Investigating carotenoid loss after drying and storage of

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1. Literature review
The performance of drying depends on the ventilation system, the model of dryer, and
the environmental conditions such as temperature/humidity values . Factors to take into
account in the choice of the dryer are efficiency of drying, cost, and effect of drying of
product quality such as provitamin A content.
1.2.6 Packaging
In addition to drying, which can affect the quality of dried sweet potato, packaging of
the final product is also important. van Hal (2000) reported that “The sweet potato flour
was packaged and sealed in different forms of packaging material, which can be
porcelain and glass jars, tin cans, paper ‘‘craft’’ bags, polypropylene or polyethylene
bags, cotton bags, or a combination of two different materials, for example polyethylene
and cotton bags together” (Table 1-2).
Table 1-2: Properties of flexible packaging materials. Commonwealth Science
Council (1985).
Material Remarks
Water
Impermeable
Oxygen Light
Cost
Paper Hygroscopic no no yes L
Aluminium
foil
Excellent yes yes yes H
Cellulose film Fragile -sealable yes no no A
*LDPE (low
density)
Thin -sealable yes no no
*HDPE (high
density)
Thick -Twice less transmission rate of
oxygen and water than LDPE- sealable
yes yes - A
Polypropylene
films
Same thickness as LDPE-sealable yes yes yes -
Polyester Very strong film yes yes no -
Polyamide
(nylon)
Used in laminate with LDPE for vacuum
packaging
no yes yes -
Coatings LDPE/Paper for e.g. yes - yes H
Metallization
Thin coating of aluminium with
polyester, polypropylene, cellulose
yes yes yes H
Laminates
E.g. Paper/foil/LDPE;
paper/LDPE/foil/LDPE
yes yes yes H
Jute Natural material- easily available no no yes L
L=low; A=average; H=high *Polythene film is of two types: LDPE and HDPE.
The use of the product (e.g. household consumption, trading, selling to consumers) will
determine the packaging type and presentation. When transporting sweet potato chips for
trade exchange, flexible material is more adaptable than rigid one because it allows use
of higher volumes at lower cost.
L