News© Institutional Communication, 19/01/2010

Home
» News
» Latest news
Printer | Subscription

A chemist at the University of Navarra proposes the use of microwaves in the preservation of vegetables

This technology, which would replace the traditional thermal processing method, saves water, energy, reduces discharge and preserves the characteristics of raw foods

The new chemist Luis Ruiz de Ojeda
Photo: Manuel Castells

"Microwave blanching is a clean technology that, compared to the conventional thermal processing method, presents interesting advantages for possible use in the food industry," says chemist Luis Ruiz de Ojeda. This is one of the principle conclusions of his doctoral thesis, defended at the School of Sciences at the University of Navarra.

The goal of this project was to study an emerging, clean technology - microwave blanching (MB) - in the processing of spinach, artichokes, borage, thistle and green beans as a possible replacement for traditional blanching (or thermal processing,)" a thermal operation widely used in the processing of canned vegetables, which consumes large amounts of energy and water resources as well as generating significant volumes of discharge," says the chemist.

According to the scientist, microwave blanching can preserve raw material while maintaining stable physical properties, texture and color characteristics similar to those obtained with conventional blanching, and achieve even better retention of nutrients.

Study of the effects of time and energy on product characteristics

This analysis consisted in studying the effects of time and processing power as well as operating load on the temperature, weight loss, size reduction, enzyme activity, texture, color and ascorbic acid (vitamin C) of certain vegetables.

The results obtained showed that with MB, vegetables experience an increase in temperature, weight loss and enzyme deactivation proportional to the intensity of the treatment. At the same time, there was a strong initial reduction in the size of raw materials, but there were no significant variations during longer operation times.

It was also found that in mild conditions, vegetables experienced a slight increase in the firmness of their tissues, although they gradually softened with a more prolonged treatment.

Ruiz de Ojeda stated that using MB can produce green beans, artichokes, thistle and borage with enzyme, texture and color characteristics similar to those currently achieved by preservation companies. "In optimal blanching conditions, the retention of ascorbic acid is similar to current preservation standards if not better, and weight loss is reasonable from the point of view of profitability. In addition, less time is required than for conventional blanching," he concluded.

Modeling was also carried out with experimental data, giving satisfactory results. As is usual, the chemist suggested that further studies are needed to evaluate microwave blanching at an industrial scale and in real cases.