Improving the water barrier properties of alginate packaging films by submicron coating with drying linseed oil

Abstract

Alginates with excellent film‐forming ability have a promising potential as a safe and biodegradable food packaging material, but as a hydrophilic biopolymer, its general weakness against water has limited its applications. To surpass this weakness, in this study, coating of calcium alginate films with linseed or sunflower oils in micrometric (about 4.55 μm) and submicrometric (about 0.45 μm) thickness was performed, and the characteristics of the films were evaluated. All of the films were homogeneous, transparent and almost colourless. Micro‐coated films presented improved ultraviolet absorbing spectra. The scanning electron microscopy (SEM) images proved the formation of homogeneous and continuous submicron‐coated oil layers for both types of the oils, while some inhomogeneity and defects were observed in the micro‐coated films. Oxidative polymerization of linseed oil was confirmed by Fourier transform infrared (FTIR) spectral analyses. The mechanical strength of the films micro‐coated with linseed oil increased. Submicron coating improved water vapour barrier properties (from 2.20 to 2.92 g/mm/m2/day/kPa) as well as water vapour absorption of the alginate film compared to other films. This result was confirmed by thermogravimetric analyses. The increase in surface hydrophobicity of the films by coating resulted in a significant increase in contact angle (from 46.3° to 89.9° in maximum) and reduction of wettability. The film submicron coated with linseed oil showed the best performance with the least water vapour permeability, water vapour absorption and wettability.

Effect of nanocomposite alginate‐based film incorporated with cumin essential oil and TiO2 nanoparticles on chemical, microbial, and sensory properties of fresh meat/beef

“…In addition, sodium alginate, at 4 and 5 mg/ml, exerted potent scavenging activities (80% and 82%, respectively) according to hydroxyl radical scavenging activity test. Meanwhile, Al may act as an oxygen barrier (Nehchiri et al., 2021 ) between meat and its surroundings, resulting in the reduction in the lipid oxidation rate. On the other hand, it has been confirmed that CEO can reduce Fe 3 ions effectively and scavenge the superoxide anion.…”

“…The prepared solutions were deaerated (at 40°C, 5 min) by a rotary vacuum evaporator (RV‐10 control; IKA). Then, 20 g of the solutions was poured into polystyrene Petri dishes (11 cm diameter) and dried in an incubator at 25°C with 40% relative humidity for 24 h (Nehchiri et al., 2021 ).…”

“…Meanwhile, Al may act as an oxygen barrier (Nehchiri et al, 2021) between meat and its surroundings, resulting in the reduction in the lipid oxidation rate. On the other hand, it has been confirmed that CEO can reduce Fe 3 ions effectively and scavenge the superoxide anion.…”

“…In this regard, the use of biopolymeric‐based coatings and films is proposed as an important solution due to their barrier, mechanical, optical, and biodegradability characteristics (Bagheri et al., 2019a ; Molayi et al., 2018 ). Sodium alginate is a biopolymer with a high potential for being used as the basic component of films and coatings due to its unique properties such as biodegradability, low cost, availability, ease of use, nontoxicity, stability, and gel formation in the presence of polyvalent cations (Bagheri et al., 2019b ; Karimi Khorrami et al., 2021 ; Nehchiri et al., 2021 ). The use of biopolymers in the forms of coating and film can restrict oxygen availability and prevent moisture loss, and thereby can increase the shelf life of many products in many researches (Bagheri et al., 2020 ; Martiny et al., 2020 ; Radi, Akhavan‐Darabi, et al., 2017 ; Radi, Firouzi, et al., 2017 ).…”

Effect of Composite Chitosan/Sodium Alginate Gel Coatings on the Quality of Fresh-Cut Purple-Flesh Sweet Potato

“…In addition, sodium alginate coating was beneficial in preserving the post-harvest quality of tomatoes [ 17 ] and peaches [ 18 ]. However, alginate has no antimicrobial properties, and their poor mechanical properties and water vapor resistance has limited their industrial applications [ 19 ]. In contrast, chitosan, a cationic polysaccharide with a high molecular weight and soluble in organic acids, is applicable as a preservative coating material for fruits due to its anti fungal mechanisms [ 20 , 21 , 22 , 23 ].…”