Heat treatments of defatted soy flour: impact on protein structure, aggregation, and cold-set gelation properties

INGRASSIA, ROMINA; PALAZOLO, GONZALO GASTÓN; WAGNER, JORGE RICARDO; RISSO, PATRICIA HILDA

Food Structure

ELSEVIER SCIENCE BV

Año: 2019

2213-3291

This study reveals that mild heat treatments of defatted soy flour promote Maillard reaction and modify its protein techno-functional properties such as solubility, aggregation, and cold-set gelation. Glycation was promoted by treatments of defatted soy flour (DSF) at 60ºC for 12, 24 and 48 h with and without relative humidity control (RHC and WRHC, respectively) at 79%. All samples presented a significant increase of glycation extent (GE), reaching the higher value after 48 h at RHC. Despite all samples presented a similar protein denaturation degree, the GE increment was accompanied by a decrease of antitryptic activity. Protein solubility (PS) of DSF remained constant for treated samples WRHC. However, PS decreased progressively with the treatment time at RHC. SDS-PAGE of soluble proteins revealed a positive relation between band intensities and PS. Despite sample dispersions showed a protein particle size increment with treatment time, further aggregation after heat-treatments at 100ºC produced a similar protein size distribution among samples. Rheological and microstructural studies of cold-set gels of samples obtained WRHC revealed no changes in the maximum elastic modulus (G?max) and a slight increase of its pore sizes. However, samples obtained with RHC showed cold-set gels with a progressive G?max decrease with the treatment time, which could be related to a coarser gel microstructure. In the more extreme condition, the sample obtained after 48 h at RHC showed a total loss of gelation capability. These results can be used to address the development of new tofu-like food products with different rheological properties.