Vitamins in Raw Milk – The Biologically Active Microfraction and Its Importance for Nutritional Value, Stability, and Quality
Vitamins in raw milk represent a relatively small fraction by mass, yet they are functionally extremely significant. They participate in key biological processes, contribute to the nutritional completeness of milk, and serve as sensitive indicators of biological origin, production
conditions, and the technological history of the product. This review article examines the vitamin composition of raw milk as an integral part of the milk system, analyzes the distribution of vitamins between the aqueous and fat phases, their biological roles, the factors influencing
their content, and their importance in assessing milk quality and authenticity.
Introduction
In the context of milk composition, vitamins are often perceived as“additional” nutritional value—important for human health but secondary to fats, proteins, and minerals. Such a view is incomplete. Vitamins in raw milk constitute a biologically active microfraction that reflects the physiological state of the animal, feeding quality, and seasonal
conditions, while also contributing to the stability and functionality of the milk system.
Raw milk represents a natural vitamin matrix—not balanced according to human requirements, but biologically logical—where water-soluble and fat-soluble vitamins are distributed between different milk phases. This distribution determines their bioavailability, stability, and sensitivity to technological treatments.
General Vitamin Profile of Raw Milk
The vitamin composition of raw milk includes representatives of both fat-soluble and water-soluble vitamins. Although their concentrations are low in absolute terms, their biological activity is high.
Fat-soluble vitamins are closely associated with milk fat and the milk fat globule membrane, while water-soluble vitamins are found primarily in the aqueous phase, often in association with proteins. This phase distribution is crucial for vitamin stability and for their response during storage and processing.
Fat-Soluble Vitamins – Lipid-Associated Bioactivity
Fat-soluble vitamins in raw milk include vitamins A, D, E, and K. Their presence is directly related to the content and condition of milk fat. They are dissolved in the lipid phase and often associated with the membrane of fat globules, which partially protects them from oxidation
and degradation.
Vitamin A and its precursors are among the most important fat-soluble vitamins in milk. They contribute to vision, cellular differentiation, and immune function. Their content in raw milk is strongly dependent on animal feeding and season, making this vitamin a sensitive biological marker.
Vitamin D is present in smaller quantities but plays a key role in calcium–phosphorus metabolism. In milk, it functions synergistically with the mineral phase and thus indirectly contributes to the stability of the protein–mineral system.
Vitamin E acts as a natural antioxidant in the lipid phase of milk. Its presence limits oxidative processes in milk fat and contributes to flavor and aroma stability. Vitamin K, although present in very small amounts, participates in biological processes related to coagulation and
bone metabolism.
Water-Soluble Vitamins – Functional Activity of the Aqueous Phase
Water-soluble vitamins in raw milk include B-group vitamins and vitamin C. They are located mainly in the aqueous phase and are often associated with protein molecules, influencing their stability and bioavailability.
B-group vitamins perform key functions in energy metabolism and the synthesis of cellular components. In raw milk, they are present in biologically active forms and contribute to the product’s high nutritional value. Their content reflects both animal physiology and
microbiological processes occurring in milk.
Vitamin C is present in limited quantities but is significant as an antioxidant and participant in redox processes. It is one of the most sensitive vitamins and serves as an indicator of freshness and minimal processing.
Factors Influencing Vitamin Composition
The vitamin profile of raw milk is highly variable and depends on multiple factors. Animal feeding is the primary determining factor, especially for fat-soluble vitamins. Seasonal changes, access to fresh forage, and farming conditions directly affect concentrations.
Physiological status and stage of lactation also influence vitamin composition. Additionally, storage conditions and exposure to light and oxygen can lead to degradation of certain vitamins even in raw milk.
Vitamins as Indicators of Quality and Freshness
Due to their sensitivity, vitamins can serve as quality indicators. Areduction in certain vitamin levels may signal prolonged storage, improper conditions, or intensive technological processing.
Fat-soluble vitamins are particularly sensitive to oxidative processes, while water-soluble vitamins are sensitive to light and temperature. These differences allow the vitamin profile to be used as part of a comprehensive milk quality assessment.
Analytical Aspects and Control
Determination of vitamins in milk requires sensitive analytical methods due to their low concentrations. In modern practice, vitamin profile analysis is used more frequently for scientific research, authentication, and nutritional assessment than for routine control.
Indirect approaches, in which vitamins are evaluated in the context of fat and aqueous phase condition, allow broader interpretation of milk quality and technological history.
An Integrative Perspective: Vitamins as a Biological Signature
Vitamins in raw milk may be viewed as a biological signature reflecting
production conditions and minimal technological intervention. They link nutritional value with biological origin and provide an additional layer of information about milk quality.
Within the milk system, vitamins do not act in isolation but in synergy with fats, proteins, and minerals, contributing to overall functionality and stability.
The vitamin composition of raw milk represents a small yet exceptionally
significant part of its biochemical structure. Fat-soluble and
water-soluble vitamins contribute to nutritional value, stability, and
biological activity, while serving as sensitive indicators of quality,
freshness, and authenticity.
Considering vitamins in a systematic and integrative context
demonstrates that they are not a secondary component but rather the
biologically active microfraction that complements and fine-tunes the
milk system. This understanding is essential for modern dairy science,
technology, and analytical control.
