Survival of lactic acid bacteria in simulated gastrointestinal juice protected by a DNA-based complex gel

Salmon milt DNA was utilized in the approach to protect functional materials, proteins, microorganisms, drugs, etc., by forming a DNA-based complex gel with gelatin and κ-carrageenan. The multiplier effect of the combination of DNA, gelatin and κ-carrageenan was examined by measuring the release of methyl orange from the gel after being incubated in simulated gastric juice. The results indicated that the hydrogel made of DNA, gelatin and κ-carrageenan can efficiently maintain the functional materials. Furthermore, a complex gel was developed and optimized by applying an emulsion of lactic acid bacteria and cacao oil onto the already prepared hydrogel. The existence of the lactic acid bacteria in the oil emulsion particles was confirmed by scanning electron microscopy. The protection capabilities in the simulated gastrointestinal juice, which had a viability of 1.50 × 10⁶ CFU/g gel after 2 h incubation in the simulated gastric juice and 2.53 × 10⁷ CFU/g gel after 6 h continued incubation in the simulated intestinal juice, were measured, in contrast to 2.58 × 10⁷ CPU/g in the original gel before treatment.