Sugar beet extract could stablise natural blue pigments in food

Pectin derived from sugar beet improves the formation and stability of anthocyanin-based blue pigments, which may help food companies to use natural blue colours, according to a recent study conducted at a German university.

The research team at Hohenheim University evaluated the ability of sugar beet pectin (SBP) and a low molecular pectic polysaccharide fraction (PPF), derived from sugar beet, in stabilising anthocyanin-based blue pigments.

The researchers evaluated their use in low acid liquids and gelled food models, and found that the colour changes were more prominent when PPF was added to anthocyanin-containing solutions, compared with model solutions based on commercial SBP.

According to the study, this may be due to higher levels of aluminium and iron, which catalyse and stabilise the colour shift.

The research also showed that highly purified anthocyanin extracts without colourless polyphenols and citric acid had the strongest shifts and average blue colour stability at pH 5.0 in model solutions with PPF.

The researchers said that for the first time the study demonstrated the promising application of SBP and PPF as additives to anthocyanin-based food colourants.

"However, further studies considering alternative anthocyanin sources, optimisation of colour retention, interactions with other food ingredients and thermal processing aiming at the improvement of shelf-life are still required," they added.

Recent studies have linked certain artificial colours to health problems, which in turn has led to increasing consumer demand for natural ingredients.

According to researchers, replacing synthetic colourants with their natural additives is a major challenge and currently reds, yellows, and oranges are the only natural colourants commercially available.

Anthocyanins are water-soluble vacuolar pigments that may appear red, purple, or blue according to pH, and they are found in edible fruits and vegetables such as grape, elderberry, red radish, red cabbage, blackcurrant, black carrot and sweet potato.