Vacuum foam drying for preservation of <i style="">lasota</i> virus: Screening of foaming agent and cycle optimization

Abstract

491-497Solid-state product of lasota virus was obtained by using vacuum foam drying (VFD). In the process, pluronic polymers, viz. F-108, F-68 and F-87 (plain and with sugars) were screened for their foaming ability. First, aqueous infrared (IR) spectrum of lasota virus harvest was obtained and pH and temperature stability of the harvest were evaluated. Then the temperature and vacuum of VFD cycle were optimized. The processed virus products were also evaluated for foam characteristics, moisture content and EID50 titre value. Aqueous solution of plain pluronic F-108 at 3.0% (w/v) strength showed the highest foaming ability as compared to other pluronics used in the study. The foaming ability of F-108 increased further in the presence of sugars. However, optimum foaming ability of pluronic F-108 during VFD was observed at 0.6% (w/v). Aqueous IR spectrum reveals symmetrical α-helix structure of lasota virus. The virus remained stable at pH 3 to 9, but denatured at temperatures above 20ºC. Effective and uniform foam formation with low residual moisture and a virus titre of 6.24 was obtained in VFD cycle III; whereas, Lasota virus was completely denatured at lower vacuum with higher temperatures. Thus, the optimized cycle III is suitable for screening of protectants for dehydration-induced denaturation of lasota virus during VFD