CHARACTERIZATION OF GLUTEN FREE CAKE BATTER WITH WALNUT FLOUR: WATER MOBILITY AND TEXTURAL BEHAVIOR

BURBANO JUAN JOSÉ; CABEZAS DARIO M; REPO-CARRASCO-VALENCIA RITVA; CORREA, MARIA JIMENA

Congreso; 16th ICC Cereal and Bread Congress; 2021

Walnut flour (WF) is a by-product of the oil industry,obtained from the press cake milling. The compositional characteristics (highlipid, protein, and fiber contents) made WF attractive for improving thenutritional and technological quality of gluten-free products. This work aimedto characterize WF and evaluate the effect of WF addition on the water mobilityand textural behavior of gluten-free batters. The proximate composition, wateractivity (aw), organic molecule absorption (OMAC), and water (WHC) and oil(OHC) holding capacities of WF were obtained. Besides, particle sizedistribution and microstructure by low vacuum scanning electron microscopy(LVSEM) of WF were evaluated. The control batter formulation contained riceflour and corn and cassava starches, and two levels of WF were used: 15% (WF15)and 20% (WF20). The water mobility and texture of batters were determined bylow-resolution 1H-NMR and back-extrusion, respectively. WF presented a aw value(0.565 ± 0.02), high lipid (55.7%), protein (24.6%), and dietary fiber content(9.4%). Regarding interaction with other ingredients, the value of WHC for WFwas 2.58 ± 0.1 mL/g WF. Also, the OHC and OMAC were 0.72 ± 0.05 and 0.77 ± 0.09g oil/g WF, respectively. With respect to WF particle size, WF exhibited onlyone peak centered at 264.8 µm (D(0.5)) but when WF was submitted to sonicationparticles deagglomerated, and a shift to smaller particle sizes were observed(D(0.5)= 13.4 µm) Besides, in this case, one defined peak was observed togetherwith two overlapped and broad peaks. The micrographs showed that WF has notintact cells and is composed primarily of thin layers of cell walls andagglomerated protein bodies. The small particle size and the absence of intactcells could contribute to the bioaccessibility of WF lipids. Otherwise,relaxation times describe the mobility of water protons in the batter matrix.The relaxation spectra were fitted with an exponential decay equation and thespin-spin relaxation times (T2) and proton fraction (Ii) wereobtained. The fraction of protons (Ii) affected by magnetic fieldincreased with the addition of WF. Also, the amount of free water decreasedwith WF level as the decrease of T2 showed. The relaxation timedecreased from 18.73 ms for the control to 14.33 ms for WF20. This effect couldbe related to the protein and fiber content of WF that bound the water in thebatter. Concerning the textural properties, the increase of WF concentration inthe batters increased their firmness, consistency index, viscosity index, andcohesiveness. Particularly, the addition of 20% WF almost doubled the batterfirmness and cohesiveness. Likewise, the higher consistency and viscosityindexes of WF20 batter were probably the reason that pouring that batter intothe beaker was easier. These results showed that besides improving thenutrition value of batters. WF addition makes the batters easier to handleduring its manufacture.