film characteristics improvement, since the next phase will be optimal film application for food packaging.

Biopolymer Packaging Materials for Food Shelf-Life Prolongation

Abstract In order to increase sustainability in the food industry, while maintaining product quality, the use of biopolymer packaging materials presents an attractive, ecofriendly alternative to synthetic polymers due to availability, low cost, and renewable raw materials and agroindustrial waste (biomass) usage. Materials used for biopolymer preparation are polysaccharides, proteins, or lipids, based on the compositional units. In order to improve biopolymer material properties, they can be laminated or formed as composites. In addition, biopolymer materials can be edible and/or active with strong antioxidant and/or antimicrobial properties. Numerous studies have been conducted with the aim of widening successful implementation of biopolymer packaging for a range of food products. It is very important to be familiar with properties of biopolymer packaging materials prior to application, as well as to produce biobased materials in terms of specificity of the product intended to be packed. The aim of this chapter is to review the possibility of biopolymer packaging material application for packing dairy, meat, fruits, and vegetable products.

Mono- and bilayer biopolymer films: Synthesis and characterisation

The purpose of this paper is to improve the properties of biopolymer protein monofilms and produce a novel bilayer biopolymer film on the basis of the monofilms analyzed. Biopolymer monolayer films, based on pumpkin oil cake (PuOC) and zein, and a bilayer film, based on PuOC and zein (PuOC/Zein), were produced as a result of the study. The visual, mechanical, physicochemical and structural properties of the films were evaluated. The results obtained showed that the PuOC film exhibited the highest elongation at break, followed by the bilayer film, whereas the zein film showed the lowest elongation at break. However, the zein film showed the highest tensile strength, followed by the PuOC film. The tensile strength of the bilayer PuOC/Zein film was almost 3 times lower than that of the PuOC film, and almost 4 times lower than that of the zein film. The physicochemical properties recorded indicate that the hydrophobic zein film is the least sensitive to moisture, affecting the moisture sensitivity of PuOC film by reducing the moisture content, swelling and total soluble mater of the bilayer PuOC/Zein film. Based on the FTIR spectra, it could be concluded that there are no significant differences between the two sides of the bilayer PuOC/Zein film. Both sides of the bilayer film examined indicated characteristic peaks for protein biopolymer films in the FTIR spectrum.

Biopolymer films synthesis and characterisation

In this study, three biopolymer films were synthesized: zein (protein), gelatin (protein), and starch (polysaccharide) films and characterized by determining mechanical and physico-chemical properties. Gelatin films proved to be the strongest (tensile strength 84 N/15 mm), while the zein were most flexible (elongation at break 41.6 %). Moisture content was higher in starch films, which is a result of the hydrophilic nature of the polysaccharide films. Swelling degree was 22.5 % for zein, 90.9 % for gelatin, while the highest average value was recorded in starch film samples (840.6 %). Starch films had highest value of solubility degree (36.5 %), while zein film had 27.9 % and gelatin film had 11.85 %.Obtained characterization results are consequences of the different structure of the raw materials and synthesis routes. All undesirable characteristics could be improved by optimizing the composition of the film, as well as synthesis of composite/laminated films.

Antimicrobial activity of composite chitosan biofilms with beeswax and caraway essential oil

In this paper, influence of increasing concentrations of beeswax on the antimicrobial activity of chitosan-caraway essential oil biofilm was investigated. Selected microorganisms for the test were Salmonella Typhimurium and Listeria monocytogenes. Reduction of S. Typhimurium and L. monocythogenes viable counts in bacterial suspension in the presence of chitosan films with or without added beeswax amounted over 80 % after 24 h contact time, and over 95 % after 3 h of contact time, respectively and influence of added beeswax on growth reduction was not detected. However, when number of S.Typhimurium viable cells was analyzed (log CFU/ml), it was shown that addition of beeswax led to increased activity of films, especially for the films with 36 kg/m and 54 kg/mof beeswax. When films were transferred, after 24 h in bacterial suspension, onto Petri dishes with nutrient agar and incubated for 24 h on 37 °C, results also showed beeswax contribution to growth inhibition of S.Typhimurium.

Primena i uticaj polimernih ambalažnih materijala na pakovanje mlečnih napitaka

Functional food is positioned above the traditional, with the potential to improve human health. Thanks to very good physico-mechanical and barrier properties polymers became very popular in food industry as a packaging materials. Wild range of fermented dairy products could be packed in this packaging materials according to their’s inertness as well. Functional milk beverage was obtained from milk with 0,9% milk fat content by applying 10% v/v of kombucha’s inoculum cultivated on a black tea sweetened with sucrose. The beverage was packed in a different packaging materials: polyamid-polyethylen (PA/PE) coextruded foil bags and polyprophylen (PP) cups closed with aluminium (Al) foil lids under atmospheric conditions (ATM). Beverages were storaged for 15 days at 4°C. The quality of kombucha inoculum, milk and obtained kombucha fermented milk beverage were analysed. Characterization of the packaging materials was done by investigating physico-mechanical, barrier and structural properties. The composition and changes in the headspace atmosphere, after production and during the storage, were analysed. The influence of packaging material properties and packaging conditions on the biochemical transformations of the milk’s components (the content of: lactose, L-lactic acid, D-galactose, ethanol, B1 and B2 vitamins) influenced by kombucha starter were analysed as well. On the bases of the obtained results of characterisation of packaging materials, it can be concluded that PA/PE and PP materials are proper to be used for analysed beverage’s packaging. Also, there is no significant difference in content of components which were quantified, between analysed materials in correlation with the packed fermented milk beverage. [Projekat Ministarstva nauke Republike Srbije, br. III-46009]

Improvement of Water Vapor Barrier Properties of Chitosan-Collagen Laminated Casings using Beeswax

Collagen casings are commercially used in sausage production. In this paper, collagen film that is used for sausage casings was laminated with chitosan film to produce barrier casing film. Chitosan coating was prepared by dissolving chitosan powder in 1% acetic acid. After dissolving chitosan, caraway essential oil, wetting agent Tween 20 and different amounts of beeswax, from 0 to 25 g were added to the solution. The solution was coated on collagen film surface in three layers, using a sponge brush to make laminated films. Films were air dried at temperature t =23 °C ± 2 °C. Uncoated collagen film was used as reference. Film thickness, water vapor barrier properties and FTIR spectra were determined. With growing amount of beeswax added to the chitosan layer, film thickness grew from 112 μm for laminated film with 5 g of beeswax to 225 μm for film with 25 g of beeswax, compared to 83 μm for collagen film. Water vapor barrier properties improved with growing amount of beeswax in chitosan layer, ranging from 130.71 g/m24h for laminated film with added 5 g of beeswax to 66.96 g/m24h for the film with 25 g of beeswax, compared to 290.64 g/m24h for collagen film. Addition of beeswax showed great potential in lowering water vapor permeability of laminated collagen-chitosan film. FTIR spectra could be used to determine quantitative law dependency between added amount of beeswax and spectra absorption values,as well as to prove compactness of chitosan-beeswax layer.

The influence of protective properties of packaging materials and application of modified atmosphere on packed dried apricot

The influence of protective properties of packaging materials and modified atmosphere on quality changes of dried apricot is shown in this paper. In our investigation, we used four different characteristic combinations of packaging materials with different barrier properties for packaging of dried apricot: polyester-polyethylene (PET/PE), paper-polyethylene (PAP/PE), paper-aluminium-polyethylene (PAP/Al/PE), polyester-aluminium-polyethylene (PET/Al/PE) and two different atmospheric conditions: normal and modified (30% CO 2 , 60% N 2 ). The parameters evaluated in this study were moisture content, the content of the brown component and the hidroxymethilfurfural (HMF) content. During the storage period of 12 months, changes in moisture content, and colour changes of brown component and HMF contents were affected by the type, combination and applied packing conditions. During the investigation period, the moisture content increased, as well as the content of the brown component and the HMF content. The highest changes in moisture content are reported for dried apricot packaged in the PAP-PE under normal atmosperic condition (increased from 31.2 to 39.6%, taking into consideration 100 g of the sample, after 12 months of storage). The highest value of HMF content was recorded for dried aprricot packaged in the PAP-Al-PE with modified atmospheric condition after nine months of storage (0.152 mg/g). The research results indicate that sustainability of dried packaged apricot is affected by the selection of packaging material and the applied atmospheric conditions. Keywords: Packaging, modified atmosphere, dried apricot