Simultaneous heat and mass transfer applied to non-respiring
foods packed in modiﬁed atmosphere
, S.F. Almonacid, C.A. Acevedo, C.A. Cort
Departamento de Procesos Qu
ıımicos, Biotecnoloogicos, y Ambientales, Universidad Teecnica Federico Santa Mar
ııa, Casilla, 110-V Valpara
Received 5 October 2002; accepted 3 April 2003
A mathematical model to predict heat and mass transport phenomena in non-respiring food packed in modiﬁed atmosphere
(MAP) was developed and validated. The model incorporates simultaneous gas convection, sorption, diﬀusion, heat convection and
conduction. The model was applied to MAP systems containing CO
O. Validation test was done with gelatin. The
average errors between experimental and simulated values were low: <0.6 (°C) for the temperatures, 3% for relative humidity and
<1.43% for the headspace gas composition. Model predictions during heating and cooling phases indicate that temperature
modiﬁcation of the packaged product can be quite slow, reﬂecting the relevance of proper chilling in the packaging, transport and
storage processes of MAP products. The model applied to shelf-life studies, for speciﬁc products, can be utilized to identify facility
and product handling improvements to generate the greater positive impact on product quality. The development of this or similar
mathematical tools would allow for more technical and informed management decisions.
Ó 2003 Elsevier Ltd. All rights reserved.
Keywords: Modiﬁed atmospheres packaging; Heat and mass transfer; Non-respiring foods
An increasing demand of natural and minimally
processed food has been observed in the last few de-
cades. A large part of this demand can be satisﬁed
through the modiﬁed atmosphere packaging (MAP)
technique, which together with chilled storage results in
a signiﬁcant shelf life increase of fresh food, without
major eﬀect on its quality (Blakistone, 1999).
Most of technological advances in MAP systems have
been empirically obtained, as such, limiting its applica-
tion to the conditions at which the experiments were
Mathematical models are quantitative tools that
when applied in food allow for design and process op-
timization, permitting the generation of high quality
products, and diminishing the time and cost of labora-
tory tests. On living MAP systems, most of the models
are focused in fruits and vegetables, where respiration
reactions determine the gas transfer between the plant
material and ambient (Talasila, Chau, & Brecht, 1995;
Emond, Chau, Bretch, & Ngadi, 1998; Lakakul,
Beaudry, & Hernandez, 1999). In non-respiring foods,
where the gas diﬀusion is the main transfer mechanism,
Simpson, Almonacid, and Acevedo (2001) developed a
mathematical model that describes the gas transfer be-
tween the food, headspace and ambient at constant
temperature. Prior to consumption, foods are frequently
exposed to temperature ﬂuctuations, especially, dur-
ing transportation and storage, these temperature abu-
ses can signiﬁcantly diminish the useful food shelf life
(Almonacid & Torres, 1993; Koutsomanis, 2001).
An adequate estimation of the variation in gas com-
position throughout time must consider the variations of
temperature to which the MAP system was exposed.
Gas composition proﬁles and temperature over time will
ﬁnally determine the food shelf life.
The objective of this research was to develop and
validate a heat and mass transfer model for non-
respiring food packed in modiﬁed atmosphere. The
model describes the temperature variation and gas com-
position in the headspace and interior of non-respiring
food packed in modiﬁed atmospheres.
Journal of Food Engineering 61 (2004) 279–286
Corresponding author. Tel.: +56-32-654302; fax: +56-32-654478.
E-mail address: email@example.com (R.J. Simpson).
0260-8774/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.