Influência das condições de armazenamento sobre a estabilidade de formulações nutracêuticas compostas por Limosilactobacillus fermentum 296, quercetina e resveratrol

Abstract

There is a close correlation between the thermal properties of powdered nutraceuticals, used in the prevention and treatment of diseases related to the intestinal microbiota, and their stability and functionality. The stability of bacteria in these formulations, in turn, depends on the relative humidity (RH) in which the powder is stored, which directly interferes with its water activity (aw). The aim of this work was to evaluate the effects of temperature and relative humidity on the thermal and microbiological stability, and the potential functionalities of nutraceutical formulations containing Limosilactobacillus fermentum 296, quercetin (QUE) and resveratrol (RES) during cold storage and at room temperature. Initially, the microbiological and thermal stability of the formulation was evaluated after the humidification process, achieved from exposure for 15 days to different relative humidities (11, 22 and 33% RH) and storage temperatures (4 and 25 °C). Differential scanning calorimetry (DSC) and thermogravimetry (TG) techniques were used to evaluate structural, physical and chemical changes in the sample. There were no significant differences in the mass reduction and endothermic reaction temperatures of the formulation under the 3 different RH, indicating a stability of the nutraceutical. The formulation under humidification at 11% RH in refrigeration showed a higher viable cell count when compared to the other RHs (22 and 33%) and at room temperature. Subsequently, the formulation was stored under a controlled RH of 11% and at refrigerated (4 °C) and ambient (25 °C) temperatures for 90 days, with viable cells being counted, the physiological profile of the cells evaluated, the measurement of QUE and RES content, and formulation antioxidant capacity. The physiological state of L. fermentum 296 cells was similar after a 15-day humidification period in the 3 RH conditions, and in the 90-day storage period at 11% RH there was also a similarity between the two temperatures (refrigeration and room temperature). L. fermentum 296 showed higher viable cell counts (>6 log CFU/g) up to day 90 of storage at refrigerated temperature than at room temperature both in the formulation containing the phenolic compounds and in the control formulation. During storage at refrigerated and ambient temperature, there were no losses in the content of QUE and RES and the antioxidant capacity of the formulation was maintained. The results showed that the highest potential functionality of the nutraceutical formulation evaluated during long-term storage (90 days) can be guaranteed under 11% RH and refrigeration temperature. This study contributed information that fills a gap regarding the stabilization process of lyophilized nutraceuticals with probiotics, quercetin and resveratrol after humidification under different RH and control of storage conditions.