Typically to C60. A total wax contents of

Typically waxes do not consist of a
single chemical compound, but are often very complex mixtures. Being oligomers
or polymers in many cases, the components differ in their molar mass, molar
mass distribution, or in the degree of side-chain branching. Functional groups (e.g.,
carboxyl, alcohol, ester, keto, and amide groups) can be detected in waxes,
sometimes several different groups. The academic definition still quoted in chemistry
text books, that waxes are esters of long-chain carboxylic acids with
long-chain alcohols, is no longer useful. It applies fairly well only to some
classical waxes, such as beeswax; others (e.g., petroleum waxes) do not fall in
this category. Today, physical and technical definitions are preferred (267). Chemical
structure of some classical waxes are shown in Figure 16.Chemically, waxes constitute a large range of
different chemical classes, including hydrocarbons, wax esters, sterol esters,
ketones, aldehydes, alcohols, and sterols. The chain length of these compounds
may vary from C2, as in the acetate of a long chain ester, to C62 in the case
of some hydrocarbons (266). The seed oil waxes
are composed of mainly long-chain fatty acids with long-chain linear or branched
alcohols (250, 272).Sunflower wax is obtained from H.
annuus (sunflower). It can be found in different parts of the plant
including the seed, seed hulls, and corncorbs. The sunflower wax is obtained
through the winterization of sunflower oil (269). Crude sunflower
oils contain soluble and partially soluble wax esters up to C42, and
crystallisable wax esters from C44 to C60. A total wax contents of 460 mg/100 g
and 135 mg/100 g have been reported for crude sunflower oil and refined high
oleic sunflower oil, respectively  (275).

Waxes are mainly located in the
hull of sunflower seeds, in concentrations up to 3% depending on the hybrid and
origin of the seed (276). Waxes are
extracted with the oil in amounts that depend on the extent of dehulling and
the extraction method (pressing or solvent extraction). As a result, the
content of waxes in oil can change according to the seed variety, its origin,
storage condition, the percentage of hull removed, and the temperature and
technology used during oil extraction step. Therefore, the total wax content
can vary between 0.02 and 0.35 wt% for crude sunflower oils. Crude sunflower
oil should be refined and wax content can be as high as 0.06 wt% for refined
sunflower oils. The main components of crude sunflower oil waxes are esters having
carbon atom numbers between 36 and 48, with a high concentration in the C40–C42
fraction (277). The composition
of the wax fraction and its fatty acid and fatty alcohol constituents in crude
sunflower oil is presented in Table 21.

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