Freeze-thaw stability of gels prepared from starches of non-conventional sources

Starch is an ingredient used in the formulation of several processed and frozen products, thus, evaluating the stability of gels of different types of starches when submitted to freezing and thawing is of great interest in order to guarantee the quality of the product at the end of the production and distribution chain. Stability of starch gels from non-conventional sources, i.e. Peruvian carrot (arracacha), sweet potato, white bean and chickpea exposed to five cycles of freezing and thawing was studied by evaluating texture and syneresis. The results were compared to those obtained using commercial starches (native corn, waxy corn and modified waxy corn). The waxy corn and Peruvian carrot starch gels were stable until the third freeze-thaw cycle studied. The sweet potato starch gel was stable until the second cycle, but presented low syneresis until the fourth freeze-thaw cycle (2.9%). During the experiment, the Peruvian carrot starch gel lost 5% water at maximum, and the waxy corn and modified waxy corn, 8% and 12%, respectively. The native corn, chickpea and white bean starch gels presented high water losses already in the first cycle. As to texture, the sweet potato and Peruvian carrot starch gels presented greater hardness values than the waxy corn and modified waxy corn starch gels during the entire storage period studied. Until the fourth freeze-thaw cycle, the modified waxy corn and Peruvian carrot starch gels showed no statistically significant alteration (p <= 0.05) in gel hardness. After the first freeze-thaw cycle, the hardness of the sweet potato starch gel was constant. The same occurred with the gels obtained from chickpea and white bean.594173215616