399
orange, to red. There are about 600 types of carotenoids are available. The most
common ones carotenoids are alpha-carotene, beta-carotene, beta-cryptoxanthin,
lutein, zeaxanthin and lycopene.
Physicochemical and Structural Characterization of Lipids
Lipids are one among the major food constituents with their characteristic physicochemical properties, such as mouth-feel, flavor, texture and appearance. Edible oils
and fats are important nutrients in the human diet, providing essential fatty acids
and energy. Several analytical techniques are available to characterize the lipids
based on their crystallization, melting point, smoke point, rheology, density
and color.
Lipids are an extremely diverse group of compounds consisting of tri-, di- and
mono acylglycerols, free fatty acids, phospholipids, sterols, carotenoids and vitamins A and D. In addition, most of these sub-groups are themselves chemically
complex. All triacylglycerols are esters of glycerol and three fatty acid molecules,
nevertheless, the fatty acids can have different chain lengths, branching, unsaturation, and positions on the glycerol molecule. Thus even a lipid which consists of
only triacylglycerols may contain a huge number of different chemical species. It is
often important for food scientists to either know or to be able to specify the concentration of the different types of lipid molecules present, as well as the total lipid
concentration.
Physicochemical Characterization of Lipids
Crystallization
The crystallization process includes the nucleation (formation of molecular aggregates) and crystal growth (incorporation of molecules from the adjacent liquid
layer). The final structure of fat is influenced by the crystallization kinetics and
linked to its rheological and plasticity properties (Ribeiro et al. 2015). The crystallization kinetics can be determined by monitoring the formation of crystalline solid
material as a function of time. The solid fat content (SFC) is the percentage of the
total lipid that is solid at a particular temperature. The solid fat content has its impact
on the sensory and physical properties, such as spreadability, firmness, mouth feel,
processing and stability. Several methods have been developed to measure the solid
fat content as affected by temperature (Vasic 1965; Torbica et al. 2016). The density
of solid fat being higher than the density of liquid oil, there is an increase in density
when a fat crystallizes and a decrease when it melts. Thus, the solid fat contenttemperature profile can be determined by measuring the density over a range of
temperatures as given in Eq. (1).
Lipids and Oils: An Overview
orange, to red. There are about 600 types of carotenoids are available. The most
common ones carotenoids are alpha-carotene, beta-carotene, beta-cryptoxanthin,
lutein, zeaxanthin and lycopene.
Physicochemical and Structural Characterization of Lipids
Lipids are one among the major food constituents with their characteristic physicochemical properties, such as mouth-feel, flavor, texture and appearance. Edible oils
and fats are important nutrients in the human diet, providing essential fatty acids
and energy. Several analytical techniques are available to characterize the lipids
based on their crystallization, melting point, smoke point, rheology, density
and color.
Lipids are an extremely diverse group of compounds consisting of tri-, di- and
mono acylglycerols, free fatty acids, phospholipids, sterols, carotenoids and vitamins A and D. In addition, most of these sub-groups are themselves chemically
complex. All triacylglycerols are esters of glycerol and three fatty acid molecules,
nevertheless, the fatty acids can have different chain lengths, branching, unsaturation, and positions on the glycerol molecule. Thus even a lipid which consists of
only triacylglycerols may contain a huge number of different chemical species. It is
often important for food scientists to either know or to be able to specify the concentration of the different types of lipid molecules present, as well as the total lipid
concentration.
Physicochemical Characterization of Lipids
Crystallization
The crystallization process includes the nucleation (formation of molecular aggregates) and crystal growth (incorporation of molecules from the adjacent liquid
layer). The final structure of fat is influenced by the crystallization kinetics and
linked to its rheological and plasticity properties (Ribeiro et al. 2015). The crystallization kinetics can be determined by monitoring the formation of crystalline solid
material as a function of time. The solid fat content (SFC) is the percentage of the
total lipid that is solid at a particular temperature. The solid fat content has its impact
on the sensory and physical properties, such as spreadability, firmness, mouth feel,
processing and stability. Several methods have been developed to measure the solid
fat content as affected by temperature (Vasic 1965; Torbica et al. 2016). The density
of solid fat being higher than the density of liquid oil, there is an increase in density
when a fat crystallizes and a decrease when it melts. Thus, the solid fat contenttemperature profile can be determined by measuring the density over a range of
temperatures as given in Eq. (1).
Lipids and Oils: An Overview