en Nutrition Nutrition پژوهشي Research <p><strong>Background and Objectives: </strong>The purpose of the present study was to investigate effects of various heat shock conditions and fast freezing and subsequent thawing on the viability and recovery of <em>Bacillus coagulans </em>and<em> Bacillus subtilis </em>as probiotic sporeformers, and also to compare spore plate and microscopic counts.</p> <p><strong>Materials and Methods: </strong>After preparing the final suspensions of<em> B. coagulans </em>and<em> Bacillus subtilis subsp. Natto </em>spores, they were spread-plated before and after fast freezing treatment (-70&deg;C for about 1 min). Heat shock treatments of the spores were carried out at 68^oC for 15, 20, and 30 min as well as at 80^oC for 10 and 15 min. Concentrations of the examined probiotic sporeformers were determined simultaneously by plate enumerations and microscopically determined counts. Student&rsquo;s t-test and one-way analysis of variance (ANOVA) of SPSS were used for statistical analysis of the data. Analysis of DoE results was carried out using Minitab.</p> <p><strong>Results: </strong>The results presented here show that the highest recovery rates for <em>B. coagulans</em> (14.75 log CFU/mL) and <em>B. subtilis </em>spores (14.80 log CFU/mL) were under a heat shock condition of 68&deg;C for 20 min in nutrient agar (p<0.05). In addition, the survival rates of<em> B. coagulans</em> and <em>B. subtilis </em>spores under the fast freezing and subsequent thawing condition were about 90% and 88%, respectively. Plate counts differed significantly from counts determined microscopically, with differences of almost 0.5 and 0.8 log for <em>B. coagulans </em>and <em>B. subtilis </em>spores, respectively (p<0.05). In addition, DoE results of the study revealed that both factors of spore count method and only freezing factor in fast freezing treatment have a significant effect on concentrations of the spores examined (p<0.05).</p> <p><strong>Conclusions: </strong>Heat shock conditions, freezing and subsequent thawing circumstances, and plate counts or enumerations determined microscopically have significant influences on the viability of probiotic sporeformers and should be considered in determining of their accurate concentrations.</p> B. coagulans, B. subtilis, Freezing, Heat shock, Probiotic sporeformers 35 42 http://nfsr.sbmu.ac.ir/browse.php?a_code=A-10-445-1&slc_lang=en&sid=1 Mojtaba Jafari Jafari_mojtaba@yahoo.com 10031947532846003045 10031947532846003045 No PhD student in Food Science and Technology, Department of Food Science and Technology, Faculty of Nutrition Sciences and Food Technology, International Branch, Shahid Beheshti University of Medical Sciences, Student’s Research Committee, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Masoud Alebouyeh 10031947532846003046 10031947532846003046 No Foodborne and Waterborne Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Science, Tehran, Iran. Amir Mohammad Mortazavian mortazvn@sbmu.ac.ir 10031947532846003047 10031947532846003047 Yes Department of Food Science and Technology, Faculty of Nutrition Sciences, Food Science and Technology/National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Hedayat Hosseini* hedayat@sbmu.ac.ir 10031947532846003048 10031947532846003048 No Department of Food Science and Technology, Faculty of Nutrition Sciences, Food Science and Technology/National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Kiandokht Ghanati 10031947532846003049 10031947532846003049 No 5- Head Research Center, International Branch, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Zohre Amiri 10031947532846003050 10031947532846003050 No Department of Basic Sciences, Faculty of Nutrition Sciences, Food Science and Technology/National Nutrition and Food Technology Research Institute, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Mohammad Reza Zali 10031947532846003051 10031947532846003051 No Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Science, Tehran, Iran.