Study the Effect of Pre-Treatment of Drying ‘Mortiño’ (Vaccinium Floribundum Kunth) with Reference to Drying Rate and Total Content of Soluble Polyphenols and Anthocyanins

Abstract: The aim of this work was to study the effect of pre-treatments on drying of ‘mortiño’, on the drying rate and total content of soluble polyphenols and anthocyanins. It was applied to fresh fruit pre-treatment of immersion bath of aqueous solution of ethyl oleate and potassium carbonate. It was used a 22 factorial design with axial points, to evaluate its effect on the drying rate and content of phenolic compounds. It was performed a second pre-treatment with SO2, it was used a 22 factorial design to study its effect on the content of phenolic compounds. Stability assays were performed with dried fruits stored in a laminated multilayer film and metalized for 2 months under refrigeration (4 °C), freezing (-17 °C) and 25 °C at 90 % RH. It was evaluated the moisture content, color, soluble polyphenols and anthocyanins. It was conducted a sensory analysis of the product. The best conditions to dry ‘mortiño’ are 40 ºC, airflow of 0.24 m3/s, immersion bath concentration of 1.55 % K2CO3 (w/w) - 1.25 % of ethyl oleate (V/V), concentration of SO2 2 000 ppm and sulfidation 2 h. The product was dried to 5 % moisture in the oven in 40 % less time required to dry without pretreatments. The dried ‘mortiño’ retained 98.2 % of anthocyanins and 99.7 % of soluble polyphenols in relation to freeze-dried ‘mortiño’. Meanwhile the ‘mortiño’ dried by solar dryer hybrid retained 88.5 % of anthocyanins and 99.7 % of soluble polyphenols. The product stored at 18 °C in a multilayer film laminated and metalized, retains 50 % of anthocyanins in relation to its initial content in 4 months and 11 days.