MICROBIAL AND PHYSICOCHEMICAL PROPERTIES OF UV-C PROCESSED Aloe vera GEL BLENDS AT DIFFERENT pHs USING A CONTINUOUS FLOW UV SYSTEM

Abstract

UV-C irradiation doses (12.8, 24.2, 35.8, and 54.6 mJ · cm − 2 ) on the physicochemical and microbiological properties of 10% Aloe vera gel at di ff erent pHs (3.5, 4.5, and 5.5) were evaluated. An unprocessed treatment (UP) and a short (45 s) thermal treatment (TT) at 90 °C were used as controls. The irradiation doses and pH levels a ff ected ( p < 0 . 05) the elimination of coliforms and aerobic mesophilic microorganisms with the same e ffi ciency as TT. Molds and yeasts were successfully eliminated at doses ≥ 24.2 mJ · cm − 2 regardless of pH. Reducing sugars, total polyphenols, and aloin A content decreased as pH increased ( p < 0 . 05). Although, the antioxidant activity was significantly reduced at doses ≥ 35.8 mJ · cm − 2 . TT and UV-C treatments a ff ected the a ∗ color parameter ( p < 0 . 05), resulting the UV-C with the highest values. In both treatments, a reddish color was present at pH ≥ 4.5. The UV-C treatment resulted in minimal changes in most physicochemical properties, compared to UP treatment. However, TT significantly a ff ected most physicochemical properties of A. vera gel blends. These results suggest that dose of 24.2 mJ · cm − 2 in a continuous flow UV system is a non-thermal alternative for the stabilization of 10% A. vera gel blends at pH of 3.5.