Effect of freezing rate and xanthan gum on the properties of corn starch and wheat flour pastes

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Abstract
Summary: The effects of freezing rate on exudate production, rheological behaviour, ice crystal size, and starch retrogradation of corn starch and wheat flour pastes (10% w/w) with and without xanthan gum (0.3% w/w) were studied by means of capillary suction, rotational viscometry, indirect microscopy, and differential scanning calorimetry (DSC).Higher freezing rates preserved textural characteristics and produced less exudate. In corn starch pastes, rates ‐1 caused a marked spongy structure, undesirable for a sauce‐like product, but only a slightly spongy structure in wheat flour pastes. Xanthan gum addition maintained the smoothness characteristic of the unfrozen pastes, avoiding amylose retrogradation. However, effects on ice crystal formation and amylopectin retrogradation were not observed. Although high freezing rates are mostly recommended, low levels of xanthan gum maintained quality characteristics even at low freezing rates, decreasing equipment cost.