Effect of freezing‐assisted treatment on the formation of stable VII‐type complex of fried sweet potato starch and its mechanism

• Published in: Journal of food science Vol. 87; no. 2; pp. 543 - 553
• Main Authors: Li, Ying‐Hui, Wang, Yu‐Sheng, Li, Xin, Chen, Hai‐Hua
• Format: Journal Article
• Language: English
• Published: Chicago Wiley Subscription Services, Inc 01.02.2022
• Subjects: Crystal structure; Crystallinity; Digestibility; Enthalpy; Freezing; freezing‐assisted treatment; Frying; frying process; Lipids; Physicochemical properties; Potatoes; Production methods; Scanning electron microscopy; Starch; sweet potato starch; Sweet potatoes; Temperature; Transition temperatures; Vegetables; VII‐type complex
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/1750-3841.16019

To comprehensively understand the effect of freezing‐assisted treatment on the physicochemical properties of the fried sweet potato starch, the structural changes at granular and crystalline level were investigated. The results suggested that the freezing temperature exerted a significant effect on the interactions between sweet potato starch (SPS) and fried oil. With decreasing the freezing‐assisted temperature, the gelatinization enthalpy of the fried frozen SPS remarkably increased by 1.5–4.9 J·g−1 and the transition temperatures of the second peak were elevated from 132.5°C to 136.5–141.1°C compared to that of native SPS, which suggested that more stable VII‐type starch–lipid complexes were formed during frying. This finding was consistent with the results of the X‐ray diffractometer that the intensity of the diffraction peak at 20.1° for V‐type complex increased sharply as the temperature decreased from 20°C to −80°C, and the corresponding relative crystallinity and R1047/1022 values were increased from 16.5% and 0.35 to 26.4% and 0.45, respectively. The scanning electron microscopy revealed that the lower freezing‐assisted temperature before frying promoted a membrane‐like material covered on surfaces. The results showed that decreasing the freezing temperature promoted the formation of stable VII‐type complex during frying. Practical Application The purpose of this study was to comprehensively understand the effect of freezing‐assisted treatment on the physicochemical properties of the fried sweet potato starch. These results provided useful information and effective method for producing fried starch‐based foods with low digestibility.