Physico-chemical, antimicrobial and antioxidant properties of gelatin-chitosan based films loaded with nanoemulsions encapsulating active compounds

Abstract

The aim of this research was to develop and characterize gelatin-chitosan (4:1) based films that incorporate nanoemulsions loaded with a range of active compounds; N1: canola oil; N2: αtocopherol/cinnamaldehyde; N3: α-tocopherol/garlic oil; or N4: a-tocopherol/cinnamaldehyde and garlic oil. Nanoemulsions were prepared in a microfluidizer with pressures ranging from 69 to 100 MPa, and 3 processing cycles. Films were produced by the casting method incorporating 5g N1,2,3,4/100 g biopolymers and using glycerol as a plasticizer, and subsequently characterized in terms of their physico-chemical, antimicrobial and antioxidant properties. No differences (p>0.05) were observed for all films in terms of moisture content (18% w/w), and thermal properties. The films' solubility in water and light transmission at 280 nm were considerably reduced as compared to the control, N1 (15% and 60% respectively) because of the nanoemulsion incorporation. The film loaded with N1 showed the greatest (p<0.05) opacity, elongation at break and stiffness reduction, and was the roughest, whilst the lowest tensile strength and ability to swell were attained by films loaded with N3 and N4, respectively. DSC and X-ray analyses suggested compatibility among the biopolymeric-blend, and a good distribution of nanodroplets embedded into the matrix was confirmed by AFM and SEM analyses. Films loaded with nanoencapsulated active compounds (NAC) were very effective against Pseudomonas aeruginosa, and also showed high antioxidant activity. Overall, the present study offers clear evidence that these active-loaded films have the potential to be utilized as packaging material for enhancing food shelf life.

Effects of the addition of ultrasound‐pulsed gelatin to chitosan on physicochemical and antioxidant properties of casting films

“…The EB percentage showed a significant decrease for the film with the control gelatin, meaning that the film became less plastic. These results contrast to those reported for the chitosan and collagen films, where the incorporation of collagen increased the elongation percentage, acting as a plasticizer, although there are also reports that show lower EB for edible chitosan‐gelatin films, and results are very similar to chitosan films with carvacrol …”

“…According to this assay, films in this study show antioxidant activity in the range 200–900 μmol TE per mg of film. These results are similar to chitosan‐starch and gallic acid films, and higher than gelatin based films containing oily tomato extract and gelatin‐chitosan based films loaded with active compounds . The increase in antioxidant activity could be related to the exposure of residues during protein unfolding, a phenomenon that has previously been reported for proteins during ultrasonic pulses …”

“…A stock solution of ABTS radical was prepared by mixing 5.0 mL of 7 mmol L –1 ABTS solution with 88 μL of 139 mmol L –1 potassium persulfate and the mixture was kept in darkness at room temperature for 18 h. An aliquot (0.5 mL) of stock solution was diluted with phosphate buffer (50 mmol L –1 , pH 7.4) to prepare the work solution of the ABTS radical with absorbance at 734 nm of 0.70 ± 0.02. Film samples of 0.1 g were stirred for 8 h in 10 mL of distilled water:ethanol mixture (1:1 v/v), and this mixture was used as the blank . For this analysis, a 30 μL aliquot of the sample was mixed with 270 μL of ABTS radical work solution and incubated for 30 min at room temperature in the dark; then the absorbance was measured at 734 nm using a microplate reader (Thermo Scientific Multiskan Sky; Waltham, MA, USA).…”

Preparation and Characterization of Chitosan‐Based Ternary Blend Edible Films with Efficient Antimicrobial Activities for Food Packaging Applications

“…However, the antibacterial properties of the CS–GE films were shown to be poor by previous research, which results from the presence of fewer effective antibacterial groups after numerous hydrogen bonds were formed between the hydroxylamines and carbonyls in GE and CS (Pérez‐Córdoba et al., ). In addition, the antibacterial and anticorrosive properties of CS were also limited by the degree of acetylation, molecular weight, environment effects, and so on (Zhu et al., ).…”

Nanoemulsions: Synthesis, Characterization, and Application in Bio‐Based Active Food Packaging

“…This technique relies upon a sensing probe that passes over the film surface, interacting with it and generating a scanning signal, which is finally converted into 3D images that allow to discern the topographic features of the studied sample (Tararam, Garcia, Deda, Varela, & de Lima Leite, ). In most cases, AFM is used together with SEM, the former allowing the quantification of surface roughness (Alexandre et al., ; Chen et al., ; Imran et al., ; Pérez‐Córdoba et al., ).…”