**9. Costs of subsequent processing**

The costs of subsequent processing of the recombinant proteins derived from plants have been estimated about 80% of the total production costs [60, 61]. This is why so much attention has been paid at sufficient strategies for reducing the costs to the least amount. The application of watery textures like tomatoes as a production system has been expanded because of their potential for reducing the costs via the ease of extracting from their textures in comparison with those of dry tissues like grains [34, 62]. In addition, tomatoes are highly regarded as a reputed host crop in terms of its bio-safety because these plants grow in greenhouses without worrying about the preservation of transgenic plants.

Nowadays, oil bodies of oilseed agricultural products, like the seeds of safflower and mustard, are being exploited by the application of oleosin fusion technology developed by SemBioSys Genetics in order to facilitate the purification of recombinant proteins and reduction of subsequent costs (http://www.sembiosys.com/). The strategies including targeting of recombi‐ nant proteins for the seeds of oilseed agricultural products as an oleosin fusion facilitate the extraction of fused proteins from oil bodies and the release of the recombinant proteins from their fusion partner; one example can be the accumulation and purification of biologically active human insulin, apolipoprotein *A-I* (Milano) and human growth hormone in safflower [63-65].

There are several recombinant proteins derived from plants that were the basic idea of edible vaccines, directly eaten as fruits (tomatoes and bananas) and vegetables (lettuce and carrots); accordingly, no processing costs will be demanded by the elimination of processing, [66]. Bananas, as a fruit host in agricultural products, have particularly attracted lots of customers for the production of edible vaccines, especially for developing countries. This has been widely developed in such countries because of long distance transports and cooling requirements [42]. Apart from the mentioned advantages, high digestibility and palatability of bananas have won a wide public acceptance for the vaccination of children [67, 68]. The sufficiency of potatoes, eaten in raw or low processed forms, for edible vaccines has resulted in their wide production. Potatoes, like seeds, have the advantage of production stability due to a special molecular environment allocated in glands [69].
