TAMARIND PULP FREEZE DRYING: EFFECT OF ACIDITY REDUCTION AND STORAGE STABILITY

This study arose from the need for the production of lyophilized tamarind pulp to evaluate consumption-related benefits (10g/day) by diabetic patients. The objective of this work was to assess the effect of tamarind pulp acidity reduction on the freeze-drying process, preparation of powder and storage stability. Tamarind pulp containing 20% of total solids, pH 2.5 (control - C), and another portion with partially neutralized acidity up to pH 3.5 (Neutralized treatment - N), were prepared, frozen and lyophilized, comparing two profiles of heating. After dehydration, samples were evaluated for texture analysis and ease of grinding. The remaining samples were ground to powder and packed in multilayer sachets, and stability study (humidity, aw, hygroscopicity, solubility, and caking degree) was performed. DSC results indicated -1.81 and -0.80 °C pulp melting temperature, for C and N, respectively. It was also observed that treatment N presented easier lyophilization and grinding to powder, indicating that the partial neutralization of acidity helps in the dehydration process. This ease of grinding was confirmed in the hardness and fracturability results for treatment N. Both treatments presented storage stability for up to six months, considering the humidity parameter (2.76 ± 0.3% and 2.53 ± 0.1%), hygroscopicity (6.9 ± 1.1% and 4.5 ± 1, 7%), for treatment C and N, respectively, besides aw and solubility, indicating good condition and barrier and heat sealing properties of the package. Caking degree increased by 72% and 60%, for C and N, respectively, up to 60 days of storage, indicating to limit the powder flow behavior inside the package. It was concluded that the partial reduction of acidity to pH 3.5 facilitates the process of lyophilization and preparation of tamarind powder when compared to non-neutralized tamarind. Both treatments have storage stability, except for applications where the increase in caking degree is limiting.