CORDIS - EU research results

Bioplastic production from tomato peel residues

Final Report Summary - BIOPROTO (Bioplastic production from tomato peel residues)

BIOPROTO project has as its main objective the fabrication of bio-plastics from the tomato fruit peel residues. They are an abundant and inexpensive waste from processing tomato industries rich in polysaccharides (chiefly cellulose, pectin and hemicelluloses) and lipids (soluble waxes and a non-soluble long-chain biopolyester named cutin). Specifically, the project is focus on the bio-mimicry of the plant cuticle (Figure 1A), this is, the protective and outermost membrane that covers the plant epidermis of parts of plant organs exposed to air (Figure 1B).

Polysaccharides and lipids present interesting properties that have been naturally used in the plant cuticles. Mainly, the polysaccharide fraction provides a strong physical support, while the lipid fraction avoids the massive water loss from internal issues. The main aim in this project, the production of plant cuticle-like plastics has been divided in two: first, the synthesis and characterization of plant cuticle-like polymers from model substances and, second, the production of tomato peel plastics. These agro-wastes have been chosen because they have an elevated amount of cutin and the crop of tomatoes is an important business in the sector of the agriculture. The European tomato processing industry processed 11,380,100 tonnes of raw tomatoes in 2004. Italy is by far the most important producer of processed tomatoes in Europe with a 53% share of European production followed by Spain (22%) and Portugal and Greece (10% each). Other minor producers include France and some of the new member countries, in particular Hungary and Poland. Production and processing is concentrated in a limited number of regions. Due to transport costs, production and processing can be found in the same or at least neighboring regions. The main products of the tomato processing industry are tomato paste (65%) and canned whole peeled tomatoes (27%). Peeling is the first unit operation performed before the manufacture of these products, with a final residue (tomato peel) of 25-28% of the total initial weight (depending of the kind of tomato and the peeling process). Nowadays, this inexpensive sub-product, tomato pomace, is used as animal feed.

Since the beginning of the project, different approaches have been developed to produce these new bioplastics, Figure 1C. Basically, they have consisted of a chemical synthesis in a very strong acid medium, a self-assembly process in water and diverse green and soft industrial processes. Also, a comprehensive study of the refinery of the tomato fruit peel residue from a perspective of IR and Raman spectroscopies has been carried out. On the other hand, interestingly, a new set of films and coatings from the lipid fraction of plant cuticles has been produced and characterized.

Despite the inherent difficulty of the combination of polysaccharides and lipids, main results achieved so far are ascribed to the development of a scale-up process for the fabrication of lipid-cellulose materials (bio-plastics) with potential applications in food packaging. Additionally, the critical review on infrared and Raman features of plant cuticles has generated significant interest among specialists in the field.

The final result has been the fabrication of plant cuticle-like bioplastics with potential applications in food packaging. The potential impact on society is threefold. First, these new bio-plastics are biodegradable with no adverse effects on the environment. Second, an inexpensive agro-waste (tomato peel) with costs to be removed is recycled and used as raw material. Third, the fabrication of these bio-plastics and the use of tomato peels could generate new business and employment opportunities.