Berry by-products may provide ‘rich source’ of natural colour
The study, published in the Journal of Agricultural and Food Chemistry, outlines the potential for using extracted pigments from fruits of the darkly coloured fruits of Basella alba L. (B. Alba) as natural food colourings.
Researchers from the National Chiayi University, Taiwan note that stability of pigments is good at lower temperature ranges around 60 oC, which indicates that the natural pigments from B. Alba “could be used in dry state or minimally processed foods.”
“This confirms B. Alba fruits as a rich source of betalain pigments, …and promotes B. Alba fruits’ value-added potential for use in the development of food colorants,” wrote the researchers, led by Robin Chiou.
Market potential
Natural colours – which lost their appeal when synthetic colours arrived on the scene, promising higher consistency, heat stability, colour range and cost – are coming back into fashion as consumer awareness increases over the link between diet and health.
The value of the international colourings market was estimated at around €731m in 2007 ($1.15bn), up 2.5 per cent from €680m ($1.07bn) in 2004, according to Leatherhead Food International (LFI).
Natural colours now make up 31 per cent of the colourings market, compared with 40 per cent for synthetics, according to LFI.
Betalains are water-soluble natural pigments that include red-violet betacyanins and yellow betaxanthins.
Betanins from red beetroot, are commonly used colorants in the food industry. However, red beet betanins have several disadvantages, including unfavourable flavour components, and a risk of microbe carry-over from the earth.
Such disadvantages are pushing researchers to examine alternative sources for the compounds.
Research interest
Basella alba L. (B. Alba) is a leafy vegetable that is commonly grown and harvested in Taiwan, particularly during the summer season when production of other leafy vegetables is reduced.
The vines of B. Alba produce fleshy, dark blue fruits that are usually discarded by farmers - however the researchers noted that the use of natural pigments from the fruits deserves research interest, claim the Taiwan-based researchers.
The researchers estimated production of the fresh fruit ‘by-product’ from B. Alba to be approximately 2 kg per plant.
In this study, the researchers identified and assessed the levels of pigments in B. Alba fruits – testing their potential use as a natural pigment.
Findings
The extracts of partially and fully mature fruits were discovered to contain three well-resolved red pigments.
The authors identified gomphrenin I as the major pigment component in B. Alba, finding its quantity to increase in correlation with increasing fruit maturity. The yield of gomphrenin I was estimated to be up to 36.1 mg/100 g of fresh (mature) fruit.
In addition to gomphrenin I, betanidin-dihexose and isobetanidindihexose were also detected in the mature berries.
The authors reported that solutions of all three pigments were stable at 60oC, but became less stable when subjected temperatures of 90 to120oC.
Value-added
The authors concluded that mature B. Alba fruits could be regarded as a potent source of natural colorant, and has “value-added potential for use in the development of food colorants”
Source: Journal of Agricultural and Food Chemistry
Published online ahead of print, doi: 10.1021/jf1017719
“Structural Identification and Bioactivities of Red-Violet Pigments Present in Basella alba Fruits”
Authors: S.M. Lin, B.H. Lin, W.M. Hsieh, H.J. Ko, C.D. Liu, L.G. Chen, R.Y.Y. Chiou
