1. Introduction
New polysaccharides are being intensively studied around the world. The purpose of these new polysaccharides goes from applications such as food (gels, additives, dietetics, thickeners, co-emulsifiers, stabilizers, etc.) [
1,
2,
3,
4,
5,
6,
7,
8,
9,
10], packaging (protective and biodegradable films) [
11,
12,
13], eco-materials [
14], pharmaceuticals (capsules, patches, excipients [
15], anticoagulants, antilipidics, anti glycemic, antioxidants, nutraceuticals, etc.) [
16,
17].
Each year approximately 400 million tons of plastics are produced, and less than 9% is recycled. The development of biopolymers is of great interest due to the environmental pollution generated by plastics production. In addition, plastics derived from petroleum are disposed of into the environment and remain for hundreds of years without decomposing. Bioplastics are materials derived from renewable sources, generally biodegradable. The use of these biomaterials would reduce environmental pollution and the consumption of fossil resources, making them a much safer alternative [
18].
Food waste as a raw material represents one of the most recent applications in the research field of bioplastics production. Different types of food waste, mostly fruits, and vegetables, have been used. This makes it possible to value food waste, and as a result, benefits the economy, providing a new source of circular economy [
18]. Agricultural waste is derived from various sources, such as grape marc, tomato, pineapple, orange and lemon peels, sugarcane bagasse, rice husks, wheat straw, and palm oil fibers, are some examples of affordable materials and available. Precursors that are rich in carbon are used for the production of the bio-based polymer through chemical, microbial, and biopolymer blending methods [
18,
19]. Despite the development of advanced synthetic methods and the application of biofilms in smart/intelligent food packaging, construction, exclusion nets, and medicine, commercial production is limited by costs, helpful life, biodegradation concerns, and availability of adequate agro-wastes [
19]. Gheorghita et al. 2021 [
20] highlight polysaccharides in the pharmaceutical industries and as encapsulation materials for controlled drug delivery systems, including probiotics, focusing on their development and benefits. Bioplastic materials have several weaknesses in terms of their mechanical and barrier properties that have resulted in several studies on composite systems [
21]. Hong et al. in 2021 [
22] present a review of bioplastics materials applied for food packaging, other possible materials, such as plastics, paper, metal, and glass, are also discussed. Lavudi et al. in 2020 [
23] study galactomannans extracted from legume seed endosperm and their multipurpose applications. Their modified structure, sulfated and carboxymethylated, could be used in nanotechnology for drug delivery and carriers.
The extraction of new polysaccharides can be achieved through different hydrolysis or complex methodologies. For example, goji gum (
Lycium barbarum) is extracted by thermal, acidic, and basic hydrolysis [
24]. Khaya gum is a purified exudate of
Khaya ivonensis, which is dissolved, filtered, and then precipitated with ethanol [
25].
Ficus glumosa gum is an exudate purified in a solution of pH 2 with HCl and then precipitated with ethanol [
26]. Other more complex extractions, such as
Dictyophora indusiata gum, use hot water, or microwave-assisted, pressurized assisted, and ultrasonic-assisted extraction [
27].
Novel sources of edible materials and novel processing techniques are a subject of great interest due to their promising potential as innovative food packaging systems [
28,
29]. Galus et al. work in 2020 [
28], presents the concept and potential application of new film-forming materials and management of food wastes from the fruit and vegetable industry, which can encounter problems at appropriate disposal. More recently, biodegradable packaging materials, sometimes edible, are also used to deliver functional ingredients, which reveals their potential for drug delivery to counter the nutrient deficiency problems. Amin et al. 2021 [
29], highlights the potentials of bio-based materials, i.e., proteins, polysaccharides, lipids, etc., to develop biodegradable packaging materials. Active packaging is a way of packaging in which the food product, the packaging material, and the environment interact positively to extend the shelf life of food [
30]. When food products are stored by an active packaging system, the system’s chemical, physical, and biological activities alter the condition of food, leading to an increase in its shelf life and without affecting its quality [
31]. Apart from packaging, edible films can also be used for the protection of food products from oxidation and microbial growth [
32].
Polysaccharides obtained from plants have been investigated to develop packaging materials with a non-petrochemical base. Films prepared from alcayota gum (AlcOH) present strong hydrophilicity, an interesting property. By crosslinking with glutaraldehyde (Glu), the modified films exhibit water resistance and low O
2 permeation, which make them very useful films [
33]. Tara gum (TG) films were evaluated as barriers for agricultural and food industries. The crosslinked films exhibit better mechanical properties [
34]. Additionally, polysaccharides from
Melia azedarach (MA) were extracted to be used, e.g., in the agricultural industry [
35]. Locust bean gum has been used alone or combined with other biopolymers (e.g., polysaccharides, proteins, and lipids) to develop films due to its superior biodegradable, rheological, and film-forming properties. These films are not only used as active packaging and edible coating in the food industry, also used in the pharmaceutical industry [
36].
Capsosiphon fulvescens (CF) is an underutilized green alga; packaging materials have been developed using
Capsosiphon fulvescens polysaccharides, which could be used as packaging materials as a natural antioxidant to develop a food usable antioxidant film [
37].
Sargassum pallidum polysaccharides were incorporated into chitosan to develop a novel edible active film via ultrasonication. The results show that combined ultrasonic treatment and the addition of sargassum polysaccharide could significantly enhance the films’ tensile strength, elongation, and transparency, whereas the water vapor permeability was decreased. In addition, antioxidant effect evaluation showed that the Chitosan films with sargassum exhibited better antioxidant activity than chitosan films [
38]. Novel biodegradable noni (
Morinda citrifolia) fruit polysaccharides films containing blueberry (
Vaccinium corymbosum) were made. The prepared films had good mechanical properties. The addition of blueberry polysaccharides enhanced the antioxidant activities of the films [
39]. Films using carboxymethyl cellulose, hydroxypropyl methylcellulose, high-methoxyl pectin, low-methoxyl pectin, sodium alginate, and locust bean gum were prepared using like source polysaccharide extracted from jambolan and grape juices. The films exhibited good mechanical properties [
40]. Citrus peel is a valuable source of pectin since it was found in the internal and external parts. Pectin is used as a film in packaging, thickener, and gelling agent in the manufacture of jellies and preserves, in wines as dehydrating plant tissues, in milk to precipitate casein, etc. [
41]. Lemon and fennel wastes were recovered and used as secondary-raw polysaccharide sources. The extracted polysaccharides were used as eco-friendly and cost-effective plasticizers of sodium alginate films [
42].
Currently, there is a growing interest in sustainably using natural resources. Finding the chañar tree (
Geoffroea decorticans) is a good objective to cover this interest since it is currently not cultivated or harvested and is little exploited in its natural habitat. The chañar develops in dry areas and on the banks of streams, growing in clay, brackish soils, or even in dunes, sometimes forming small groves called chañarales. The species is characterized by forming islets or groves of rounded shape, which as a result of its asexual reproduction expands along its edges, progressively occupying more and more surface area. The spread of this species constitutes an excellent problem for farmers since their fields, originally pastures, end up being invaded with chañares. Therefore, chañar is considered a pest due to its ability to colonize the lands used for grazing [
43]. All of the above ratifies the attractiveness of chañar as a raw material for obtaining polysaccharides in our study and allows revaluation of the tree that is considered as a pest that is deforested. Chañar blooms from September to October and bears fruit from November to January. The fruit is a drupe, very fleshy, sweet, and edible. The fruit of Chañar is globose or ovoid, reddish in color, and its size is from 1.5–3 cm. It is edible, with a sweet and pleasant taste [
44]. The fruit could be used to get food, flour-based, with considerable fiber content, gluten-free, satisfying population health needs, and taking advantage of a nutritional resource with economic potential. In turn, its sustainable exploitation would generate a vast work and production area with innovative and straightforward processes [
45]. For a long time, its safety has been made known thanks to the consumption of fruits by humans and animals in many semi-arid places in Argentina, especially in aboriginal and rural communities [
46].
This work’s aim was to obtain polysaccharides from chañar fruit. Two different extraction methods were used: thermal (CHT) and acid hydrolysis (CHA). A whole study of the hydrodynamic properties in solution of the obtained polysaccharides was carried out; the technique used was intrinsic viscosity. The polysaccharides films (CHTF, CHAF) were properly characterized using different physical-chemical methods. Mechanical tests, water vapor permeation, colorimetry, antioxidant capacity, and biodegradability properties were also studied to determine potential applications of chañar films.