Drying of Tunisian sardine (Sardinella aurita) experimental study
and three-dimensional transfer modeling of drying kinetics
ne Boudhrioua, Nabil Kechaou
Groupe de Ge
nie des Proce
s Agro-alimentaires, Unite
de Recherche en Me
canique des Fluides Applique
e et Mode
Ecole Nationale d’Inge
nieurs de Sfax, BP ‘W’ 3038 Sfax, Tunisia
Received 5 May 2006; received in revised form 22 January 2007; accepted 19 April 2007
Available online 3 May 2007
Experimental drying curves of sardine muscles (Sardinella aurita) in parallelepiped form were performed under diﬀerent drying air
conditions (three air temperatures: 35, 40 and 50 °C±1°C, two air velocities: 1 and 2.5 m s
, and at atmosphere humidity). A diﬀusive
three-dimensional model was established to describe drying of sardine sample in parallelepiped form. The calculated drying curves was
compared to the experimental ones in order to determine apparent moisture diﬀusivity. An empirical equation describing the apparent
moisture diﬀusivity within the sardine muscles was suggested versus temperature and local moisture content of the product. A good
agreement was found between experimental and calculated drying kinetics.
Ó 2007 Elsevier Ltd. All rights reserved.
Keywords: Sardine muscles; Drying curves; Three-dimensional transfer; Apparent moisture diﬀusivity; Modeling
Many food products are characterized by their high
humidity content which can be the most important cause
of their contaminations. Air drying could be used for
enhancing the resistance of high humid products to the
degradation by decreasing their water activity. In many
countries, drying is one of the most common method of ﬁsh
preservation. Proteins contained in marine products are
nutritiously complete and may represent a high value die-
tary food. In Tunisia, sardine (Sardinella aurita) can be val-
orised by transforming it to other forms of commercial
product (dried, salted...).
The second Fickian law is always used to describe mois-
ture movement through homogeneous products during
drying (Crank, 1975). Biological products are heteroge-
neous and they shrink during drying. To simplify the prob-
lem, the second Fickian law is also applied to describe mass
transfer in biological products. As a result an apparent
moisture diﬀusivity is suggested.
Determination of apparent moisture diﬀusivity is neces-
sary to optimize the drying processes, especially in highly
automated computer systems. A lot of theoretical and
experimental researches have been conducted in order to
estimate apparent moisture diﬀusivity and there is an
increasing interest in establishing more sophisticated dry-
ing models (Boudhrioua, Bonazzi, & Daudin, 2003a,
2003b, 2005; Kechaou & Maa
lej, 2000; Nguyen, Verboven,
Scheerlinck, Vandewalle, & Nicolai Bart, 2006; Zogzas,
Maroulis, & Marinos-kouris, 1996). However, it seems
unreasonable to consider that a speciﬁc method of estima-
tion can be applied to all cases, because the complexity of
the involved phenomenon.
Therefore, the objective of this work is to develop a dif-
fusive three-dimensional model which takes into account
the shrinkage of the material. The model was applied to
experimental drying curves of sardine muscles (Sardinella
0260-8774/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
Corresponding author. Tel.: +216 74274088; fax: +216 74275595.
E-mail addresses: email@example.com (B. Hadrich), nourhene.
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Journal of Food Engineering 84 (2008) 92–100