Siberian Federal University: Way to Extend the Shelf Life of Products
Russian researchers have proposed a way to improve glass containers used by manufacturers of various food products, particularly vegetable oils. The method consists of applying transparent protective films of indium tin oxide (ITO) to the glass, which delay ultraviolet and infrared radiation, as well as electromagnetic fields. After conducting studies of sunflower oil in glass containers protected with oxide films and unprotected, the researchers proved that the product stored in an insulated container retains its useful properties and taste merits much longer.
Under the influence of changing temperature due to fluctuations in humidity or light falling on products, the fats in them can undergo chemical or biochemical transformations. Nuts, seeds, or oil extracted from them gradually deteriorate, acquiring a rancid taste. The researchers of Siberian Federal University and their partners from VOENMEH Baltic State Technical University came up with a way to preserve the freshness and useful properties of products by slowing down the changing of fats with the help of solid oxide films.
“The intensity of exposure to light is influenced by the optical properties of the packaging used. This means that to improve the quality of food and increase its shelf life, we need to create protective coatings that will slow down food spoilage as much as possible. We tried to pump the glass, which is usually used for packaging and storing vegetable oils, with a thin transparent film of indium tin oxide In-Sn-O (ITO). To achieve this goal, we used an extraction-pyrolytic method for producing oxide films on large-scale surfaces without using a vacuum,” said Svetlana Marchenkova, assistant professor of the Department of Technology and Organization of Catering, SibFU.
The researcher said that during the experiment, the scientific team checked how the oil feels in a modified glass container. To do so, they determined the acid and peroxide value of the product. It turned out that the transparent oxide film covering the glass extends the shelf life of the oil by inhibiting the process of fat decomposition, and it is possible to verify the excellent quality of oil in such a package, even visually. Unlike containers made of dark glass, which are traditionally considered more reliable for storing oils, the glass coated with oxide films does not hide anything. The buyer can easily see the absence of sediment and other signs of trouble just by looking at a bottle.
“Milk, cream, and sour cream deteriorate after one or two hours of continuous exposure to light; sausages, chocolate, and sugar become spoiled after three days. Perhaps, only pasta can withstand sunbaths for a month without losing its nutritional value and normal appearance. Protective films based on metal oxides effectively prevent the penetration of UV radiation, protect against humidity and aggressive environmental conditions, and increase the mechanical strength of glass containers. Among complex oxide materials, indium tin oxide In-Sn-O delays not only ultraviolet radiation but also infrared and microwave radiations,” continued the expert.
The researchers emphasized that with such a capricious product as vegetable oil, you should adhere to strict storage requirements; otherwise, sunlight and oxygen will accelerate its oxidation and produce free fatty acids and glycerin in the oil, the amount of which the acid value shows. Even if little peroxide compounds release in fat oxidation, they are already dangerous to health and have a toxic effect on the human body.
“We believe that indium tin oxide films, which are transparent in the visible range of the spectrum, can reliably protect food from oxidation. In the future, vacuum-free solution technology for producing films on large-scale surfaces will allow applying such solid films not only on glass containers but even on supermarket showcases. It will help increase the shelf life of products and make them as safe as possible for humans,” concluded Svetlana Marchenkova.