Effects of probiotics on the content and bioaccessibility of phenolic compounds in red pitaya pulp

This study assessed the effects of the incorporation of Lactobacillus acidophilus LA-05 or Bifidobacterium animalis ssp. lactis BB-12 in the content and bioaccessibility of phenolics in red pitaya pulp. The oxygen radical absorbance capacity (ORAC) of the dialyzed (bioaccessible) fraction of red pitaya pulp fermented by these probiotics was also assessed. After 48 h of cultivation in red pitaya pulp, the pH and sugar contents decreased, while organic acids and viable counts of the tested probiotics increased (p < 0.05). After exposure to simulated gastrointestinal conditions the viable counts of L. acidophilus LA-05 and B. lactis BB-12 in fermented red pitaya pulp were close to 8 and 7 log CFU/mL, respectively. Fermentation with probiotics decreased (p < 0.05) the contents of phenolic acids and flavonoids in red pitaya pulp. Both, L. acidophilus LA-05 and B. lactis BB-12 increased the presence of phenolics in the non dialyzed fraction of the red pitaya pulp. The bioaccessibility of catechin, epigallocatechin gallate, and procyanidin B2 increased (p < 0.05) in red pitaya pulp fermented by L. acidophilus LA-05 or B. lactis BB-12. The bioaccessible fraction of red pitaya pulp fermented by L. acidophilus LA-05 or B. lactis BB-12 showed higher antioxidant activity than that of the non-fermented red pitaya pulp. These findings indicate the fermentation of red pitaya by probiotics as an alternative to increase the bioaccessibility of specific phenolics, as well as the antioxidant activity in this fruit.