Process Development for the Spray-Drying of Probiotic Bacteria and Evaluation of the Product Quality

This protocol details the steps involved in the production and physicochemical characterization of a spray-dried probiotic product.

Probiotics and prebiotics are of great interest to the food and pharmaceutical industries due to their health benefits. Probiotics are live bacteria that can confer beneficial effects on human and animal wellbeing, while prebiotics are types of nutrients that feed the beneficial gut bacteria. Powder probiotics have gained popularity due to the ease and practicality of their ingestion and incorporation into the diet as a food supplement. However, the drying process interferes with cell viability since high temperatures inactivate probiotic bacteria. In this context, this study aimed to present all the steps involved in the production and physicochemical characterization of a spray-dried probiotic and evaluate the influence of the protectants (simulated skim milk and inulin:maltodextrin association) and drying temperatures in increasing the powder yield and cell viability. The results showed that the simulated skim milk promoted higher probiotic viability at 80 °C. With this protectant, the probiotic viability, moisture content, and water activity (Aw) reduce as long as the inlet temperature increases. The probiotics' viability decreases conversely with the drying temperature. At temperatures close to 120 °C, the dried probiotic showed viability around 90%, a moisture content of 4.6% w/w, and an Aw of 0.26; values adequate to guarantee product stability. In this context, spray-drying temperatures above 120 °C are required to ensure the microbial cells' viability and shelf-life in the powdered preparation and survival during food processing and storage.

To be defined as probiotics, microorganisms added to foods (or supplements) have to be consumed alive, be able to survive during passage in the gastrointestinal tract of the host, and reach the site of action in adequate amounts to exert beneficial effects^1,2,7.

The growing interest in probiotics is due to the several benefits to human health they confer, such as the stimulation of the immune system, the reduction of serum cholesterol levels, and the enhancement of gut barrier function by acting against harmful microbes, as well as their beneficial....

1. Production of the probiotic cells

1. Prepare De Man Rogosa and Sharpe (MRS) broth.
2. Reactivate 1% (v/v) of the culture of interest in the MRS broth (here, Lactiplantibacillus paraplantarum FT-259 was used).
3. Incubate for 24 h at an adequate temperature (we used 37 °C).

2. Separate the bacteria from the culture

1. Centrifuge the bacterial culture at 7,197 x g for 5 min at 4 °C using 50 mL.......

In this study, L. paraplantarum was encapsulated by SD using food-grade encapsulating agents (inulin:maltodextrin and simulated milk powder), showing high product quality and efficacy in preserving the bacterial cell viability^17,19.

The results of the SD of probiotics at 80 °C showed that the distinct protectants systems (inulin:maltodextrin and simulated skim milk) promoted efficient protection of the probiotic cells, wi.......

L. paraplantarum FT-259 is a Gram-positive, rod-shaped bacterium, is a producer of bacteriocins with antilisterial activity, and has high probiotic potential²⁰. Son et al.²⁴ previously demonstrated the immunostimulant and antioxidant capacity of L. paraplantarum strains. Besides, they have great probiotic potential, with properties such as stability under artificial gastric and bile conditions, susceptibility to antibiotics, and binding to intestinal cells.......

This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. This study was also supported in part by FAPESP - São Paulo Research Foundation. E.C.P.D.M. is grateful for a Researcher Fellowship from National Council for Scientific and Technological Development (CNPq) 306330/2019-9.