Delivery of probiotics in easy-to-prepare protein gels designed for safe swallowing

Abstract

A powder formulation was developed, based on plant proteins, containing calcium and the probiotic strain Lacticaseibacillus casei-01. This powder forms gels upon the mere addition of water, resulting in an easy-to-prepare and safe-to-swallow probiotic functional food. One hundred grams of the resulting gels contained 11.7 g soybean proteins, 1.3 g amaranth proteins, 88.4 mg calcium, and 1011 CFU. The gels exhibited excellent water-holding capacity (WHC, 93.8 %) and rheological properties that make them safe to swallow in patients with dysphagia (apparent viscosity at 50 s−1 was 2.4 Pa·s). The maintenance of L. casei-01 viability through simulated gastrointestinal digestion (sGIT) was due to the reinforcement of its resistance induced by freeze-drying (one of the steps necessary to prepare the powder) and to the protection exerted by the three-dimensional protein matrix. This would enable sufficient viable L. casei-01 quantities to reach the intestine to exert their probiotic effect. The percentage of adhesion of L. casei-01 to Caco2/TC7 cells after sGIT was 13.1 %, indicating that the lactobacilli retained this ability after the necessary processing to generate the powder and the passage through the sGIT. Powders were stored at 4 °C and 20 °C, and the resulting gels were evaluated, revealing that the limiting property was WHC, which began to deteriorate after 18 weeks at 4 °C or 6 weeks at 20 °C. The reduction in viable lactobacilli during storage correlated with the decline in WHC; however, the viable enumeration obtained after sGIT remained sufficiently high to exert probiotic effects.