According to the new review by Florian Stintzing and Reinhold Carle in Trends in Food Science & Technology, betalains, the class of compounds almost exclusively exploited from red beet, could soon be colouring a wide range of foods, from desserts to instant meals, and different sources could offer interesting alternatives.
Confronted by growing consumer demand for natural and healthy foodstuffs, food makers have increasingly been looking for alternatives to artificial food colours such as Sunset Yellow, Tartrazine and Quinoline Yellow.
Market figures confirm the trend. While the European colouring market faces an annual growth rate of just 1 per cent between 2001 and 2008, the colouring foodstuffs market is ripping ahead on growth of 10 per cent to 15 per cent.
"Since markets are increasingly orientated towards natural colourants, extension of the well-established range of fruit and vegetable preparations is required," wrote Stintzing and Carle.
"Coloured extracts are preferred over purified colours because declaration of the former allows clean labelling. In this respect, the betalains deserve intense research as they offer hues and stability characteristics uncommon to anthocyanic sources."
Stintzing and Carle state that despite cost advantages for colours from red beet, this source had several disadvantages, including unfavourable flavour components, no nitrate accumulation, and the risk of microbe carry-over from the earth.
While Swiss chard and cactus pear may offer significant opportunities, research is still needed to fully exploit their potential, said the reviewers.
"Preliminary data from differently coloured cactus pear clones were promising," they said. "And future investigations will have to address selected cactus fruits with respect to colour, shade, pigment and juice yield both for the fresh market but also for fruit manufacture."
Currently, the main obstacle in obtaining high quality and cost efficient colourants from cactus fruit, said Stintzing and Carle, was the pectic substances that must be degraded into order to release the pigment from the fruit.
Work must also focus on the how the betalains change their properties when added to food, since the food matrix may be beneficial for stabilising the pigment but may be disadvantageous towards the expected colour.
"The enormous potential of plant breeding to improve the pigment crop quality and quantity has only been realised for red beet m but not fully considered for others," they concluded. "It is up to all disciples dealing with the food chain to join forces to fully exploit the scientific and applicative potential of betalains, including nutritional implications."
Source: Trends in Food Science & Technology
Published on-line ahead of print, doi: 10.1016/j.tiffs.2007.04.012
"Betalains - a Bunch of Prospects for Food Scientists"
Authors: F.C. Stintzing and R. Carle