INFLUENCE OF HYDROCOLLOIDS IN THE FREEZE-THAWED STABILITY OF WHITE

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INFLUENCE OF HYDROCOLLOIDS IN THE FREEZE-THAWED STABILITY OF WHITE Powered By Docstoc
					DO HYDROCOLLOIDS IMPROVE THE FREEZE/THAW
STABILITY OF NATIVE STARCH WHITE SAUCES?
A Arocas, T Sanz1, SM Fiszman

Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Apartado de Correos 73,
Burjassot, Valencia 46100, Spain.
1To whom correspondence should be addressed. Tel.: 0034963900022. Fax:
0034963636301. E-mail: tesanz@iata.csic.es

TOPIC: FOOD RHEOLOGY
Keywords: white sauces, hydrocolloids, freeze-thawed stability, syneresis,
rheology


The lack of time in occidental society has increased the consumption of prepared food.
Many of these products are sold frozen and they are frequently accompanied by
sauces. White sauces are one of the types more commonly used. Among the white
sauce ingredients starch play a decisive role in the desired texture properties. Native
starches posses the disadvantage in comparison with modified starches of their lower
heating and freezing stability, but they are a cheaper and a clean label alternative.

The aim of this work was to evaluate if the reheating and frozen stability of white
sauces prepared with native starches can be improved by hydrocolloids incorporation.
The employed hydrocolloids were xanthan (XG) and locust beam gum (LBG) and the
native starches were maize starch, waxy maize starch, potato starch and rice starch.

Linear viscoelastic properties were studied with a control stress rheometer in the fresh
sauces and after a freeze/thawed cycle. A temperature sweep from 30 to 80ºC was
applied and mechanical spectra were performed at both 30ºC and 80ºC.
In addition, the influence of the hydrocolloids addition in the pasting properties of water
dispersions of the starches and in the pasting properties of the white sauces were
studied by means of a starch cell attached to the rheometer.
The influence of the hydrocolloids in the appearance of syneresis in the different white
sauces was also studied.

The results showed that the incorporation of both hydrocolloids produced an increase
in the viscoelasticity of the white sauces, with the exception of the corn sauce, being
the effect higher for XG than for LBG, in the freshly prepared sauces.
The presence of the hydrocolloids in the white sauce improved, in major or minor
degree, the freeze/thawed white sauce quality. In general, XG improvement was
greater than LBG.
In the potato and corn sauces the increase in the viscoelastic functions and the
syneresis were reduced. In the rice sauces containing hydrocolloids no differences
were found among the fresh and the freeze/thaw sauces.


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