Investigating the effect of water-soluble soybean polysaccharide (SSPS) on the basic properties of sago starch film

Dissertation for receiving a master's degree in a field

Food Science and Engineering

Abstract

Every year, millions of tons of plastic waste including bags, plastic envelopes and packaging materials enter the environment and cause problems to the environmental cycle due to their irreversibility. And as a result, the need for degradable plastics in nature is increasing day by day. Today, the pollution caused by synthetic polymers has turned everyone's attention to the use of biodegradable raw materials, and during the last two decades, the study of biodegradable materials derived from proteins and carbohydrates has expanded widely. Recently, a polysaccharide has been extracted from the cell wall material of soybean. This soy soluble polysaccharide (SSPS) has a pectin-like structure. The purpose of this research is to investigate the effect of SSPS on the physicochemical, mechanical, colorimetric and water vapor permeability properties of sago starch films. In this research, sago starch films were prepared with SSPS in concentrations of 0, 10, 30, and 50% using the solvent casting method. All physicochemical, mechanical, colorimetric and water vapor permeability properties were performed according to the American national standard method. The mechanical test of sago starch films containing SSPS showed an increase in tensile strength and Young's modulus, a decrease in elongation percentage due to an increase in SSPS concentration. Physicochemical properties such as water absorption rate, solubility and moisture content and water vapor permeability barrier properties of sago starch films containing SSPS showed a significant increase (P < 0.05) due to the hydrophilic nature of SSPS. In general, according to the investigations, SSPS have the ability to improve the mechanical properties of sago starch films, but due to their hydrophilic nature, they are not recommended for moisture-sensitive food. style="direction: rtl;"> 

1-1- Introduction

About 125 million tons of plastic are produced in the world, of which about 30 million tons are used in the packaging sector. The pollution caused by packaging materials produced from petroleum derivatives and the problems caused by different methods of decontamination (such as burying, burning and recycling them) have turned the attention of researchers in recent years to find suitable alternatives for this type of packaging materials. Biodegradable packaging is made of natural polymers (Mez Staka [2] et al., 2009). Today, a large part of the materials used in the packaging industry are obtained from petroleum and petrochemical products, which are non-degradable in nature and cause environmental problems. Therefore, researchers are always looking for solutions for this issue. The increasing growth of biological products and the development of new technologies have reduced the dependence on the use of fossil fuels. In the last few decades, people's attention and interest in using biopolymers has increased due to the increased awareness of consumers, the increase in the price of crude oil, the increase in environmental pollution, the indestructibility of petroleum polymers, and attention to global warming, and this has led to many efforts to produce packaging materials of natural origin (protein, fat, and carbohydrates) in the form of films or coatings. Such biopolymers have less destructive effects on the environment compared to the use of plastics (Pine [3] et al., 1992). Edible films that are used in connection with food are biodegradable, that is, they have the ability to be decomposed into constituent elements by soil microscopic organisms (Figueroa [4] et al., 2004).For this reason, food packaging materials, like other packaging materials, cause serious problems in terms of the environment. As a result, studies have been conducted to use degradable bio-based packaging. About 125 million tons of plastic are produced annually in the world, of which about 30 million tons are consumed in the packaging sector (Marinello[5] et al., 2003; Lin[6] et al., 2005). In order to reduce non-biodegradable plastic packaging waste, use biodegradable plastics such as starch, cellulose, PLA, gelatin, etc. It is essential (Almasi[7] et al., 2009; Wilhelm[8] et al., 2003). It is certain that most food products reach the consumer with some kind of packaging method, and as a result, packaging is an important part of the food chain (Kim[9] et al., 2003). But the old packaging materials that were derived from petroleum materials are not biodegradable and are not environmentally acceptable and pose health risks; For example, the migration of harmful additives to food. The biodegradability of synthetic plastic materials derived from petroleum derivatives is very slow and their complete decomposition takes several years, and this causes an increase in environmental pollution. Therefore, in recent years, finding a suitable alternative for synthetic plastics that has high biodegradability and leaves less environmental pollution has attracted the attention of researchers. Edible biopolymers with high biodegradability, which are obtained from renewable agricultural resources, are considered a suitable option in this field. Despite the obvious environmental benefits and sustainability of biopolymers, it is the growing price of crude oil and natural gas that is the driving factor for economic investment in this field. This issue and the two driving factors of trying to recycle more waste as well as the stability of the environment and agricultural management make it necessary to make a change towards bio-plastics. The physical barrier between the food products and the external environment ensures product hygiene and increases the shelf life of perishable goods. In recent years, due to the increase in the consumption of plastics and due to their long lifespan and their almost non-biodegradability1, the synthesis of biodegradable polymers has increased (Qanbarzadeh et al. 2008).

In food packaging, various materials such as glass, hard and semi-hard plastics, hard metals (cans) are used. 1387). Polymer packaging materials, which are widely used in the packaging industry, are non-degradable and non-returnable to the environment, and for this reason, they are considered one of the most important pollutants in nature (Almasi, 2018 and Iran Menesh, 2018). The desirable features for any packaging are its easy recycling and minimal damage to the environment. Every year, more than several million tons of plastic waste, including bags, plastic envelopes and packaging materials, enter the environment and cause many problems for the environment due to not returning to the environmental cycle. Producing natural degradable films and replacing them instead of synthetic plastics is a solution to minimize the adverse and harmful effects of waste from synthetic materials (Darai et al., 2018). Edible films are layers of digestible materials that are used as food coatings (food coatings) or as a barrier between food and other materials or environments. Degradable edible coatings are consumed by microorganisms and converted into simple compounds. Polysaccharides such as chitosan, starch and cellulose, proteins such as zein and collagen and fats such as triglycerides and fatty acids can be used as edible films. Polysaccharide films have a low price, but they are not a good barrier against moisture penetration.