Butanol starch complex

According to Hollo et al.,709 the low stability of starch-alcohol complexes (lower than that of the starch-iodine complex) is caused by the relatively small amount of space inside the amylose helix that is available for the hydrophobic moiety of the alcohol. The data in Table XXX appear to confirm this assumption and indicate iodine sorption amounts by starch complexes with subsequent members of the homologous series of alcohols. With the exception of ferf-butanol, the iodine uptake decreases as the alcohol inside of the helix becomes more bulky. 

Starch complexation with thymol was proposed for the fractionation of starch,704 but the procedure is not as efficient as that with 1-butanol. Fractionation with thymol followed by the use of 1-butanol is used to produce high-purity components. Complexation with naphthols revealed that 1-naphthol forms complexes with starch more readily than does its 2-isomer.673 1-Naphthol complexes in two modes, as suggested by the Scatch-ard plot, and the binding is rather weak.717 Complexes between a formalde-hyde-hydroquinone polymer and starch have also been detected.718... 

X-ray diffraction analysis754 of a series of amylose complexes with lower and higher fatty acids revealed that the crystal structures depend on whether amylose was complexed in the dry or wet state. Both the 6, and 7i helical conformations of amylose were found in these complexes. The conformation appears to depend on the length of the hydrophobic moiety. Dry amylose forms crystalline complexes with a unit cell identical to that of the anhydrous 1-butanol-starch complex (lattice parameters a = b = 25.6 A). An orthorhombic unit cell was proposed for the 7i -helical structure of the wet complexes of monobasic acids (acetic, butanoic, pentanoic, hexanoic,... 

The most widely used complexing agents are alcohols (butanol, n-propyl alcohol and n-pentyl alcohol1). Schoch33 now recommends the use of Pen-tasol, a commercial mixture of pentyl alcohols, for the first precipitation, and 1-butanol for recrystallizations. For com (maize) starch, this avoids contamination of the amylopectin with an intermediate fraction which is sufficiently linear to be precipitated with Pentasol and yet has a degree of branching which prevents complex formation with butanol. 

Microbiological action in starch dispersions results in a drop in pH, loss of viscosity and the development of odor. Retrogradation may be accelerated by the drop in pH or especially if butanol, which complexes with amylose, is generated via starch fermentation. Sulfate-reducing bacteria will cause black deposits due to reaction with iron in the process water. For quality control, preservatives are added to starch slurry, cooked starch, surface size and coating color. 

Broad categories of starch granule sizes are possible by fractionation with butanol (Schoch, 1942). This solvent enters the interior of the amylose helix and forms an insoluble inclusion complex. 

It should be noted that the different structures of amylose and amylopectin confer distinctive properties to these polysaccharides (Table II). The linear nature of amylose is responsible for its ability to form complexes with fatty acids, low-molecular-weight alcohols, and iodine these complexes are called clathrates or helical inclusion compounds. This property is the basis for the separation of amylose from amylopectin when starch is solubilized with alkali or with dimethylsulfoxide, amylose can be precipitated by adding 1-butanol and amylopectin remains in solution. 

Several reports discuss inclusion complexes of starch and its components with alcohols. In Fig. 42, all tested alcohols, with the exception of tert-butanol, follow line 1. This suggests that the size of the hydrophobic moiety of alcohols is a key factor.654 The complexation yield of lower alcohols depends on the starch-to-alcohol ratio.673 The number of turns of the helix in the complex also depends on the complexed alcohol.685... 

The discovery of the V-type, helical amylose (see p. 265) that forms when amylose interacts with 1-butanol was crucial for the development of the chemistry of starch inclusion complexes. It soon appeared that 1-butanol complexes solely with the amylose component. This selectivity became the first convenient method of fractionating starch. This method was first described by Schoch699 and later developed by Kerr et al.700-702 and oth-ers 680,703 An impr0ved procedure was subsequently patented.704 The amount of 1-butanol adsorbed in amylose is increased by the presence of moisture and is also dependent on two key factors the time of contact with that alcohol and the origin of the amylose, as shown in Table XXIX. 

Starch fractionation using 1-pentanol,657,705 cyclohexanol,706 2-butanol, and 2-propanol698 instead of 1-butanol have also been proposed. Amylose complexes with all of the normal-chain alcohols have essentially the same X-ray diffraction pattern, which differs from the patterns of amylose complexes with branched alcohols.707,708... 

Other starch varieties chemically bind metal atoms only to the hydroxyl groups, in the same manner as alcoholates. Alkali metal starchates were obtained for the first time by the use of either metal amides in liquid ammonia641 or metals in liquid amines.642 These methods were subsequently used by others.643 Sodium 2-starchate could be prepared by refluxing an alcohol solution of NaOH and dry starch.644 The reaction of dry starch with controlled amount of NaOH in 1-butanol provided either monosodium 2-starchate or disodium 2,3-starchate.645,646 However, complexes of NaOH with starch were also characterized.37,38 Thallation of starch could be performed with thallous hydroxide.647... 

Fourier transform infrared (FTIR) second-derivative spectra of thermoplastic starch and vinyl alcohol copolymer systems with droplet-like structure, in the range of starch ring vibrations between 960 and 920 cm , provide for an absorption peak at about 947 cm (Figure 2.7), as observed for amylose when complexed (V-type complex) by low-molecular-weight molecules such as butanol and fatty acids. 

Separation 88) of amylose and amylopectin can be made by adding to a hot starch dispersion certain agents such as butanol, nitropropane, nitrobenzene, and thymol, which form a complex with amylose and cause it to... 

Kim J-Y, Lim S-T (2009) Preparation of nano-sized starch particles by complex formation with n-butanol. Caibohydr Polym 76 110-116... 

There are many cases in which alternative or modified procedures must be used. For example, butanol saturated with water appears to be the very useful solvent mixture to disrupt the inclusion complexes of lipids in starch and give the best extraction... 

Most starches contain 20-30% amylose (Table 4.24). New corn cultivars (amylomaize) have been developed which contain 50-80% amylose. The amylose can be isolated from starch, e. g., by crystallization of a starch dispersion, usually in the presence of salts (MgS04) or by precipitation with a polar organic compound (alcohols, such as n-butanol, or lower fatty acids, such as caprylic or capric), which forms a complex with amylose and thus enhance its precipitation. 

---