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Phase and State Transitions and Transformations in Food Systems
Published in Dennis R. Heldman, Daryl B. Lund, Cristina M. Sabliov, Handbook of Food Engineering, 2018
Retrogradation of starches is a complex phenomenon involving rapid crystallization of amylose and less rapid crystallization of amylopectin from a solution or gel. This leads to textural changes known as staling. Amylopectin crystallization has been described as a nucleation-limited growth process that occurs above the glass transition temperature of the amorphous starch in the gel network plasticized by water (Slade and Levine, 1988a). Indeed, a strong relationship between the extent and rate of crystallization with glass transition in corn starch was found by Jouppila and Roos (1997) and Jouppila et al. (1998). The extent of recrystallization increases with increasing water content in the range of 27%–50% and then decreases with further increase in water content. However, this behavior seems to depend on water content and the temperature difference above the glass transition, T − Tg (Jouppila et al., 1998). Sugars have been shown to act as antistaling agents, probably because of the increase of glass transition temperature caused by increased average molecular weight of the solution (Slade and Levine, 1990). Mestres et al. (1988) reported that pasting, drum drying, and extrusion lead to different types of crystallization phenomena of amylose and amylopectin. Retrogradation and re-melting properties of various starches were further discussed by Singh et al. (2003).
Starch Nanocomposite Films for Food Packaging
Published in V Ravishankar Rai, Jamuna A. Bai, Nanotechnology Applications in the Food Industry, 2018
Oswaldo Ochoa Yepes, Lucas Guz, Santiago Estevez Areco, Roberto Candal, Silvia Goyanes, Lucía Famá
During storage, starch molecules can reassociate into crystalline segments forming an ordered structure, such as double helices, whose length depends on several factors such as the source of starch, amylose/amylopectin ratio, molecular weight, the structure of the starch molecules, time, speed and heating temperature, moisture content, and starch concentration (Biliaderis 1992). This is due to the recrystallization of the starch molecules. This phenomenon is known as retrogradation. Generally, retrogradation occurs in two stages. The first stage is due to the dissolution of amylose molecules, followed by orientation in parallel alignments. The second stage involves the formation of an ordered structure of amylopectin (Miles et al. 1985; Ring et al. 1987). During the retrogradation, molecular interactions appear, such as hydrogen bonding between starch chains, which are dependent on time and temperature. Among the factors influencing retrogradation that may be mentioned are the source of starch (cereal versus tuber) and the amylose/amylopectin ratio.
Application of Nanobioformulations for Controlled Release and Targeted Biodistribution of Drugs
Published in Anil K. Sharma, Raj K. Keservani, Rajesh K. Kesharwani, Nanobiomaterials, 2018
Josef Jampílek, Katarina Král’ová
Starch NPs for the delivery of gemcitabine·HCl that could reduce its dose related side effects and may prolong its retention time (24 h) for the treatment of pancreatic cancer was developed by Khaira et al. (2014). Ultrasmall cationic starch nanospheres with size of 50 nm possessing a good capacity in delivering negatively charged molecules, biocompatibility, and biodegradability were prepared by Huang et al. (2013). Spherical particles of amylose-IBU inclusion complexes with the sizes ranging from 30 to 80 nm were stable in the simulated gastric fluid, IBU was sustainably released from the complexes in the simulated medium of the small intestine, which is connected with the hydrolysis of the inclusion complexes by amylase. Thus, these complexes can be used as carriers releasing drug in an intestinally targeting and controlled manner (Yang et al., 2013). Situ et al. (2015) developed an oral colon-specific controlled release system suitable for delivery of polypeptides or proteins coated with a resistant starch-based film through aqueous dispersion coating process. A dramatic increase in the resistibility against enzymatic digestion resulting in the formation of resistant starch can be achieved by high-temperature-pressure modification of starch, enzymatic debranching, and retrogradation. A novel oral pH-responsive protein drug delivery vehicle made of starch NPs as backbone and poly(l-glutamic acid) as graft chains was synthesized by Zhang et al. (2013b). The loaded insulin released from the copolymers more slowly in artificial gastric juice (pH = 1.2) than in artificial intestinal liquid (pH = 6.8) due to the excellent stability in acidic condition.
A Review on the Application of Starch as Depressant in Iron Ore Flotation
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Swagat S. Rath, Hrushikesh Sahoo
Starch is insoluble in water at room temperature as the chains are aligned alongside each other and interact via hydrogen bond. Starch is considered nonionic, having a slight anionic character (Pearse 2005). Generally, boiling or causticization breaks the structure and solubilizes starch. When heated along with water, the granules swell, and amylose diffuses out of the swollen granules. On cooling, it forms a homogenous gel phase of amylose and amylopectin. Similarly, the swollen amylopectin-rich granules agglomerate to form gel particles, resulting in a viscous solution. This two-phase structure, termed as starch paste, is responsible for the binding and thickening action of starches (Santelia and Zeeman 2011). Usually, starch gelatinization is carried out by chemical and thermal processes. The gelatinization temperature decreases with an increase in the amylopectin content. Hydroxides such as NaOH are required for chemical solubilization of starch. Starch is prone to spontaneous retrogradation when the starch solution is stored at low temperatures, especially at the neutral pH range (Pinto, de Araujo and Peres 1992).
Ozone Processing of Cassava Starch
Published in Ozone: Science & Engineering, 2021
Dâmaris Carvalho Lima, Nanci Castanha, Bianca Chieregato Maniglia, Manoel Divino Matta Junior, Carla Ivonne Arias La Fuente, Pedro Esteves Duarte Augusto
The setback represents the retrogradation tendency of starch molecules. The retrogradation process can be defined as a re-association between starch molecules (after the system being cooled), especially amylose (Liu 2005). The rearrangement in starch molecules can be determined according to the affinity of hydroxyl groups of one molecule to another, especially the amylose, which has a huge affinity to form hydrogen bonds between hydroxyls and adjacent molecules (Castanha, da Matta Junior, and Augusto 2017). However, starch retrogradation is not favored by chains that are too long or too short, which reduces the capacity of hydrogen bonds formation (Wang et al. 2015). In oxidized starches, the hydrogen bonds are affected in such a way that their tendency to retrogradation is reduced (Rapaille and Vanhemelrijck 1997).
Preparation and application of potato flour with low gelatinization degree using flash drying
Published in Drying Technology, 2018
Juan Li, Cunkuan Shen, Bingquan Ge, Li Wang, Ren Wang, Xiaohu Luo, Zhengxing Chen
Pasting viscosity profiles of the PF, CPF, and CPG are shown in Fig. 2. The curve of flash dried PF was very similar to a raw starch with a minimum initial viscosity and sharply raised after 70°C as a result of swelling of starch granules leading to onset of gelatinization.[24] The viscosity of PF reaching a peak (2,625 cP) then shows a clear break down with the increased treatment time, which caused by disintegration of swollen granules and structural of starch during cooking.[25] Setback was observed to be highest for PF, which is a measure of retrogradation tendency of the starch. The viscosity raised during the cooling stage on account of starch retrogradation.[26] Therefore, it has also been suggested that the absence of peak and viscosity remaining constant or increasing during continued heating is ideal for good quality noodles.[27]