From a clinical point of view, oxidative stress (OS) is considered the primary cause of numerous metabolic processes in
Today, oxidative stress (OS) is considered a metabolic disturbance that affects organ systems and its presence will affect not only the health status of the animals but also the quality of the final products, such as milk or meat [
In this paper, we stress that antioxidant supplementation not only will have a preventive effect on the health of the mother and calf, but in turn can enhance the final product (milk/meat) in line with what is now called
The value of a cow lies in its production. And the quality of milk is closely linked to the health of mammary gland. Milk quality is usually defined in terms of mastitis [
In previous studies, milk and several fractions thereof were found to have antioxidant properties. For example, milk, kimmed milk, whey and casein inhibit lipid peroxidation and peroxyl/superoxide radicals generation. Furthermore, casein inhibits peroxide and TBARS (thiobarbituric acid reactive substances) formation, and whey inhibits copper-catalysed peroxides, TBARS formation and O2 uptake. Lactoferrin can bind iron and inhibit Fe-induced lipid peroxidation and finally hydrolysates from milk, fermented milk, casein, and whey were found to be antioxidative and some of them have been patented. These examples show that several components are active in preventing lipid peroxidation and maintaining milk quality and also point to their potential usage as ingredients in foods to provide products for enhanced consumer health [
On average, most fluid milk is judged to have a good flavor up to 14 days of storage, but off-flavor of milk is still an important problem [
Antioxidant systems found in mammalian cells [
Component (location in cell) | Nutrients involved | Function |
---|---|---|
Superoxide dismutase (cytosol) | Cu and Zn | An enzyme that converts superoxide to hydrogen peroxide |
Superoxide dismutase (mitochondria) | Mn and Zn | An enzyme that converts superoxide to hydrogen peroxide |
Ceruloplasmin | Cu | An antioxidant protein may prevent copper from participating in oxidation reactions |
Glutathione peroxidase (cytosol) | Se | An enzyme that converts hydrogen peroxide to water |
Catalase (cytosol) | Fe | An enzyme (primarily in liver) that converts hydrogen peroxide to water |
|
Vitamin E | Breaks fatty acid peroxidation chain reactions |
|
Vitamin A | Prevents initiation of fatty acid peroxidation chain reactions |
Antioxidant supplementation comprises less milk waste in the form of free radicals as well as reducing the number of somatic cells in milk. Supplements fed through the diet (vitamin E, vitamin C, carotene, and trace elements such as selenium, zinc or
The antioxidant activity of dairy products has also been considered in fermented milks [
Fermented milks with antioxidant activity [
Type of milk | Bacterial strain | Type of assay | Antioxidant mechanism |
---|---|---|---|
Bovine milk |
|
|
DPPH radical chelating activity |
Bovine milk |
|
|
Chelating activity of superoxide anion; inhibition of lipid peroxidation |
Buffalo whey |
|
|
Inhibiting the decomposition of peroxides; chelation of transition metals |
Bovine whey | n.r. |
|
Reduction of oxidative stress in rats with dietary vitamin E deficiency |
Goat milk |
|
|
Antiatherogenic effects in healthy humans |
DPPH: free radical diphenyl picrylhydrazyl; n.r. not reported.
However, one should be cautious about antioxidant supplementation, because as stated by Weiss [
The fatty acid profile of milk fat is a major factor in the development of OF [
An alternative could be supplementation with the disaccharide trehalose. A recent study [
Other reviews [
Finally, despite the numerous studies describing the beneficial effects of various antioxidants on the quality of milk and its derivatives, still others report that dietary antioxidants have no effect on milk protein, fat, lactose, total solids, and nonfat solids of cows [
An increasing number of dairy farms in Europe, New Zealand/Australia, and North America are adapting “lower-input” production methods (also called sustainable farms) similar to those used in organic farming but do not comply with all input restrictions prescribed by organic farming standards.
It has been shown that this system indirectly affects milk quality through the increased amount of antioxidants in milk associated with pasture consumption [
For these reasons, there is growing interest in the biodiversity of pastures, because they included some microconstituents (phenolic compounds, terpenes, and carotenoids) that contribute to the taste and nutritional properties of milk and cheese [
Several studies have highlighted the richness in soluble phenolics of the main dicotyledon plants, such as
Meat can be defined as the product that results from the continuous changes that occur in muscle after the death of the animal. The principal factors determining the organoleptic quality of meat are tenderness, colour, and flavour, the latter being composed in turn of the two distinct factors taste and odor [
Colour of meat and associated forms of mioglobin [
Oxidation manifests as a conversion of the red muscle pigment myoglobin to brown metmyoglobin and the development of rancid odors and flavors from the degradation of the polyunsaturated fatty acids in the tissue membranes [
Lipid oxidation in meat increases after 4 or 7 days of storage; although synthetic antioxidants are widely used in meat industry, the consumer concern over their toxicity initiated the search for natural sources of antioxidants [
Lipid oxidation is the limiting factor for PUFAs to serve as nutritionally beneficial lipids in functional foods (see Figure
Lipid oxidation is an autocatalytic process that occurs in food and biological membranes [
In addition, the fatty acid compositions of concentrate (grain-based) and forage (grass-based) diets are quite different and lead to different fatty acid compositions in tissues. Different studies [
Nevertheless, meat oxidation is not only due to the lipids instability; the presence of transition metals such as Fe and Cu (given in many cases as mineral supplementation) favors the formation of highly reactive free radicals in meat [
Dietary antioxidants can be delivered to the muscle where, together with the native defense systems, they counteract the action of prooxidants [
Vitamin E (
Nevertheless, concentrations of endogenous antioxidants depend not only on diet, but also on animal species and muscle type [
When vitamin E is combined with Se supplementation, researchers have observed that in muscle, the antioxidant functions of vitamin E and Se persist after slaughter and delay the onset of oxidation reactions in meat and meat products, demonstrating also that muscle Se levels respond to dietary Se supplementation in beef cattle [
In addition to
However, research was performed with other vitamins or their precursors: a vitamin C solution of sodium ascorbate injected in beef was also effective in improving color stability and extending the meat’s retail display life [
In recent years, substances derived from the plants have been successfully used to reduce lipid oxidation in meat products [
Table representing common plant extracts and main active substances fed to cattle [
Common name | Scientific name | Main compounds (class) |
---|---|---|
Alfalfa |
|
Coumestrol (flavonoid) |
Allspice |
|
Eugenol (EO) |
Apple |
|
Phloretin (flavonoid) |
Bael tree |
|
Limonene (terpene) |
Barberry |
|
Berberine (alkaloid) |
Basil |
|
Linalool (terpene); estragol (EO) |
Bay |
|
Linalool (terpene); cineole (EO) |
Betel pepper |
|
Eugenol (EO) |
Black pepper |
|
Piperine (alkaloid) |
Brazilian pepper tree |
|
Terebinthina (terpene) |
Burdock |
|
Cinarin, Quercetin; caffeic acid (phenols) |
Caraway |
|
Carvone; limonene; germacrene (terpenes) |
Cascara sagrada |
|
Anthraquinone (phenolic: quinone) |
Ceylon cinnamon |
|
Pinene (terpene); cinnamaldehyde; eugenol (EOs) |
Chamomile |
|
Anthemic acid (phenolic) |
Chili peppers, paprika |
|
Capsaicin (terpene) |
Clove |
|
Eugenol (EO) |
Dill |
|
Carvone; limonene (terpene) |
Echinacea |
|
Polyenes (polyacetylenes); Cyarin (phenolic); tussilaginea (alkaloid) |
Garlic |
|
Allicin; Ajoene (S-terpene) |
Ginseng |
|
Ginsenoside (saponin) |
Glory lily |
|
Colchicine (alkaloid) |
|
|
Berberine (alkaloid) |
Gotu kola |
|
Asiaticoside (terpene) |
Grapefruit peel |
|
Ocimene |
Green tea |
|
Catechin (flavonoid) |
Hops |
|
Lupulone (phenolic), humulone (terpene) |
Horseradish |
|
Kaempferol (flavonol) |
EO: Essential oil.
Common name | Scientific name | Main compounds |
---|---|---|
Legume |
|
Alpinumisoflavone |
Lemon balm |
|
Tannins; carveol (EO); saponins; citronellol (terpene) |
Lemongrass |
|
Citral (EO) |
Lemon verbena |
|
|
Mace, nutmeg |
|
Sabinene (terpene) |
Oak |
|
Quercetin (flavonoid) |
Olive oil |
|
Oleuropein (phenolics) |
Onion |
|
|
Orange peel |
|
Limonene (terpene) |
Oregon grape |
|
Berberine (alkaloid) |
Papaya |
|
Papain (polypeptide) |
Peppermint |
|
Menthol (EO) |
Purple prairie clover |
|
Petalostemumol (flavonol) |
Quinina |
|
Quinine (alkaloid) |
Rauvolfia, Chandra |
|
Reserpine (alkaloid) |
Rosemary |
|
Rosmarinic acid (phenolic); carnosol (terpene) |
Sainfoin |
|
Tannins |
Savory |
|
Carvacrol (terpenoid) |
Senna |
|
Rhein (phenolic quinine) |
Tansy |
|
Chrysanthenyl acetate (EO) |
Tarragon |
|
Caffeic acid (phenolic) |
Thyme |
|
Thymol (EO) |
Turmeric |
|
Curcumin (terpene) |
Valerian |
|
Linarin (flavone); elemol (terpene) |
Willow |
|
Salicin (phenolic) |
Wintergreen |
|
Anthocyanins (phenolic) |
Many herbs, spices, and their extracts have been added to a variety of foods to improve their sensory characteristics and extend shelf-life. Herbs of the
It has been observed that surface application of vitamin C, taurine, rosemary, vitamin E, and combinations of the last three with vitamin C has a positive effect on oxidative stability of beef steaks packaged in modified atmosphere [
Meat quality can be improved by incorporating these natural antioxidants into animal diets, adding these compounds onto the meat surface, or using active packaging. Some authors have reported that natural antioxidants have no effect on sensory characteristics of meat. There are studies that demonstrate that the addition of essential oil compounds to the diet of growing lambs (carvacrol and cinnamaldehyde) did not affect the sensory characteristics of sirloins [
Reduction of meat oxidation during refrigeration was obtained adding oregano and sage essential oils to beef meat [
Lower oxidant formation in dietary oregano essential oil treatments is probably the result of the presence of oregano antioxidant compounds, which might be absorbed into the circulatory system after ingestion, distributed, and retained in muscle and other tissues [
In the modern bovine farming systems, where the main objective is to obtain products of high quality (milk or meat); the concept of quality do not only include a safe product for the consumer, but also the use of farming practices that respect animals’ health, either in intensive or extensive systems. Antioxidant supplementation would enhance the health of the cow in a sensitive stage such as the transition period but also can have an additional value, giving to the final product (milk/meat) value added that benefits consumer’s health.
It seems that, considering the reviewed studies, animals kept in sustainable conditions, where their production is in line with the physiological processess associated with lactation and/or growth, provide the most complete human foods from the standpoint antioxidant.
Grazing animals and their diet rich in plant extracts are reflected in the production of milk and meat that responds perfectly to the concept of functional food in the human diet.
The authors declared that there is no conflict of interests.
The authors thank the Galician Government (Xunta de Galicia-Spain) through grant funds (Ref. 10MRU261004PR and Ref. 2012-PG210) to conduct studies of oxidative stress in cattle. These funding sources played no role in the design of the different studies, collection, analysis and interpretation of data, or preparation or approval of the manuscript. Ángel Abuelo is a FPU fellowship holder (ref. AP2010-0013) from the Spanish Ministry of Education, Culture, and Sports.