50 countries, the USA, South Africa, the Netherlands, Thailand and
France being among the leading exponents. In South Africa 1,754 tonnes
of herbs and spices were irradiated in 2004 and in the USA in 2003
22,000 tonnes of hamburgers were irradiated. In the UK, the applica-
tions listed in Table 4.10 have been permitted since 1991, although
consumer resistance and the requirement that irradiated foods are
labelled as such have meant that, to-date, only one licence has been
granted covering the treatment of some herbs and spices.
4.3 High-Pressure Processing–Pascalization
Hite, working at the University of West Virginia Agricultural Experi-
mental Station at the turn of the 20th century, showed that high
hydrostatic pressures, around 650 MPa (6500 atm), reduced the micro-
bial load in foods such as milk, meats and fruits. He found that 680 MPa
applied for 10 min at room temperature reduced the viable count of milk
from 10^7 cfu ml^1 to 10^1 102 cfu ml^1 and that peaches and pears
Table 4.9 Applications of food irradiation
Application Commodity Dose (kGy)
Inhibition of sprouting Potatoes 0.1–3
Onions
Garlic
Mushrooms
Decontamination of food ingredients Spices 3–10
Onion powder
Insect disinfestation Grains 0.2–7
Destruction of parasites Meats 0.3–0.5
Inactivation ofSalmonella Poultry 3–10
Eggs
Shrimps and frog’s legs
Delay in fruit maturation Strawberries 2–5
Mangoes
Papayas
Mould and yeast reduction 1–3
Table 4.10 Foods which may be treated with ionizing
radiation in the UK
Maximum permitted dose (kGy)
Fruit and mushrooms 2
Vegetables 1
Cereals 1
Bulbs and tubers 0.2
Spices and condiments 10
Fish and shellfish 3
Poultry 790 The Microbiology of Food Preservation