The Effect of Edible Plant Oils on Increasing the Viability of Lacticaseibacillus rhamnosus GG During the Microencapsulation by Spray Drying Process

This work concerns the spray drying of probiotic bacteria Lacticaseibacillus rhamnosus GG suspended in a solution of starch, whey protein concentrate, soy lecithin, and ascorbic acid, with additional selected natural plant-origin liquid oils. The aim of this study was to examine these oils and their concentrations (20% and 30%) on bacterial viability during the spray drying (inlet temperature was 180 °C, outlet temperature from 50 to 54 °C, feed rate around 9 mL/min) and storage for 4 weeks at 4 °C and 20 °C, with attempts to explain the protective mechanism in respect including their fatty acid composition. The viability of microencapsulated bacteria, moisture content, water activity, color properties, morphology, particle size of obtained powders, and thermal properties of encapsulated oils were evaluated. The highest viability of bacterial cells after spray drying 83.7% and 86.0%, was recorded with added borage oil respectively with 20% and 30% oil content. This oil has a lower content of oleic and linoleic acid compared to other applied oils, but a high content of both vitamin E and γ- linoleic acid. However, this study did not confirm unambiguously whether and which of the components present in natural plant oils specifically affect the overall viability of bacteria during spray drying.