Preparation of High-Grade Powders from Honey-Glucose Syrup Formulations by Vacuum Foam-Drying Method

Abstract

This article presents rapid and gentle-drying method for the preparation of high-grade honey powders from honey–glucose syrup formulation. The honey invertase was used as a marker of final product quality. Honey–glucose syrup ratio was 0.55:0.45 w/w; 1% whey protein isolate was added as surfactant. Drying of honey–glucose syrup formulation was carried out in the foamed state. The material was pre-foamed to an initial air volume fraction of 0.25–0.30, subsequently expanded in vacuo to 0.65–0.70. Drying trials were performed at a vacuum level of 100 mbar in a temperature range of 40–60C chosen in accordance with invertase degradation kinetic data. Powders that were vacuum foam dried at 40C and 50C showed insignificant invertase loss and thus similar quality to powders obtained by the much more time-consuming freeze-drying method. Furthermore, the powders proved very stable as no powder caking was observed after 6 months of storage at ambient conditions. Practical Applications The vacuum foam-drying method presented in our study is suitable for the preparation of high-grade honey powders for premium products in pharmaceutical or dietary supplements. As a result of gentle-drying conditions, i.e., low temperature and reduced pressure, there is a high retention of valuable thermo- and oxidative-sensitive nutrients, indicated by the high residual invertase activity in the dried powders. Regarding the retention of valuable nutrients, this method is comparable with freeze drying, which is currently used in pharmaceutical applications, but vacuum foam drying is faster and less expensive. The composition of the honey formulation also facilitates good powder storage stability.