Chemical, Physicochemical, Microbiological, Bioactive, and Sensory Characteristics of Cow and Donkey Milk Kefir during Storage

Abstract

This study aimed to evaluate essential traits of donkey’s milk and cow’s milk kefir during storage for 28 days at + 4 °C. The results showed that the pH decreases significantly during fermentation from 6.75 ± 0.045 to 4.22 ± 0.062 for cow’s milk and from 7.01 ± 0.011 to 4.28 ± 0.030 for donkey’s milk. Acidity values increased significantly during storage from 63 ± 2.08 °D to 170 ± 2.80 °D for cow’s milk and from 92 ± 1.0 °D to 163 ± 1.30 °D for donkey’s milk (p < 0.05). A significant variation in total solids was observed during storage. Stability in protein content was observed for kefirs during storage time. While the level of lactose decreased significantly during storage, the fat content did not vary in kefirs during storage time at 4 °C. For microbiological properties, donkey milk kefir presents a significant difference (p < 0.05) compared to bovine kefir. Donkey’s milk always contains the lowest average germs, suggesting a better microbiological quality than cow’s milk samples. The fermented milks showed an interesting antioxidant activity measured by the DPPH and ABTS assays, which were improved during storage. The Aeromonas hydrophila was the most sensitive bacterium to the action of kefir samples. Results from the sensorial test show that participants prefer kefirs freshly prepared than those stored after 28 days at 4 °C. In conclusion, related to its unique bioactive activities and microbiological properties, donkey’s milk could be an interesting kefir fermentation source materials alternative.

Comparative Study of Carcass Characteristics and Meat Quality of Local Mediterranean Donkey Breeds

“…Breeds do not differ in adult weight. All donkeys, raised in the same breeding system, as previously described [8], were kept on grass pasture in a mountainous area, with free access to water and daily supplementation with barley (1 kg/head) to match the animals' nutritional needs. For the present study, donkeys were transported to Ellouhoum Company, a slaughterhouse under the supervision of the Tunisian Ministry of Trade and Export Development.…”

“…These differences can be attributed to various factors. Firstly, morphological variations between the two populations may influence the distribution of fat and muscle tissues, leading to disparities in fat and protein content [8]. Additionally, rearing and feeding practices and behavior play a crucial role in shaping the meat's composition [9].…”

“…In recent times, there has been a renewed worldwide interest in donkeys due to the exceptional quality of their milk and meat. Donkey meat is considered a sustainable source of high-quality and eco-friendly meat [6,7], with excellent nutritional value owing to their access to large pastures in the equine breeding system [8,9]. Donkey meat presents appealing quality characteristics, including low fat contents ranging from 1.6% to 3.5% for breeds such as Martina Franca, Amiata, Littoral Dinaric, and Istrian [10,11].…”

“…In Tunisia, the annual production of donkey meat stands at 4000 tons [19]. Despite a substantial population of approximately 123,000 autochthonous donkeys [8], there is a noticeable dearth of research focusing on these indigenous breeds. The utilization of indigenous donkey breeds like Masri and North African for meat production holds potential social and economic significance, as it contributes to the augmentation of local production systems.…”

Effect of Time Fermentation on The Microbiological Properties of Coconut Water Kefir

“…There isn't much study on coconut water kefir, but milk kefir is the subject of the majority of studies. These studies cover whatever changes in the bacterial community during fermentation [12], [13], to the creation of sensory-friendly beverage items [14], [15], the duration of fermentation plays a crucial role in determining the microbial composition of coconut water kefir. The result will determine the optimal duration that maximizes probiotic populations for enhanced health benefits.…”