The dual effect of shellac on survival of spray-dried Lactobacillus rhamnosus GG microcapsules

Authors: YIN, MING - Jiangnan University; YUAN, YONGKAI - Jiangnan University; CHEN, MAOSHEN - Jiangnan University; LIU, FEI - Jiangnan University; SAQIB, MD - Jiangnan University; Chiou, Bor-Sen; ZHONG, FANG - Jiangnan University

Submitted to: Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/18/2022
Publication Date: 4/18/2022
Citation: Yin, M., Yuan, Y., Chen, M., Liu, F., Saqib, M., Chiou, B., Zhong, F. 2022. The dual effect of shellac on survival of spray-dried Lactobacillus rhamnosus GG microcapsules. Food Chemistry. 389. Article 132999. https://doi.org/10.1016/j.foodchem.2022.132999.
DOI: https://doi.org/10.1016/j.foodchem.2022.132999

Interpretive Summary: Probiotic bacteria have low survival rates in food systems due to moisture sorption during storage. In this study, we added shellac, a hydrophobic material, to whey protein isolate for use as encapsulants to protect probiotic bacteria during storage. We used spray drying to encapsulate the bacteria and then stored them under different humidity conditions. The addition of shellac led to a decrease in survival rates of the bacteria during spray drying. However, samples containing shellac improved bacteria survival during storage under moderate and high humidity conditions. These results indicated that the incorporation of shellac can be used to improve survival of probiotic bacteria during storage.

Technical Abstract: Heat shock and hygroscopicity are two main factors that resulted in low viability of probiotics in spray-dried microcapsules. Hydrophobic polyester shellac was combined with whey protein isolate (WPI) to solve this problem. The results suggest that although the survival rate after drying decreased from 94.15% to 64.85% with increased shellac to WPI ratio, the 1:1 shellac-WPI provided the best protection among all samples during storage. The consistence between moisture-adsorption-isotherm and bacterial inactivation kinetics confirmed the moisture barrier effect of shellac under moderate humidity. Dynamic vapor absorption and morphology tests revealed that shellac addition reduced the drying rate and glass transition temperature of microcapsule, which in turn decreased the membrane integrity and growth capability of the probiotics right after drying. This study revealed the positive-negative dual effect of hydrophobic material on instant and long-term survival of spray-dried probiotic microcapsules, provided new sight to the design of composite wall materials.