The aim of this study was the evaluation of the effect of three types of pretreatment (acid, alkaline and organosolv) on the removal of lignin from the biomass of cassava stems. The concentration of solids was 10% (w/v). In the acid treatment acid concentration between 0.79 and 2.21% w/v and time between 8 and 22 minutes, at 121 °C and 15 psi were evaluated. In the alkali treatment NaOH concentration between 0.59 and 3.41% w/v and time between 4 and11 h, at 60 °C were evaluated; while in the organosolv treatment, ethanol concentration between 41.7 to 98.3% v/v and time between 4 and 11 h at 60 °C were evaluated. Multiple regression analysis was performed taking the reaction time and concentration of the delignifying agent as continuous numerical variables, in order to assess the effect of the method used on the removal of lignin lignocellulosic matrix. Variables with significant influence on the removal of lignin were acid concentration, time and alkali concentration, and time in the organosolv process. The alkaline pretreatment had the highest percentages of lignin removal while the organosolv pretreatment showed lower levels.

BACKGROUND: The microencapsulation process using spray drying (SD) represents an effective alternative in protecting the active components present in strawberries. However, microcapsules of strawberry powder mixtures present problems of instantanisation and flowability; an aspect that can be solved by agglomeration of the particles. OBJECTIVE: The aim of this study was to evaluate the influence of the fluidised bed agglomeration process on the flow, instantaneity and antioxidant properties of strawberry powder obtained by SD. METHODS: The response surface methodology (RSM) was used with a centred composite central design (α=1), considering the factors: fluidisation air temperature (50-70°C), time (30-50 min) and atomisation air pressure of the binder agent (1-2 bar). RESULTS: An increase in particle size was observed in the agglomeration process; the agglomerated particles showed a decrease in wetting time, the agglomerates of strawberry powder mixtures presented excellent instantanisation and fluidity, solving the problems identified in the microcapsules obtained by SD. CONCLUSIONS: Although the moisture and aw levels were increased in the agglomeration process, the values are within the microbiological and physicochemical food safety range; moreover, there was no effect on the phenol content and antioxidant capacity. The experimental optimisation achieved desirability of 68.4%, the optimum conditions being 70°C, 30 min and 1 bar.