# Factorial Design to Stimulate Biomass Development with Chemically Modified Starch
## 1 Introduction  
The use of polysaccharides in biomedical and biological application receives great attention. These materials, which can be used for biomass production, are cheap, non-toxic, renewable, and biodegradable [1; 2; 3; 4; 5; 6]. For biomass development, the most commonly used materials are glucose, starch, cellulose, and chitosan, in their native or chemically modified form. Starch is the main source of energy for animal life, and 50% of the starch produced industrially is intended for human consumption. Starch is also a low-cost polymer of biodegradable nature. The native starch is naturally available in two forms: amylose and amylopectin. The amylose is chemically formed from a linear chain of (\(\alpha\)-1\(\rightarrow\)4) linked glucose molecules. Ambjection is a highly branched structure with glucose molecules linked via (\(\alpha\)-1\(\rightarrow\)6) branch points [6]. On consumption of microorganisms, the molecule of starch is hydrolyzed into glucose. Recent research explains that modified starch molecules can increase crystallinity and digestive enzyme resistivity and have attained great interest in the gastronomic field due to their augmented functional properties [7; 8; 9; 10; 11]. The growth and multiplication of microorganisms are the result of the metabolism of bioanalysis, which forms cellular constituents. The production of the product used by the cultivation of microorganisms on different substrates, as is the case with biotechnology, is only possible under known and targeted conditions for maximum yield. In situations when the imbalance between the cell surface and volume reaches the maximum, a critical moment appears when the growth stops and then starts the cellular division. In the division following, microorganisms are multiplying and restoring normal equilibrium [8; 9; 10]. The multiplication is realized through fragmentation or the creation of a special type of spores. The idea is that multiplication increases the number of microorganisms. The cultivation of microorganisms on the medium culture dynamics of cell multiplication and the establishment of the generation duration are very important [12; 13; 14; 15; 16]. The generation duration is the time required for a cell to divide and, consequently, lead to a doubling of the population that is growing. Polysaccharides, particularly modified biopolymers derived from chitin and starch, can be used in different industries [11]. These polysaccharides are abundant, renewable, and biodegradable resources and can be considered as potential materials for biomass development [17; 18; 19]. Nevertheless, the weak aqueous solubility of the starch molecule is also known to be a major constraint that limits the development of starch-based materials. For non-food industries, starch is modified in order to obtain soluble products with properties suitable for various applications [20; 21; 22; 23; 24; 25]. In the present work, potato starch was synthesized by esterification in order to fulfill the objective: to increase the aqueous solubility of modified starch. The objective of chemically modifying starch is to solubilize the starch in various ways so that microorganisms are capable of developing. For starch modification, propylene glycol was used in order to increase the water solubility of starch. Chemical modification was confirmed by the \({}^{1}\)H NMR spectrum [6]. Hydroxypropylated potato starch (HP), potato starch, and glucose were used as carbon sources for biomass development. Mathematical modeling uses a factorial design, which is a numerical method, giving the investigator close results with significantly fewer experiments than a conventional experimental technique [16; 17; 18; 19]. Mathematical modeling through factorial design procedures have been used in different domains for optimizing and modeling different processes.