Tomato skin – a natural lining for metal cans

Tuesday, 14 January, 2014

The packaging industry is under pressure to improve its environmental performance and become more competitive. In addition, food packaging safety has come under more scrutiny.

An innovative EU-funded project has addressed all three of these objectives at once, with a straightforward yet potentially revolutionary solution using tomato skins.

The BIOCOPAC project developed a novel bio-lacquer for metal food packaging designed to meet current demand for sustainable production and safety. The project team expects their innovation will increase the competitiveness of the EU’s metal cans industry, cut unnecessary waste and better protect consumers.

The natural lacquer was developed from tomato skins, a by-product that food processors often treat as waste. The lacquer can be applied to the internal and external surfaces of cans used for foodstuffs.

Metal packaging is often coated to protect the contents from the metal itself which, for example, can lead to discolouration in some dark-coloured fruits, or to protect the metal from acidic products such as soft drinks.

Three challenges for Europe

From the very beginning, the BIOCOPAC team sought to address three key challenges facing Europe: unnecessary waste, consumer safety and industrial competitiveness. The project has made important steps forward in all three areas.

“With regards to the environmental challenge, the development of new food contact packaging bio-lacquers from the by-products of tomato processing will promote the exploitation of waste by reusing it,” explains project coordinator Angela Montanari of Stazione Sperimentale per L'industria delle Conserve Alimentari in Italy. “The bio-lacquer will increase the sustainability of metal cans, promoting their recyclability and decreasing the environmental impact of packaging and waste.”

Food safety was another key priority. Natural bio-lacquers designed specifically for food contact packaging should help ensure that there is no chance that food will be contaminated by the migration of synthetic substances from the packaging to the product. The innovation is expected to provide can manufacturers with an environmentally friendly solution they can offer to food processors worldwide.

“In the past few years, growing demand for environmentally friendly products has encouraged the development of the biopolymer and bioplastics sectors,” says Montanari.

She says the BIOCOPAC solution will provide packagers with an alternative to Bisphenol A, a carbon-based compound used to coat many food and beverage cans. Bisphenol A has come under public scrutiny over claims it affects health.

The new BIOCOPAC lacquer will also be trademarked, making its use immediately recognisable to consumers.

Good use of waste

BIOCOPAC’s research began with an analysis of tomato waste, and continued with the development of an experimental method of extracting cutin (a waxy ‘polymer’) from tomato peel.

“We then studied different formulations of bio-lacquers suitable for metallic materials,” says Montanari.

Extracting raw cutin from tomato peel proved highly successful in terms of yield and applicability on an industrial scale. Different formulations of lacquer containing from 10 % to 100 % cutin were prepared and studied to find the ideal formulation for the final bio-lacquer.

“The more promising formulations were then applied to different metallic substrates – tin plate, tin-free steel and aluminium,” continues Montanari. “Properties such as the degree of curing, appearance and sterilisation resistance were measured.”

From the initial lacquered sheets, the team was able to produce two- and three-piece cans, crown corks and caps. In every case, the lacquer demonstrated an excellent performance, she says.

As a result of this research, the partners plan to file for two patents to be registered. One will cover the extraction method for cutin from tomato peel – a method that will probably be developed on an industrial scale – while the other will cover the formulation of the bio-lacquer.

“This experience has been wonderful,” says Montanari. “It has given me the possibility to work in the EU with European partners in a very professional way, and at the international level. Moreover, this project has provided me with an opportunity to see and understand that collaboration between industries and research centres can lead to positive results, even in low-technology sectors such as metallic packaging.”

Related article:

Food packaging made from tomatoes

Latest on the project (May 2015)

The EU-funded project LIFE-BIOCOPACPlus aims to advance BIOCOPAC’s research, also supported by the European Union, on the use of an extract from tomato skins as a natural coating for food tins by bringing it closer to commercialisation. LIFE-BIOCOPACPlus, which ends in May 2017, also plans to build a prototype pilot plant for extracting ‘cutin’ – a waxy substance found in plants – from tomato skins, says project coordinator Angela Montanari of Italy’s Stazione Sperimentale per l'Industria delle Conserve Alimentari (SSICA).

After BIOCOPAC ended in September 2014, three of the project’s small business partners filed three applications for patents. Two cover the extraction process to obtain cutin resin from tomato skins. The third is for bio-lacquer formulations developed by the project and their main ingredient, the cutin resin.

BIOCOPAC developed three formulations of its novel bio-lacquer. Two are for application to the surfaces of metal tins that are in contact with food. The third is meant for beverage tins.

Some multinational food packaging companies, beverage manufacturers and producers of infant food products have requested information on the new process, says Montanari, who was BIOCOPAC’s scientific officer. The project’s tests showed the bio-lacquer coatings had good adhesion, flexibility and corrosion resistance, a performance comparable, she says, to standard lacquers used to line tin cans.



Development of bio-based coating from tomato processing wastes intended for metal packaging
Project Acronym: