Lemon and Lime - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 377

without unnaturally long shelf lives (Ohlsson, 1994). This
resulted in demand for high-quality fruits and vegetables
with convenience and safety (Perera, 2007). Consumers'
perception of high quality implies freshlike quality char-
acteristics in terms of flavor, texture, color, aroma, and
overall acceptance. Furthermore, consumers are becoming
health conscious with increasing interest in the role of food
for maintaining and improving human well-being (Allende
et al., 2006) and the role of fruits and vegetable consumption
to decrease the risk of cardiovascular disease and cancer
(Ragaert et al., 2004; Allende et al., 2006). These changes
in consumer lifestyle have led to increased desire for ready-
to-eat or ready-to-use products. These consumers' desires
emerged a new era of food preservation known as mini-
mally, lightly processed products, partially processed, fresh
processed, fresh-cut, or prepared products (Perera, 2007).
Some of these products are sold as precut, prepared, and
prepackaged (Lee and Smith, 1995).
Minimal processing of fruits and vegetables generally in-
volves washing, peeling, slicing, or shredding before pack-
aging and storage at low temperature (Perera, 2007). The
objectives of minimal processing of raw fruits are: (1) to
keep the product fresh but convenient without losing its nu-
tritional quality and (2) to get a final product with enough
shelf life to make distribution feasible within the region of
consumption (Perera, 2007).
Fresh-cut produce has been defined by the International
Fresh-Cut Produce Association (IFPA) as any fresh fruit or
vegetable that has been physically altered from its origi-
nal form (by trimming, peeling, washing and cutting), but
remains in a fresh state to obtain a 100% usable product
that is subsequently bagged or prepackaged to offer con-
sumers high nutrition, convenience, and value while still
maintaining freshness. Maintaining quality is a challenge
in fresh-cut products due to rapid deterioration as a result
of: (1) fruit does not have the natural barrier that protects
them from dehydrations; (2) abrasive (peeling and dicing)
steps in the processing of fruit promote natural biochemical
tissue degradation; (3) the end products are constantly ma-
turing until consumed; and (4) micro-organisms enhance
decomposition.
Lemon slices are served as garnish on fish or meat or
with iced or hot tea, to be squeezed for the flavorful juice.
There is no current potential of lime as a fresh-cut product.
Though the fresh-cut fruit market is expanding, the expan-
sion of fresh-cut citrus fruit has been slow due to their rel-
atively short shelf life and excessive juice leakage from the
cut segments (Artes-Hernandez et al., 2007). The authors
reported that fresh-cut 'Lisbon' lemon products (wedges,
slices) stored up to 10 ◦ C retained marketable quality for up

to 7 days. To extend the shelf life to 10 days, the wedges,
slices, and half slices of fresh-cut lemons should be stored
at 0 ◦ -5 ◦ C and protected from water loss by proper pack-
aging with high RH during distribution. Sensory quality of
these fresh cuts was preserved with good retention of vita-
min C and antioxidant content and a decrease in total phe-
nolic compounds. The main fermentative metabolite was
ethanol (88% of the total) which increased threefold in the
slices.

PROCESSING AND PROCESSED PRODUCTS

Juice concentrate and juice blends
Codex (CAC, 2000) defined fruit juice as unfermented but
fermentable juice, obtained from the edible part of sound,
appropriately mature and fresh or fruit preserved by physi-
cal means by (1) mechanical extraction processes for single-
strength juices not from concentrate and (2) physical pro-
cesses for all other juice forms. The juice may be turbid or
clear; may have been concentrated and later reconstituted
with water suitable for the purpose of maintaining the es-
sential composition and quality factors of the juice. The
fluid expressed from lemons and limes, though excessively
acidic, is certainly juice. However, the liquid is too sour to
consume directly without dilution with sugar and water to
produce lemonade or limeade (FAO, 1989; Kimball et al.,
2005).
Lemon and lime juice is commonly used as ingredients
in both commercial and home kitchens as well as a compo-
nent of many processed food and beverage formulas (Street,
1996; Goodrich, 2003). Lemon and lime juice can be pre-
pared following similar process for orange and grapefruit
juices, using similar equipment.
Sound fruit, freshly harvested from the field or taken
from refrigerated or frozen storage, is delivered to the pro-
cessing plant. Thorough washing is necessary to remove
dirt and foreign objects and may be followed by a san-
itation step to decrease the microbial load. Sanitizing is
important for minimally processed juices that rely on hy-
gienic conditions to ensure the safety of perishable products
(FAO, 1989). Sorting and inspection to remove decayed and
moldy fruit is necessary to ensure that the final juice will
not have a high microbial load, undesirable flavors, or my-
cotoxin contamination. The quality parameters of interest
are microbial load, pathogens, pesticide residues, aflatoxin
level, color, sugar, acid, flavor, or other safety and quality at-
tributes. The juice is extracted using either of the two major
types of citrus juice extractors: the FMC (FMC Corpora-
tion) or Brown (Automatic Machinery Corp.). Either prior