Biomedical Engineering Reference
In-Depth Information
9.3.3
Consumer Retail: Packaging
The most usual method for storing the part-baked bread was freezing. The freezing
is generally carried out in industrial bakeries and products are kept frozen until its
distribution to retailers. However, lately the ambient part-bake category is also
emerging. Market research indicated that in UK this type is growing 1.8 % per year.
In this picture, packaging characteristics are rather important to keep the proper-
ties of the part baked product. The packaging barrier properties might affect the
phenolic and phytosterol content, oxidative stability and crumb texture of part-
baked. A study carried out by Novotni et al. (
2011
) tested different materials, like
blue coloured high density polyethylene (PE-HD) and transparent polyester-
polyethylene-ethylene-vinyl alcohol copolymer (PET-PE/EVAL/PE). The part-
baked breads stored at −18 °C using above plastics showed that their oxygen
permeability did not change during storage. During frozen storage of part-baked
total phenolic content and oxidative stability decreased. Oxidative stability of bread
in PE-HD package was better than in PET-PE/EVAL/PE due to their blue colour and
lower light transparency. Neither total sterol content nor crumb fi rmness depended
on the packaging material (Novotni et al.
2011
).
In 1983, AlbroBakkerijen BV presented a process of extending shelf life of
partly baked products. In this process air was evacuated and a protective gas (e.g.
carbon dioxide with or without nitrogen) inserted in a sealed pack containing part-
bake bread. The gas mixture of nitrogen and carbon dioxide is used to prevent spoil-
age and retained fresh characteristics. Bread must be inserted into the pack
immediately after baking (i.e. whilst still hot) and is cooled by subsequent evacua-
tion. Later, a method of packaging for hot part baked breads from oven into a gas-
barrier package under a preservative gas was presented. This process was carried
in-line while products were hot (Deighton et al.
2003
). This method was considered
as modifi ed atmosphere packaging and this are being used extensively for storing
part baked bread at ambient temperature. The fungi static and bacteriostatic action
of the carbon dioxide besides the low levels of oxygen (<1 %) ensures the inhibition
of moulds and other aerobic spoilage organisms. In addition bread staling is retarded
owing to the hindering effect of carbon dioxide on the starch retrogradation. The
most commonly used levels of carbon dioxide and nitrogen are 60 and 40 %, respec-
tively (Galic et al.
2009
; Leuschner et al.
1999
) or 70 % carbon dioxide in
polyethylene-polyamide-polyethylene vinyl alcohol bags (Doulia et al.
2000
).
Under those conditions the shelf life of the part baked bread might be extended
more than 2 weeks. Nevertheless, the level of carbon dioxide can rise up to 100 %
in some specifi c type of bakery products (Galic et al.
2009
). For instance, brown
soda bread packed in an atmosphere of 40 % CO
2
and 60 % N
2
and storage at 4 °C
can avoid microbial growth for 13 weeks (Leuschner et al.
1999
).
Effectiveness of the modifi ed atmosphere packaging against microbial growth
sometimes is not suffi cient, and some forms of spoilage organisms can grow during
summer months. In fact, Deschuyffeleer et al. (
2011
) analysed spoiled part baked
breads packaged under a low oxygen and high carbon dioxide atmosphere and
