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Processes 2019, 7(3), 127;

Effect of the Freeze-Drying Process on the Physicochemical and Microbiological Properties of Mexican Kefir Grains

Instituto Tecnológico de Orizaba, División de Estudios de Posgrado e Investigación, Oriente 9 No. 852 Orizaba, Veracruz 94320, Mexico
Instituto de Ciencias Básicas, Universidad Veracruzana, Dr. Luis Castelazo s/n. Col. Industrial Animas Xalapa, Veracruz 91000, Mexico
Author to whom correspondence should be addressed.
Received: 26 December 2018 / Revised: 15 February 2019 / Accepted: 16 February 2019 / Published: 1 March 2019
(This article belongs to the Section Biological Systems)
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The purpose of this study was to investigate how the properties of Mexican kefir grains (MKG) are affected by the operating parameters used in the freeze-drying process. The factors investigated were the freezing time (3–9 h), freezing temperature (−20 to −80 °C), pressure (0.2–0.8 mbar), and lyophilization time (5–20 h). The maximum range of change and one-way analysis of variance showed that lyophilization time and freezing time significant affects (p < 0.05) the response variables, residual moisture content and water activity, and pressure had a significant effect on the color difference and survival rate of probiotic microorganisms. The best drying conditions were a freezing time of 3 h, a freezing temperature of −20 °C, a pressure of 0.6 mbar, and a lyophilization time of 15 h. Under these conditions, we obtained a product with residual moisture content below 6%, water activity below 0.2, and survival rates above 8.5 log cfu per gram of lactic acid bacteria and above 8.6 log for yeast. View Full-Text
Keywords: freeze-drying; operating parameters; properties; kefir grains; probiotic freeze-drying; operating parameters; properties; kefir grains; probiotic

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This 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 (CC BY 4.0).

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Conde-Islas, A.Á.; Jiménez-Fernández, M.; Cantú-Lozano, D.; Urrea-García, G.R.; Luna-Solano, G. Effect of the Freeze-Drying Process on the Physicochemical and Microbiological Properties of Mexican Kefir Grains. Processes 2019, 7, 127.

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