Effects of two fermentative methods on cacao (Theobroma cacao L.) Trinitario, induced with Rhizobium japonicum to reduce cadmium

Abstract

7.5 million tons of chocolate are produced worldwide, and 64 % is consumed as filled chocolate. In 2012, the European Union indicated cadmium levels should not exceed 0,8 mg kg-1 in products with a cocoa paste base of 70 %. The goal in this research was to evaluate the effectiveness of Rhizobium japonicum in decreasing cadmium present in cocoa beans. Therefore, three concentrations of Rhizobium japonicum 0 ml, 300 ml and 600 ml were applied for every two kilos of fresh mass of Trinitario cocoa, for fermentation two methods were applied by Rohan and coolers in two farms (Los Ríos and Guayas).  She used a completely random Trifactorial design (12 treatments and 2 repetitions), evaluating 24 seeds in total, the quality variables in the seed evaluated were: pH, temperature, percentage of fermentation, seed index, test of testa and cotyledon. The sensory analysis was determined by a panel of semi-trained tasters, for the analysis of cadmium was performed with perchloric nitro acid digestion by spectrometry of ICP OES. During fermentation there was an increasing increase in pH (3,6 – 4,2), temperature (27 – 40,2 °C), the seed index showed the highest average in T5 (1,65 g), cadmium content decreased by 79 %, by the method of fermentation in rows in the province of Los Ríos and 78 %, by the method of fermentation in Rohan boxes in the province of Guayas. Rhizobium japonicum can be considered a potential species to decrease cadmium in cocoa almond grown above permissible levels.