Cloudy olive oil

Olive oil

Olive oil is an oil obtained from the olive , a traditional tree crop of the Mediterranean Basin. It is commonly used in cooking, cosmetics, pharmaceuticals, and soaps and as a fuel for traditional oil lamps...

is an intermediate product of olive oil extraction

Olive oil extraction

Olive oil extraction is the process of extracting the oil present in the olive drupes for food use. The oil is produced in the mesocarp cells, and stored in a particular type of vacuole called a lipo vacuole, i.e., every cell contains a tiny olive oil droplet...

. It is actually the initial cloudy juice of the olive

Olive

The olive , Olea europaea), is a species of a small tree in the family Oleaceae, native to the coastal areas of the eastern Mediterranean Basin as well as northern Iran at the south end of the Caspian Sea.Its fruit, also called the olive, is of major agricultural importance in the...

 drupe

Drupe

In botany, a drupe is a fruit in which an outer fleshy part surrounds a shell of hardened endocarp with a seed inside. These fruits develop from a single carpel, and mostly from flowers with superior ovaries...

s soon after crushing, separation and decanting and before final filtration

Filtration

Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...

. Normally this oil, also called veiled olive oil, is stored in tanks to settle for a period of weeks or months where clarification takes place.

Application

Although filtered and clarified olive oil is the only recognisable and commercially available form of olive oil in the world market, cloudy olive oil is gaining increasing popularity amongst olive oil small scale producers, world class Mediterranean cuisine chefs and people with ecological background. They believe that this oil has superior sensorial characteristics compared to filtered olive oil, because it is less processed and more "green" or organic food

Organic food

Organic foods are foods that are produced using methods that do not involve modern synthetic inputs such as synthetic pesticides and chemical fertilizers, do not contain genetically modified organisms, and are not processed using irradiation, industrial solvents, or chemical food additives.For the...

 product. Research is carried out to determine the differences between cloudy and filtered olive oil.

Nature of cloudiness

According to recent scientific evidence, cloudy olive is a special type of suspension

Suspension (chemistry)

In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...

 and emulsion

Emulsion

An emulsion is a mixture of two or more liquids that are normally immiscible . Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion is used when both the dispersed and the...

. Plant material from olive drupes is suspended in oil due to lack of the filtering step. On the same time, cloudy olive oil containing microdroplets of vegetative and non-vegetative water

Water

Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...

 in small amounts (0.1-0.3%) forming an w/o emulsion. This unique physicochemical state of cloudy olive oil maybe responsible for the observed increased oxidative stability of that type of oil compared to the filtered one. Cloudy olive oil has higher levels of polyphenol

Polyphenol

Polyphenols are a structural class of natural, synthetic, and semisynthetic organic chemicals characterized by the presence of large multiples of phenol structural units...

s, or polar

Chemical polarity

In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...

 phenols

Natural phenol

Natural phenols, bioavailable phenols, plant phenolics, low molecular weight phenols or phenoloids are a class of natural products. They are small molecules containing one or more phenolic group. These molecules are smaller in size than polyphenols, containing less than 12 phenolic groups...

 that form a complex polyphenol-protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 complex

Protein complex

A multiprotein complex is a group of two or more associated polypeptide chains. If the different polypeptide chains contain different protein domain, the resulting multiprotein complex can have multiple catalytic functions...

. This complex interacts within the suspension/emulsion system and contributes to the formation and maintenance of the physicochemical properties of this oil.

The polyphenols found in olive oil are caffeic

Caffeic acid

Caffeic acid is a hydroxycinnamic acid, a naturally occurring organic compound. This yellow solid consists of both phenolic and acrylic functional groups...

, vanillic

Vanillic acid

Vanillic acid is a dihydroxybenzoic acid derivative used as a flavoring agent. It is an oxidized form of vanillin...

, p-coumaric

Coumaric acid

Coumaric acid is a hydroxycinnamic acid, an organic compound that is a hydroxy derivative of cinnamic acid. There are three isomers, o-coumaric acid, m-coumaric acid, and p-coumaric acid, that differ by the position of the hydroxy substitution of the phenyl group...

, syringic

Syringic acid

Syringic acid is a naturally occurring O-methylated trihydroxybenzoic acid, a type of chemical compound. It can be found in the açaí palm and its oil , in Ardisia elliptica...

 and p-hydroxy benzoic acids, 3-hydroxyphenylethanol and 3,4-dihydroxyphenyl-ethanol.

Natural cloudiness vs. low temp cloudiness

It has to be noted that olive oil cloudiness discussed in this article is different from the characteristic cloudiness and precipitation

Precipitation (chemistry)

Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...

 of olive oil due to storage at low temperatures [REF]. This type of cloudiness is the result of congealing saturated fat

Saturated fat

Saturated fat is fat that consists of triglycerides containing only saturated fatty acids. Saturated fatty acids have no double bonds between the individual carbon atoms of the fatty acid chain. That is, the chain of carbon atoms is fully "saturated" with hydrogen atoms...

. When these oils are returned to room temperature, they become again transparent. Cloudy olive oil has a veiled appearance that can persist months after the oil has been returned to room temperature.