Bogdan Demczuk Junior

Physicochemical properties of modified citrus pectins extracted from orange pomace

Modified pectin is a polysaccharide rich in galacturonic acid altered by pH adjustment and thermal treatment used especially as an anti-cancer agent. The aim of this work was to study the physical and chemical properties of modified pectins extracted from orange pomace with citric and nitric acids. The galacturonic acid content, degree of esterification, Fourier Transform Infrared Spectroscopy profile, molecular weight, intrinsic viscosity, rheological properties and antioxidant activity of the pectins were evaluated. The modification process caused the de-esterification of pectins and a decrease of molecular weight due to removal of neutral sugars, maintaining the linear chain of galacturonic acid. Such changes also caused a significant increase in the in vitro antioxidant activity (p ≤ 0.05) and influenced the rheological properties of pectin, reducing its viscosity. This work showed that the modification of pectin from orange pomace with citric and nitric acids altered its structural and physical characteristics as well as its biological activity toward a free-radical.

Granules morphology and rheological behavior of green banana (Musa cavendishii) and corn (Zea mays) starch gels

No presente trabalho foi utilizado amido obtido de banana verde (Musa cavendishii) e amido de milho (Zea mays) comercial, com o objetivo de comparar a morfologia dos grânulos e o comportamento reologico dos geis. As imagens da morfologia dos grânulos foram obtidas por microscopia eletronica de varredura. Os grânulos de amido da banana apresentaram forma oval e elipsoidal com diâmetros irregulares, todavia, os grânulos do amido de milho mostraram forma poliedrica e diferentes tamanhos. As analises reologicas dos geis das solucoes de amido mostraram carater nao-newtoniano, pseudoplastico. O modelo de Herschel-Bulkley foi o que melhor representou comportamento reologico dos geis. O gel de amido de banana verde obteve maiores valores de tensao de cisalhamento e viscosidade aparente quando comparada ao gel de amido de milho. Ocorreu um decrescimo progressivo na tensao de cisalhamento e na viscosidade com a adicao de cloreto de sodio e sacarose aos geis.

Bioactive compounds of 44 traditional and exotic Brazilian fruit pulps: phenolic compounds and antioxidant activity

ABSTRACT Bioactive compounds and antioxidant activity from 44 fruit were evaluated. The data were statistically evaluated by analysis of common components and specific weights (CCSWA). Panã, acerola, açaí, and jabuticaba showed higher values of total phenolic compounds (TPCs) and antioxidant activity. The analysis of CCSWA was able to explain almost 100% of the variance of the data and established the correlation between TPC and antioxidant capacity, being the most influential variables in the classification of samples. This statistical method is ideal for quickly analyzing a large amount of data, as obtained in this research, which facilitates routines of industrial analysis.