Optimisation Of Microbiological, Physicochemical And Textural Quality Attributes Of Goat’s Milk Kefir
Citation (APA 7)
Ayed, M., Gonzales-Barron, U., & Cadavez, V. (2024). Optimisation Of Microbiological, Physicochemical And Textural Quality Attributes Of Goat’s Milk Kefir. 16th AgroStat Conference (AgroStat 2024), Bragança, Portugal. ISBN: 978-972-745-344-3. https://doi.org/10.5281/zenodo.14761360
Abstract
Kefir is a popular probiotic drink known for its fermented, acidic, and slightly alcoholic properties. This study aimed to determine key processing variables, namely, the ratio of kefir grains/milk, incubation temperature, and incubation time, that optimise the quality of goat’s pasteurised milk kefir. AgroStat 2024, Portugal 21 Fourteen kefir treatments built upon three grain/milk ratios (0.5%, 1%, and 1.5%), three incubation times (16 h, 20 h, and 24 h), and three incubation temperatures (15 °C, 20 °C, 25 °C) were carried out, according to a Box-Behnken design with three central points, to determine the best triplet variables regarding these properties: pH, acidity (% of lactic acid), syneresis (%), mesophiles and lactic acid bacteria concentration, firmness, consistency, cohesiveness and viscosity index. Response surface analysis was applied to each of the quality attributes. It was found that all the quality properties were affected by the three factors, having in all cases significant effects (p<0.05) for the first-order estimation. Kefir acidity was maximised at 0.66%, 25.3 ºC, and 22.8 h; although the temperature had a much greater effect than time, and in turn, the latter had a greater effect than the grains/milk ratio. In terms of the textural properties, firmness, and viscosity index could be maximised at the conditions of 1.07%, 19.9 ºC, and 17.4 h; and 1.28%, 18.5 ºC, and 20.4 h, respectively. At an incubation temperature of 25 ºC, the syneresis was found between 38.5 – 39.9%; the lower (4.46 – 4.49%) was attained at 15 ºC. Lower incubation temperatures or longer incubation times can also produce kefir with the desired acidity and textural quality of hardness and consistency, only if the ratio is increased (>1.0%). Thus, this study has been instrumental in understanding the effects of the three key processing variables and helped in the determination of the variables to obtain goat’s milk kefir of good technological quality for subsequent studies.
Keywords: Kefir grains; Box-Behnken; Acidity; Hardness; Viscosity; Lactic