Development of a non-dairy probiotic fermented product based on almond milk and inulin

A new fermented almond "milk" that combined the properties of both almonds and probiotics was considered to cover the current versatile health-promoting foods' demand. Almond milk fermentation with probiotic Lactobacillus reuteri and Streptococcus thermophilus was studied by using a Central Composite design with response surface methodology, and different factors (glucose, fructose, inulin and starters) were optimised to assure high probiotic survivals in the final product. The optimal formulation was physicochemically characterised throughout cold storage (28 days) and both probiotic survivals to in vitro digestion and proteolysis were quantified. Results showed that a high probiotic population (>10(7) cfu/mL) was obtained in the previously optimised almond milk throughout storage time, which correspond to the addition of 0.75 g of glucose/100 mL, 0.75 g of fructose/100 mL, 2 g/100 mL inulin and 6 mL/100 mL inoculum. Glucose was used as the main nutrient and the production of mannitol by L. reuteri was detected. The fermentation process increased the viscosity values, forming a weak gel structure, whose physical properties hardly changed. Probiotic bacteria notably survived (51%) to the in vitro digestion, surely related to the inulin presence, which would add value to the developed product by enhancing the potential health benefits of its consumption.