Recent Processing Methods for Preparing Starch-based Bioproducts - Food and Industrial Bioproducts and Bioprocessing - page 68

oil content and pH effects (Garzon et al ., 2003a), oxidation of encapsulated oil under
different storage conditions (Garzon et al ., 2004), methods of preparing composites with
higher oil content (Fanta et al ., 2009a), and factors affecting the particle size of drum-
dried composites (Singh, 2008 ).
Research on the chemical and physical properties of jet-cooked starch-oil composites
supported the development of many applications for the technology, including fat replacers
in ground beef patties (Warner et al ., 2001; Garzon et al ., 2003c), cookies (Garzon et al .,
2003b), soft-serve ice cream (Byars, 2002), and yogurt (Singh and Kim, 2009; Singh and
Byars, 2009). Non-food applications demonstrating the efficacy of oil delivery in aqueous
starch-based media included biodegradable polyurethane foams (Cunningham et al ., 1997 ),
lubricants for water-based oil drilling muds (Fanta et al ., 2002a ; Sifferman et al ., 2003 ) and
lubricants for metal working (Biresaw, 2004; Biresaw and Erhan, 2002; Biresaw et al .,
2007 ; Kenar et al ., 2009). The jet-cooked starch-oil technology was also used to deliver a
soybean oil-based UV absorbing agent to provide UV protection in cosmetic and
agricultural applications, and was shown to increase the efficiency of UV absorption
(Compton et al ., 2007 ).
In addition to adsorption onto the surfaces of oil droplets, starch was also shown to
adsorb onto the hydrophobic surface of a polyethylene film, presumably by a similar
mechanism (Fanta et al ., 2002 b); the adsorption of starch rendered the film surface hydrophilic.
Polyacrylonitrile could be graft polymerized onto the surface coating of starch, imparting
the interesting property of reversible curling in response to humidity changes (Fanta et al .,
2003). The reverse process of depositing polyethylene dissolved in various organic solvents
onto dried starch films was also observed and provided a means of imparting water resistance
to the starch films (Fanta et al ., 2009b ).
Another technology resulting from the excess steam jet cooking of starch was based on
the observation that slow cooling of dilute solutions of jet-cooked starch resulted in the
formation of crystalline spherulites composed of amylose-lipid complexes. Davies and
co-workers (1980) also observed the formation of crystalline particles in cooked starch
dispersions, but did not study their morphology and properties. Similar particles were noted,
but not described, in other reports (Kitamura et al ., 1984 ; Zobel, 1988 ; Jane et al ., 1996 ;
Heinemann et al ., 2003). The crystallization of amylose into various structures, including
spherulites, has also been studied extensively in the context of investigations of in vivo
starch granule biosynthesis (Buleon et al ., 2007 ; Nordmark and Ziegler, 2002 , 2002 ; Ziegler
et al ., 2003 , 2005 ).
A detailed description of the different morphological types of spherulites obtained from
dispersions of jet-cooked starch was made in 2002 (Fanta et al ., 2002c ). Micrographs of the
spherical, toroidal, and small-particle spherulites isolated under different processing and
cooling conditions are shown in Figures 2.3 and 2.4. Conditions for spherulite formation
were further investigated by using defatted corn starch and supplementing the starch with
specific fatty acids (Fanta et al ., 2006). Spherulite yields of about 60%, based on total starch,
were obtained with high amylose corn starch; different types of spherulites could be obtained
by selecting specific cooling rates and stirring conditions (Fanta et al ., 2008 ). The identity
of the complexed fatty acid ligands in these spherulites was determined by extraction with
different solvent systems (Peterson et al ., 2005) and research has been carried out to
understand the factors that determine the formation of a particular type of spherulite particle.
It was also observed that crystal transformations can take place in these spherulites after
their formation, due to changes in hydration and extraction conditions (Shogren et al .,
2006). Although the formation of crystalline spherulites from jet-cooked starch has been