Agriculture Reference
In-Depth Information
Table 15.6
Radiation doses for safe microbe
levels in some herbs and spices.
Herb or spice
Table 15.7
Respiration rates of some fresh herbs.
Respiration rate (mg CO
2
kg
−1
h
−1
)
Dose (kGy)
Herb
0°C
5°C
7.5°C
10°C
20°C
Anise 5
Basil 4-10
Capsicum 5-8
Caraway 4
Cardamom 5-8
Cinnamon 5-10
Coriander 5
Cumin 5-6
Fennel 8
Fenugreek 5-10
Garlic powder 5-7
Ginger 5-10
Mace 5
Mustard seed 4-10
Nutmeg 5
Onion powder 5-10
Organo 4-10
Paprika 4-8
Pepper, black 4-6
Pepper, white 5-10
Sage 4
Thyme 5-7
Turmeric 5-7
From Kiss & Farkas 1988; Sjöberg
et al
. 1991.
Basil 36 — — 71 176
Chervil 12 — — 80 170
Chive 22 — — 110 540
Chinese chive 54 — — 99 432
Coriander 22 30 46 — —
Dill 22 — — 103 324
Marjoram 28 — — 68 —
Mint 20 — — 76 252
Oregano 22 — — 101 176
Sage 36 — — 103 157
Tarragon 40 — — 99 234
Thyme 38 — — 82 203
Turmeric (rhizome) 5 9 — 17 28
From Cantwell & Reid 1993; Peiris
et al
. 1997; Loaiza &
Cantwell 1997.
quality loss post-harvest. As well as CO
2
and H
2
O, res-
piration produces vital heat that presents a heat load to
cooling systems. Knowledge of respiration behaviour is
therefore important in prediction of shelf lives and
demands for storage cooling (Peiris
et al
. 1997). Some
respiration rates at different temperatures are shown in
Table 15.7.
depended on the source. Aerobic mesophile counts varied
from 2.9 × 10
2
to 3.2 × 10
7
cfu/g, coliform counts were
7.9 × 10
2
to 1.9 × 10
7
cfu/g and salmonella levels were
7.9 × 10
2
to 2.7 × 10
5
cfu/g. Fungal,
B. cereus
and
C. perfringens
counts ranged from undetectable to
1.7 × 10
7
, 1.4 × 10
6
and 8.0 × 10
3
cfu/g, respectively.
Washing reduced the aerobic mesophile counts by
0.25-1.0 log
10
; and dipping in chlorine at 25 ppm reduced
levels by an additional 0.2-log
10
. The efficacy of washing
and dipping depended on the initial microbial load.
POST-HARVEST LOSSES
Over the years a great deal of attention has been given to
the magnitude of post-harvest losses in general perishable
commodities, although there is little reliable information
(Coursey & Proctor 1975). Conservative data in the
literature, and anecdotal evidence, suggest losses in the
order of 25% in the developed world. Losses in tropical
countries are certainly worse but even less hard
information is available (FAO 2002). Nor have losses in
fresh herbs and spices been quantified but they are likely to
be in the same range.
Given the difficulty in assessing losses in perishables,
and the huge range of losses (anywhere between 0% and
100%) depending on the commodity, it has generally been
accepted that the magnitude of loss is impossible to
quantify without reference to the specific crop and
post-harvest regime. Rather the value of loss figures lies in
indicating the size and extent of the problem and
highlighting the need for remedial action (FAO 2002).
Respiration
Given the relatively short shelf lives of fresh herbs
increasing life by an extra day or two could extend
display times by a large percentage. Maximising shelf
life is thus valuable in fresh herbs, and information on
their post-harvest behaviour is very important. One of
the most notable inherent aspects is respiration rate,
which is often a fairly good indicator of the rate of
