Steam Extraction System Use in the Gluten-Free Cereal Snacks Technology
When developing new types of gluten-free products, the extrusion and biocatalysis technologies use is promising. Extrusion enables to obtain ready-to-eat products of the high consumer demand with a porous structure from gluten-free cereals (snacks, ready-made breakfasts, crispbreads and various types of food concentrates), without using the functional structure-forming properties of gluten. In turn, biocatalytic technologies can provide enzymatic proline and glutamine protein bond hydrolysis of structural protein domains resistant to the digestive enzyme action. The main extrusion processing problem of wheat hydrolysates with a reduced gluten amount mixed with other raw materials is the high moisture content in the extruder. The work aimed at studying the process of additional steam extraction from the extruder cabinet during the high-moisture mixtures extrusion and its influence on the quality of finished products, i.e. gluten-free snacks. The study object was rice flour and wheat hydrolysate mixtures with a mass fermentolysate fraction of 25 and 35 %, extruded using a steam extraction system. As a result of the conducted studies, a man revealed that with an increase in steam extraction, the pressure in the extruder cabinet and the shear moment significantly increased, the process temperature slightly increased. This effect is due to the moisture content decrease in the extruder cabinet after steam extraction and, accordingly, the shear deformations energy increase. There was an additional steam extraction accompanied by an increase in specific electricity consumption by 64-79 %. The texture samples analysis demonstrated that the steam extraction and the amount of hydrolysate introduced had a significant effect on the snacks texture: the hardness decreased from 10.5 to 3.5 N, while the number of micro-fractures characterizing the crispness increased from 11.4 to 13.6. The color characteristics evaluation of the obtained snacks showed their insignificant dependence on the steam extraction. The use of a steam extraction device enables to increase the hydrolysate content in the extruded mixture and improve finished products quality during high-moisture mixtures processing.