Soy protein–gum karaya conjugate: emulsifying activity and rheological behavior in aqueous system and oil in water emulsion

The main objective of this study is to investigate the effects of mixing and conjugation of soy protein isolate (SPI) with gum karaya on the characteristics of the hybrid polymer (protein–gum) in both aqueous systems and oil-in-water (O/W) emulsions. It was hypothesized that the covalent linkage of gum karaya with SPI would improve the emulsifying activity and rheological properties of both polymers. Conjugation occurred under controlled conditions (i.e., 60 °C and 75 % relative humidity, 3 days). The conjugated hybrid polymer produced smaller droplet with better uniformity, higher viscosity and stronger emulsifying activity than native gum karaya, suggesting the conjugated polymer provided a bulkier secondary layer with more efficient coverage around oil droplets, thereby inducing stronger resistance against droplet aggregation and flocculation. Emulsions containing the native gum karaya produced the largest droplet size among all prepared emulsions (D 3,2 = 8.6 μm; D 4,3 = 22.4 μm); while the emulsion containing protein–gum conjugate (1:1 g/g) had the smallest droplet size (D 3,2 = 0.2 μm; D 4,3 = 0.7 μm) with lower polydispersity. The protein–gum conjugate (1:1 g/g) also showed the highest elastic and viscous modulus, the lowest polydispersity (span) and the highest emulsifying activity among all native, mixed and conjugated polymers. Therefore, the percentage of gum karaya used for production of O/W emulsion can be decreased by partially replacing it with the conjugated gum

Antioxidant dietary fibre recovery from Brazilian Pinot noir grape pomace

Brazilian grape pomace was extracted in hot water using a factorial design to evaluate polysaccharide recovery. Dependent variables were temperature, particle size and solute:solvent ratio. Polysaccharide yields varied from 3 to 10%, and the highest sugar content was observed when extraction was carried out at 100 °C, from fine particle sizes (≤249 μm), in a 1:12 solute:solvent ratio. Monosaccharide compositions of the flours afforded, in average, Rha,Ara,Xyl,Man,Gal,Glc,GalA in a 3:32:2:13:11:20:19 molar ratio, with varied Glc:GalA ratios. 13C NMR and HSQC spectra confirmed the presence of pectic and glucose-based polysaccharides in the extracts. Phenolic compounds were found after pomace extractions, and cathechin, gallic acid and epicatechin were the main identified compounds. Extracts also presented ABTS radical scavenging capacity (from 8.00 to 46.60 mMol Trolox/100g pomace), which means that these grape pomace flours are rich in antioxidant dietary fiber and have a potential use as food ingredients.Fil: Beres, Carolina. Universidade Federal do Rio de Janeiro. Centro de Tecnologia. Instituto de Química; BrazilFil: Beres, Carolina. Embrapa Agroindústria de Alimentos; Brazil.Fil: Simas-Tosin, Fernanda F. Universidade Federal do Paraná (UFPR). Departamento de Bioquímica e Biologia Molecular; Brazil.Fil: Cabezudo, Ignacio. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Instituto de Procesos Biotecnológicos y Químicos (IPROBYQ-CONICET); Argentina.Fil: Freitas, Suely P. Universidade Federal do Rio de Janeiro. Centro de Tecnologia. Escola de Química; Brazil.Fil: Iacomini, Marcello. Universidade Federal do Paraná (UFPR). Departamento de Bioquímica e Biologia Molecular; Brazil.Fil: Mellinger-Silva, Caroline. Embrapa Agroindústria de Alimentos; Brazil.Fil: Cabral, Lourdes M. C. Embrapa Agroindústria de Alimentos; Brazil