Effect Of Dry-heat Treatment On The Structure And Oil-binding Ability Of Gluten-free Flour

Dry heating treatment is a commonly used technique in the food processing.Dry heating treatment has a significant effect on the oil-binding ability and structure properties of cereal flour.The paper uses gluten-free flour(rice flour,pinto bean cells)as a raw material with dry heating treatment.The rice flour is divided into fine,medium,and coarse size fraction,and the pinto bean cells are treated with different dry heating temperatures.The effects of dry heating treatment on the structure and oil-binding ability of gluten-free flour were investigated.The results of the study have important guiding significance for food processing.The main findings are as follows:(1)The particle size affects oil-binding ability and structure properties of rice flour.The rice flour of fine size fraction shows better oil-binding ability.With the particle size of rice flour decreases,the three-phase contact angle and oil-binding ability increases,the relative crystallinity and the T_p,T_c,△H of rice flour reduces.the smaller the rice flour particle size is,the more severe the grinding process is,and the rougher the surface is,and the rice flour of fine size fraction appears rice flour enveloping oil droplets after oil-binding.(2)The oil-binding ability and starch structure of rice flour after dry heating treatment are mainly affected by the internal proteins of rice flour.After dry heating treatment,the oil-binding ability of rice flour increased significantly,the gelatinization temperature range and the peak viscosity of the rice flour were significantly reduced.The gelatinization temperature range from 19.4~20.0°C to 14.4~14.6°C,and the peak viscosity decreased from30.0~35.0 BU to 20.0~24.0 BU.Due to the surface protein denaturation of rice flour,the surface hydrophobic coefficient was increased by about 1.5 times,and the hydrophobicity was significantly increased.The starch and the protein inside the rice flour interacted with each other,the formation of a spatial network structure hinders the expansion and gelatinization of the starch.(3)Dry heating treatment temperature significantly affects the oil-binding ability of pinto bean cells.With the increase of dry heating treatment temperature,the three-phase contact angle of pinto bean cells increased,and the oil-binding ability increased gradually.When the dry heating treatment temperature is higher than 100°C,the stability of pinto bean cells deteriorated after oil-binding.Because of dry heating treatment will have a certain influence on the permeability of the cell wall,and the higher the dry heating treatment temperature,the stronger destruct of the cell wall.(4)Dry heating treatment temperature affects the internal proteins of pinto-bean cells,resulting in the changes of oil-binding ability and starch structure.At lower dry heat treatment temperatures(80°C,100°C,120°C),the relative crystallinity decreases slightly as the dry heating treatment temperature increases,and the enthalpy of the starch gelatinization peak and the enthalpy of the protein denaturation peak decrease.Small;When the temperature of dry heat treatment reaches 140°C and 160°C,the protein denaturation peak disappears,and the enthalpy of starch gelatinization peak increases.Protein denaturation and formation of amyloid complexes due to higher dry heat temperature conditions.