Fermented mare milk product (Qymyz, Koumiss)

International audienceMare milk has been consumed for thousands of years in Central Asia and neighbouring regions. Its composition is similar to human milk, but different from cows’ milk. Fermentation with lactic acid bacteria and yeasts leads to the production of a traditional drink called qymyz. Qymyz, which is a symbol of good health, is a central part of the national cuisine and of the traditional cycle of horse husbandry, as well as playing a role in the cultural identity of Central Asian people. Mare milk, along with qymyz, has been reported to have a wide range of therapeutic effects. In this article, the authors have compiled information on mare milk composition, qymyz production and the therapeutic effects of mare milk and its products

Detection of milk fat adulteration in commercial butter and sour cream

Background and Objective: Adulteration of dairy products by substitution of milk fat by vegetable oil is common in the Eurasian Economic Union. The objective of the paper is to investigate the potential adulteration of the fat and to test the more convenient methods of detection, i.e., determination of fatty acids or sterols profiles in commercial butter and cream. Materials and Methods: Ten samples of commercial butter and 8 samples of commercial sour cream were collected on the national market of Kazakhstan. The analyses involved the original sour cream and butter without any modification (deep-freezing) and were achieved within the shelf-life period. The fatty acid composition was analyzed by GS-FID and Sterol fractions were analyzed by GS-MS. Statistical analysis was achieved by principal components analysis (PCA), Pearson types, Kruskal-Wallis test. Results: Sixty percent of the butter samples contained traces of phytosterols and one sample contained up to 78% $-sitosterol. In sour cream samples, only three contained 100% cholesterol while two contained more than 60% sitosterol. The detection of fat adulteration by analyzing the fatty acids patterns is convenient in case of massive substitution of milk fat, but a discrete substitution does not modify the fatty acids profiles leading to misinterpretation. Conclusion: The results exhort to give preference to sterol profile determination as an official method to detect fat adulteration in dairy products. This is even more important as the current standard used in Central Asia based on some fatty acids ratios can lead to incorrect conclusions

Growth and Metabolism of Lacticaseibacillus casei and Lactobacillus kefiri Isolated from Qymyz, a Traditional Fermented Central Asian Beverage

International audienceThe growth characteristics of two strains of lactic acid bacteria (LAB), Lacticaseibacillus casei and Lactobacillus kefiri, isolated from qymyz, a traditional fermented mare milk beverage, were studied and modeled, including the effect of different carbohydrates, pH, and temperature. Along with population, substrates, and metabolites, lactic acid and ethanol were monitored by HPLC. Growth parameters were obtained from mono- and biphasic logistic growth models that fit the population evolution of L. casei and L. kefiri, respectively. The effect of temperature and pH on the growth rate was represented with the gamma concept model, while the effect of the limiting substrate was evaluated according to the Monod equation. Lastly, a simplified Luedeking and Piret equation was used to represent metabolite production. The optimum values of pH and temperature were 6.69 ± 0.20, 38.63 ± 0.32 °C, 5.93 ± 0.08, and 33.15 ± 0.53 °C, with growth rate values of 0.66 ± 0.01 h−1 and 0.29 ± 0.01 h−1 for L. casei and L. kefiri, respectively. L. casei had a homofermentative pathway, while L. kefiri was heterofermentative, with an ethanol production rate of 2.90 × 10−9 mg·CFU−1. The Monod model showed that L. casei had the lowest Ks value for lactose, while for L. kefiri, it was the highest among milk carbohydrates. These results show that the population of the two LAB strains and therefore the concentrations of acid and ethanol can be controlled by the fermentation conditions and that our model can help to significantly improve the production of qymyz

Comparative study of fatty acid and sterol profiles for the investigation of potential milk fat adulteration

International audienceMilk fat adulteration is a common issue in Central Asia. To assess the current situation in the commercial milk market, 17 milk samples were checked for fatty acid (FA) and sterol profiles to detect potential adulteration using multivariate analysis. Analysis of FA and sterols was performed using gas chromatography with flame ionization detection and gas chromatography with mass-spectrometric detection, respectively. Cluster analysis of FA profiles revealed 3 types of milk samples: (1) samples containing a higher proportion of short-chain FA, (2) samples containing a higher proportion of long-chain FA, and (3) samples with significant amounts of C18 FA. Analysis of sterols showed that samples included (1) milk fat containing 100% cholesterol, sometimes with traces of phytosterols, (2) milk fat with high proportions of beta-sitosterol and campesterol, and (3) milk fat containing high proportions of brassicasterol. We found significant relationships between FA profiles and sterol profiles. The profiles were compared with vegetable oil patterns reported in the literature. More than 50% of the samples appeared to be counter-feited. We conclude that identification of adulteration in milk can be based solely on determination of sterol patterns

Growth Kinetics of <i>Kazachstania unispora</i> and Its Interaction with Lactic Acid Bacteria during Qymyz Production

Qymyz is a traditional acidic and ethanolic beverage in central Asian countries made from mare milk fermentation with lactic acid bacteria (LAB) and yeasts. Modeling the growth of microorganisms during fermentation is one of the methods used to control the quality of fermented products. The objective of the study was, firstly, to model the growth kinetics of Kazachstania unispora found in qymyz, and, secondly, to understand their interaction with Lacticaseibacillus casei and Lactobacillus kefiri during the fermentation of mare milk. The K. unispora optimum values of pH and temperature were 4.81 ± 0.22 and 30.16 ± 0.53 °C, respectively, with an optimal growth rate (µopt) of 0.56 ± 0.02 h−1. K. unispora had an ethanol production rate of 6.1 × 10−8 mg·CFU−1. Growth, in terms of limiting substrates showed a lower Ks value for galactose at 0.13 ± 0.04 mg·mL−1 with µopt of 0.45 ± 0.01 h−1, while, for glucose, the Ks was 0.24 ± 0.03 mg·mL−1 with the same µopt. Cocultures of K. unispora were conducted with L. casei and L. kefiri in a synthetic medium and mare milk. The results showed that K. unispora growth was limited and, thus, its ethanol production capacity was inhibited. VOC analysis of mare milk fermented with the studied strains and their cocultures resulted in 37 major volatile compounds. Statistical analysis of the VOC profiles showed that K. unispora modulates the aroma production in coculture with LAB

Growth Kinetics of Kazachstania unispora and Its Interaction with Lactic Acid Bacteria during Qymyz Production

International audienceQymyz is a traditional acidic and ethanolic beverage in central Asian countries made from mare milk fermentation with lactic acid bacteria (LAB) and yeasts. Modeling the growth of microorganisms during fermentation is one of the methods used to control the quality of fermented products. The objective of the study was, firstly, to model the growth kinetics of Kazachstania unispora found in qymyz, and, secondly, to understand their interaction with Lacticaseibacillus casei and Lactobacillus kefiri during the fermentation of mare milk. The K. unispora optimum values of pH and temperature were 4.81 ± 0.22 and 30.16 ± 0.53 °C, respectively, with an optimal growth rate (µopt) of 0.56 ± 0.02 h−1. K. unispora had an ethanol production rate of 6.1 × 10−8 mg·CFU−1. Growth, in terms of limiting substrates showed a lower Ks value for galactose at 0.13 ± 0.04 mg·mL−1 with µopt of 0.45 ± 0.01 h−1, while, for glucose, the Ks was 0.24 ± 0.03 mg·mL−1 with the same µopt. Cocultures of K. unispora were conducted with L. casei and L. kefiri in a synthetic medium and mare milk. The results showed that K. unispora growth was limited and, thus, its ethanol production capacity was inhibited. VOC analysis of mare milk fermented with the studied strains and their cocultures resulted in 37 major volatile compounds. Statistical analysis of the VOC profiles showed that K. unispora modulates the aroma production in coculture with LAB