Development of Edible Films and Coatings with Antimicrobial Activity

Effect of Pullulan Coating on Postharvest Quality and Shelf-Life of Highbush Blueberry (Vaccinium corymbosum L.)

Fruits form an important part of a healthy human diet as they contain many ingredients with proven pro-health effects such as vitamins, phenolic compounds, organic acids, fiber, and minerals. The purpose of this work was to evaluate the effect of pullulan coating on the quality and shelf life of highbush blueberry during storage. General appearance, weight loss, dry matter, soluble solid content, reducing sugars, content of L-ascorbic acid, phenolic compounds (total phenolics, phenolics acids and anthocyanins) were determined in uncoated and coated blueberries fruits. The microbiological efficiency of pullulan coating was also evaluated. All parameters were monitored during storage at 4 °C and 16 °C by 28 and 14 days, respectively. The study showed that pullulan coating protects perishable food products especially susceptible to mechanical injury including fruits such as blueberries. Pullulan acts as a barrier that minimizes respiration rate, delaying deterioration and controlling microbial growth.

Combination of Poly(lactic) Acid and Starch for Biodegradable Food Packaging

The massive use of synthetic plastics, in particular in the food packaging area, has a great environmental impact, and alternative more ecologic materials are being required. Poly(lactic) acid (PLA) and starch have been extensively studied as potential replacements for non-degradable petrochemical polymers on the basis of their availability, adequate food contact properties and competitive cost. Nevertheless, both polymers exhibit some drawbacks for packaging uses and need to be adapted to the food packaging requirements. Starch, in particular, is very water sensitive and its film properties are heavily dependent on the moisture content, exhibiting relatively low mechanical resistance. PLA films are very brittle and offer low resistance to oxygen permeation. Their combination as blend or multilayer films could provide properties that are more adequate for packaging purposes on the basis of their complementary characteristics. The main characteristics of PLA and starch in terms of not only the barrier and mechanical properties of their films but also of their combinations, by using blending or multilayer strategies, have been analyzed, identifying components or processes that favor the polymer compatibility and the good performance of the combined materials. The properties of some blends/combinations have been discussed in comparison with those of pure polymer films.

Alginate edible films containing microencapsulated lemongrass oil or citral: effect of encapsulating agent and storage time on physical and antimicrobial properties

Active edible films have been proposed as an alternative to extend shelf life of fresh foods. Most essential oils have antimicrobial properties; however, storage conditions could reduce their activity. To avoid this effect the essential oil (EO) can be microencapsulated prior to film casting. The aim of this study was to determine the effects of the type of encapsulating agent (EA), type of EO and storage time on physical properties and antimicrobial activity of alginate-based films against Escherichia coli ATCC 25922. Trehalose (TH), Capsul^® (CAP) and Tween 20 (Tw20) were used as EA. Lemongrass essential oil (LMO) and citral were used as active agents. The results showed that the type of EA affected the stability of the film forming-emulsions as well as the changes in opacity and colour of the films during storage but not the antimicrobial activity of them. Both microencapsulated EOs showed a prolonged release from the alginate films during the 28 days of storage. Trehalose was selected to encapsulate both active compounds because the films made with this microencapsulated EA showed the greatest physical stability and the lowest color variation among all the films studied.

Natural antimicrobial/antioxidant agents in meat and poultry products as well as fruits and vegetables: A review

Synthetic preservatives are widely used by the food industry to control the growth of spoilage and pathogenic microorganisms and to inhibit the process of lipid oxidation extending the shelf-life, quality and safety of food products. However, consumer's preference for natural food additives and concern regarding the safety of synthetic preservatives prompted the food industry to look for natural alternatives. Natural antimicrobials, including plant extracts and their essential oils, enzymes, peptides, bacteriocins, bacteriophages, and fermented ingredients have all been shown to have the potential for use as alternatives to chemical antimicrobials. Some spices, herbs and other plant extracts were also reported to be strong antioxidants. The antimicrobial/antioxidant activities of some plant extracts and/or their essential oils are mainly due to the presence of some major bioactive compounds, including phenolic acids, terpenes, aldehydes, and flavonoids. The proposed mechanisms of action of these natural preservatives are reported. An overview of the research done on the direct incorporation of natural preservatives agents into meat and poultry products as well as fruit and vegetables to extend their shelf-life is presented. The development of edible packaging materials containing natural preservatives is growing and their applications in selected food products are also presented in this review.

Antimicrobial Polymers in the Nano-World

Infections are one of the main concerns of our era due to antibiotic-resistant infections and the increasing costs in the health-care sector. Within this context, antimicrobial polymers present a great alternative to combat these problems since their mechanisms of action differ from those of antibiotics. Therefore, the microorganisms' resistance to these polymeric materials is avoided. Antimicrobial polymers are not only applied in the health-care sector, they are also used in many other areas. This review presents different strategies that combine nanoscience and nanotechnology in the polymer world to combat contaminations from bacteria, fungi or algae. It focuses on the most relevant areas of application of these materials, viz. health, food, agriculture, and textiles.

Involvement of ROS in nanosilver-caused suppression of aflatoxin production from Aspergillus flavus

A possible mechanism involving transmembrane release of O₂⁻was revealed to explain nanosilver-caused suppression of aflatoxin production fromAspergillus flavus.

Effect of Hydroxypropyl Methylcellulose-Beeswax Composite Edible Coatings Formulated with or without Antifungal Agents on Physicochemical Properties of Plums during Cold Storage

The influence of hydroxypropyl methylcellulose- (HPMC-) beeswax (BW) composite edible coatings formulated with or without food additives with antifungal properties on physicochemical and sensory properties of plums(Prunus salicina)cv. “Friar” stored for 11 and 22 d at 1°C followed by a shelf life period of 5 d at 20°C was evaluated. Food preservatives selected from previous research included potassium sorbate (PS), sodium methyl paraben (SMP), and sodium ethyl paraben (SEP). Emulsions had 7% of total solid content and were prepared with glycerol and stearic acid as plasticizer and emulsifier, respectively. All the coatings reduced plum weight and firmness loss and coated fruit showed higher titratable acidity, soluble solids content, and hue angle values at the end of the storage period. In addition, physiological disorders such as flesh browning and bleeding were reduced in coated samples compared to uncoated controls. Paraben-based coatings were the most effective in controlling weight loss and the SMP-based coating was the most effective in maintaining plum firmness. Respiration rate, sensory flavor, off-flavors, and fruit appearance were not adversely affected by the application of antifungal coatings. Overall, these results demonstrated the potential of selected edible coatings containing antifungal food additives to extend the postharvest life of plums, although further studies should focus on improving some properties of the coatings to enhance gas barrier properties and further increase storability.

Surface attachment of active antimicrobial coatings onto conventional plastic-based laminates and performance assessment of these materials on the storage life of vacuum packaged beef sub-primals

Two antimicrobial coatings, namely Sodium octanoate and Auranta FV (a commercial antimicrobial composed of bioflavonoids, citric, malic, lactic, and caprylic acids) were used. These two antimicrobials were surface coated onto the inner polyethylene layer of cold plasma treated polyamide films using beef gelatin as a carrier and coating polymer. This packaging material was then used to vacuum pack beef sub-primal cuts and stored at 4 °C. A control was prepared using the non-coated commercial laminate and the same vacuum packaged sub-primal beef cuts. During storage, microbial and quality assessments were carried out. Sodium octanoate treated packages significantly (p < 0.05) reduced microbial counts for all bacteria tested with an increase of 7 and 14 days, respectively compared to control samples. No significant effect on pH was observed with any treatment. The results suggested that these food grade antimicrobials have the potential to be used in antimicrobial active packaging applications for beef products.

Properties and storage stability of whey protein edible film with spice powders

The impact of spice powders on physical, mechanical, thermal and barrier properties, and on storage stability, of whey protein isolate (WPI)-based films was determined. Films with added spices were prepared from casting solution containing 10 % (w/w) heat-denatured WPI, glycerol (WPI:glycerol of 3:2 w/w), sodium chloride (0.4 g/100 g solution), garlic and pepper powders (≤3 g each/100 g solution). Water activity (a_w) of all films was 0.53-0.57. Addition of spice powders increased thickness, darkness and yellowness of the WPI films. Films with added spices had lower tensile strength (TS), percent elongation (%E), and melting enthalpy of WPI matrices, but possessed higher water vapor permeability (WVP) than WPI film without sodium chloride and spices. The WPI film containing highest amount of garlic powder and lowest amount of pepper powder was selected for storage tests at 25-45 °C. Storage for up to 49 days resulted in reduced a_w and %E, increased TS, and color changes at 35 and 45 °C, with few changes at 25 °C. However, film WVP and OP were not affected by storage conditions after 7 days storage. Active ingredients decreased over time with up to 81 % allicin and 37 % piperine retained in the film matrix after 47 days storage.

Polysaccharide-Based Membranes in Food Packaging Applications

Plastic packaging is essential nowadays. However, the huge environmental problem caused by landfill disposal of non-biodegradable polymers in the end of life has to be minimized and preferentially eliminated. The solution may rely on the use of biopolymers, in particular polysaccharides. These macromolecules with film-forming properties are able to produce attracting biodegradable materials, possibly applicable in food packaging. Despite all advantages of using polysaccharides obtained from different sources, some drawbacks, mostly related to their low resistance to water, mechanical performance and price, have hindered their wider use and commercialization. Nevertheless, with increasing attention and research on this field, it has been possible to trace some strategies to overcome the problems and recognize solutions. This review summarizes some of the most used polysaccharides in food packaging applications.

Gelatine-Based Antioxidant Packaging Containing Caesalpinia decapetala and Tara as a Coating for Ground Beef Patties

The development of antioxidant-active packaging has numerous advantages, such as the reduction of synthetic additives in food, the reduction of plastic waste and food protection against oxidation reactions. Different concentrations of extracts of the plants Caesalpinia decapetala (CD) and Caesalpinia spinosa "Tara" (CS) were incorporated into gelatine films as natural antioxidants. The physical, mechanical and antioxidant properties of these films were studied. Films containing plant extracts at a high concentration had lower tensile strength with higher elongation at break points, compared to the control film (p < 0.05). Films exhibited antioxidant activity in the oxygen radical absorbance capacity (ORAC) and Trolox equivalence antioxidant capacity (TEAC) assays when added at 0.2%. The application of gelatine film containing CD and CS was found to be effective in delaying lipid oxidation and deterioration of beef patty quality during storage. Therefore, the films prepared in this study offered an alternative edible coating for the preservation of fresh food.

Preservation of Brussels Sprouts by Pullulan Coating Containing Oregano Essential Oil

In this study, the effectiveness of pullulan (a fungal polysaccharide) film containing oregano essential oil (OEO) at 1.0 to 10.0% was evaluated against bacteria, yeasts, and molds. The quality of the sprouts, as determined by weight loss, color, and appearance, was monitored during storage at 2 and 16°C. An organoleptic evaluation of odor preference and odor acceptability of OEO on the Brussels sprouts was also conducted. The antimicrobial activity of pullulan films with OEO increased significantly with the increase in OEO concentration (1 to 10%). Pullulan films with OEO were more effective for inhibiting the growth of yeasts and molds than for inhibiting gram-positive and gram-negative bacteria. Pullulan with 1.0% OEO was an effective combination and was used subsequently as the base coating for maintaining the safety and quality of fresh Brussels sprouts stored at 16°C for 14 days. The pullulan coating containing 1.0% OEO reduced Aspergillus niger populations by 2 log CFU/g. This coating also reduced weight loss in the sprouts. Compared with uncoated Brussels sprouts, the percent weight loss after 14 days was reduced in samples coated with pullulan and with pullulan plus 1% OEO by 3.81 and 6.06%, respectively, after storage at 2°C and by 8.04 and 9.30%, respectively, after storage 16°C. The coating also significantly reduced changes in general appearance and color during storage. Evaluation of the organoleptic properties indicated that pullulan containing OEO had only a slight detrimental effect on odor properties. Incorporating OEO into a delivery system for antimicrobial compounds in pullulan coatings extended the microbiological shelf life of Brussels sprouts.