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Gewählte Doctoral Thesis:

Maximilian Gratz (2021): Impact of selected process and product parameters during ohmic heating applied for cooking, baking and preservation.
Doctoral Thesis - Institut für Lebensmitteltechnologie, BOKU-Universität für Bodenkultur, pp 150. UB BOKU obvsg

Data Source: ZID Abstracts
Ohmic heating (OH) refers to an alternative heating technology for foods and exhibits several advantages compared to traditional heating processes. The technology is based on the direct application of electrical current to food, which results in a rapid and uniform heating of the products. Although OH is able to reduce heating times and to improve heating uniformity, this is not an a priori advantage. Challenges occur related to the uniformity of the electric field, the homogeneity of the treated product and the behavior of food compounds. Therefore, there is a need for further concepts to improve the treatment uniformity during OH treatments. To address these challenges, the role of selected process and product parameters on temperature profiles, the kinetics of structural changes and the resulting product quality were studied in this thesis. To investigate the impact of the frequency and the conductivity distribution on the treatment uniformity in intact cellular tissue, heating experiments using potatoes were conducted. A crucial impact of both parameters on the heating uniformity was observed and ideal process windows allowing rapid and uniform heating in whole potato tubers were identified. Moreover, the impact of OH on the structure formation of starch in gluten free batters was investigated. By enabling high heating rates within the whole volume, ohmic baking led to an improved volume expansion and functional properties. Further advantages were identified for batch sterilization applications compared to the traditional retort processing. By OH, the temperature gradient during the sterilization of a carrot puree was reduced and the formation of food processing contaminants could be mitigated. The results from the conducted studies, revealed a high potential for commercial OH applications. It was shown that a careful selection and control of the process parameters and the product formulation are crucial to fully benefit from the volumetric heating technology.

Betreuer: Jäger Henry
1. Berater: Domig Konrad
2. Berater: Schreiner Matthias

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