On the gamma-irradiated black pepper rheo-viscometric identification possibility

The aim of this paper is to discuss the significance of rheological parameters in evidencing the gamma-ray treatment of the black pepper. It has been investigated the influence of granulation on the rheological properties of gamma- irradiated black pepper gelled suspensions prepared from powder grains of two sizes: φ1≤150 μm and φ2≤700 μm. Experimental data as well as the rheograms show a significant difference as function of particle size. Each shear stress τ diagram system, τ f(γ',D)/φ1≤ 150μm and τ = f(γ',D)/φ2≤ 700μm, where γ' is the shear rate, are resolutive enough for practical purpose, at least as screening method, from shear rate value γ'≥27 s-1 up to γ'≥437.4 s-1 and for two particle sizes. In fact, value of τ = f(γ',D)/φ2≤ 700μm < τ f(γ',D)/φ1≤ 150μm, where the shear rate values ranged from 3.0 s-1 to 437.4 s-1 and the irradiation doses, D, were 0, 4, 8, 10, 16, 20 kGy. As in recent developments on gamma-irradiation effects on starch, our findings suggest that variation in rheological behavior of powdered black pepper suspension occurs mainly as results of starch radio-depolymerization. In this respect, the particle size plays an important role in the identification method of gamma-ray treatment as result of its influence on the suspension behavior and gel formation process. (authors)