White sauce stability boosted by gums

Precooked frozen dishes formulations extensively use white sauce, said the Spanish researchers, but the quality of white sauces based on native starches may deteriorate following so-called freeze-thaw cycles.

The researchers, led by Dr Teresa Sanz from Instituto de Agroquımica y Tecnologıa de Alimentos (CSIC) in Valencia, therefore set about investigating if a combination of native starches and hydrocolloids could be a viable option for improving their stability.

“There are no scientific studies that evaluate the effect of gums on the freeze/thaw and heating stability of white sauces,”​ they said.

Their findings, published in Food Hydrocolloids​, represent the first report of how adding small amounts of xanthan gum (Satiaxane CX 91, Cargill) and locust bean gum (Viscogum BE, Cargill) could improve the stability, and thereby the quality, of white sauces made from starches of corn, waxy corn, potato, and rice. Cargill supplied the corn and potato starches, while the rice starch was supplied by Ferrer Alimentacion.

Sauces made from corn and potato were found to be the most affected by the freeze/thaw cycle, although all the sauces formulated did display a deterioration of quality and stability.

Both hydrocolloids were found to reduce the structural changes that occurred after thawing, with xanthan gum the top performer of the two.

Explaining their results, Dr Sanz and her co-workers noted that the hydrocolloids were probably interacting with the amylose in the sauces. This would decrease the amount of interaction between amylose molecules, which were responsible to the degradation.

“When planning white sauce formulations it is important to take into consideration the relative proportions of the starch and gums, their ionic character and the presence of other ingredient such as milk proteins, among other factors, due to the complex interactions that could develop both during the preparation process and during the cold storage of the sauce,”​ concluded the researchers.

The study was funded by the Spanish Ministry of Science and Innovation.

Frozen foods heating up​

The latest available data from TNS Worldpanel indicated total market value for frozen foods of £4.94 billion (€5.74 billion) in the 12 months to 25th January, growth of 6.7 per cent on the previous year.

Two segments – frozen savoury food and frozen vegetables – experienced growth of more than 10 per cent, to £867m (€1 billion) and £399m (€463 m).

Source: Food Hydrocolloids​
Published online ahead of print, doi: 10.1016/j.foodhyd.2009.08.001
“Improving effect of xanthan and locust bean gums on the freeze-thaw stability of white sauces made with different native starches”​
Authors: A. Arocas, T. Sanz, S.M. Fiszman