Effects of starch source and treatment type - Conventional and ohmic heating - On stability and rheological properties of gels

• Published in: Food science & technology 2019-07, Vol.109, p.7-12
• Main Authors: da Silva, Alexandre Martins, Scherer, Laura Gräbin, Daudt, Renata Moschini, Spada, Jordana Corralo, Cardozo, Nilo Sérgio Medeiros, Marczak, Ligia Damasceno Ferreira
• Format: Article
• Language: English
• Subjects: Ohmic heating; Physical stability; Rheological characterization; Starch
• ISSN: 0023-6438; 1096-1127
• DOI: 10.1016/j.lwt.2019.04.006

The present work aimed to evaluate ohmic heating (OH) as an alternative technology to produce starch gels, and compare it with conventional heating (CH) process. Thermal properties of starches were characterized through differential scanning calorimetry. Native maize (MS) and cassava (CS) starches showed onset gelatinization temperatures of 70 °C and 57 °C, respectively. Suspensions of MS and CS were submitted to CH and OH at 90 °C and the resulting gels were evaluated regarding their physical stability (water holding capacity (WHC), sedimentation index (SI), and stability to freeze-thaw cycles) and rheological properties. Concerning the physical stability, CS gels showed better values of WHC and SI. However, when freeze-thaw cycles stability was analyzed, MS gels showed lower values of syneresis than CS gels, 20%, and 54%, respectively. Regarding rheological tests, MS gel data (tan δ∼0.1) showed a true gel-type structure, differently from CS gel (tan δ∼1) that shows a soft gel-type behavior. MS presented higher values of quality factor (Q) than CS, indicating the formation of a more stable gel. OH can replace CH in the food industry since it did not interfere in the structure of the starch gels analyzed, meanwhile there was no difference between all properties analyzed. •Starch-based gels properties were investigated in the present work.•Physical and rheological properties of samples heated by conventional and ohmic processes did not show differences.•Maize gels presented higher viscosity and freeze-thaw stability than cassava gels.•Ohmic heating can be used alternatively to conventional heating to cook starch-based foods.•The gel stability corroborates with the dynamic rheological properties.