Foam drying of kefir powders: physicochemical and microbiota impact

This study explores the impact of foam drying on the phytochemicals, microbiota, and quality of kefir powder. The egg white, maltodextrin, and carboxymethyl cellulose were used as foaming agents to obtain stable kefir foam. The lyophilized foam kefir powder (LFK), lyophilized non-foaming kefir powder (LNK), and foam kefir powders were obtained by convective drying at three different temperatures, which were 50 °C, 60 °C, and 70 °C. Some properties, such as color, solubility, total phenolic compounds, bulk and tapped density, and antioxidant and antihypertensive activity, were evaluated. Among the samples, especially, the LNK contains a higher concentration of microorganisms. Some properties, such as color, solubility, and total phenolic compounds, showed positive development by drying using a lyophilizer. Data on moisture, water activity, bulk, and tapped density of the powders were 3.43–6.04%, 0.17–0.46, 0.30–0.59, and 0.40–0.76 g/cm 3 , respectively. ABTS and DPPH tests showed radical scavenging activity ranging from 33.47 to 55.79 mmol/g in non-foaming kefir powders and 35.09–46.42 mmol/g in foam kefir powders. ACE inhibition in kefir samples ranged from 29.83 to 37.13%. Foam drying altered kefir powder’s biological properties, while lyophilization and convective drying at 50–60 °C better preserved its industrial and health benefits.