Agriculture Reference
In-Depth Information
16.9.1.5
WAX COATINGS
Wax, the first edible coating known, is the most effective coating to block
moisture migration. There are a number of waxes used but the most effec-
tive one is paraffin wax, followed by beeswax. The resistance is related to
their compositions. Paraffin wax consists of a mixture of long-chain satu-
rated hydrocarbons while beeswax comprises a mixture of hydrophobic,
long chain ester compounds, long chain hydrocarbons and fatty acids. The
absence of polar groups in paraffin and presence in low levels in beeswax
account for their resistance to moisture transport. An increase in ethanol,
acetaldehyde, total soluble solids content and a decrease in total solids and
titratable acidity was observed for waxed mandarins during storage rela-
tive to unwaxed fruits stored in film lined boxes. Storing waxed mandarins
at room temperature can lead to anaerobic respiration with higher levels of
ethanol and acetaldehyde. Oranges coated with commercial solvent type
wax had less weight loss than those with comparable amounts of water
wax or polyethylene coatings. There was an increase in storage life and a
decrease in weight loss when mangoes were coated with a wax emulsion
in water compared to mineral oil coated and control samples.
16.9.1.6
WHEY PROTEIN COATINGS
The mechanical properties of whey protein films adequately provide du-
rability when used as coatings on food products or films separating layers
of homogeneous foods. Adding glycerol and sorbitol reduces internal hy-
drogen bonding in films, thereby increasing film flexibility. Incorporating
whey protein edible films in food product can results in reduction of food
losses due to spoilage and thus extend the shelf-life.
16.9.1.7
CASEIN COATINGS
Research conducted in different countries of the world showed that casein-
lipid coatings provide protection of fruits from moisture loss and oxidative
browning. Calcium caseinate and whey protein solutions efficiently delays
browning of apple by acting as oxygen barriers. Respiration rate of Red
Delicious apples increased for both caesinate coated and uncoated apples.
This indicated that caesin coated formulations cannot modify fruit respira-
tion rate.
