Solid-State Fermentation: A Novel Approach in Food Processing Technology Using Food Industry Wastes

Introduction

Environmental problems and public health risk mostly occur due to wrong waste management practices and these wastes generally accumulate on land sites or are consumed by animals (Yazid et al., 2017). The source of these wastes is generally agriculture, household, industries, and certain waste produced by animals or humans (Mussatto et al., 2012). The practices that most people were following for disposal of these wastes were contributing to air and water pollution as people in the past used incinerators to burn waste, producing harmful gases like carbon dioxide and methane (Sánchez et al., 2015) or broken down waste accumulated on land sites by a microorganism which contaminated groundwater (Eco-Cycle, 2011). These problems increase the need for the development of sustainable technology for food processing that will be highly efficient (Fig.1) and able to solve the problem of disposal (Mussatto et al., 2012; Chen and He, 2012).

Figure 1.

The efficiency of Solid-state fermentation

Source:(Yazid et al., 2017)

Background

In previous years, solid-state fermentation (SSF) became an emerging technology with sustainable features of bioconversion of waste to functional components. SSF utilizes and reuses the waste, as these wastes are composed of macro and micronutrients like carbohydrates, proteins, and minerals (Mussatto et al., 2012). Under certain standard conditions, the wastes were utilized in the development of microorganisms in differently designed bioreactors and yield products from low-cost residues, with lower energy consumption and hence, were economically feasible. The process of SSF is described in figure 2.

Figure 2.

Steps involved in solid state fermentation process

Aspects considered important for SSF process include substrate nature, substrate particle size, selection of bioreactors, selection of microorganisms according to moisture conditions, pH, temperature, water activity, and aeration. SSF technology opens up great possibilities of waste management using biochemical engineering and biotechnology field advancement to produce bioactive compounds, chemicals, and functional components (Singhania et al., 2009).

Advantages And Challenges Of Ssf Over Submerged Liquid Fermentation (Sfl)

Nowadays, the use of SSF is increasing over SFL in the biotechnology field. In the SLF process, liquid media are required for the growth of microorganism. The water content required for fermentation decreases the media concentration and contaminates media due to higher water activity. The liquid waste produced from SLF process causes a dumping problem due to its higher quantity (Manpreet et al., 2005). The overall process of the SLF is expensive as it requires processed substrate and large-scale practice which leads to an increase in the cost for the labors (Kapilan, 2015; Pandey et al., 1996). Whereas the SSF process has many advantages (figure. 3) over SLF, which are as follows:

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  It does not require liquid for media preparation, which lowers production of wastewater, reducing contamination and sterility demand (Holker et al., 2004).

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  Low-cost solid substrates from agricultural and household waste are available in abundance and economically cheap (Durand, 2003).

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  SSF did not require complex, large-scale bioreactors or machinery because of lesser water requirements (Singhania et al., 2009).

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  SSF provides greatest advantage due to lower energy consumption, lower plant and machinery cost, and ultimately reduction in labor cost (Pandey et al., 2001).

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  The product yield of SSF is generally high with higher stability, with the higher productivity of fermentation with lower moisture requirements (Sabu et al., 2006; Pandey et al., 2001).