Bulbs, tubers, and rhizomes undergo a natural process of sprouting during storage and transport. Due to sprouting the commodities lose weight, appearance and thus marketability. The crops permitted for radiation processing as per PFA rules include potato, onion, shallots (small Madras onion), and fresh ginger. The sole purpose of radiation processing here is to inhibit sprouting during storage and transport. The radiation may not destroy rot causing microbes, and would thus control only sprouting in these commodities which is a physiological process.

Only varieties suitable for radiation processing and long term storage should be used. The bulbs should be of uniform maturity. The onion should be harvested after the foliar fallover is complete and dry. The bulb should preferably be topped 3-5 cm above the neck. The bulbs for radiation processing should be fully mature, sound, firm, and well covered with dry scales. The effectiveness of sprout inhibition caused by radiation processing may vary with variety, soil, and climatic conditions. Proper curing of onion prior to radiation processing is essential.

Only varieties suitable for radiation processing and long term storage should be used. The bulbs should be of uniform maturity. The onion should be harvested after the foliar fallover is complete and dry. The bulb should preferably be topped 3-5 cm above the neck. The bulbs for radiation processing should be fully mature, sound, firm, and well covered with dry scales. The effectiveness of sprout inhibition caused by radiation processing may vary with variety, soil, and climatic conditions. Proper curing of onion prior to radiation processing is essential.

Conditions of maturity at harvest, curing, postharvest storage, irradiation and post-processing storage as applicable to the commodities of this class also apply these commodities. In all the commodities irradiated for sprout inhibition, procedures such as screening, sorting, grading and packaging, are applicable as for the normal commodity under the best of the farming or trading practices.

The purpose of radiation processing of banana and mango is to extend their normal shelf-life by delay in their ripening. Other possible effects of radiation processing such as reduction of spoilage micro-organisms or insect disinfestation may be secured, but is not the primary purpose here.

Bananas are harvested in mature green state, given fungicide treatment, and appropriately packed prior to processing by radiation treatment. Irradiation should be carried out with a minimum delay after harvesting. A minimum delay of 7-8 days could be achieved at ambient temperature after processing by radiation. Best results are obtained when the fruits after radiation processing are stored at lower temperatures.

Mango should be picked in mature green stage with a specific gravity index of more than 1.0. Fruits should be thoroughly dried before packaging and processing by radiation. Hot water treatment at 45° C for 2-5 min could be given prior to radiation processing to obtain the best results. Radiation processing of immature fruits should be avoided. A delay in ripening of 7-14 days could be obtained at ambient temperature after processing. However, the best results are obtained when fruits are stored at lower temperatures. Radiation Processing of Foods –Technical Document, 2014.

The specific purpose of the radiation processing of spices, herbs and dry vegetables are to eliminate or reduce microbial load, eliminate pathogenic microbes, and insect disinfestation. Use of chemical fumigants has several disadvantages and therefore is being phased out all over the world. The radiation processing offers several advantages. Unlike fumigants it does not leave harmful residues and it is safe for the environment and workers. It is a cold process and at the same time it is highly effective. The usual considerations regarding the quality and good manufacturing practices would apply to all these commodities, as radiation processing cannot be used to correct quality deficiencies.

Dry cereal grains such as rice, wheat products such as atta, semolina, sooji or rawa, pulses (legumes) and pulse products can be infested with insects. Storage insects severely damage these commodities resulting in huge economic losses. Insect activity also increases moisture content of the commodity and promotes microbial activity. The initial moisture content of the commodity is crucial for the quality of these commodities and hence must be strictly controlled as a part of the good manufacturing practices. Packaging material that cannot be penetrated by insects should be used to avoid post-processing infestation. It is possible to carry out grain processing but this should be coupled with storage in insect proof silos or containers.

Insect infestation of dry fruits and raisins is a major problem during storage. Radiation processing of these commodities can destroy metamorphic stages of storage insects and prevent their emergence and subsequent damage. As for other radiation disinfested commodities, packaging material that cannot be penetrated by insects should be used to avoid post-processing infestation. Radiation Processing of Foods –Technical Document, 2014 18

Raw meat products, such as chopped or comminuted meat, mechanically deboned meat and poultry meat, whether fresh or frozen, can be processed by radiation. The purpose of radiation processing is to inactivate pathogenic microorganism present in meat and thereby make it safer for human consumption. The process can also inactivate protozoan and helminthes parasites present in these meats. The radiation processing is also carried out for assurance of quality and extension of shelf-life fresh meats by reducing the population of spoilage microbes. Relevant international codes for hygienic, good manufacturing practices and prescribed microbiological standards in these commodities should be adopted.

Frozen fish and shrimp may be contaminated with pathogenic bacteria. Radiation processing can inactivate pathogenic bacteria in pre-packed frozen fish and shrimp. In case of fresh fish and shrimp radiation processing can bring down the microbial load and extend the Shelf-life when kept under refrigeration. It can also inactivate the pathogens present in these foods. The fish or shrimp should be dressed, handled and stored as per the good manufacturing practices. In case of frozen fish or shrimp the freezing should be carried out on product produced under good manufacturing practices. Quick freezing should be practiced. Packaging should be adequate and functionally protective and should be approved for the purpose. Additional measures, such as vacuum packaging may be applied for preventing non-bacterial spoilage. In order to prevent risk of botulism, fresh fish should be stored at temperature below 3°C. Frozen products should be maintained below -20°C during radiation processing and post-processing storage and transport. Radiation Processing of Foods – Technical Document, 2014 19

Dried fish can be infested with storage insects. These insects feed on the fish tissue and cause damage and economic losses. Radiation processing can be used as an effective means of disinfestation of dry fish. Although mould growth can cause spoilage of these foods, doses employed for insect disinfestation may not control it. Therefore, mould growth should be prevented by using other measures such as salting and using preservatives. Good manufacturing practices should be followed in maintaining the initial quality of fish before and during drying and also during pre-process handling and packaging. Packaging should be done in packaging material impervious to insect. Improved packaging under vacuum and inert atmosphere can give better product quality. The moisture level should be maintained below 14 % during pre- and postprocessing storage. Radiation processed dry fish can be stored up to 6-9 months at ambient temperatures without changes in quality.