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Schmidt U.S.,Karlsruhe Institute of Technology | Pietsch V.L.,Karlsruhe Institute of Technology | Pietsch V.L.,Herbstreith and Fox KG Pektin Fabriken | Rentschler C.,Herbstreith and Fox KG Pektin Fabriken | And 3 more authors.
Food Hydrocolloids | Year: 2016

Conjugates were prepared from whey protein isolate (WPI) and pectins in a dry heating process (80 °C, 79% RH). Citrus pectins with different degree of esterification (DE) were employed: low methylesterified (LMCP, DE = 34%), high methylesterified (HMCP, DE = 72%), very high methylesterified (VHMCP, DE = 84%). SDS-PAGE of heat treated WPI-pectin samples showed typical patterns of conjugate formation with substances of Mw > 100 kDa being detected first after 6 h of reaction time. Fluorescence intensity measurements of conjugate solutions indicated a maximum for WPI-HMCP and WPI-VHMCP after 15-18 h of reaction time. However, the fluorescence intensity of WPI-LMCP solutions increased continuously reaching the highest values of the three mixtures. Zeta potential measurements of conjugate solutions exhibited the opposite behavior. A minimum was found for WPI-HMCP. The zeta potential of WPI-LMCP solutions decreased monotonously reaching values of around -50 mV. In emulsification experiments, a significant reduction of the emulsion's Sauter mean diameter d3,2 was found when conjugates were employed at pH 5.5 and 7. The smallest droplet sizes in the hundred nanometer range were obtained for WPI-LMCP conjugate emulsions. Linking fluorescence measurements of conjugate solutions to emulsion d3,2 revealed that 1.) the stabilizing mechanism of WPI-pectin conjugates is mostly steric, 2.) the conjugate yield is the main factor dominating emulsion droplet size and 3.) the conjugate yield is highest when low esterified pectin is used. © 2015 Elsevier Ltd.

Nagel A.,University of Hohenheim | Neidhart S.,University of Hohenheim | Anders T.,University of Hohenheim | Elstner P.,University of Hohenheim | And 12 more authors.
Industrial Crops and Products | Year: 2014

Fresh industrial mango peel waste (MPW0) has to be processed into a storable commodity to enable its upgrading into dietary fibers or pectin and antioxidants regardless of its seasonal availability. In this feasibility study, 19 prototype processes that involved hot-air drying for stabilizing the juicy MPW0 of fully ripe fruit were evaluated regarding the efficiency of the drying step, the recyclable mass percentage of MPW0, and the functional quality of the dried mango peel (DMP). Depending on the process variant, hot-air drying was applied directly or after different types of peel preprocessing in order to assess the efforts needed for mechanical dewatering, the prevention of enzymatic browning by peel blanching, the control of the Maillard reaction by adjusting the drying temperature, and the removal of mesocarp from MPW0 by blanching or pressing. As shown by principal component analysis, the process variants, which proved to be most efficient regarding drying due to included peel blanching (88°C, 1min), pressing (150bar, 5min), and cutting, also ensured optimal performance of DMP. At best, the yields and purity of extractable pectins (11.4-13.2ghg-1 with 77-83% of galacturonic acid) as well as the dietary fiber contents, the antioxidant capacity, and the technological functionality were maximal. Especially the slurry viscosity of powdered DMP (15%, w/v; 16-31Pas at 2.5s-1) and the water-holding capacity (6.5-7.1gg-1) were decisively improved, but at the expense of slurry yellowness and β-carotene contents. Separation of puree (61ghg-1) from MPW0 by intensive pressing before peel processing into DMP (8.7ghg-1) yielded the maximal amount of reusable by-products without affecting DMP functionality. © 2014 Elsevier B.V.

Schmidt U.S.,Karlsruhe Institute of Technology | Schmidt K.,Herbstreith and Fox KG Pektin Fabriken | Kurz T.,Herbstreith and Fox KG Pektin Fabriken | Endress H.-U.,Herbstreith and Fox KG Pektin Fabriken | Schuchmann H.P.,Karlsruhe Institute of Technology
Food Hydrocolloids | Year: 2015

The effectiveness of different commercially available pectin types in forming and stabilizing oil-in-water-emulsions was investigated. Sugar beet pectin as well as apple and citrus pectins with different degree of methoxylation were tested. In emulsions containing small molecule emulsifiers, all investigated pectins behave similarly. They show stabilizing properties by increasing the viscosity of the aqueous phase. This also influences the effective viscosity ratio of emulsions and it results in the formation and stabilization of submicron droplets. In emulsions without small molecule emulsifiers, the investigated pectins differ in their emulsifying behavior depending on their molecular structure. The higher the amount of covalently bound protein a pectin has, the smaller the characteristic droplet size of the resulting emulsions. Pectins with intermediate degrees of esterification produce the emulsions with the largest characteristic droplet size. Furthermore, differences in the surface activity of pectins were found. Sugar beet and citrus pectins lower the surface tension more than apple pectin. Upon the addition of sucrose, an increase in surface tension is detected but only for sugar beet and citrus pectin solutions. © 2014 Elsevier Ltd.

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