Determination of Ethanol and Lactic Acid Content from Goat Milk Kefir Fermentation
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Annisa Utami, Anny Sartika Daulay, Ridwanto Ridwanto, Ainil Fithri Pulungan (2026). Determination of Ethanol and Lactic Acid Content from Goat Milk Kefir Fermentation. Journal of Pharmaceutical and Sciences, JPS Volume 9 Nomor 3 (2026). https://doi.org/10.36490/journal-jps.com.v9i3.1812
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Abstract
Goat-milk kefir contains lactic acid and ethanol formed through the symbiotic metabolism of lactic acid bacteria and yeasts; however, information on their changes during prolonged fermentation remains limited. This study aimed to characterize ethanol accumulation during six days of goat-milk kefir fermentation and to determine lactic acid after 24 h. Goat milk (250 mL) was heated at 75 °C, inoculated with 4% (w/v) kefir grains, and fermented at 25 ± 2 °C. Ethanol was screened using iodoform, acidified potassium dichromate, and esterification reactions, followed by visible spectrophotometric quantification at 443 nm after Conway microdiffusion. Lactic acid was quantified using HPLC-UV at 210 nm with 50 mM phosphate buffer (pH 2.8), a flow rate of 1 mL/min, and an injection volume of 20 µL. The pH decreased from 4.19 on day 1 to 2.15 on day 6, while ethanol increased from 0.227 to 0.657 g/dL (p<0.001). Commercial kefir contained 0.453 g/dL ethanol. The ethanol and lactic-acid calibration models showed R² values of 0.996; lactic acid in 24-h kefir was 3.923%. Prolonged fermentation therefore produced progressive acidification accompanied by ethanol accumulation, with the greatest change occurring during the first three days. These findings establish fermentation time as an important determinant of the metabolite profile of goat-milk kefir and provide a basis for subsequent studies using independent fermentation batches and fully validated analytical methods.
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Fiorda FA, de Melo Pereira GV, Thomaz-Soccol V, Rakshit SK, Pagnoncelli MGB, Vandenberghe LPS, et al. Microbiological, biochemical, and functional aspects of sugary kefir fermentation—A review. Food Microbiol. 2017;66:86–95. doi:10.1016/j.fm.2017.04.004.
Bengoa AA, Iraporda C, Garrote GL, Abraham AG. Kefir micro-organisms: their role in grain assembly and health properties of fermented milk. J Appl Microbiol. 2019;126:686–700. doi:10.1111/jam.14107.
Sánchez-Rodríguez R, Terriente-Palacios C, García-Olmo J, Osorio S, Rodríguez-Ortega MJ. Combined metabolomic and NIRS analyses reveal biochemical and metabolite changes in goat milk kefir under different heat treatments and fermentation times. Biomolecules. 2024;14:816. doi:10.3390/biom14070816.
Azizi NF, Kumar MR, Yeap SK, Abdullah JO, Khalid M, Omar AR, et al. Kefir and its biological activities. Foods. 2021;10:1210. doi:10.3390/foods10061210.
M’hir S, et al. Comparison of milk kefirs obtained from cow’s, ewe’s and goat’s milk: antioxidant role of microbial-derived exopolysaccharides. Antioxidants. 2024;13:335. doi:10.3390/antiox13030335.
Park YW, Juárez M, Ramos M, Haenlein GFW. Physico-chemical characteristics of goat and sheep milk. Small Rumin Res. 2007;68:88–113. doi:10.1016/j.smallrumres.2006.09.013.
Ranadheera CS, Naumovski N, Ajlouni S. Non-bovine milk products as emerging probiotic carriers. Int Biodeterior Biodegradation. 2018;131:1–7. doi:10.1016/j.ibiod.2018.01.009.
Walsh AM, Crispie F, Kilcawley K, O’Sullivan O, O’Sullivan MG, Claesson MJ, et al. Microbial succession and flavor production in the fermented dairy beverage kefir. mSystems. 2016;1:e00052-16. doi:10.1128/mSystems.00052-16.
Dertli E, Çon AH. Microbial diversity of traditional kefir grains and their role on kefir aroma. LWT. 2017;85:151–157. doi:10.1016/j.lwt.2017.07.017.
Prado MR, Blandón LM, Vandenberghe LPS, Rodrigues C, Castro GR, Thomaz-Soccol V, et al. Milk kefir: composition, microbial cultures, biological activities, and related products. Front Microbiol. 2015;6:1177. doi:10.3389/fmicb.2015.01177.
Leite AMO, Miguel MAL, Peixoto RS, Rosado AS, Silva JT, Paschoalin VMF. Microbiological, technological and therapeutic properties of kefir: a natural probiotic beverage. Braz J Microbiol. 2013;44:341–349. doi:10.1590/S1517-83822013000200001.
Rusdhi A, Siswoyo P, Adelia T. Test the chemical quality of kefir from goat’s milk and cow’s milk with different fermentation times. J Pharm Sci. 2023;6:1626–1634. doi:10.36490/journal-jps.com.v6i4.284.
Wulansari PD, Widodo, Sunarti, Nurliyani. Physicochemical, microbiological, and sensory evaluation of kefir produced from goat milk containing Lacticaseibacillus casei AP and/or oat milk during storage. Food Sci Technol. 2023;43:e127322. doi:10.5327/fst.127322.
Setiawati L, Rizqiati H, Susanti DS. Analisis rendemen, kadar alkohol, nilai pH dan total BAL pada kefir whey susu kambing dengan lama fermentasi yang berbeda. J Teknol Pangan. 2019;3:1–6.
Wihenti HR, Susanti S, Nurwantoro, Al-Baarri AN, Slamet YB. Pengaruh waktu fermentasi terhadap sifat fisikokimia kefir whey dari susu kambing. Warta IHP. 2021;38:54–60.
Sari M, Fajar N. Analisis kualitatif dan kuantitatif kandungan alkohol pada tapai ketan di Kota Batusangkar. Sainstek. 2018;10:33–36.
Nahak BRH, Aliah AI, Karim SF. Analisis kadar alkohol pada minuman beralkohol tradisional (arak) dengan metode spektrofotometri UV-Vis. J Sains Kesehat. 2021;3:448–454. doi:10.25026/jsk.v3i4.360.
Milagres MP, Brandão SCC, Magalhães MA, Minim VPR. Development and validation of the high performance liquid chromatography-ion exclusion method for detection of lactic acid in milk. Food Chem. 2012;135:1078–1082. doi:10.1016/j.foodchem.2012.05.047.
Chen YF, Wang JC, Yun ZY, Zhang HP. Study on organic acids in traditionally fermented milk by HPLC. China Dairy Ind. 2007;35:54–58.
International Council for Harmonisation. ICH Q2(R2): Validation of analytical procedures. Geneva: ICH; 2023.
Rutkowska J, Antoniewska-Krzeska A, Żbikowska A, Cazón P, Vázquez M. Volatile composition and sensory profile of lactose-free kefir. Molecules. 2022;27:5386. doi:10.3390/molecules27175386.
Bourrie BCT, Willing BP, Cotter PD. The microbiota and health promoting characteristics of the fermented beverage kefir. Front Microbiol. 2016;7:647. doi:10.3389/fmicb.2016.00647.
Rosa DD, Dias MMS, Grześkowiak ŁM, Reis SA, Conceição LL, Peluzio MCG. Milk kefir: nutritional, microbiological and health benefits. Nutr Res Rev. 2017;30:82–96. doi:10.1017/S0954422416000275.
Marsh AJ, O’Sullivan O, Hill C, Ross RP, Cotter PD. Sequence-based analysis of the bacterial and fungal compositions of multiple kefir grains and milks. PLoS One. 2013;8:e69371. doi:10.1371/journal.pone.0069371.
Farag MA, Jomaa SA, El-Wahed AA, El-Seedi HR. The many faces of kefir fermented dairy products: quality characteristics, flavour chemistry, nutritional value, health benefits, and safety. Nutrients. 2020;12:346. doi:10.3390/nu12020346.
Alraddadi FAJ, Ross T, Powell SM. Evaluation of the microbial communities in kefir grains and kefir over time. Int Dairy J. 2023;136:105490. doi:10.1016/j.idairyj.2022.105490.
Ströher JA, Oliveira WDC, de Freitas AS, Salazar MM, da Silva LDFF, Bresciani L, et al. A global review of geographical diversity of kefir microbiome. Fermentation. 2025;11:150. doi:10.3390/fermentation11030150.
Wang Y, Wang Z, Yu Y. Kefiran production by Lactobacillus kefiranofaciens under conditions mimicking yeast activities in kefir grains. Front Microbiol. 2023;14:1236634. doi:10.3389/fmicb.2023.1236634.
De Souza HF, Monteiro GF, Bogáz LT, Freire ENS, Pereira KN, de Carvalho MV, et al. Bibliometric analysis of water kefir and milk kefir in probiotic foods from 2013 to 2022: a critical review of recent applications and prospects. Food Res Int. 2024;175:113716. doi:10.1016/j.foodres.2023.113716.
Kurniawan R, et al. Kefir as a functional probiotic: microbial composition and therapeutic potential. Front Food Sci Technol. 2025;5:1725280. doi:10.3389/frfst.2025.1725280.