PHYSICOCHEMICAL PROPERTIES AND ACCEPTANCE OF JELLY AND NECTAR OF ARAZA AND PAPAYA

The main objective of this work was to evaluate the acceptance of jelly and nectars made from araza (Eugenia stipitata Mc Vaugh) and papaya. The following percentages of araza and papaya were, respectively, used: 50:50; 40:60; 30:70 and 20:80. For both pulps and products the variables studied were: acidity, pH, total content of soluble solids. Acceptance tests were conducted for the developed products. An inverse relation was observed between the papaya proportion and the soluble solids content and titratable acidity. The jelly made with skin araza presented higher levels of soluble solids, higher pH and lower titratable acidity compared with those obtained with fruit without the peel. Higher concentrations of papaya pulp improved the acceptance of nectar and jelly in all formulations. It was observed an increased in the acceptance when using araza with skin, until levels of 45% of papaya for the jelly and 24% for the nectar. This was probably due to specific sensorial attributes of the araza skin and it is an indicator for future researches

Decoupling of the S=1/2 antiferromagnetic zig-zag ladder with anisotropy

The spin-1/2 antiferromagnetic zig-zag ladder is studied by exact diagonalization of small systems in the regime of weak inter-chain coupling. A gapless phase with quasi long-range spiral correlations has been predicted to occur in this regime if easy-plane (XY) anisotropy is present. We find in general that the finite zig-zag ladder shows three phases: a gapless collinear phase, a dimer phase and a spiral phase. We study the level crossings of the spectrum,the dimer correlation function, the structure factor and the spin stiffness within these phases, as well as at the transition points. As the inter-chain coupling decreases we observe a transition in the anisotropic XY case from a phase with a gap to a gapless phase that is best described by two decoupled antiferromagnetic chains. The isotropic and the anisotropic XY cases are found to be qualitatively the same, however, in the regime of weak inter-chain coupling for the small systems studied here. We attribute this to a finite-size effect in the isotropic zig-zag case that results from exponentially diverging antiferromagnetic correlations in the weak-coupling limit.Comment: to appear in Physical Review