Effects of Environmental Stress on the Viability of Lactobacillus plantarum Encapsulated in Double Emulsions

Background: The primary objective of encapsulating probiotics is to enhance their survival rate during food processing and the challenging conditions of the gastrointestinal tract. Methods: In this specific investigation, Lactobacillus plantarum was introduced into the Inner aqueous phase (W1) of Double Emulsions (DEs) referred to as Water-in-Oil-in-Water (W1/O/W2). This entrapment process involved inducing a transition from solid to gel state of W1 using gelatin, alginate, tragacanth gum, and carrageenan across multiple samples. The study then explored the resistance of L. plantarum to various environmental pressures, including thermal treatments (such as pasteurization at 72 °C for 40 s, microwave heating at 72 °C for 40 s, and sterilization at 145 °C for 40 s), as well as exposure to sodium chloride (NaCl), bile salt, lysozyme, and penicillin. Additionally, the viability of the encapsulated probiotics was investigated in simulated gastrointestinal conditions. Results: It was found that the sensitivity of free bacterial cells to heat processing was significantly higher compared to encapsulated bacteria. Among the different samples, those containing tragacanth gum exhibited the highest cell viability when subjected to various heat treatments (14.67% reduction for microwave, 13.72% reduction for pasteurization). Furthermore, the study demonstrated that DEs effectively improved the survival of probiotics against NaCl, bile salt, lysozyme, and penicillin. Generally, the gastric conditions (0.55 to 3.30 log Colony Forming Unit (CFU)/g reduction) had a more detrimental impact on probiotic viability compared to the intestinal conditions (0.1 to 0.8 log CFU/g reduction). Conclusion: Ultimately, DE samples containing tragacanth gum in the W1 phase displayed the most effective protective effects. This encapsulation technique holds potential for various applications in dairy, meat, and other fermented products.