Effects Of Different Particle Size And Heat Treatment On The Functional Properties Of Cottonseed Meal

This paper was mainly to investigate the effects of different Particle sizes and dry heat treatment on the functional properties(mainly including water absorption,oil absorption,emulsifying property,emulsifying stability,protein solubility and protein digestibility)of cottonseed meal.The trial methods were as follow: 1)The cottonseed meal with hull was finely ground into 4 sample groups with different geometric average particle sizes(40 μm,75 μm,129 μm,188 μm)and the dehulled cottonseed meal was finely ground into 4 sample groups with different geometric average particle sizes(10 μm,78 μm,122 μm,169 μm).Then these samples were treated with 4temperature(60 ℃,80 ℃,100 ℃,120 ℃)for 4 different times(30 min,50 min,70 min,90 min),then the functional properties of these treated samples were analyzed.2)The cottonseed meal was finely ground into 3 geometric average particle sizes(86.85μm,129.18 μm,170.41 μm).These samples were treated with 3 different steam pressures(0.1,0.15,0.2 MPa)for 3 different conditioning times(60,90,120 s)separately,then the functional properties were analyzed.3)The cottonseed meal samples with 3 different particle sizes were extruded under 120,135,150 ℃ with17%,19%,21% water contents,then,their functional properties were analyzed.4)The comprehensive score of each treatment group was calculated,and reasonable processing parameters were obtained on the basis of comprehensive scores.The results showed that: 1)The oil absorption,protein solubility,protein digestibility and emulsifying stability of dehulled cottonseed meal increased with the decrease of particle size from 169 μm to 78 μm(P<0.05).However,when the particle size continued to decrease from 78μm to 10μm,the water absorption,emulsifying property and emulsifying stability were decreased(P<0.05).2)With the particle size of cottonseed meal with hull decreasing from 188 μm to 40 μm,the emulsifying property and emulsifying stability were decreased(P<0.05),while the protein solubility increased(P<0.05),and the water absorption showed decreasing at first stage and then rising trend which is contrary to the oil absorption(P<0.05).3)With the increasing of temperature and processing time,the water absorption of cottonseedmeal in both groups increased(P<0.05),while the protein solubility and protein digestibility decreased(P<0.05),but it has no significant effect on other indexes(P>0.05).4)For the conditioning,particle size is the main factor affecting the water absorption,oil absorption,emulsifying property,emulsifying stability,protein solubility and protein digestibility of cottonseed meal,while the main factor influencing NDF and gossypol content of cottonseed meal is conditioning time and steam pressure,respectively.5)For the extrusion processing,the most important factor that affect the protein solubility,NDF content,emulsifying property,emulsifying stability of cottonseed meal is particle size,and the moisture content is the main factor influencing the gossypol content,protein digestibility and oil absorption of cottonseed meal,and the extrusion temperature is the main factor affecting the water absorption of cottonseed meal.6)Evaluation value showed that the optimum heat treatment conditions for cottonseed meal with hull,were as follows:the particle size:75 μm,the temperature:60 ℃,the heating time:30 min;For dehulled cottonseed meal,the particle size:10μm,the temperature:120 ℃,the treatment time:70 min;The optimized parameters for conditioning were as follows:particle size:86.85 μm,conditioning time:120 s,steam pressure:0.2 MPa;And for extrusion processing,the optimized parameters were as follows: particle size:129.18μm,moisture content:17%,extrusion temperature:150 ℃.