Name: RODRIGO MAZOLINI IMBERTI
Type: MSc dissertation
Publication date: 30/03/2017
Examining board:
Name |
Role |
|---|---|
| PAULO SÉRGIO DA SILVA PORTO | Internal Examiner * |
| TAISA SHIMOSAKAI DE LIRA | Internal Examiner * |
Summary: The purpose of cocoa processing, the fruit of which is highlighted in the north of ES, is to maintain the quality of dried almonds for use as raw material in the manufacture of cocoa products such as chocolate, cocoa butter and others. Solar drying is common because of its easy implementation. However, the quality of the almonds can be compromised, as this process depends on the climatic conditions. Thus, it exists as an alternative to the use of artificial convective dryers. Among the models of dryers already on the market, for grain drying in general, the wind tunnel was selected, with temperature and airflow control. The dryings were conducted through a single layer using the CCN 51 cultivar, modulating the drying air temperature in step up (SD), step up (SU) or fixed (FX) schemes, with variations of air flow Between 1 and 3 ms-1. The objective is to maximize the preservation of the phenolic compounds by finding the best operational conditions for drying the cocoa beans, previously fermented in 5 days, having as response variable 𝑥𝑏𝑠 (𝑓𝑖𝑛𝑎𝑙), shrinkage, CFT and antioxidant activity with EC50 of Each experiment. Through the techniques of Process Engineering, a tree of states with six subsystems was developed, including root, pulp, fermentation, drying method, type of air flow and modulation of air temperature. For the selection of the promising branches, the heuristic and evolutionary methods were used. Drying was stopped when the mass change was less than 1% in periods of 30 min. With the acquisition of images of the almonds during drying by means of digital camera, they were treated by the ImageJ® software, which enabled the determination of the area as a function of time. The air temperature measurements before and after the sample inside the tunnel allowed to obtain energy efficiency values of drying, which was lower than 10% in arithmetic mean and the results were not satisfactory, and improvements in the process were required. For the quantification of the total phenolic compounds, the Folin-Ciocalteu method, based on gallic acid, was used as the standard phenolic compound. The antioxidant activity was determined by the spectrophotometric assay of the DPPH radical. By means of statistical analysis, it was verified that there was a greater influence on the temperature modulation in relation to the speed of drying air. From this study, the step-down scheme was defined as the best operational condition in the artificial drying stage, in which it gave better functional characteristics for dry almonds with CFT contents higher than 3.0 mgEAG/100 mg Cocoa.
