Introductory Chapter: What We Know about Starch

1. Introduction

Several studies abound in literature expounding the meaning and frontiers of starch, which is the major dietary source of carbohydrates, and the most abundant storage polysaccharide in plants, occurring as granules in the chloroplast of green leaves and the amyloplast of seeds, pulses, and tubers. Starches are polysaccharides, made up of a number of monosaccharides or sugar molecules connected with a-D-(1–4) and/or a-D-(1–6) linkages. It consists of two major structural components: amylose, which is a linear polymer with glucose residues of α-(1–4) linked typically constituting 15–20% of starch; and the major component called amylopectin, which is a larger branched molecule with α-(1–4) and β-(1–6) linkages. The former is said to be linear or slightly branched. It is reported to have up to 6000 and 105–106 g/mol as its degree of polymerization and molecular mass respectively. The respective corresponding values for amylopectin are 2 million and 107–109 g/mol.; it is thus considered one of the largest naturally occurring molecules [1].

2. Starch and nations development

In the past two decades, the global market value for both native and modified starches has been put at 48.5 million tons worth €15 billion per year. Since the first century, Celsius, a Greek physician, had described starch as a healthy food, having been added to several foods, confectioneries, and wine as well as salad dressing ingredients in mayonnaise during the late 1800s in Germany and England. Later, combinations of cornstarch and tapioca were used by salad manufacturers. Starch is also used as a sweetener; Sweeteners resulting from the hydrolysis of starch with acid were used to improve wine in Germany in the 1830s.

Between 1940 and 1995, an increase in the use of starch in the US food industry was reported from about 30,000 to 950,000 metric tons. The main consumers of starch are believed to be the fermentation, leavening, and confectionary industries. A similar study in Europe in 1992 found that 2.8 million tons of starch were used in food. The uses of starch abound in literature, and the reader is advised to refer to reviews on the application of starch in the food industry. In fact, starch’s versatility is unmatched by other biomaterials, making this polymer stand tall in the quest for natural products with high potentials to contribute to national development.

Local manufacturing is continually expanding, and there is heavy dependence on imported pharmaceutical-grade starch as a raw material for use in the manufacturing of various medicines used in healthcare delivery. This high dependence on foreign sources for raw material makes cost of production of the medicines used in healthcare delivery very high. Import dependence is the farmer’s enemy while also hurting the country, because it replaces local production and creates unemployment, especially in developing countries of the world. This should not be acceptable, because it is neither economical or sustainable. Every country of the world has a number of locally available sources of starch, which if developed will reduce or eliminate heavy dependence on importation, thereby conserving foreign reserves, and invariably affects the cost of production of the medicines used in healthcare delivery. It is no brainer that local production of starch will create employment and equally put smiles on the faces of farmers. The production of pharmaceutical-grade starch will equally enable countries to compete in the global starch production [1, 2, 3, 4].

3. Recent advances

In the last five decades, the general tendency in the starch industry has been in the utilization of raw materials other than maize and potato. Research has proven that the chemical composition and physical characteristics of a starch are essentially typical of its botanical and biological origin. It has also been found that, regardless of their origin, native starches are undesirable for many applications because they cannot withstand processing conditions such as extreme temperatures, variable pH, high shear rates, and frost variations. To overcome this challenge, changes are often made to improve or suppress the inherent properties of these native starches or to provide new properties that meet specific application requirements; such modified starches have found usefulness in the pharmaceutical, food, paper, and textile industries applications such as adhesives, disintegrants, fillers, emulsion stabilizers, and adhesives.

Although various methods of starch modification have been well documented in the literature, progress continues to be made in this area, and these changes have led to improved functional and physicochemical parameters of starch in various industries, especially where native starch itself cannot offer optimal performance. Recent studies have shown that starch is not just an important biopolymer because of its robust application in various spheres of life, but it has the potentials for use in sensitive and precision-driven areas such as in the preparation of various drug delivery systems; transitioning starch granules from its native micro- to the artificial submicron levels, thereby conferring on it new properties. Although carbohydrates are generally considered to be safe, their constituents especially at submicron level can present some safety issues, especially in pharmaceutical systems. It is only recently that the modified carbohydrate safety has been studied. This book provides detailed introduction of the historical and recent developments in carbohydrate research. It is clear that the demand for carbohydrates will continue to increase, especially with the use of this biopolymer in other industries. For example, in medical science, carbohydrates evolved from human food to effectively dry skin lesions. In the field of biological science, carbohydrates are also considered essential. Starch has today evolved from its traditional role as food to more modern roles in medicine, pharmacy, agriculture, life sciences, and the biopolymer industries [5, 6, 7].

4. Conclusions

In many countries of the world, especially developing countries, local drug manufacture is characterized by a complete dependence on importation of all pharmaceutical actives and excipients required for the manufacture of drugs and cosmetics, and starch is key among these excipients. Many of these countries have the challenge of not only the cost of foreign exchange in addition to the lack of infrastructure, which not only results in a very high cost of production but also leads to low capacity utilization. This situation can be rectified if the local raw materials available in these countries are processed into pharmaceutical-grade raw materials. This would have a direct impact on the national economy by enhancing natural resource utilization. The problem of locally producing pharmaceutical grade starch can be tackled in either of two ways, i.e. either undertake primary production of starch as required by the pharmaceutical industry or by improving available grades of commercial starch to officially acceptable pharmaceutical grade. It has been opined that the second option should be cheaper, therefore, undertaking studies of locally produced starches with a view to identifying areas where they fall short of pharmaceutical-grade and subsequently determine methods required to correct such that would lead to the upgrading of locally produced starch to pharmaceutical-grade starch is a viable strategy, and this book will serve as a veritable tool in the hands of students, researchers, and industry players.