Development and Characterization of Films for Food Application Incorporating Porphyran Extracted from Porphyra dioica

Abstract

Non-biodegradable plastic is one of the biggest environmental problems of our lifetime and, considering the present societal needs, it will get worse. Consequently, there is an urgent need to develop sustainable and renewable alternatives to plastic, such as plastic-like materials obtained from biodegradable polymers, namely sulfated polysaccharides, considered one of the most viable alternatives. There is also a need to obtain these materials in an environmentally and economically sustainable way. The hereby developed process of obtaining film-forming solutions from semi-refined porphyran (PorphSR) uses a green solvent (hot water) with a high extraction yield of semi-refined porphyran (26.66 ± 0.27%) in a reproducible way and with low levels of contaminants. The obtained semi-refined porphyran showed good antioxidant potential in all tests performed: HPSA (Δ0.066 ± 0.002), DPPH (2.23 ± 0.78%), FRAP (0.420 ± 0.014 eq. ascorbic acid µg mg−1 of extract) and ABTS (20.46 ± 0.90%). After being cast into films, the most notable antioxidant properties were those of the semi-refined porphyran in the DPPH, FRAP and ABTS assays and of the pectin, (PorphSR_PcT and PorphSR_PcT_Gly) in the HPSA assay. Morphologically, the films showed relatively homogeneous and low roughness surfaces. It is concluded that the described method to obtain semi-refined porphyran is feasible and reproducible, and that the developed films, mainly PorfP2_PcT_Gly, proved to be a potential candidate for non-biodegradable plastic substitutes.

Use of Limestone Sludge in the Preparation of ɩ-Carrageenan/Alginate-Based Films

“…Based on these results, it can be concluded that the presence of D-(-)sorbitol on the crosslinking solution Overall, the use of plasticizer decreased Young's modulus, yield stress and tensile strength values. This behavior is in line with previous work in porphyran-based films plasticized with glycerol or sorbitol [69] and in alginate and κ-carrageenan films using glycerol as a plasticizer [65].…”

Morphological and Mechanical Characterization of Films Incorporating Porphyran Extracted from Porphyra Dioica

“…In this context, the current authors have been developing novel biodegradable edible films based on porphyran extract isolated from the red macroalgae Porphyra dioica [8]. Porphyran is an anionic, water-soluble polysaccharide, with a linear backbone and a very complex structure consisting of repeating arrangements of D-galactose and L-galactosesulfate units in alternating sequence (Figure 1a), disturbed by the partial substitution of D-galactose by methylether (Figure 1b) and of L-galactose-sulphate by anhydrous-Lgalactose (Figure 1c) [7,9].…”

“…Gelation can, however, be induced by desulfation, which decreases electrostatic repulsion among chains, allowing interactions through non-covalent bonds (hydrophobic interactions or electrostatic interactions via hydroxyl groups) [10,14]. Excellent gelation and filmogenic properties can thus be developed [8,10,14], such that porphyran has potential for use as a gelling agent in edible food packaging films. Furthermore, the antioxidant and anti-inflammatory properties that have been shown by its use in pharmacy and cosmetics [4,14,15] are potentially very useful for extending the shelf lives of contained food products.…”

“…However, to the best of the authors' knowledge, only a small number of reports are available regarding its application in food packaging [16][17][18][19]. Bearing this in mind, porphyran-based films for edible packaging were envisioned and produced in a previous work [8]. A porphyran biopolymer was used as a matrix after extraction and water was used as the solvent.…”

“…In order to improve structural cohesion, the incorporation of other food-grade polysaccharides-amidated pectin, sodium alginate, and sodium carboxymethylcellulose-was tested [4]; glycerol was used as a plasticizer to increase the films' flexibility [4]. The suitability of the produced porphyran-based films from chemical, toxicity, durability, and organoleptic standpoints was previously established [8]. The materials also display antioxidant properties [8].…”