Agriculture Reference
In-Depth Information
Figure 7.4. Various processed coconut products: UHT coconut milk for cooking meals (top left) and dessert
(top right), and pasteurized coconut milk (bottom left) and UHT coconut water (bottom right). Reprinted with
permission from Ampol Food Processing, Ltd.
traditional products such as jams, jellies, and marmalades.
Plastic trays are another form of plastic retortable packages,
which are increasingly gaining in popularity in the food in-
dustry today as they perform additional functions such as
serving and stacking.
The desired characteristics required for all retortable ma-
terials include resistance to high temperature and pressure,
which are critical factors during processing, as well as hav-
ing a high barrier to oxygen and moisture, which is a critical
factor during storage. In addition, they should possess suf-
ficient strength for handling and distribution. However, dif-
ferent retortable materials possess different characteristics,
the main differences being heat penetration, barrier prop-
erties, and product-package interactions. The differences
in heat penetration primarily affect temperature and time
during the heating and cooling processes. Glass is imperme-
able and inert. Metal is an excellent barrier to oxygen and
moisture and has minimum interaction if properly treated.
Plastic has a wide variety of barrier properties and different
interactions with fruit products.
Two basic forming processes of glass containers are the
press-and-blow process (P&B) for wide-mouth containers,
mostly used for canned foods, and the blow-and-blow pro-
cess (B&B) for narrow-neck containers, mostly used for
beverages. Typically, the P&B process is easier to control,
uses less glass, and produces even thickness as compared
to the B&B process. Currently, a new glass manufacturing
process that is increasingly being used is the narrow-neck
press-and-blow process, which has been modified from
B&B and P&B processes in manufacturing narrow-neck
bottles.
In metal containers, made from tin plate and tin-free
steel, minimum interactions occur if they are properly
treated or coated to control corrosion. In addition to tin
coating, chromium coating was developed as an alternative
cost-effective process that offers strong lacquer adhesion
and corrosion resistance. Applications of chromium-coated
steels include can tops, caps, closures, and shallow-drawn
food cans. Lacquer (epoxy, vinyl, acrylic, polyester, and
oleoresin) may be applied to tinplate internally and/or ex-
ternally to prevent corrosion and interactions between the
metal container and its contents, as well as contamination
caused by micro-organisms. Special features and designs
are incorporated into cans for convenience and use, for ex-
ample, necked-in cans for easy stacking and peelable foil
ends for easy and safe opening. Metal cans present good
recyclability, which is in keeping with the trend toward
reduced energy consumption.
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