Chapter 1

Functional Polymers for Food Processing

Giuseppe Cirillo*, Umile Gianfranco Spizzirri and Francesca Iemma

Department of Pharmacy, Health and Nutritional Sciences, University of Calabria, Rende, Italy

*Corresponding author: giuseppe.cirillo@unical.it

Abstract

Polymeric materials can be used as functional elements for reaching an efficient food production and processing, with considerable advantages for the whole food industry. Among others, the applicability of polymers involves their use in agriculture, animal feed, modification of food rheology, and the development of functional food and nutraceutics.

Keywords: Functional polymers, agriculture, animal feed, food rheology, functional foods, nutraceutics

1.1 Introduction

Living a long healthy life is the desire of every human on earth. This basic desire is affected by almost every activity of human beings, with nutrition acting as one of the key elements, since it provides the essential elements for the cell cycle, such as carbohydrates, fats, proteins, vitamins and minerals [1].

Food, basically of plant or animal origin, is defined as any substance consumed to provide nutritional support for the human body. The rapid development of economies allows consumers to access foodstuff by the food industry, while the direct production has sensibly been reduced over the last century. The main challenge of the food industry is to address the growing global emphasis and attention on food quality and safety concerns, which are related not only to the consumers' rising and persistent demand for requirements for safe food and better quality of food and beverage, but also the strict norms of government regulations.

"Food quality" refers to the quality characteristics of food that are acceptable to consumers, including such external factors as appearance (size, shape, color, gloss and consistency), texture, and flavor, and other internal factors (chemical, physical and microbial contamination).

The improvement of food quality can be related to one of the foodstuff production steps, namely production, manufacturing and storage. Each of these industrial activities acts as a key determining step for the final food quality assessment, and several different technologies have been developed for a substantial and sustainable quality improvement.

Polymers, from both natural and synthetic origin, are practically indispensable for everyday life in modern society, representing one of the main classes of compounds within the global chemical market. Almost every human activity in life highly depends on polymers, which are used in technological fields such as communications, transportation, electronics, as well as in the pharmaceutical, medical and food industries [2]. One of the reasons for the great popularity exhibited by polymers is their ease of processing. Polymer properties can be tailored to meet specific needs by varying the "atomic composition" of the repeat structure and by varying molecular weight. The flexibility can also be varied through the presence of side-chain branching and according to the lengths and the polarities on the side chains. The degree of crystallinity can be controlled through the amount of orientation imparted to the polymers during processing, through copolymerization, by blending with other polymers, and via the incorporation (via covalent and noncovalent interactions) of an enormous range of compounds [3].

1.2 Food Preparation

Providing for the health and welfare of its population with abundant, safe, and affordable food has long been the goal of food systems all around the world. This is related to the production of foodstuffs of both plant and animal origins, where the use of polymeric materials in the production step is explored differently.

1.2.1 Functional Polymers in Agriculture

As a consequence of the impressive technological progress of the last decades, agriculture is becoming an industrial sector with complex supply chains and electronically aided information and logistics systems [1].

In the agricultural field, polymers are widely used for many applications [4]. Although they were first used just as structural materials for creating a climate beneficial to plant growth (inhert polymers), in the last decades functionalized polymers have revolutionized the agricultural and food industries with new tools for the molecular treatment of diseases, rapid disease detection, enhancing the ability of plants to absorb nutrients, etc. [5].

Smart polymeric materials and smart delivery systems help the agricultural industry combat viruses and other crop pathogens. Functionalized polymers are used to increase the efficiency of pesticides and herbicides, allowing lower doses to be used and to protect the environment indirectly through filters or catalysts to reduce pollution and clean up existing pollutants [6].

The first application of polymeric materials is related to the enhancement of the soil stability, including aridity remediation. The use of polymeric materials with good water absorption and retention capacities even under high pressure or temperature represents a valuable approach to these aims. An important class of systems with this behavior is composed of the Superabsorbent polymers (SAPs), organic materials with lightly cross-linked three-dimensional structure possessing high to very high swelling capacity in aqueous media [7].

Generally, the SAP materials used in agriculture are polyelectrolyte gels often composed of acrylamide, acrylic acid, and potassium acrylate. Therefore, they swell much less in the presence of monovalent salt and can collapse in the presence of multivalent ions [8,9]. These ions naturally exist in the soil or are introduced through fertilizers and pesticides.

Interesting base elements for the preparation of highly engineered SAPs are natural polymers such as starch [10], chitosan [11], guar gum [12] and poly (amino acid)s [13], since they are environmentally friendly, biodegradable, and independent of soil resources.

A further development in the use of polymers in agriculture for soil protection is related to the use of plastic mulch [4], which offers the advantages of increased soil temperature, reduced weed pressure, moisture conservation, reduction of certain insect pests, higher crop yields, and more efficient use of soil nutrients.

Nanotechnology represents another area holding significant promise in the agricultural scenario [14]. Polymeric nanomaterials hold great promise regarding their application in plant protection and nutrition due to their size-dependent qualities, high surface-to-volume ratio and unique optical properties, making them suitable for developing agrochemical carriers for pesticides (inhibitors, antibiotics and toxins), biopesticides (bacteria, viruses and fungi enzymes), fertilizers, and biofertilizers (live formulations of beneficial microorganisms) [15]. Furthermore, they are suitable to be used for the assisted delivery of genetic material for crop improvement and as nanosensors for plant pathogen and pesticide detection.

In recent years, the removal of hazardous heavy metals from water and soil environments and industrial waste streams has attracted considerable attention. Enhanced metal separation techniques that require less energy with minimal impact on the environment are desirable [16,17]. When soils are contaminated with heavy metals, the clean-up is one of the most difficult tasks for environmental engineering. For remediating sites contaminated with inorganic pollutants, several techniques have been developed. An efficient technique for the removal of metal ions from wastewaters is the use of functionalized water-soluble polymers combined with the membrane-based separation method of ultrafiltration [18]. It consists of making heavy metals react with a water-soluble macromolecular ligand to form a macromolecular complex. Solution containing macromolecular complex is pumped through an ultrafiltration membrane. Unbound chelates pass through the membrane, while metal-loaded polymers are of sufficient molecular size to be retained.

1.2.2 Functional Polymers and Animal Feed

Animal feed is an industrial field that has drastically increased in the last decades, since efforts have been made to improve its production to obtain a substantial reduction in production costs and to improve the quality of animal-based foodstuffs [19].

In animal feed, key issues are related to the safety of the components. Directive 2002/32/EC of the European Parliament and of the Council of 7 May 2002 on undesirable substances in animal feed is the Directive governing the measures on undesirable substances in feed. "Undesirable substance" is defined as any substance or product, with the exception of pathogenic agents, which is present in and/or on the product intended for animal feed and which presents a potential danger to animal or human health or to the environment or could adversely affect livestock production [20].

Specific protocols have been developed for the the detection of contaminants (e.g., heavy metals, botanical species, alkaloids, toxins, bacteria and fungi), some of them involving the use of polymer-based biosensors.

Furthermore, various attempts have been made to develop efficient delivery system for animals based on pH-sensitive polymers [21].

1.3 Food Processing: Rheology

The quality and desirability of food products depends on their flavor and texture [22]. Food texture has historically been considered those properties that are not covered in the classical definitions for taste and flavor compounds. This...