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IntroductionProbiotic efficacy relies on administration of live and active probiotic strains in adequate dose. Growth yield and stress tolerance during probiotic production and delivery thus constitute a key bottleneck. Probiotics are widely produced, stored and used under a dried form, mainly by freeze-drying. Drying process generally comprises culture, harvesting, washing and drying steps in which preservation of viability remains a quest for the Holy Grail.MethodsThe aqueous phase of fermented dairy products was shown to enhance stress tolerance in both lactic and propionic acid bacteria. We used sweet whey, a dairy industry byproduct, as a two-in-one medium to sustain both growth of probiotics, and then directly spray-drying without harvesting and washing steps. Moreover, hyperconcentrated sweet whey was developed to achieve one-step drying with higher level of dry matter.ResultsBoth lactic and propionic acid bacteria were adapted to growth within sweet whey and resulting cultures were directly spray-dried with various survival rates, depending on dairy components concentration. Interestingly, growth of probiotics in hyperconcentrated sweet whey led to enhanced stress tolerance, overexpression of key stress proteins, accumulation of intracellular storage molecules and compatible solutes, consequently resulting in yet unknown survival upon heat, acid and bile challenges, as well as spray-drying and storage.DiscussionSpray- being far more cost-effective than freeze-drying, this innovation opens new avenues for sustainable development of probiotic products with enhanced delivery efficiency. This patent-protected new process indeed uses a dairy industry byproduct, requires limited amounts of energy, affords high bacterial viability and protects probiotics from injury undergone within the digestive tract.

IntroductionProbiotic efficacy relies on administration of live and active probiotic strains in adequate dose. Growth yield and stress tolerance during probiotic production and delivery thus constitute a key bottleneck. Probiotics are widely produced, stored and used under a dried form, mainly by freeze-drying. Drying process generally comprises culture, harvesting, washing and drying steps in which preservation of viability remains a quest for the Holy Grail.MethodsThe aqueous phase of fermented dairy products was shown to enhance stress tolerance in both lactic and propionic acid bacteria. We used sweet whey, a dairy industry byproduct, as a two-in-one medium to sustain both growth of probiotics, and then directly spray-drying without harvesting and washing steps. Moreover, hyperconcentrated sweet whey was developed to achieve one-step drying with higher level of dry matter.ResultsBoth lactic and propionic acid bacteria were adapted to growth within sweet whey and resulting cultures were directly spray-dried with various survival rates, depending on dairy components concentration. Interestingly, growth of probiotics in hyperconcentrated sweet whey led to enhanced stress tolerance, overexpression of key stress proteins, accumulation of intracellular storage molecules and compatible solutes, consequently resulting in yet unknown survival upon heat, acid and bile challenges, as well as spray-drying and storage.DiscussionSpray- being far more cost-effective than freeze-drying, this innovation opens new avenues for sustainable development of probiotic products with enhanced delivery efficiency. This patent-protected new process indeed uses a dairy industry byproduct, requires limited amounts of energy, affords high bacterial viability and protects probiotics from injury undergone within the digestive tract.

Preservation of probiotic bacteria still represents a challenge as the market of probiotic products has been growing over the past decade. Among the different preservation techniques, spray drying has been recognized as an adapted technique to produce amount of dried probiotics at relatively low production cost, compared to freeze-drying. However, the challenge of producing probiotic powders by spray drying is primarily related to the existence of high temperature during process, which can damage bacterial cells and cause the reduction of their viability. In this work, a simplified process from growth to spray drying of two probiotic strains, Lactobacilllus casei BL23 and Propionibacterium freudenreichii ITG20, was proposed by using sweet whey as a two-in-one medium for growth and drying purposes. Interestingly, after increasing the TS of sweet whey from the original level of 5% to 30%, the two probiotic strains had higher final biomass production, instead of being inhibited by the high osmolality. The survivals of the probiotics after spray drying were also significantly improved when growing in media in the range of 20% -30% TS. Moreover, the probiotics in these powders maintained a considerably stable viability during 4 month storage at 4 ºC.