Agriculture Reference
In-Depth Information
shelf lives are usually indicated as 'best before end' or
'sell by' dates. The shelf lives of dried spices or herbs in
sealed containers (glass, plastic or sealed bags) are
usually 2-3 years. Shelf lives are typically 4-5 days for
most fresh herbs, though chervil will last for 1 week
(Gorini 1988), coriander and dill for 2 weeks and savory
up to 3 weeks (Wright 2002a).
Table 15.5
Effect of Temperature and Ethylene on
the Equality of Herbs after 10 Days.
Visual quality score
1
Herb
0°C
10°C
20°C
Basil 2 8 7
Chervil 8 6* 1
Chive 9 6 3
Dill 9 6* 2
Epazote 9 7* 5
Mache 8 5 2
Marjoram 9 8* 1
Mint 9 6* 2
Mitsuba 9 7* 4
Rosemary 9 9 7
Sage 9 8 -
Shiso 6 8* 3
Tarragon 8 6 -
Thyme 9 8 7
* Indicates reduced quality after exposure to ethylene at
5-10 ppm.
1
9: excellent; 7: good, minor defects; 5: fair, moderate
defects, limit of saleability; 3: poor, major defects; 1:
unusable.
Source: Modified from Cantwell and Reid (1993).
Traceability
Increasing consumer interest in food safety and
convenience, allied to improvements in packaging, has
increased the amount of pre-packed produce to over
90% in the United Kingdom. Traceability is also an
issue, and the rise of the web and bar coding
techniques has allowed much more information to be
made available to consumers. For example, in the United
Kingdom all fresh produce must have a unique code
and web address on it, so that consumers can search for
the origin of the product (growers' name and address),
when it was harvested, packed and shipped and which
route it took to the retail outlet from where it was
purchased (Anon. 2003).
Cultivation, harvesting and handling
Herbs are grown in the field or under glass, in cloches
or greenhouses, and production is usually small scale.
Harvesting, grading and packing are often done manually
or with small mowers and so labour costs are high. In the
United States, fresh plants are cut with scissors and
bunched in the field or taken to packing houses for
trimming and packaging in bulk or bunches, or packed into
plastic bags or rigid plastic boxes designed as point-of-sale
containers (Cantwell & Reid 1993).
Most herbs for fresh culinary use are best harvested
before flowering, except for marjoram and oregano
(occasionally sold with flower buds) and chive blossoms.
Basil also keeps its quality with some flowers still
attached (Wright 2002a).
Methods of drying depend on the crop and locality.
Thus in tropical countries much use is made of sun
drying in the field for three to four days, by hanging the
stalks on racks or laying them out on screens in the sun.
Alternatively, plants may be spread on wire trays in
ventilated drying sheds for a week or so. Once dried,
leaves are separated from stems by rubbing on hand
sieves (Potty & Kumar 2001). Delicate species should
not be hung in bunches since the soft foliage will dry too
slowly and may spoil. Oven drying is not dependable
since leaves are liable to scorch, but forced air dryers are
effective (Simon 1984).
produce to distributors who handle the main leafy vege-
tables and who have facilities for cooling. Alternatively,
the more robust fresh herbs have been stored on ice, or
forced-air or room cooling used for the more tender
types. Vacuum cooling has also been employed (Aharoni
et al
. 1989; Cantwell & Reid 1993). Refrigerated road
and rail transport of fresh herbs may be done in mixed
loads with other leafy greens. However, given their light
weight, high perishability and low volume, fresh herbs
are more usually transported by air to reduce the time in
transit. Gel-ice packs are sometimes used to limit the
build-up of heat during the journey (Cantwell & Reid
1993). Producers in Australia faced similar problems in
that temperature and humidity control during handling,
distribution and marketing were identified as key issues
in limiting expansion of the industry (Lopresti &
Tomkins 1997).
Shelf life
The shelf life of a commodity depends on the conditions
under which it was packed and stored, and the form in
which the product is maintained. In stores and supermarkets
