ABSTRACT
Cassava starch was hydrolyzed with 2.2 M hydrochloric acid for different periods of time. The soluble starches obtained were subsequently used for microsphere preparation by a water-in-water emulsion crosslinking technique. The average chain lengths of starches hydrolyzed for 6, 12, 24, 36, and 48 h were 122.0, 106.3, 65.4, 33.2, and 28.3, respectively. Starches hydrolyzed for 6 and 12 h did not form regular shaped microspheres, while those hydrolyzed for 24, 36, and 48 h mostly formed separate spherical-shaped microparticles with average particle sizes of 14.6, 10.1, and 10.4 µm, respectively. The swelling power of starch microspheres (SMs) produced from 24 h hydrolyzed starch was 6.5-7.0 g/g, whereas those of SMs from 36 and 48 h hydrolyzed starch were higher and comparable (8.0-9.0 g/g). All the SMs were stable against high temperature (>140 °C). Susceptibility of the SMs to α-amylase hydrolysis decreased when the degree of starch hydrolysis increased.
Subject(s)
Manihot/chemistry , Starch/chemistry , Hot Temperature , Hydrochloric Acid/chemistry , Hydrolysis , Microspheres , Particle Size , Water/chemistry , alpha-Amylases/chemistryABSTRACT
Effects of the concentration of plasticizers applied during heat-moisture treatment (HMT) on the properties of canna starch were investigated. The modified starches were prepared by soaking starch in 0 (water), 1, 3, 5, 10, 20 and 30% w/w glycerol or sorbitol solution for 24h and adjusting the moisture content to 25% before HMT (100°C, 1h). Changes in the pasting profiles of heat-moisture treated starches were more obvious when glycerol solutions were used instead of water. An increase in the concentration of glycerol solution from 1% to 5% resulted in a progressive decrease in paste viscosity; paste viscosity then increased as the glycerol concentration rose from 10 to 30%. A similar trend was observed when sorbitol was used as a plasticizer, but with a lesser effect. A scheme for arrangements of the molecular structure of starch during the process of HMT was suggested.
Subject(s)
Food Handling , Plasticizers/analysis , Starch/chemistry , Zingiberales/chemistry , Glycerol/chemistry , Hot Temperature , Sorbitol/chemistry , Viscosity , X-Ray DiffractionABSTRACT
Starch microspheres (SMs) were prepared by a water-in-water emulsion-crosslinking technique at 4 °C and 30 °C for 1, 6, 12 and 24h; the SMs obtained were analyzed for crosslinking density, morphology, crystalline structure, and stability against temperature, pH, and α-amylase hydrolysis. The crosslinking degree at 30 °C was considerably higher than that at 4 °C. SMs prepared at 4 °C for less than 12h incubation had larger size and more porous structure as compared with those prepared at 30 °C, but the morphology became comparable (spherical shape with smooth surface and dense structure) after 24h incubation. All SMs samples displayed amorphous structure. Stability tests revealed that the SMs were very stable under acidic and mild basic pH; however, stability against α-amylase hydrolysis varied depending on incubation temperature and time.
Subject(s)
Manihot/chemistry , Microspheres , Starch/chemistry , Temperature , Drug Stability , Hydrogen-Ion Concentration , Hydrolysis , Solubility , Starch/metabolism , Time Factors , alpha-Amylases/metabolismABSTRACT
Different plasticizers (propanol, propylene glycol, glycerol, erythritol, xylitol and sorbitol) were used for plasticizing canna starch during heat-moisture treatment (HMT). Pasting properties of the modified starches were determined and compared with those of native starch and of HMT starch using water as a plasticizer. Canna starch was soaked in 5% (w/w) plasticizer solutions and adjusted to 25% moisture content before heating at 100 °C for 1h. The least change in paste viscosity was found when water was used as a plasticizer. Viscosity of the modified starches decreased as the molecular weight of plasticizers decreased. Plasticizer content in starch granules increased with decreasing molecular weight of the plasticizer, as well as with increased soaking time (from 10 min to 4 and 24h). However, pasting profiles of HMT starches prepared by soaking for 4h were comparable to those soaked for 24h, indicating that there was an effective limit of plasticizers. The plasticizer content in starch granules played a greater role in HMT than the number of hydroxyl groups.
Subject(s)
Hot Temperature , Plasticizers/chemistry , Starch/chemistry , Zingiberales/chemistry , Hydroxides/chemistry , Ointments , Time FactorsABSTRACT
Canna starch and its derivatives (retrograded, retrograded debranched, and cross-linked) were evaluated for their suitability to be used as prebiotic sources in a rice noodle product. Twenty percent of the rice flour was replaced with these tested starches, and the noodles obtained were analyzed for morphology, cooking qualities, textural properties, and capability of producing short-chain fatty acids (SCFAs). Cross-linked canna starch could increase tensile strength and elongation of rice noodles. Total dietary fiber (TDF) content of noodles made from rice flour was 3.0% and increased to 5.1% and 7.3% when rice flour was replaced with retrograded and retrograded debranched starches, respectively. Cooking qualities and textural properties of noodles containing 20% retrograded debranched starch were mostly comparable, while the capability of producing SCFAs and butyric acid was superior to the control rice noodles; the cooked noodle strips also showed fewer tendencies to stick together.
Subject(s)
Flour , Food Technology , Oryza , Starch/chemistry , Cooking , Dietary Fiber/analysis , Fatty Acids, Volatile/analysis , Fermentation , Flour/analysisABSTRACT
Surface regions of untreated and heat-moisture treated (HMT) normal rice, waxy rice, normal corn, waxy corn, normal potato, and waxy potato starch granules were examined by atomic force microscopy (AFM). AFM images revealed surface roughness of untreated starch granules and protrusions with a diameter of approximately 15-90 nm. After treatment, the smooth surface region on starch granules was observed, especially in normal rice, waxy rice, and normal corn starches. A significant reduction in the size of protrusions on the surface of HMT potato starch granules was also detected. The newly formed structures may act as barriers and retard water penetration into starch granules. The blocklet model of starch granule architecture was also confirmed by the AFM images.
ABSTRACT
Starch and flour from the same rice grain source (with 20, 25 and 30% moisture content) were exposed to heat-moisture treatment (HMT) at 100 °C for 16 h in order to investigate whether there were differences in their susceptibility to modification by HMT and, if any, to determine the main causes of the differences. HMT had a far greater effect on paste viscosity of flour than of starch. A significant increase in paste viscosity after removal of proteins from HMT flour - as well as images of fast green-stained HMT flour gels - indicated that an important role was played by proteins in affecting properties of the modified samples. Greater effects of HMT on thermal parameters of gelatinization and gel hardness values of flours were observed - more so than those for starches. Following this observation, it was ascertained that components in rice flour other than rice starch granules also underwent alterations during HMT.
