Coffee brews as food matrices for delivering probiotics: Opportunities, challenges, and potential health benefits

The past decade has seen probiotics being incorporated into non-dairy food matrices at a proliferating rate. Concurrently, functional coffees fortified with cannabidiol, l-theanine, turmeric etc. have emerged. As non-dairy probiotic foods and functional coffees become more mainstream amid health and wellness trends, lucrative opportunities exist for coffees fortified with probiotics. Yet, the concept of probiotic coffees is still relatively new. This review summarises recent scientific and commercial developments in using coffee as a probiotic delivery matrix. To ensure successful development, technological challenges unique to coffee as a matrix are addressed, pertaining to probiotic viability, sensorial, and manufacturing aspects. Potential health benefits of probiotic coffees are also discussed, followed by anticipations on how prebiotics, synbiotics, and postbiotics may be applied within the domain of functional coffees. Key findings and Conclusions: Probiotic coffees can be developed either by using Bacillus spores to produce non-fermented formulations, or by fermenting coffee brews with vegetative cells. Non-fermented formulations are easier to develop as Bacillus spores are heat-resistant during brewing. Contrastingly, fermented formulations are more challenging to develop as heat, nutrient scarcities, and acidity impair probiotic viabilities. Fermented formulations also have shortcomings relating to flavour changes, and additional installations to existing coffee manufacturing processes. Nevertheless, vegetative probiotics potentially offer greater functionalities than spores, by biotransforming amino acids, melanoidins and chlorogenic acids into more bioactive and bioavailable forms. However, additional functionalities will require further substantiation from mechanistic and clinical studies. Finally, besides probiotics, ample opportunities similarly exist for coffees fortified with prebiotics, synbiotics, and postbiotics.