The properties of gluten are governed by sulphur-sulphur bonds, and replacing these with calcium bonds in caseinates, potentially leading to a distinct ingredient to replace gluten in certain foods, according to findings published in International Journal of Dairy Technology.
“A concentration of 30 milligrams of calcium per gram of protein appeared to provide the platform for a material that under the correct ionic and temperature conditions could provide a single ingredient for gluten substitution,” wrote Costas Stathopoulos from the University of Newcastle in Australia and Brendan O’Kennedy from Ireland’s Teagasc, Moorepark Food Research Centre.
According to background information in the journal, dairy ingredients have used in the formulation of gluten-free foods for years.
“At present, mixtures of gums, hydrocolloids and dairy protein products are the most popular approach, however, many gluten-free breads available in the market are of poor quality and flavour, and many exhibit a dry crumbling texture,” said Stathopoulos and O’Kennedy.
According to market analyst Mintel the overall 'free-from' market has already enjoyed sales growth of over 300 per cent since 2000. The growing demand has opened up a new lucrative sector that many food makers are keen to exploit.
The free-from market was worth €90 million ($123 million) in 2005, and Mintel said that the gluten and wheat-free sector has benefited in particular from the nation's increasing interest in healthy eating. Sales of products such as wheat-free breads and cakes have grown by almost 120 per cent over the last three years alone, to reach €48 million ($65 million).
Preparation protocol
Stathopoulos and O’Kennedy dispersed acid-casein in water and subsequently added calcium hydroxide and calcium chloride to achieve final calcium concentrations of 15, 20, 30 and 40 mg calcium per gram of protein.
“The addition of calcium hydroxide was intended to raise the pH of the solution, while calcium chloride was added to promote precipitation,” they explained.
They then added sodium hydrogen phosphate to bind calcium and form the linkages that would form the gel.
In order to compare the properties of the calcium-fortified caseinate with gluten, a gluten sample was prepared by simply mixing gluten with water to achieve a protein concentration of 33 per cent.
While an increase in the elasticity of the aggregated casein samples was observed, relative to gluten, behavioural differences when they were heated were also observed.
“It is envisaged that additional cross-linking will help towards this goal [of substitution of gluten by a similarly behaving material is to be achieved], as is the case with dough and gluten,” stated Stathopoulos and O’Kennedy.
“In gluten-free research a number of ingredients are being used to this effect, such as transglutaminase, tyrosinase and laccase.”
Commercial benefits
“Producing an ingredient exhibiting such behaviour from a relatively cheap raw material could have a two-fold practical significance,” wrote the researchers.
“The development of such a component would provide adequate quality and versatility, while at the same time lowering costs and thus increasing accessibility to gluten-free products to celiac sufferers.
“Further studies should be carried out assessing the effect of NaCl, an important ingredient in bread-making, and cross-linking enzymes on both the yield and the performance of the casein-based ingredient,” they concluded.
Source: International Journal of Dairy TechnologyPublished online ahead of print, Early View, doi: 10.1111/j.1471-0307.2008.00424.x“A rheological evaluation of concentrated casein systems as replacement for gluten: calcium effects”Authors: C.E Stathopoulos, B.T. O’Kennedy