Research Article Stability of Encapsulated Lactobacillus reuteri during Harsh Conditions, Storage Period, and Simulated In Vitro Conditions Abdolazim Soltani Lak , 1 Mohammad Hossein Marhamatizadeh , 1 and Hossein Fattahi 2 1 Department of Food Hygiene, Faculty of Veterinary Medicine, Kazeroon Branch, Islamic Azad University, Kazeroon, Iran 2 Department of Microbiology, Faculty of Veterinary Medicine, Kazeroon Branch, Islamic Azad University, Kazeroon, Iran Correspondence should be addressed to Mohammad Hossein Marhamatizadeh; drmarhamati@gmail.com Received 7 May 2021; Revised 25 June 2021; Accepted 15 October 2021; Published 23 October 2021 Academic Editor: Muhammad Imran Copyright © 2021 Abdolazim Soltani Lak et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Viability of probiotics in the foods and human bodies is important, because a certain minimum count of bacteria is necessary to impose health promoting effects. In the present work, we encapsulated Lactobacillusreuteri within whey protein isolate (WPI), soy protein isolate (SPI), WPI + inulin (WPI4I), and SPI + inulin (SPI4I) through spray drying method and investigated the efficiency of the microcapsules on the protection of the cells under different conditions (heat, salt, bile salt, penicillin, pH, simulated gastrointestinal condition, and storage). e particle size of the samples was in the range of 195.2–358.1nm. e sensitivity of unencapsulated bacteria to heat was considerably higher than that to the encapsulated bacteria, so that, at 80 ° C, no growth (of unencapsulated type) was observed. At 60 ° C and 40 ° C, the cell count of free bacteria decreased to 5.81 and 8.04log CFU/mL, respectively. e bacteria encapsulated within SPI4I showed the highest viability at these temperatures. A comparison between the effects of different pH values showed pH 1.5 more lethal than 2.5 and 7. e effect of NaCl at 4% concentration on decreasing the bacterial count was more notable than 2%. However, the used wall materials in all conditions resulted in higher viability of the cells compared to the free cells. Among different types of wall materials, it was observed that WPI4I imposed the best protective effect. e higher viability of cells within WPI4I wall material was also observed during the storage time. e viability of encapsulated cells decreased from 10.35 to 10.40 log CFU/g in the first week and to 8.93–9.23 log CFU/g in the last week of storage. 1. Introduction Probiotic foods are a kind of functional foods containing living microorganisms (M.Os) that can induce health bene- ficial effects on human [1, 2]. Based on the report of FAO and WHO, the minimum count of live probiotic M.Os in the foods to be effective on health status is 10 6 –10 7 CFU per g [3]. ese M.Os should reach their appropriate site of operation in the gastrointestinal track (GI) to efficiently apply their positive impacts; however, their survival in the GI and against food processing (especially about Lactobacilli strains) is low [4–6]. Scientists are looking for methods to enhance the via- bility of probiotic M.Os in an adequate count in the food products and during processing conditions until reaching human body. Using the probiotics in microcapsules, which can protect them against harsh conditions, is among the proposed methods [7–9]. ere are reports on survival of probiotic M.Os in a protected state in temperature range of 40–65 ° C [10, 11]. In the present work, the viability of the probiotic M.O, Lactobacillus reuteri, in the free and en- capsulated (within different wall materials) forms was in- vestigated against heat treatment, acidic pH, and high salt concentration, as well as in the presence of chemical sub- stances and during the storage period. 2. Material and Methods 2.1. Material. WPI and SPI were bought from Hilmar (USA), and inulin was purchased from Sensus (Lawrence- ville, NJ, USA). LiCl, NaCl, HCl, NaOH, Lactobacilli de Man Hindawi Journal of Food Quality Volume 2021, Article ID 3872190, 9 pages https://doi.org/10.1155/2021/3872190