Oat Milk
BOTANY
Avena sativa L. Commonly known as oat. This annual herb – member of the Poaceae (Gramineae)
family – typically grows 0.70-1.25m tall; leaves are alternate, lineal-lanceolate, plain, rough, 0.4-1cm
wide, 15-30cm long. Short ligules with inflorescences, which are 15-25cm long terminal panicles, with
2cm long spikelets with 2 flowers each. Differently from other Poaceae plants, oat has pedunculated
spicules, which form branched, often bent inflorescences.
The fruit is a brown caryopsis, composed of the following
parts:

The hull, made of two structures called lemma and
palea. It can be removed by milling the grains.

The pericarp is the outermost layer that envelops the
caryopsis. It is a thin layer, welded to the seed.
Beneath the pericarp, there is the integument, or seed
coat.

The endosperm (nutritious tissue) and the embryo.
The endosperm consists of the starchy endosperm
and the aleurone layer. The embryo is attached to the
endosperm by means of the scutellum; it bears the
leaves and roots primordia (plumule and radicle).
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Oat is native to southern Europe and Asia, although some have proposed that this plant is native to
Sicily. It probably derives from the wild oat Avena fatua or from hybrids between the later and Avena
sterilis. Nowadays, oat is cultivated in almost every temperate region in the world, especially in northern
latitudes (lat. 45-65). Oat plants can be often found in the wild, coming from cultivation. It grows wild in
Chile and Argentina. This plant is adapted to mountain regions, growing up to 1800m altitude in the Alps.
About 25 different oat cultivars are known.
Oat milk is an extract of Avena sativa seeds, which contains oat lipids, proteins and carbohydrates as an
emulsion.
CHEMISTRY
The main components in oat caryopsis are lipids, proteins, and carbohydrates. It also contains minerals
and vitamins.
Water
Protein
(N
x
6.25)
Lipids
Starch
Other
carbohydrates
Row Fiber
Minerals
Thiamin
Niacin
Riboflavin
Pantothenic acid
% weight
13.0
12.6
5.7
40.1
22.8
1.56
2.85
mg/kg
7.0
17.8
1.8
14.5
Table 1. Chemical composition of oat
caryopsis (Belitz HD. & Grosch W., 1997).
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Lipids
Oat endosperm contains one of the highest lipid proportions among cereals (6-8%). Lipids are
preferentially stored in the germ and the aleurone layer. Lipids from different cereals are not significantly
different in their fatty acids composition; linoleic acid is always the most abundant one.
Table 2 shows the average fatty acids composition of oat seeds.
Myristic acid (14:0)
Palmitic acid (16:0)
Stearic acid (18:0)
Oleic acid (18:1)
Linoleic acid (18:2)
Linolenic acid (18:3)
0.6
18.9
1.6
36.4
40.5
1.9
Table 2. Average fatty acid composition of the acyl-lipids in
oat -% weight- (Belitz HD. & Grosch W., 1997).
Proteins
The proteins in oat kernels include a globulin (avenalin), a prolamin (glutin), a glutelin (avenin), myosin,
free amino acids (especially sulfur-containing ones) and a number of enzymes.
Table 3 shows the amino acids composition of total proteins in oat flour.
Asx
Thr
Ser
Glx
Pro
Gly
Ala
Cys
Val
Met
Ile
Leu
Tyr
Phe
His
Lys
Arg
Trp
Amide groups
Amino acid
4.9
3.8
6.0
24.8
14.3
6.0
5.1
1.5
6.1
1.6
3.7
6.8
2.7
4.3
1.8
2.6
3.3
0.7
26.1
Table 3. Amino acid composition
(% mol) of total proteins in oat
flour (Belitz, HD. & Grosch, W.,
1997).
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In 1907, T.B Osborne separated the proteins in a wheat-flour sample into four fractions on the basis of
their solubility, successively extracting: albumin with water, globulin with saline solution, and prolamin
with 70% ethanol in water.
Table 4 shows the proportions of the Osborne fractions in oat proteins:
Fraction
Albumin
Globulin
Prolamin
c
Glutelin
a
b
%
20.2
11.9
14.0
53.9
Table 4. Osborne fractions in oat proteins
(Belitz, HD. & Grosch, W., 1997).
a
Calculated from amino acid analysis.
b
Ash content in flour (calculated as % dry
product): 1.0
c
Protein residue after extraction of prolamin.
All of the vegetable proteins in the market are available as hydrolyzates with higher or lower average
molecular weight. The “molecular weight” parameter must be defined as “average molecular weight”
since the hydrolysis process never produces uniform peptides but a mixture of different peptides, whose
molecular weights show a Gaussian distribution.
Carbohydrates
Starch is the main reserve carbohydrate in cereals. Oat contains relatively small amounts of
carbohydrates. Cereal starch is made of 25% amylose and 75% amylopectin. Cereals also contain
polysaccharides other than starch such as hemicellulose, pentosan, cellulose, -glucan (2.2-4.2%) and
glucofructan. These are constituent polysaccharides of the cell walls and are more abundant in the outer
than in the inner parts of the grain (Belitz HD. & Grosch W., 1997).
Minerals
Oat grains contain the following minerals and oligoelements: sodium, potassium, calcium, magnesium,
iron, phosphorus, sulfur, chlorine, silicon, copper, zinc, manganese, fluoride, iodine and cobalt.
Vitamins
Oat vitamins include: vitamins B1 and B2, vitamin PP and traces of vitamins K, E and D.
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TRADITIONAL USES
Archeological findings revealed oat grains in pile houses built during the Bronze Age. The seeds of
Avena fatua (from which Avena sativa possibly derives) used to be harvested in the Nile. German
peoples introduced it into Europe. Neither Romans, nor Egyptians nor Greeks knew this cereal. In China,
oat was not cultivated until 1000 B.C. In the Formulary by Dujardin-Beaumetz (1899) dehulled oat seeds
were recommended as an excellent food for children’s healthy growth and vitality.
External applications of oat seeds have a helpful emollient effect in cases of skin irritation, seborrhea
and different types of pruritus. Oat mucilage is used in creams to treat sun-induced erythema. Oat flour
has long been used in cosmetics as an ingredient of face masks and as an additive of soaps to relieve
irritation and itching. It has been claimed that the topical use of oat was discovered by chance, as a
group of railway workers, who had been walking among dense bushes and abundant nettles, applied oat
flour poultices on the rash they had on their hands. Oat flour preparations were also believed to leave a
protective film on the skin.
COSMETIC PROPERTIES
Skin conditioning activity
This activity is due to oat’s proteins and carbohydrates content.
Because of their polar nature, proteins easily bind water molecules through hydrogen bonds. When
superficial moisturizing is involved, this action is almost not influenced by the molecular weight; however,
if penetration and moisturizing of deeper skin layers is required, short-chain peptides – with lower
molecular weights – are more effective.
Challoner, NI et al. (1997) evaluated the moisturizing effect of different proteins, including vegetable
proteins and derivatives. In a first assay, they evaluated the moisturizing effects of an O/W emulsion
containing 1% protein hydrolyzate. The results showed that the protein hydrolyzate-containing emulsion
significantly increased skin immediate extensibility (Ei).
They also evaluated the lifting effects of two high molecular weight proteins in aqueous solution. The
results showed that incorporating proteins into an aqueous formulation significantly decreased Ei during
the treatment period. This finding could be explained by the capacity of proteins to form a coating film on
the skin surface, which resulted in a lifting effect.
Thus, low molecular weight proteins are good moisturizers for deep skin layers and high molecular
weight proteins – because of their filmogenic action – are good moisturizers for the skin surface, as well
as good firming and soothing agents.
Additionally, regardless the molecular weight, all protein hydrolyzates and their derivatives improve the
compatibility between tensioactive substances and skin/mucosa, thus reducing tensioactive-induced
irritation (Griesbach et al., 1998).
Oat β-glucan is structurally similar to hyaluronic acid, which is extensively used to produce high-viscosity
preparations and as a skin moisturizing and smoothing agent. Comparative flow curves for hyaluronic
acid 1% and oat β-glucan (which plot viscosity response versus shear strength) show that even when the
viscosity behaviors of both compounds are not identical, each one behaves as a pseudo-plastic fluid,
namely their viscosity decreases as the shear strength increases. Thus, oat β-glucan is a helpful agent
to form a film, moisturize and lubricate. As an example, an after-shave lotion has been formulated with 2
oat-derived ingredients (β-glucan and hydrolyzed oat protein) and 2 plant oils. The β-glucan and
hydrolyzed oat protein combination effectively moisturized and soothed the skin and reduced abrasionrelated redness (Paton D et al., 1996).
Therefore, oat milk is recommendable to formulate skin conditioning cosmetic products.
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Hair conditioning activity
Conditioning agents are expected to provide smoothness and shine to the hair, facilitate combing and
reduce static electricity. A number of ingredients may be used to formulate hair conditioners including
protein hydrolyzates (Dureja, H. et al., 2005).
Proteins protect the hair from environmental damage, repair and condition it, increase elasticity and
reduce the risk of breakage (Griesbach U. et al., 1998).
Substantivity is a measure of a molecule’s ability to establish bonds with the skin or the hair. Several
studies have demonstrated the substantivity of protein hydrolyzates on the hair surface (Chahal, S.P., et
al., 1999).
Proteins are polymer chains with hydrophilic groups (hydroxyl, carboxyl and amine groups), which easily
bind water molecules. Protein hydrolysis generates more carboxyl- and amine-terminal groups, thus
increasing water-retention under high relative humidity conditions.
Thus, because of their hydrophilic nature, protein hydrolyzates can retain water; the more hydrolyzed the
protein, the higher the water-retention. Qualitative data have demonstrated higher water-retention and
better regulation of water-absorption and release for protein hydrolyzate-treated hair (Chahal, S.P.,
1999).
Low molecular weight proteins can penetrate to the hair-shaft cortex, thus repairing, strengthening and
protecting it from the inside. High molecular weight proteins are good hair soothing and protecting
agents, because of their ability to coat the hair-shaft surface (Huetter, I., 2003).
Therefore, oat milk is recommended to formulate cosmetic products with hair conditioning and repairing
activity.
Cell regeneration stimulating activity
This activity is due to the carbohydrates content of oat milk, remarkably including -glucans. These are
compounds of the oligosaccharide type, which activate the non-specific immune system; namely they
activate the Langerhans cells at the dermal level and consequently, boost the production of cytokines.
Cytokines first eliminate rests of dead cells or substances foreign to the organism and subsequently
activate cell regeneration factors, which repair the vascular system and consequently increase oxygen
supply to the tissues. Then, they activate factors involved in the synthesis of collagen and elastin. Cell
regeneration and consequent stimulation of this system occurs, which result in an anti-aging action.
Such cell regeneration action is also useful in anti-acne and anti-irritation treatments.
Zülli F et al. (1996) studied the in vivo efficacy of -glucan as a cell regeneration stimulating agent and
as a moisturizing agent. The results showed increased renewal rates for the stratum corneum and
increased skin moisture level. In both cases, the increase depended on the concentration of -glucan in
the cosmetic formulation.
Thus, oat milk is helpful in the formulation of cosmetic products with anti-aging, anti-acne and antiirritation activities.
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Anti-inflammatory activity
It has been found that patients with dermatitis have low tissular levels of all of the poly-unsaturated
derivatives of linoleic acid. Different clinical tests demonstrated that topical applications of linoleic acid
(as well as its poly-unsaturated derivatives) soothes the skin and reduces trans-epidermal water loss
(Wright S., 1991). Conti A. et al. (1995) as well as Jiménez-Arnau A. (1997) also verified these
properties of linoleic acid.
Skolnik P. et al. (1977) carried out a study, where they demonstrated in three cases that local
applications of linoleic acid reversed the effects of essential fatty acids (EFA) deficiency produced by
chronic EFA malabsorption, and increased the epidermal levels of this acid.
Thus, oat milk is helpful to formulate products for sensitive and/or irritated skin.
COSMETIC APPLICATIONS
Action
Active
Skin conditioning
Proteins
Carbohydrates
Hair conditioning
Proteins
Cell regeneration stimulation
Carbohydrates
Anti-inflammatory
Linoleic acid
Cosmetic Application
-Skin conditioner
-Moisturizer
-Lifting effect
-Filmogenic effect
-Hair conditioner
-Hair moisturizer
-Hair repair
- Anti-aging
- Anti-acne/anti-irritation treatments
- Sensitive/irritated skin
RECOMMENDED DOSE
The recommended dose is between 0.5% and 5.0%.
BIBLIOGRAPHY
Alonso, J. Tratado de Fitofármacos y Nutracéuticos. Barcelona: Corpus, 2004, p: 185-188 (633.8 ALO).
Aburjai T & Natsheh M. Plants used in cosmteics. Phytother Res, 2003; 17 (9): 987-1000 8ref. 6958).
Belitz HD. & Grosch W. Química de los Alimentos. Zaragoza: Ed.Acribia S.A, 1997. Capítulo 15 (613
BEL).
Chahal, S.P.; Challoner, N.I.; Jones, R.T. Moisture regulation of hair by cosmetic proteins as
demonstrated by dynamic vapour sorption –a novel efficacy testing technique. XIV Congreso
Lationoamericano e Ibérico de Químicos Cosméticos & I.F.S.C.C. International Conference. I.F.S.C.C.
Internacional Conference Plataform Presentation Preprints. Santiago de Chile, 1999; p: 45-47 (Cong.
2144-2168).
Challoner, N.I. Cosmetic Proteins for Skin Care. C&T, 1997; 112 (12): 51-63 (ref.2453).
Conti A. et al. Seasonal influences on stratum corneum ceramide 1 fatty acids and the influence of
topical essential fatty acids. J Cosmet Sci, 1995; 18: 1-12 (ref.1735).
Dureja, H.; Kaushik, D.; Gupta, M.; Kumar, V.; Alter, V. Cosmoceuticals: An emerging concept. Indian J
Pharmacol, 2005; 37 (3): 155-159 (ref. 7657).
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Griesbach, U., Klingels, M., Hömer, V. Proteins: Classic Aditives and Actives for Skin and hair care.
C&T, 1998; 113 (11): 69-73 (ref.2858).
Huetter, I. Hair care with depth effects by low molecular proteins. SOEFW Journal, 2003; 129 (1/2): 1216.
Jimenez-Arnau A. Effects of Linoleic Acid Supplements on Atopic dermatitis. Adv. Exp. Med. Biol., 1997;
433: 285-9.
Mauricio A. Avena, Acofar, 1995; 330: 48-49 (ref. 24).
Paton D, Bresciani S, Fong Han N, Hart J. Oat: Chemistry, Tecnology and Potential Uses in the
Cosmetic Industry. C&T, 1995; 110: 63-70 (ref. 1322).
Skolnik P. et al. Human Essential Fatty Acid Deficiency. Arch Dermatol, 1977; 113: 939-41 (ref.6751).
Wright S. Essential fatty acids and the skin: Cosmetic application of research. Br J Dermatol, 1991;
125(6): 503-15 (ref. 1212).
Zülli F, et al. Carboxymethylated -(1-3)-glucan. Cosmetics & Toiletries 1996; 111 (12): 91-98 (ref.2134).
Web sites:
www.fitoterapia.net [accessed March 2006].
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