Thermotolerance, Survival, and Stability of Lactic Acid Bacteria After Spray Drying as Affected by the Increase of Growth Temperature
2021
Hao, Fan | Fu, Nan | Ndiaye, Hamadel | Woo, Meng Wai | Jeantet, Romain | Chen, Xiao Dong | FoodPRINT International Associated Laboratory INRAE, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science ; Soochow University | Department of Chemical &Materials Engineering ; University of Auckland [Auckland] | Science et Technologie du Lait et de l'Oeuf (STLO) ; Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-INSTITUT AGRO Agrocampus Ouest ; Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro) | This work was supported by the Natural Science Foundation of China (grant numbers 31601513), Jiangsu AgricultureScience and Technology Innovation Fund (JASTIF, grant number CX(20)3048), the National Key Research and Development Program of China (project number 2016YFE0101200, International S&T Cooperation Program, ISTCP), and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions. The first author thanks Miss YanWang for fruitful discussion on the cultivation of L. cremoris.
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Show more [+] Less [-]English. Microencapsulation of lactic acid bacteria (LAB) via spray drying differs from that of common bioactive substances in that theintrinsic stress tolerance of cells can be modulated to improve cell survival. In this study, elevated growth temperatures that were 3–5 °C above the standard conditions were used to culture Lactococcus lactis subsp. cremoris, Lactobacillus rhamnosus GG (LGG), and Lactobacillus acidophilus for spray drying. The heat-adapted cultures showed lower bacterial population than the controls by 0.45 log at stationary growth phase and produced lactobacilli cells with elongated shape, while their metabolic activities were maintained similar to the controls. Heat-adapted L. cremoris and LGG demonstrated increases in survival by 0.7– 1.5 log and 0.3 log, respectively, after heat treatment at 60 °C. The thermotolerance of L. acidophilus grown at 42 °C was dependent on growth phase, and the culture entered death phase within 24 h of incubation. The survival of heat-adapted L.cremoris and L. acidophilus after spray drying was increased by 21.0% and 13.7%, respectively, whereas the increase shown by LGG was relatively insignificant (9.9%). Spray-dried powders containing heat-adapted cells showed substantial reduction of viability at the first week of storage, reaching 1.03–1.23 log, compared to 0.87–0.90 log of reduction shown by the controls. The findings demonstrated that strain-specific cellular response toward variations in growth conditions is crucial to the intrinsic properties of LAB and to cell survival during spray drying and storage. Controlling cellular response is one of the key factors in developing a viable spray drying scheme for active LAB.
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