Secagem de polpa de cupuaçu em spray dryer e leito de jorro: avaliação dos processos e caracterização dos pós

Abstract

Cupuaçu (Theobroma grandiflorum) is an Amazonian fruit that has nutritional value and considerable phenolic content. The fruit pulp is the main product used; however, it needs to be kept refrigerated until consumption. Drying cupuaçu pulp favors its consumption throughout the year and not just during the harvest period, in addition to allowing the incorporation of fruit powder in the preparation of various food products. The objective of this research was to obtain cupuaçu powder through drying in a spouted bed and spray dryer, in order to comprehensively study the drying conditions and define the most appropriate one, in addition to comparing the characterization of the powders obtained. Experimental designs were carried out for each dryer in order to obtain the best drying conditions. The powders were evaluated in relation to their physical-chemical and physical characteristics, flow properties and morphological analysis, in addition to the evaluation of stability for 120 days. As a result of the best conditions, in the spouted bed the drying temperature and maltodextrin concentration were 85°C and 22%, respectively, while for the spray dryer it was 160°C and 22%. The powder resulting from spray drying differed (p < 0.05) from that obtained in a spouted bed, presenting lower moisture content (2.10%) and water activity (0.17) and higher solubility (98.42%). There was no difference (p > 0.05) between the powders in relation to acidity, pH and soluble solids content. Regarding color, the coordinates a* and b* showed that there is a departure from the original yellow color of the pulp due to the addition of maltodextrin. The morphology revealed that the increased addition of maltodextrin reduced the amount of bonds between the particles, making the powders less agglomerated. Regarding the flow of the powders, regardless of the dryer used, they were classified as having excessively difficult fluidity, with a compressibility index and Hausner ratio ranging from 45.04 to 59.20% and 1.82 to 2.46, respectively. In the evaluation of the stability of the powders from each dryer, it was found that the moisture content, hygroscopicity and solubility did not vary (p > 0.05). However, between the powders from the dryers, a difference (p < 0.05) was found between the moisture and hygroscopicity values. The solubility of the powders showed values above 90%. The values of L* and a* between the powders from the two dryers did not show any difference, only b* was higher (p < 0.05) in the powder from the spray dryer at all times evaluated. It was concluded that the dryers produced powders with good physical-chemical characteristics and similar to each other, but spray drying generated a powder with lower moisture and greater solubility. The spouted bed produced a less agglomerated powder with more uniform particles. Both dryers produced powders with low fluidity, but with good stability for 120 days.