Enhancement Of Functional Properties Of Soy Isolate Protein By Ultrasonic-assisted Curdlan Gel And Its Application In 3D Printing Of Chicken Breast

Soy protein isolate(SPI)has attracted much attention in food industry because of its excellent nutritional properties(low fat,low cholesterol,high protein and high nutritional value,etc.)and functional properties(emulsification,foaming and water retention,etc.).However,SPI is sensitive to the external environment and is easily aggregated and denatured during production and processing.The modification of SPI by proper method can broaden its application in food field.As green modification methods,ultrasound and add polysaccharide have been widely concerned in protein modification.In this paper,the effects of low frequency and high intensity ultrasonic treatment on the physical and chemical properties of SPI with different power and time were studied,and the optimal ultrasonic pretreatment conditions were obtained.In addition,combined with ultrasonic treatment,the influence of the addition of curdlan on SPI gel characteristics and structural characteristics was studied,and the synergistic mechanism of ultrasonic combined curdlan on improving SPI characteristics was explored.Finally,the composite modified SPI is applied to 3D printing of minced chicken breast to improve the characteristics of minced chicken breast and improve the printing performance.The specific research results are as follows:(1)The power of ultrasonic treatment(200,400,600 W)and time(10,20,30 min)were used as variables,and the solubility,particle size and rheological properties of SPI were used as indexes to study the optimal conditions of ultrasonic pretreatment of SPI.The results showed that low frequency and high intensity ultrasonic treatment reduced the particle size,improved the solubility of the protein,improved the rheological properties and promoted the gelation,and the protein with the power of 400 W ultrasonic treatment for 10 min had the highest solubility(up to 90.72%).Therefore,the optimal conditions of ultrasonic pretreatment and modification are 400 W and 10 min.(2)Different concentrations(0.1%,0.2%,0.3%,0.4%and 0.5%)of thermo-reversible curdlan gel(TRC)and thermo-irreversible curdlan gel(TIRC),combined with ultrasonic pretreatment,the fluorescence intensity and particle size of soy protein isolate solution decreased significantly in a concentration-dependent manner.With the addition of TRC and TIRC,the gel strength of SPI increased by 41.79%and 40.44%,and the cooking loss decreased by 42.10%and 39.48%.Fourier transform infrared spectroscopy(FTIR)of the SPI composite gel showed that the peak at 3268 cm^-1 for the O–H vibration exhibited a blue shift compared to the control SPI and a red shift compared to pure TRC or TIRC,which indicated formation of hydrogen bond between SPI and TRC or TIRC.Circular dichroism spectroscopy(CD)showed that the addition of TRC or TIRC significantly decreased the?-helix content but increased the?-sheet contents of SPI gels due to denaturation and unfolding of SPI.Scanning electron microscopy(SEM)showed that the addition of TRC or TIRC led SPI gel to form a more regular and homogeneous network.These results revealed that the ultrasonic treatment and curdlan gels had obvious synergistic effects that improved the quality of SPI gels.Moreover,compared with TIRC,TRC addition promoted expansion and interactions of SPI molecules and formed a more stable network.Therefore,ultrasonic treatment combined with curdlan addition significantly improved the thermal gelation and structural properties of SPI.(3)SPI was added to chicken breast for 3D printing after composite modification by ultrasonic and curdlan.The addition of SPI improved the protein content of chicken samples promoted protein interactions.The cooking loss was significantly reduced,with the most significant reduction below 20%,and the water-holding capacity of chicken breast was significantly improved.The addition of SPI improved the viscoelasticity of chicken breast,making it easier to extrude with higher accuracy and more complete shape during 3D printing.By textural analysis,the springiness,chewiness,cohesiveness,and hardness of chicken breast meat with the addition of SPI were significantly improved.The modified SPI applied to chicken breast not only improves the quality and palatability of chicken meat,but also increases the dietary fiber that is not present in chicken breast and has a more comprehensive nutritional value.