Writing in the journal Food Research International, Brazilian researchers report that alpha-cyclodextrin can form complexes with various amino acids and hydrolysed soy protein, and this results in a reduction in the bitter taste of the ingredients.
“Alpha-CD alters the bitter taste perception of the amino acids and reduces the bitter taste from of hydrolyzed soy protein,” wrote the researchers, led by Giani Andrea Linde from Universidade Paranaense in Brazil.
“These results indicate a potential use of alpha-CD for de-bittering protein hydrolysates in acidic beverages.”
Wacker Chemie was granted novel foods approval for alpha-cyclodextrin by the European Commission last year.
According to background information in the article, hydrolysed proteins have a high functional value because of their bioactive peptides content. These compounds have important functional and technological aspects, including high solubility in acidic solutions and stability during thermal treatments. However, the process of hydrolysis tends to liberate highly bitter amino acids, “limiting the use of these products in human food”, explained the researchers.
The new research suggests that adding alpha-cyclodextrin to an acidic beverage solution (pH 4.5) could mask the bitter taste profile of amino acids such as phenylalanine, tryptophane, tyrosine, isoleucine, proline and histidine.
Linde and his co-workers prepared model beverages using the isolated soy protein (donated by the Solae Company), and alpha-CD (donated by Cargill Food & Pharma Specialties North America). The soy protein was hydrolysed using Alcalase (donated by Novozymes).
Analysis of the solutions showed that cyclodextrin formed inclusion complexes with the amino acids, with the greatest affinity for phenylalanine and tryptophane, followed by praline, isoleucine, tyrosine, and histidine.
Furthermore, sensory tests showed that addition of 5 and 10 per cent alpha-cyclodextrin to the soy protein hydrolysate solution reduced the bitterness by 40 and 60 per cent, respectively, said the researchers. An improvement in the “characteristic soy odour” was also recorded. At a lower level (3 per cent) alpha-cyclodextrin had no affect on the bitter taste of the soy protein hydrolysate solution, they added.
“The main bitter peptides hold in their chains non-polar amino acids situated at the middle or the extremity of the peptide chain and this structural characteristic is fundamental for the interaction of these amino acids with the taste sensitive cells at the tongue,” explained the researchers.
“Thus the higher proportions of alpha-CD, which have led to significant reduction in the bitterness of the soy hydrolysate, were sufficient to increase the amino acid and peptide complexed populations in the hydrolysate mixture up to the point of significantly lowering the solution bitterness intensity.”
Source: Food Research International Published online ahead of print, doi: 10.1016/j.foodres.2009.03.016 “Taste modification of amino acids and protein hydrolysate by alpha-cyclodextrin” Authors: G.A. Linde, A.L. Junior, E.V. de Faria, N.B. Colauto, F.F. de Moraes, G.M. Zanin