ReviewSpray drying of probiotics and other food-grade bacteria: A review

•The factors influencing growth, spray drying, storage and application.•Selection of robust strain and application of cellular stress response.•Employment of protective agent coupled with optimization of drying process.•Stability and functionality of spray-dried probiotics.•Current key message, future trends and challenges for spray drying of probiotics.

BackgroundProbiotic and starter bacteria are generally dried to produce easy-to-use ingredients that are stable and flexible for applications in the food, feed and pharmaceutical industry. The overall demand for dried probiotic bacteria has increased in the context of a rapidly growing market, evidencing the need for their larger scale production.Scope and approachThe spray-drying of bacteria enables a larger production scale than the freeze-drying currently used; energy costs are lower and the process is sustainable. This is also a promising way to microencapsulate bacteria within various protective matrices to ensure their improved resistance during storage, technological processes and digestive stresses.Key findings and conclusionsThis review highlights some key strategies to improve the viability and efficacy of probiotics spray-drying, such as the enhancement of bacterial resistance, improved protection of the drying medium and optimization of the drying process. It also focuses on factors during the pre- and post-drying stages which may influence the quality and efficacy of spray-dried probiotic powders.