Comparison of composition, sensory properties and aroma compounds of kefir produced from donkey milk and cow milk

Abstract

In this study, donkey milk and cow milk used for kefir production and the kefir samples were characterised based on compositional and microbiological properties, volatile aroma compounds, amino acid composition, and sensory analyses during storage for 21 days at 5 °C. Compared to cow milk kefir (CMK), donkey milk kefir (DMK) had lower contents of total solids, fat, and protein. Using donkey milk resulted in a weaker body characteristic in the kefir sample due to its low total solids content and the low ratio of casein. Acetaldehyde and acetic acid formation were at a remarkable level in DMK. Besides, the high lactose content of donkey milk caused more ethanol production in the kefir. Tyrosine, valine, and arginine were the primary amino acids in DMK. Donkey milk kefir was evaluated as acceptable in the aspect of sensorial properties such as taste and odour. Based on the present results, it could be concluded that a probiotic fermented beverage can be produced from donkey milk.

Comparing Nutritional Values and Bioactivity of Kefir from Different Types of Animal Milk

“…Protein content was determined by the Kjeldahl method [ 84 ] with the same modification, using a semiautomatic Kjeldahl Apparatus “Velp Scientifica” with two separate parts: 6 digestion blocks and 1 distillation unit. The Kjeldahl method is recognized by Codex Alimentarius as the standard for quantifying milk proteins [ 7 ]. The principle of the method is that a strong acid facilitates the digestion of milk so that it releases nitrogen, which can be determined by a suitable titration technique.…”

“…Donkey milk shows similarities to human milk, especially in respect to lipid and protein composition [ 6 ]. It contains high levels of polyunsaturated fatty acids and vitamins A, B, and C, low cholesterol, and high levels of lysozyme and lactoferrin, conferring antimicrobial activity [ 7 ]. It has high digestibility and a low renal load due to low levels of proteins and inorganic substances, and it can be a good alternative to cow milk in feeding infants or children [ 3 ].…”