Potato starch processing

In the potato starch industry, the starch itself represents 90% of the sales value, while the co-products (fiber, protein and concentrated deproteinized potato juice) represent 10% of the sales value. Nevertheless, protein quality is becoming increasingly important to the economics of the total process. 

---

A possible potato starch process which attempts to combine the best elements of the described processes (Figure 11.8) and to find an optimum which can be implemented is shown in Figure 11.9. This process is described in more detail in the rest of the chapter. 

Figure 11.9 A schematic overview of a potato starch process.

Figure 11.14 Reduced efficiency curves [G (X)] fora potato starch process.

Similar materials are available based on potato starch, eg, PaseUi SA2 which claims DE below 3 and has unique properties based on its amylose—amylopectin ratio pecuhar to potato starch. The product contains only 0.1% proteia and 0.06% fat which helps stabilize dried food mixes compounded with it. Another carbohydrate raw material is waxy-maize starch. Maltodextrias of differeat DE values of 6, 10, and 15, usiag waxy-maize starch, are available (Staley Co.). This product, called Stellar, is offered ia several physical forms such as agglomerates and hoUow spheres, and is prepared by acid modification (49). Maltodextrias based oa com starch are offered with DEs of 5, 10, 15, and 18 as powders or agglomerates (Grain Processing Corp.). 

One of the commercial methods for production of lysine consists of a two-stage process using two species of bacteria. The carbon sources for production of amino acids are corn, potato starch, molasses, and whey. If starch is used, it must be hydrolysed to glucose to achieve higher yield. Escherichia coli is grown in a medium consisting of glycerol, corn-steep liquor and di-ammonium phosphate under aerobic conditions, with temperature and pH controlled. 

Horigome et al. (3J5) reported a PER of 1.9 for protein recovered from an industrial sweet potato starch facility. They were able to increase the PER to 2.5 by supplementing the diets with lysine and methionine. A portion of these amino acids were either destroyed or made biologically nonavailable by the processing operation. The possibility also exists that these amino acids were limiting in the cultivars studied. 

The production of CDs via enzymatic reaction with starch has been recently reviewed (i 7). CGTase is an extracellular protein and is usually isolated as a crude mixture from the medium. This crude protein is used directly for industrial fermentations. The basic process involves standard enz3miatic fermentation, with careful attention to reaction temperature. All three CDs and some Unear oligosaccharides are normally produced. Yields are highly dependent on the source of starch substrate. Potato starch is normally used or an extract of potato starch is often added to other starches 18-19), The potato starch component(s) responsible for stimulating CD formation have not been determined. Low starch concentrations (5%-10%) are normally used industrially. Published yields are in the 50% - 80% conversion range. 

The particle size distribution depends on the type of plant (see Table 5). The size of the potato starch granules is considerably higher than the size of com and tapioca starch granules. Also, the moisture absorption of potato starch is much higher than for com and tapioca starch. Thus, processing of tapioca starch in technical processes like compounding is similar to that of com starch [10]. 

The potato is processed into French fries (chips in the UK) and chips (crisps in the UK), and is used for dried products and starch production. In North America and some European countries between 50 and 60% of the crop is processed (Li et al., 2006 Kirkman, 2007). Furthermore, processors are building factories in countries where the potato is primarily grown as a staple... 

The bulk of potato tubers is made up of parenchyma cells that have thin, non-lignified, primary cell walls (Reeve et al., 1971 Bush et al, 1999, 2001 Parker et al., 2001). Unless stated to the contrary, potato cell walls refers to parenchyma cell walls. These walls and their component polysaccharides are important for a number of reasons they form part of the total intake of dietary fiber, influence the texture of cooked potato tubers and form much of the waste pulp that is produced in large amounts by the potato starch industry when starch is isolated. The pulp is usually used as cattle feed, but potentially could be processed in a variety of ways to increase its value (Mayer, 1998). For example, the whole cell-wall residues could be used as afood ingredient to alter food texture and to increase its dietary-fiber content, or cell-wall polysaccharides could be extracted and used in a similar way or for various industrial applications (Turquois et al., 1999 Dufresne et al, 2000 Harris and Smith, 2006 Kaack et al., 2006). 

Moledina, K. H., Fedec, P, Hadziyev, D., Ooraikul, B. (1978). Ultrastructural changes in potato during potato granule process as viewed by SEM. Starch/Stdrke, 30, 191-199. 

Mita, T. (1992). Structure of potato starch pastes on the ageing process by the measurement of their dynamic moduli. Carbohydrate Polymers, 12,269-276. 

---