Foam-mat drying kinetics for acerola and adjustment of the mathematical models

Abstract

Acerola (Malpighia emarginata DC) is a fruit rich in nutrients, especially vitamin C, but the in natura fruit is highly perishable and hence processing of the acerola pulp becomes indispensable. The aim of this paper was to study the foam mat drying process of acerola pulp to evaluate the effect of temperature on the drying kinetics of the pulp and fit mathematical models in order to describe the operation. The experiment was carried out with three repetitions. The foam was prepared with 250 mL of the pulp plus 4% of foaming agent and spread evenly in stainless steel trays. The selected drying air temperatures were 50 °C, 55 °C, 60 °C, 65 °C and 70 °C. The moisture ratios were then calculated and the Page, Henderson and Pabis and Lewis mathematical models fitted for each temperature. The Page model showed the highest determination coefficient (> 0.99) and lowest standard error for the regression at all temperatures (<0.03). The proposed generalized model presented a determination coefficient of 0.9933. The Page model and the generalized model were adequate to describe the drying process of the acerola pulp. The moisture contents of the dehydrated products were in accordance with the values established by Brazilian law.

Keywords:  Malpighia emarginata DC.; Acerola pulp; Page model; Henderson and Pabis model; Lewis Model