{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,9]],"date-time":"2026-01-09T00:31:39Z","timestamp":1767918699507,"version":"3.49.0"},"reference-count":32,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2020,8,18]],"date-time":"2020-08-18T00:00:00Z","timestamp":1597708800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"University of Aveiro and FCT\/MCT for the financial support for the QOPNA research Unit (FCT UID\/QUI\/00062\/2019) and Associate Laboratory LAQV-REQUIMTE (UIDB\/50006\/2020) through national founds and, where applicable, co-financed by the FEDER, within the PT","award":["Author Ana C. Ribeiro and \u00c1lvaro T. Lemos are also grateful for the financial support from \u201cFunda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia - FCT\u201d through the fellowship Grant SFRH\/BD\/129540\/2017 and SFRH\/BD\/129848\/2017, respectively."],"award-info":[{"award-number":["Author Ana C. Ribeiro and \u00c1lvaro T. Lemos are also grateful for the financial support from \u201cFunda\u00e7\u00e3o para a Ci\u00eancia e Tecnologia - FCT\u201d through the fellowship Grant SFRH\/BD\/129540\/2017 and SFRH\/BD\/129848\/2017, respectively."]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Foods"],"abstract":"<jats:p>Food fermentation under pressure has been studied in recent years as a way to produce foods with novel properties. The purpose of this work was to study kefir production under pressure (7\u201350 MPa) at different temperatures (17\u201332 \u00b0C), as a case study of unconventional food fermentation. The fermentation time to produce kefir was similar at all temperatures (17, 25, and 32 \u00b0C) up to 15 MPa, compared to atmospheric pressure. At 50 MPa, the fermentation rate was slower, but the difference was reduced as temperature increased. During fermentation, lactic and acetic acid concentration increased while citric acid decreased. The positive activation volumes (Va) obtained indicate that pressure decreased the fermentation rate, while the temperature rise led to the attenuation of the pressure effect (lower Va). On the other hand, higher activation energies (Ea) were observed with pressure increase, indicating that fermentation became more sensitive to temperature. The condition that resulted in a faster fermentation, higher titratable acidity, and higher concentration of lactic acid was 15 MPa\/32 \u00b0C. As the authors are aware, this is the second work in the literature to study the combined effect of pressure and temperature on a fermentative process.<\/jats:p>","DOI":"10.3390\/foods9081133","type":"journal-article","created":{"date-parts":[[2020,8,18]],"date-time":"2020-08-18T11:15:27Z","timestamp":1597749327000},"page":"1133","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["The Combined Effect of Pressure and Temperature on Kefir Production\u2014A Case Study of Food Fermentation in Unconventional Conditions"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-8701-2455","authenticated-orcid":false,"given":"Ana C.","family":"Ribeiro","sequence":"first","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4837-5130","authenticated-orcid":false,"given":"\u00c1lvaro T.","family":"Lemos","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"given":"Rita P.","family":"Lopes","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"given":"Maria J.","family":"Mota","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4347-9878","authenticated-orcid":false,"given":"Rita S.","family":"In\u00e1cio","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"},{"name":"CBQF\u2014Centro de Biotecnologia e Qu\u00edmica Fina, Laborat\u00f3rio Associado, Escola Superior de Biotecnologia, Universidade Cat\u00f3lica Portuguesa, 4200-374 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7883-2446","authenticated-orcid":false,"given":"Ana M. P.","family":"Gomes","sequence":"additional","affiliation":[{"name":"CBQF\u2014Centro de Biotecnologia e Qu\u00edmica Fina, Laborat\u00f3rio Associado, Escola Superior de Biotecnologia, Universidade Cat\u00f3lica Portuguesa, 4200-374 Porto, Portugal"}]},{"given":"S\u00e9rgio","family":"Sousa","sequence":"additional","affiliation":[{"name":"CBQF\u2014Centro de Biotecnologia e Qu\u00edmica Fina, Laborat\u00f3rio Associado, Escola Superior de Biotecnologia, Universidade Cat\u00f3lica Portuguesa, 4200-374 Porto, Portugal"}]},{"given":"Ivonne","family":"Delgadillo","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5536-6056","authenticated-orcid":false,"given":"Jorge A.","family":"Saraiva","sequence":"additional","affiliation":[{"name":"LAQV-REQUIMTE, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2020,8,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"780","DOI":"10.3168\/jds.2012-5753","article-title":"Effects of different fermentation parameters on quality characteristics of kefir","volume":"96","author":"Seydim","year":"2013","journal-title":"J. Dairy Sci."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"451","DOI":"10.1017\/S0022029900024353","article-title":"Methods for making kefir and fermented milks based on kefir","volume":"52","author":"Marshall","year":"1985","journal-title":"J. Dairy Res."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"54","DOI":"10.3923\/pjn.2003.54.59","article-title":"Kefir: A probiotic dairy composition, nutritional and therapeutic aspects","volume":"2","author":"Otles","year":"2003","journal-title":"Pak. J. Nutr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"613","DOI":"10.1016\/j.foodchem.2004.04.021","article-title":"Microbiological, physicochemical, and sensory characteristics of kefir during storage","volume":"90","author":"Irigoyen","year":"2005","journal-title":"Food Chem."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1111\/j.1365-2621.1996.16-316.x","article-title":"Microbiological and rheological studies on Portuguese kefir grains","volume":"31","author":"Pintado","year":"1996","journal-title":"Int. J. Food Sci. Technol."},{"key":"ref_6","first-page":"631","article-title":"Influence of different technological parameters in the evolution of pH during fermentation of kefir","volume":"58","author":"Irigoyen","year":"2003","journal-title":"Milk Sci. Int."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1016\/j.profoo.2011.09.088","article-title":"Effect of incubation temperature and caseinates on the rheological behaviour of kefir","volume":"1","author":"Dimitreli","year":"2011","journal-title":"Procedia Food Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"593","DOI":"10.1016\/S0268-005X(01)00090-X","article-title":"Effect of fermentation temperature on the rheology of set and stirred yogurt","volume":"15","author":"Haque","year":"2001","journal-title":"Food Hydrocoll."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"456","DOI":"10.1016\/j.anaerobe.2011.06.007","article-title":"Effect of non-thermal processing by high ydrostatic pressure on the survival of probiotic microorganisms: Study on Bifidobacteria spp.","volume":"7","author":"Tsevdou","year":"2011","journal-title":"Anaerobe"},{"key":"ref_10","unstructured":"Vieira, A.P.P. (2019). Estudo da Conserva\u00e7\u00e3o e Caracteriza\u00e7\u00e3o de um Iogurte Fermentado sob Press\u00e3o. [Master\u2019s Thesis, University of Aveiro]."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"445","DOI":"10.1007\/s00792-006-0054-x","article-title":"In situ monitoring by quantitative Raman spectroscopy of alcoholic fermentation by Saccharomyces cerevisiae under high pressure","volume":"11","author":"Picard","year":"2007","journal-title":"Extremophiles"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"424","DOI":"10.1016\/j.foodres.2018.07.034","article-title":"Lactobacillus reuteri growth and fermentation under high pressure towards the production of 1,3-propanediol","volume":"113","author":"Mota","year":"2018","journal-title":"Food Res. Int."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"906","DOI":"10.1016\/j.procbio.2015.03.016","article-title":"Probiotic yogurt production under high pressure and the possible use of pressure as an on\/off switch to stop\/start fermentation","volume":"50","author":"Mota","year":"2015","journal-title":"Process Biochem."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"222","DOI":"10.1016\/j.foodres.2019.04.010","article-title":"Combined effect of pressure and temperature for yogurt production","volume":"122","author":"Lopes","year":"2019","journal-title":"Food Res. Int."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"423","DOI":"10.1016\/j.lwt.2018.09.074","article-title":"Physicochemical and microbial changes in yogurts produced under different pressure and temperature conditions","volume":"99","author":"Lopes","year":"2019","journal-title":"LWT"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1007\/s00253-004-1554-1","article-title":"Metabolic selectivity and growth of Clostridium thermocellum in continuous culture under elevated hydrostatic pressure","volume":"65","author":"Bothun","year":"2004","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"2847","DOI":"10.1016\/j.febslet.2005.03.100","article-title":"Adaptation of Saccharomyces cerevisiae to high hydrostatic pressure causing growth inhibition","volume":"579","author":"Iwahashi","year":"2005","journal-title":"FEBS Lett."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2093","DOI":"10.1007\/s00253-012-4356-x","article-title":"High hydrostatic pressure activates gene expression that leads to ethanol production enhancement in a Saccharomyces cerevisiae distillery strain","volume":"97","author":"Bravim","year":"2013","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"87","DOI":"10.1080\/0895795031000147858","article-title":"Influence of high pressure on some biochemical properties of kefir microflora (effect of HPP on kefir microflora)","volume":"23","author":"Jankowska","year":"2003","journal-title":"High Press. Res."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/S0958-6946(01)00038-3","article-title":"Deactivating the bacteria and yeast in kefir using heat treatment, irradiation and high pressure","volume":"11","author":"Mainville","year":"2001","journal-title":"Int. Dairy J."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Chandan, R.C., and Kilara, A. (2006). Manufacturing Yogurt and Fermented Milks, Blackwell Publishing. [1st ed.].","DOI":"10.1002\/9780470277812"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"426","DOI":"10.1021\/ac60147a030","article-title":"Use of dinitrosalicylic acid reagent for determination of reducing sugar","volume":"31","author":"Miller","year":"1959","journal-title":"Anal. Chem."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"162","DOI":"10.1016\/j.talanta.2016.01.061","article-title":"Simultaneous analysis of carbohydrates and organic acids by HPLC-DAD-RI for monitoring goat\u2019s milk yogurts fermentation","volume":"152","author":"Costa","year":"2016","journal-title":"Talanta"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"307","DOI":"10.1111\/j.1574-6968.1995.tb07736.x","article-title":"Hydrostatic pressure promotes the acidification of vacuoles in Saccharomyces cerevisiae","volume":"130","author":"Abe","year":"1995","journal-title":"FEMS Microbiol. Lett."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"49","DOI":"10.1016\/S0076-6879(82)90106-9","article-title":"Phosphofructokinase from Yeast","volume":"90","author":"Hofmann","year":"1982","journal-title":"Methods Enzym."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"2660","DOI":"10.1128\/AEM.70.5.2660-2666.2004","article-title":"Heat shock protein-mediated resistance to high hydrostatic pressure in Escherichia coli","volume":"70","author":"Aertsen","year":"2004","journal-title":"Appl. Environ. Microbiol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"e12332","DOI":"10.1111\/jfpe.12332","article-title":"Kefir grain biomass production: Influence of different culturing conditions and examination of growth kinetic models","volume":"40","author":"Apar","year":"2017","journal-title":"J. Food Process. Eng."},{"key":"ref_28","first-page":"365","article-title":"Some physicochemical analyses of kefir produced under different fermentation conditions","volume":"70","author":"Ismaiel","year":"2011","journal-title":"J. Sci. Ind. Res."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1241","DOI":"10.1007\/s11274-009-0294-x","article-title":"Microbial communities and chemical changes during fermentation of sugary Brazilian kefir","volume":"26","author":"Pereira","year":"2010","journal-title":"World J. Microbiol. Biotechnol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1111\/j.1365-2672.1996.tb03286.x","article-title":"Irish kefir-like grains: Their structure, microbial composition and fermentation kinetics","volume":"81","author":"Rea","year":"1996","journal-title":"J. Appl. Bacteriol."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"529","DOI":"10.1016\/S0958-6946(03)00058-X","article-title":"Production of volatile aroma compounds by kefir starter cultures","volume":"13","author":"Beshkova","year":"2003","journal-title":"Int. Dairy J."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1517","DOI":"10.3168\/jds.2014-8755","article-title":"Manufacture and characterization of kefir made from cow and buffalo milk, using kefir grain and starter culture","volume":"98","author":"Gul","year":"2015","journal-title":"J. Dairy Sci."}],"container-title":["Foods"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2304-8158\/9\/8\/1133\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T10:02:23Z","timestamp":1760176943000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2304-8158\/9\/8\/1133"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2020,8,18]]},"references-count":32,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2020,8]]}},"alternative-id":["foods9081133"],"URL":"https:\/\/doi.org\/10.3390\/foods9081133","relation":{},"ISSN":["2304-8158"],"issn-type":[{"value":"2304-8158","type":"electronic"}],"subject":[],"published":{"date-parts":[[2020,8,18]]}}}