Ohmic Heating—a Novel Approach for Gluten-Free Bread Baking

Abstract

Gluten-free (GF) batters usually present several technological challenges that limit the performance during conventional baking and the resulting product quality. Due to the volumetric heating principle and faster heating rates, ohmic heating (OH) may be advantageous compared with conventional baking. Therefore, the potential of using ohmic heating as a novel approach for gluten-free bread baking was explored. In detail, the effect of different OH process parameters (power input, holding time) on the chemical and functional properties (specific volume, crumb firmness and relative elasticity, pore properties, color, starch gelatinization) and digestibility of breads was investigated. Results showed that GF breads could benefit from the uniform rapid heating during processing, as these breads showed superior functional properties (specific volume, 2.86-3.44 cm 3 /g; relative elasticity, 45.05-56.83%; porosity, 35.17-40.92%) compared with conventional oven-baked GF bread (specific volume, 2.60 cm 3 /g; relative elasticity, 44.23%; porosity, 37.63%). In order to maximize bread expansion and the OH performance, it was found that the OH process could be improved by applying the electrical energy in three descending power steps: first step with high power input (in this study, 2-6 kW for 15 s), followed by 1 kW for 10 s, and 0.3 kW for 1-30 min. In total, ohmic baking only needed a few minutes to obtain a fully expanded GF bread. The determination of pasting properties and starch digestibility demonstrated that these breads were comparable or even superior to GF breads baked in a conventional baking oven.

Chemical and Physical Characterization of Sorghum Milling Fractions and Sorghum Whole Meal Flours Obtained via Stone or Roller Milling

“…Color analyses were carried out as described in Bender et al [ 12 ]. A DigiEye device (VeriVide, Leicester, United Kingdom) including a D-90 Nikon camera (Tokyo, Japan) was used to characterize the flour color.…”

Texture design of gluten-free bread by mixing under controlled headspace atmosphere

“…This applies especially for the mentioned liquid dough types, since these have no intermediate forming and shaping step, in which the incorporated gas from the mixing process would be re-distributed. Studies on these gf dough types showed an increased finale volume of gf bread by 12-21% [12] by varying process parameters, as mixing speed and time, or the geometry of mixers, or introduction of novel heating methods, as Ohmic heating [13]. However, a further crucial factor-the headspace atmosphere (HSA)-was, to the best of our knowledge, not studied so far.…”

Ohmic Baking of Gluten-Free Bread: Role of Starch and Flour on Batter Properties

“…For breads baked by ohmic baking, parameters were adapted from a previous study [2] with slight modifications. A pilot-scale ohmic heating unit (German Institute of Food Technologies, Quakenbrück, Germany) was used with a frequency of 12 kHz and a maximum voltage of 1000 V. The ohmic chamber resembled the conventional baking tin with stainless steel electrodes that were 3 mm thick and 15.4 cm apart.…”

“…Ohmic heating is a volumetric heating method that passes an electrical current through food, resulting in fast and uniform heating [1]. Recently, this technology has been successfully applied for baking GF bread, improving bread volume and pore properties [2]. However, fundamental knowledge of how each ingredient contributes to increasing GF bread quality using ohmic heating is still missing.…”