ABSTRACT
Yuqiao Reservoir, an important adjusting reservoir in the project of diverting water from the Luanhe River to Tianjin City, is an important water resource for Tianjin City. Concentrations and spatial variation characteristics of Cd, As, Pb, Cu, Cr, and Zn from 33 sub watershed sampling sites of Yuqiao reservoir and the relationship to landscape pattern were discussed. The result showed that average concentrations of Cd, As, Cu, Cr in suspended particulate matter were higher than Chinese environmental quality standard Grade one for soils, and there were ecological risks for them because they could arrive at Yuqiao reservoir. The average concentrations of Cd, As, Pb, Cu, Cr, and Zn in surface sediments were 0.32 mg·kg-1, 30.39 mg·kg-1, 33.49 mg·kg-1, 58.20 mg·kg-1, 90.16 mg·kg-1 and 94.80 mg·kg-1 respectively. The average concentrations of Cd, As, Cu and the concentrations of Pb, Cr, Zn in partial samples exceeded Chinese environmental quality standard Grade one for soils. The average concentrations of Cd, Cr, Zn in surface sediments of three tributaries increased in the order of Linhe River >Shahe River >Lihe Rier, Cu decreased in the order of Linhe River < Shahe River < Lihe River, and As, Pb increased in the order of Shahe River >Linhe River >Lihe Ricer. Land use types in Yuqiao reservoir basin had some impact on the distribution of heavy metal concentrations in river surface sediments. Woodland and shrub grass land determined the natural distribution trend of heavy metals in surface sediments. Gardenland and industrial & mining land usage had impact on Cd, As, Pb, Cr distributions. Farmland and village & town land usage did not produce negative influence on heavy metal distribution.
ABSTRACT
Sodium caseinate (SC) cross-linked by microbial transglutaminase (MTGase) for encapsulating microalgal oil was investigated. Protein cross-linking was evidenced in the SDS-PAGE graph. The emulsifying properties of SC depended on the cross-linked time with MTGase. The emulsifying activity and stability indexes of SC increased with the cross-linking time of 30 to 90 min (P30 to P90), and then declined with longer cross-linked time of 180 to 420 min (P180 to P420). The P30 to P90 as wall material for microencapsulation was superior to P180 to P420 and control sample. The microcapsules prepared with P30 to P90 showed more than 97% of microencapsulation efficiency in contrast to about 90% with the P180 to P420. During storage, the microcapsules prepared with P30 to P90 exhibited higher oxidative stability as compared with other microcapsules. A sustained release of microalgal oil was observed, and core release was time dependent and affected by cross-linking degree. Results showed that the powdered microalgal oil prepared with P30 to P90 demonstrated enhanced physicochemical properties and oxidative stability. Practical Application: The novel method using cross-linked proteins as wall material induced by microbial transglutaminase in food industry for sensitive ingredients could convert microcapsules into a stable form, which would lead to its more widespread utilization as a kind of food additive.
