Handbook of Herbs and Spices - Volume 3

64 Handbook of herbs and spices

longer periods. The presence of invisible microorganisms, many of which could

cause, disease poses risks to human health, especially when spices are added to food

after cooking.

At present fumigants like methyl bromide, ethylene dibromide and ethylene oxide

are used to treat spices and herbs for insect disinfestation and microbial decontamination.

Besides being less effective, these fumigants leave chemical residues on spices that

are harmful to human health. These fumigants are also harmful to the environment as

halogenated hydrocarbons deplete ozone in the atmosphere. Many countries have

banned the use of fumigants. Other countries, including India, are planning to ban

them.

3.2.2 Quality improvement by irradiation

Radiation processing offers a very effective and safe alternative for disinfestation

and microbial decontamination of spices and herbs. It is a cold process, sometimes

also referred to as cold pasteurization, therefore it does not affect the delicate aroma

and flavor compounds in spices. Radiation processing can be carried out in pre-

packed spices without running the risk of post-treatment contamination. The process

is very effective compared to fumigants and does not leave any harmful residues on

spices.

Table 3.7 shows the effect of irradiation on bacterial and fungal microflora of

spices. It is clear that a radiation dose of 5 kGy can eliminate fungal microflora,

whereas, a dose of 10 kGy destroys all bacterial contaminants, making spices

commercially sterile. Table 3.8 shows the microbial profile of irradiated and non-

irradiated spices during storage. It is evident that irradiated spices retain their

Ta ble 3.7 Effect of gamma radiation on total bacterial and fungal population in spices

Spice Total bacteria (CFU/g) Total fungi (CFU/g)
Dose (kGy) Dose (kGy)

05 7.5 10 0 1 5 7.5 10

Pepper 1 ¥ 107 1 ¥ 103 4 ¥ 102 09 ¥ 102 1 ¥ 101 00 0
Nutmeg 4 ¥ 104 6 ¥ 102 008 ¥ 103 8 ¥ 101 00 0
Cinnamon 2 ¥ 103 1 ¥ 102 003 ¥ 102 0000
Cardamom 1 ¥ 104 3 ¥ 102 2 ¥ 101 01 ¥ 103 5 ¥ 101 00 0
Clove 9 ¥ 102 4 ¥ 102 009 ¥ 102 4 ¥ 101 00 0

Ta ble 3.8 Total bacterial count of non-irradiated and irradiated spices during storage at ambient
temperature

Spice Dose (kGy)
Storage period (mo)
05 10

036 036 036

Pepper 3 ¥ 106 3 ¥ 106 3 ¥ 106 2 ¥ 103 2 ¥ 103 5 ¥ 102 000
Chili 4 ¥ 106 2 ¥ 106 1 ¥ 103 2 ¥ 104 2 ¥ 103 2 ¥ 102 35 0 0
Turmeric 1 ¥ 106 9 ¥ 105 8 ¥ 102 2 ¥ 102 2 ¥ 102 0000
Coriander 1 ¥ 105 1 ¥ 105 1 ¥ 105 2 ¥ 102 1 ¥ 102 1 ¥ 102 000