ABSTRACT
The aim of this study was to investigate the rheological properties, particle size distribution, color change, and stability of lily juice under different ultrasonic treatment conditions (152 W, 304 W, 456 W, 608 W, and 760 W). The results showed that the lily juice exhibited non-Newtonian shear thinning behavior, and the viscosity decreased with the increase in ultrasonic power. Under ultrasonic treatment conditions, there was no significant change in the pH value and zeta potential value of the samples. The content of cloudy value and total soluble solids (TSS) increased gradually. However, both the sedimentation components and centrifugal sedimentation rate showed a downward trend and an asymptotic behavior. In addition, high-power ultrasound changed the color index (L* value decreased, a* value increased), tissue structure, and particle distribution of the sample, and small particles increased significantly. To sum up, ultrasonic treatment has great potential in improving the physical properties and suspension stability of lily juice.
ABSTRACT
Two types of special structures, homogeneous and secondary nuclei, form during fibril formation. The structural and functional properties of amyloid fibrils in whey protein concentrate (WPC) with different ratios of added homogeneous nuclei to secondary nuclei were investigated. Thioflavin T fluorescence analysis and kinetic equations indicated that two types of nuclei could accelerate WPC fibrillation compared with WPC self-assembling into amyloid fibrils, thereby reducing the lag time and increasing the number of fibrils. However, there were considerable differences in the nucleation-inducing capability of WPC fibrillation between homogeneous and secondary nuclei. The number of fibrils formed by adding homogeneous nuclei was higher than that obtained with secondary nuclei, the increase in the Th T fluorescence intensity induced by homogeneous nuclei was 1.83-fold much than secondary nuclei. Meanwhile, secondary nuclei yielded a 2.71-fold faster aggregation rate of WPC than homogeneous nuclei, particularly during the first hour of thermal treatment (protein mass ratio of nuclei to WPC 1:1). The gelation time of WPC after secondary nuclei addition was shorter, from 10â¯h (WPC (2.0/6.5)) to 4â¯h (WPCâ¯+â¯HN) to 2â¯h (WPCâ¯+â¯SN); however, the gel microstructure of WPC after the addition of homogeneous nuclei was denser, yielding a preferred water holding capacity.
