Liyan Liu1, Zerong Lu2, Lin Li1, Bing Li1, Xia Zhang1, Ximei Zhang3, Zhenbo Xu4. 1. School of Food Science and Engineering, South China University of Technology, Guangzhou, 510640, PR China; Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Guangzhou, 510640, PR China. 2. School of Food Science and Engineering, South China University of Technology, Guangzhou, 510640, PR China. 3. School of Food Science and Engineering, South China University of Technology, Guangzhou, 510640, PR China. Electronic address: femzhang@scut.edu.cn. 4. School of Food Science and Engineering, South China University of Technology, Guangzhou, 510640, PR China; Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety, Guangzhou, 510640, PR China; Department of Microbial Pathogenesis, University of Maryland, Baltimore, 21201, USA. Electronic address: zhenbo.xu@hotmail.com.
Abstract
OBJECTIVE: This study aimed to investigate the physical relation and mechanism of bactericidal activity on pathogenic E. coli by ultrasonic field with whey protein isolate (WPI). METHODS: Ultrasound treatment was performed under the conditions of intensity at 65 W/cm2, pulse duty ratio at 0.5 for 0-15 min with WPI concentration ranged from 0 to 10%. Viscosity, granularity, surface hydrophobicity, free radical scavenging activity, and thermal denaturation were assessed by rotational viscometer, Malvern Mastersizer 2000 particle size analyzer, fluorescent probe ANS method, DPPH method, and differential scanning calorimetry, respectively. RESULTS: The thermal denaturation of WPI was not altered by ultrasound field, but the viscosity of WPI was increased upon 10 min treatment. Additionally, its ability to scavenge free radicals and hydrophobicity were increased. The result also showed that the bacteria viability was improved by WPI during ultrasound treatment. However, the WPI protection was decreased by the prolonged treatment. CONCLUSION: Ultrasound treatment resulted in the increasing of the viscosity, free radicals scavenging activity and hydrophobicity of WPI which led to reduced bactericidal activity on E. coil, while WPI protection was disintegrated by prolonged treatment.
OBJECTIVE: This study aimed to investigate the physical relation and mechanism of bactericidal activity on pathogenic E. coli by ultrasonic field with whey protein isolate (WPI). METHODS: Ultrasound treatment was performed under the conditions of intensity at 65 W/cm2, pulse duty ratio at 0.5 for 0-15 min with WPI concentration ranged from 0 to 10%. Viscosity, granularity, surface hydrophobicity, free radical scavenging activity, and thermal denaturation were assessed by rotational viscometer, Malvern Mastersizer 2000 particle size analyzer, fluorescent probe ANS method, DPPH method, and differential scanning calorimetry, respectively. RESULTS: The thermal denaturation of WPI was not altered by ultrasound field, but the viscosity of WPI was increased upon 10 min treatment. Additionally, its ability to scavenge free radicals and hydrophobicity were increased. The result also showed that the bacteria viability was improved by WPI during ultrasound treatment. However, the WPI protection was decreased by the prolonged treatment. CONCLUSION: Ultrasound treatment resulted in the increasing of the viscosity, free radicals scavenging activity and hydrophobicity of WPI which led to reduced bactericidal activity on E. coil, while WPI protection was disintegrated by prolonged treatment.
Authors: Yanmei Li; Tengyi Huang; Caiying Bai; Jie Fu; Ling Chen; Yi Liang; Kan Wang; Jun Liu; Xiangjun Gong; Junyan Liu Journal: Front Microbiol Date: 2020-08-21 Impact factor: 6.064