Edible lecithin, stearic acid, and whey protein bigels enhance survival of probiotics during in vitro digestion

Bigels are materials with semi-solid organic and aqueous phases and, therefore, have the potential to deliver both lipophilic and hydrophilic compounds to humans. Additionally, because bigels are two-phase systems, a diverse array of synthesis options are possible, allowing many unique characteristics to be achieved. The purpose of this study was two-fold: to assess the ability of bigels to protect probiotics during in vitro digestion in a simulated gastrointestinal system and to determine the effect of phospholipids on probiotic survival. A standardized COST INFOGEST Network in vitro digestion system was used, and survival of Bifidobacterium lactis and Lactobacillus acidophilus was measured. By measuring the increase in free fatty acids, the enzymes' lipolytic activity was confirmed. A control, with no gelators, had the greatest lipolysis. The formulated bigel was effective at protecting probiotics from the harsh conditions of the digestive tract compared to the control. L. acidophilus was more resistant to high shear conditions than B. lactis during gel preparation. Probiotics in bigels with phospholipids had greater survival during digestion; nonetheless, the difference was not statistically significant. It was hypothesized that this was due to the phospholipids being enzymatically broken down in the in vitro system. Therefore, for phospholipids to have a beneficial impact on probiotic survival, they must be in their native form. Overall, this study showed the potential of bigels to efficiently protect probiotics during digestion.