Encapsulation improves viability and stability of spray-dried Lactococcus lactis A12 for inclusion in fish feed

Abstract

During probiotics manufacturing, drying is a crucial process for stabilization of probioticsafter fermentation, since drying condition could affect viability and functionalityas well as physical properties such as moisture content and water activity, which playkey role in stability of dried probiotics during storage. Therefore, this study aimed toevaluate the effect of spray-drying parameters on the survival of Lactococcus lactisA12 after drying and exposure to gastrointestinal conditions. A combined mixture-processdesign was carried out by evaluating three factors: whey (10–30% w/v),maltodextrin (10–30% w/v), and atomization pressure (1.0–1.5 bar). As the mainresults, a high concentration of whey (30% w/v), low concentration of maltodextrin(10% w/v), and high atomization pressure (1.4 bar) improved survival of spray-driedL. lactis A12 after drying and exposure to pH 3.00 or bile salts with survival ratesranged within 69.25 to 86.24%, 65.89–98.93%, and 89.09–100%, respectively.Under optimal conditions, spray-dried probiotic powder with wall materials (encapsulated)exhibited higher glass transition temperature (64.44 vs 12.65 °C), and lowerhygroscopicity (12.65 vs 64.44%) than spray-dried probiotic without wall materials(non-encapsulated). Moreover, SD probiotic powder exhibited the highest survivalrate (85.88%) at 4 °C during 60 days of storage in comparison to 25 °C and 37 °Cwhich did not survive. Finally, spray-dried L. lactis A12 was included in fish feed andexhibited a survival rate of 80.83% when it was stored at 4 °C after 60 days. It can beconcluded that the use of encapsulating materials, particularly whey and maltodextrin,improved the physical and thermal stability of L. lactis A12 powder during dryingand storage. Also, the results from the stability of supplemented fish feed suggestedthat L. lactis A12 could be included in fish feed.