*3.8. Assesment of Production Cost of Pigment Production*

The utilization of agricultural residues and organic waste from agro-industries as carbon sources for the production of value-added products reduce the production cost and provide environmental sustainability. On the other hand, product yield, transporting, handling and pretreatment costs should be considered when wastes are used as inexpensive organic substrates for fermentation processes. The operational cost includes the handling and pretreatment processes of raw materials, fermentation, downstream processes, labor, and maintenance along with the plant and administrative costs. Furthermore, the pretreatment process of the waste substrate should be appropriate in terms of process and environmental sustainability. Physical, chemical and hydrothermal processes are among the several pretreatments applied to agricultural waste materials [58].

As can be seen from Table 1, the amount of pigment produced from soybean, coconut and bagasse is low, therefore transportation and handling costs for utilizing large volumes of waste materials for pigment production will be very high. The concentration of pigment produced from corn meal supplemented with glucose (6%) and whey (1%) is higher than pigment concentrations when other waste materials are used. The addition of whey to the fermentation medium may have provided the necessary nitrogen and mineral sources for cell proliferation. Since coconut and bagasse contain glucose sources in the form of cellulose, the pigment yield will also be low unless the substrate is pretreated. Hence, the use of cellulosic agricultural waste in fermentation requires a costly pretreatment process and more waste will be generated after the fermentation limiting the environmental sustainability of the process. However, instead of lignocellulosic waste, the use of agro industrial wastes such as whey that does not require many pre-treatment unit operations prior to the fermentation seems to be a more economical and sustainable alternative for the red pigment production process.


**Table 1.** Pigment yields and necessary waste material for red pigment production.

In this study, the operational cost of red pigment production by *M. purpureus* is calculated as 14.92 dollars/kg when commercially processed, demineralized whey was used for pigment production. This calculated cost is close to the pigment production process cost when glucose is used as the carbon source, since both are processed products. Pigment production cost can be reduced by the use of raw liquid whey coming directly from cheese production, but the membrane filtration process needed to concentrate the sugar will possibly increase the production cost of the process. Therefore, it is important to concentrate more on the economic feasibility of the process for future work.
