Enhancing understanding of microstructure-texture relationship in doughnuts: A comparative study of deep-fat and hot-air frying

Abstract

This research evaluated the effects of frying temperature (150, 165, and 180 °C) and method (deep-fat and hot air) on doughnut crumb and texture changes. The findings indicated that the dough phase progressively transformed into crumb from the exterior to the interior, accompanied by significant alterations in pore size, shape, and color, as well as the composition of the dough phase. The conversion process duration was influenced by frying temperature and method, lasting approximately 1–1.5 min. The conversion rate was higher in the deep-fat method than in the hot-air one. Overall, textural changes occurred at a lower rate in the hot-air method, as the most changes took place during the first and second 30 s of the process in the deep-fat (180 °C) and hot-air methods, respectively. The doughnut microstructure was assessed using micro-computed tomography (Micro-CT) to study the process of changes in the product's wall thickness and pore size. Considering the front view of the doughnut dough Micro-CT images before frying, it can be asserted that a greater number of small pores were present in the vicinity of the product's surface. The current study's findings could provide a fundamental understanding of microstructure and texture development during doughnut frying, showing that the air frying could be an alternative method to make healthier foodstuff with less oil content while preserving more or less same texture properties.