Lemon and Lime - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 379

Table 20.9. Physical-chemical properties of lemon and lime oil.

Property Lemon Oil Lime Oil

Color Pale to deep yellow or greenish yellow Colorless to greenish yellow

Odor Fresh citrus, intense Fresh citrus, intense

Specific gravity 0.849-0.855 0.855-0.863

Refractive index 1.474-1.467 1.4477-1.4745

Optical rotation + 57 to + 65.6 + 34 to + 47

Stability Air/Light sensitive Air/Light sensitive

Solubility
Water Insoluble Insoluble

Ethanol Soluble Soluble

Propylene glycol Soluble Soluble

Source: Secondini (1990); Poucher (1991).

Lemon oil quality is related to the aldehyde content,
specifically citral, which ranges from about 2.0% to 5.5%,
depending on horticultural factors. D-limonene, the major
constituent ( > 95%) of orange and grapefruit CP oils, is
significantly less in lemon and lime oil but still the ma-
jor volatile component of CP lemon oil (Goodrich, 2003;
Berry, 2003). The largely flavorless but oxidatively unstable
d-limonene may be removed through various concentration
techniques to produce a folded lemon oil that is more sta-
ble and more highly concentrated in desirable flavor com-
pounds (Goodrich, 2003; Bakkali et al., 2008).
The dehydrated lime peel is fed to cattle. In India,
the powdered dried peel and the sludge remaining after
clarifying lime juice are employed for cleaning metal. The
hand-pressed peel oil is mainly utilized in the perfume in-
dustry (Kimball et al., 2005). In tropical Africa, lime twigs
are popular chewsticks for cleaning the teeth (Morton,
1987b) and the use is believed to have some therapeutic
effects.

and process it into a commercially useful product. The
major processing steps in refining citrus pectin, involves
extraction from the peel through an acid treatment, and
recovery by precipitation with alcohol (Goodrich, 2003).
Lemon, grapefruit, and lime albedo have a higher level of
pectins than that of orange or tangerine, neither of which is
typically used for commercial pectin production (Goodrich,
2003; Kimball et al., 2005).

Other products and uses
The use of lemon or lime in diverse food applications is
very common and consumers all over the world have an
excellent preference for lemons or lemon flavor. Lemon-
flavored teas and other beverages, including carbonated
types and lemonade, are popular choices of drinks among
consumers. Lemon-flavored baked goods, especially cakes,
are commonly available in the market. The dried lemon
peel pieces are used in many Asian home recipes, along
with other spices, to add flavor.
In 2009, a new product “Bits O Juice,” a frozen natural
lemon pods (100% natural flavor burst), was launched by
the Dynamic Commodities South Africa for potential cus-
tomers in Japan (Anon, 2009). The frozen product is said
to have identical flavor profile as the natural lemon; adds
an extra dimension to what could otherwise be a very ordi-
nary meal; tastes great when sprinkled on salad, broccoli,
cauliflower, or any fish or meat dish; and with a flavor pro-
file very different to lemon juice because the juice remains
intact in the pod until bitten (Jones, 2010). The better flavor
profile of the frozen lemon pods was obtained because all
the bitter parts (pith and segment membranes) have been
removed in squeezed lemon.

Pectin
The albedo portion of spent lemon peel is an important
source of raw material for commercial pectin production
and contains about 35-40% pectin on a dry-weight basis.
Pectin is a functional ingredient in many processed food
products, where it is used extensively as a gelling agent
and mouth-feel enhancer. Pectin is primarily a polymer of
galacturonic acid units, some of which are esterified with
methanol, and has a molecular weight of between 100,000
and 300,000 (Jitpukdeebodintra and Jangwang, 2009). As
most pectin is sold as a dry powder, there is a complex
recovery scheme to obtain the pectin from the spent peel