Biopolymers for food packaging applications

LOPEZ-RUBIO and J. M. LAGARON, Institute of Agrochemistry and Food Technology (lATA-CSIC), Spain 

Abstract This chapter reviews the various uses of renewable polymers in food-related apphcations and explains how the material chemistry and formulation relate to the required end properties. Biopolymers are currently used in food coatings, food packaging materials and encapsulation matrices for fimctional foods. They provide unique solutions to enhance product shelf-life whilst also reducing the overall carbon footprint related to food packaging. 

Key words biopolymers, food packaging, food coatings, encapsulation, nanotechnology. 

Polymers from renewable resources are currently attracting increasing attention as a method for manufacturing environmentally friendly materials. These polymers can be classified into three groups  

polymers directly extracted from biomass, such as polysaccharides (including chitosan, starch and cellulose) and proteins (including caseinates, soy protein, whey protein, gluten and zein)  

---

There are other biomaterials with great potential in food packaging applications which are directly extracted from biomass, such as proteins (gluten, zein, etc.) and polysaccharide (i.e., chitosan). Some proteins and polysaccharides have excellent barriers under dry conditions, comparable to EVOH. However, under humid conditions these deteriorate to a much larger extent than EVOH. On the other hand, thermoplastic biopolymers such as PLA or PCL are not as strongly affected by moisture but have lower barriers than the benchmark PET. Research should therefore aim to diminish the water sensitivity of proteins and polysaccharides and to enhance the gas barrier of thermoplastic biopolyesters to make them suitable for monolayer and multilayer food packaging applications. 

Alginate is another biopolymer extensively studied for its gel formation property with applications in the food packaging and pharmaceutical industries as well as for membranes and as biosensors. Such LDH hybrid assemblies were recently used for the detection of cations such as Ca [HO]. 

Modified polysaccharide biopolymers have found applications from permselective membranes to ionically conductive membranes for fuel cells. In this review, ionically selective membranes in particular will be explored. Recent studies and advances in using modified polysaccharides for food applications will also be reviewed with specific attention given to their potential uses in the development of active food packaging solutions, which include antimicrobial systems, coatings and bioactive compound delivery systems. 

Food packaging is another remarkable application of carbon nanotube composites. Usually, poor mechanical and barrier properties have limited the application of biopolymers hence, an appropriate filler is necessary for promoting the matrix properties. The unique properties of CNT have improved the thermal stability, strength and modulus, as well as the water vapour transmission rate of the industrially applied composites. 

---