Fat is one of the most important nutrients in milk; however, unsaturated fatty acids in milk, especially polyunsaturated fatty acids, are prone to oxidation. As transparent packaging has been increasingly applied by milk producers, the light-induced oxidation of milk fat has become one of the most important causes of the quality deterioration and rancidity of milk, which is detrimental to the flavor of milk. Furthermore, the oxidation products pose a huge threat to human health. This article reviews the mechanism, the main influence factors and the evaluation methods of milk fat photooxidation, which will provide a theoretical basis for evaluating and inhibiting photooxidation in milk, ensuring the quality of milk, and guiding the production, packaging and marketing of milk.

A comparative analysis of fatty acid contents between ultra-high temperature (UHT) milk and reconstituted milk was carried out using 1H nuclear magnetic resonance (1H NMR) spectroscopy. The results showed that the relative contents of linolenic acid, linoleic acid, oleic acid and saturated fatty acid in UHT milk and reconstituted milk were (0.98 ± 0.11)% and (0.90 ± 0.04)%, (1.15 ± 0.36)% and (1.11 ± 0.36)%, (27.30 ± 0.56)% and (26.78 ± 0.78)%, and (43.26 ± 1.56)% and (43.81 ± 2.34)%, respectively. Orthogonal partial least squares discriminant (OPLS-DA) analysis and independent sample t test were performed on the 1H NMR spectrum peaks and fatty acid contents of the two milks. It was found that the relative content of linolenic acid was significantly different (P < 0.05) between the two milks. Nutritional assessment showed that UHT milk was more suitable than reconstituted milk for people with hyperlipidemia and/or high cholesterol, while the nutritional value of other fatty acids was similar between both milks.

The periparturient period is one of the most important period in the process of dairy farming, implicating the transition from the dry period to lactation, during which cows may undergo physiological stress that results in a decrease of dry matter intake (DMI) and negative energy balance (NEB) during early lactation. Besides, the early-lactating cows have poorer milk production and reproductive performance, which are often accompanied by metabolic diseases such as fatty liver, ketosis, mastitis, etc. Choline contributes favorably to milk production and reproductive performance, participates in fat metabolism, reduces the incidence of fatty liver and strengthens immunity in dairy cows. Therefore, dietary rumen-protected choline (RPC) can improve metabolic functions and increase the supply of choline in the small intestine, consequently improving milk yield and milk composition, relieving fatty liver and reducing perinatal diseases. This paper summarizes the effects of feeding RPC to periparturient dairy cows on DMI, milk production performance, milk composition and health condition, aims to provide the theoretical basis for feeding of periparturient dairy cows.

A dairy beverage was developed mainly from ginseng roots and milk powder. One-facor-at-a-time and orthogonal array design experiments were used for formulation optimizatio of the dairy beverage based on stability and sensory score. Four factors in decreasing order of their effect on its quality were ginseng powder granulity, citric acid concentration, ginseng powder concentration and xanthan gum concentration. The optimum beverage formulation was milk powder 5%, soft sugar 8%, ginseng powder 0.3%, xanthan gum 0.20%, citric acid 0.15%, and ginseng powder granulity 0.076 mm. The beverage obtained under these condiitons was stable and abundant in nutrients and had a pure taste without bitterness.