foam-mat freeze drying of egg white and ... - McGill University

ABSTRACT
ARUN MUTHUKUMARAN
M. Sc. Bioresource Engineering
Eggs are a rich source of high-quality proteins as they contain all amino acids necessary for
the human body. They also contain all vitamins (except for vitamin C) and many essential minerals.
Eggs mainly consist of egg white (albumen) and egg yolk. Egg white is mainly made up of proteins
and has excellent foaming properties; it is widely used in the baking and confectionary industries
(e.g., cake mixtures, meringue).
Dehydration is widely used for the preservation of egg. Dehydrated egg products usually
have a shelf life of one year under refrigeration. Spray drying and pan drying are widely used for
producing egg powder. The higher drying temperature associated with these drying methods could
adversely affect the nutritional value of egg. Freeze drying is well known for its excellent
dehydrated product quality. The high cost of operation associated with freeze drying restricts its
usage to high value products like coffee. Foam-mat drying can be used for the products that can be
foamed to increase the surface area to improve the mass transfer rate. But the higher drying
temperature involved in this method is not suitable for producing a high quality dehydrated product.
Foam-mat freeze drying is one of the promising methods of drying, which tries to utilize the
advantages of both freeze drying and foam-mat drying to produce better quality egg white powder.
Preliminary experiments showed that the stability of foams made with egg white alone is not
adequate for foam-mat freeze drying. Experiments were thus conducted using different stabilizers
(Methyl cellulose, Propylene glycol alginate and Xanthan gum) to optimize foam stability. Bubble
size distribution was determined using microscopy to understand foam structure. The results showed
that Xanthan gum at 0.125% provide sufficient stability for freeze drying. Experiments were
conducted to study foam-mat freeze drying of egg white, in an effort to determine the suitability of
this method. The results showed that the addition of Xanthan Gum during foaming has a positive
impact in reducing the total drying time and also produces excellent quality egg white powder. The
addition of stabilizer also plays an important role in improving drying. Heat and mass transfer
models were applied for determining drying time and diffusion coefficients during freeze drying.
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