Agriculture Reference
In-Depth Information
Onions for retail sale may be sold loose or be packaged
into smaller mesh packs or in plastic bags, though these
are not ideal due to their limited ventilation. Well venti-
lated bags are a better option. Often certain types of onions
are sold in recognisable packs, such as large Spanish-type
onions in 'in-line' packs of three in the United Kingdom.
The consumer tends to assume that these onions will
be mild, though surveys in the United Kingdom have
shown that this is not always true (B.M. Smith, personal
communication, 2001). Similarly, there seems to be an
assumption here that red onions are usually mild, and
again this generalisation is not justified since red onions
can show a wide range of pungency levels. Developments
in onion selling are the use of ready-peeled and cut onions
for catering uses. Some research has been done on the use
of modified atmospheres to retain quality in such packs
(Blanchard
et al
. 1996).
In the United Kingdom, there is little attempt at
marketing onions for specific uses and consumers are
usually left to find the best uses for themselves. However,
in the United States, with its large and distinct production
areas, speciality crops such as seasonal sweet onions (e.g.
Vidalia onions from Georgia), or large mild onions, are
well publicised by state or regional grower groups which
can obtain funds through federal marketing orders (i.e.
levies on crops sold). In many countries, it is noticeable
that the growers themselves show little interest in the
marketing aspect of onion production, an omission which
leaves them open to having their market share taken by
more enterprising exporters. The need to educate consum-
ers in how best to store onions and garlic in the home is
ignored, leading to complaints that onions do not keep
well and that garlic sprouts rapidly when kept in the
refrigerator; in fact, traditional methods of keeping bulbs
under warm dry conditions are as effective as ever, but
often they have not been put over to younger consumers.
Garlic tends to be treated as a speciality crop or a
condiment and its high value allows it to be marketed in a
range of units, from single bulbs through sleeved or boxed
pairs of bulbs up to strings, small wooden crates or sacks.
Treatment by smoking is sometimes used to add value. For
the catering trade, 'peeled' garlic is a valuable commodity
since the preparation work can be omitted at the factory.
Chinese peeled garlic can be shipped to markets such as
the United States, which can be reached within 18 days of
peeling the bulbs. 'Fresh' garlic (i.e. bulbs sold with their
green tops) is also seasonally popular in European mar-
kets. In East Asia, special green leaved varieties are grown
for the leaves which are traditionally used in cooking, as
well as the dry bulb varieties. As well as fresh garlic for
culinary uses, other uses such as dietary supplements
(including 'aged' garlic, no-odour garlic etc.), pest
repellents and so on are being rapidly developed. Novel
time-saving preparations such as ready-crushed frozen
garlic are being developed (J.K. Lee, 2003, personal
communication.). The health-giving properties of garlic
are of great interest, since it can also serve as an antiseptic
in cases where antibiotics are not effective. Health aspects
of garlic were reviewed by Milner (2001), Keusgen (2002)
and Corzo-Martínez
et al
. (2007).
Research on prepared allium products
The increasing use of prepared onions and garlic, usually
for the catering trade, is bringing a need for research on
methods of conservation of these products. Lee
et al
.
(2000) investigated the dynamics of internal atmosphere
and humidity in perforated plastic packages of peeled
garlic. These workers developed a mathematical model
which can predict the changes that take place in the package
atmosphere over time: however, they found that hermetic
packaging, which produced a water-saturated atmosphere
with nil O
2
and 5% to 15% CO
2
, performed better than
perforated plastic in maintaining the freshness of the
peeled cloves.
Diced yellow onions packaged in a range of modified
atmospheres were studied by Blanchard
et al
. (1996) in
France. The work included studies on microbial develop-
ment in the packs. The conclusions were that high CO
2
and
low O
2
delayed both the rise in respiration and the reduction
in sucrose content. The levels of reducing sugars and total
sugars were not affected during the 12-day experiments at
4°C. The data obtained will be used to develop the safest
methods to package cut onion products.
WASTE DISPOSAL
The problems associated with waste disposal from allium
storage and processing is presenting increasing problems,
especially where laws on waste disposal are becoming
more stringent. Allium waste is not suitable for animal feed
or landfill as it rapidly produces phytopathogens and can-
not be reintroduced into the soil due to the high levels of
sulphur compounds. Work is therefore being commissioned
on ways to make constructive use of waste products from
alliums. In California, Zhang and Zhang (1999) developed
a method of anaerobically digesting garlic waste to produce
biogas. After the digestion process, 51% of dry matter and
62% of volatile solids in the garlic waste were converted to
biogas. It was planned to develop this to pilot plant scale.
Roldán
et al
. (2008) investigated methods of processing
onion by-products to produce a safe product which retained
