Biomedical Engineering Reference
In-Depth Information
after storage of 24 h). Frozen storage of the part baked chapatties is an effective
option for retarding staling, since after thawing and rebaking chapatties exhibit tex-
ture equivalent to that of conventionally baked chapatties (Gujral et al.
2008
).
Barbari is one of the fl at bread specialties consumed in Iran, Turkey, and some
Arab countries. Majzoobi et al. (
2011
) investigated the quality of part baked and
part baked frozen Barbarito preserve the quality of Barbari bread for longer time
and to delay its staling. Part baked Barbari had higher moisture content, which was
responsible of the short shelf life (72 h), but quality was fully recovered after full
baking. However, when storing under frozen conditions it was possible to extend the
shelf life of Barbari up to 2 months. In addition, full baking was able to overcome
the adverse effects of growth of ice crystals during freezing, although a reduction in
bread volume was observed (Majzoobi et al.
2011
). Their microstructural studies
showed that the crumb of Barbari bread was fully formed after part baking, thus
staling started after that stage, and full baking allowed obtaining bread with soft
texture, and adequate colour, taste and fl avour. The reduction in bread volume after
full-baking was barely detected by consumers owing to its fl at shape (Majzoobi
et al.
2011
).
Very often part baked fl at breads are re-heated in microwaves before consump-
tion, but that practice requires to adapt the formulation for reducing the texture
stiffness. The substitution of 20 % of wheat fl our with soy blends has been recom-
mended to obtain softer and less chewy texture. This was due to the action of soy
lipids (Serventi et al.
2011
). Proton nuclear magnetic resonance relaxation tests
confi rm that soy blends change the water dynamics leading to a more solid-like
matrix due to the high hygroscopic properties of soy protein and the plasticizing
effects of the lipids (Serventi et al.
2011
). These analysis also suggest that soy addi-
tion increases mobility of the water. Thus, soy addition affects the texture and water
properties of part baked fl at bread and these are more stable during frozen storage
(Simmons et al.
2012
).
As it has been mentioned before, sometimes refrigeration is preferred for keep-
ing the part baked breads and quality might be superior to as compared to conven-
tional ones. Karaoglu (
2006
) found that re-baked bran bread stored for 7 and 14 days
at refrigerator temperature gave softer crumb than the bread obtained by conven-
tional process. However, quality differences have been found even within the tem-
perature of refrigeration (Lainez et al.
2008
). In fact, partially baked bread stored at
1 °C can be stored for 28 days without showing microbial growth; in opposition, if
the storage is carried out at 7 °C part baked breads show mould growth after 9-days
(Lainez et al.
2008
). Despite that microbiological shelf life can be extended when
stored is carried out at 1 °C, the quality of the full baked bread is strongly affected,
because lower temperatures induces high hardness and from the sensory point of
view breads obtain lower scores (Lainez et al.
2008
).
Fibers or hydrocolloids affect the microstructure of the crumb leading to changes
in the pore roundness and pore size distribution. This was observed in the crumbs
analyzed by digital image analysis and scanning electron microscopy (Polaki et al.
2010
). Pore roundness has been correlated to organoleptic attributes such as aroma and
adhesiveness. At microstructural level the status of carbohydrates (fi brous, soluble,
