Abstract: Enzymatic modification of rice flour can produce highly functional derivatives use in food industries. This study aimed to evaluate the physical properties and resistant starch content of rice flour residues hydrolyzed by α-amylase. Rice flour hydrolyzed by α-amylase (60 and 300 u/g) for 1, 24 and 48 hours were investigated. Increasing enzyme concentration and hydrolysis time resulted in decreased rice flour residue’s lightness (L*) but increased redness (a*) and yellowness (b*) of rice flour residues. The resistant starch content and peak viscosity increased when hydrolysis time increased. Pasting temperature, trough viscosity, breakdown, final viscosity, setback and peak time of the hydrolyzed flours were not significantly different (p>0.05). The morphology of native flour was smooth without observable pores and polygonal with sharp angles and edges. However, after hydrolysis, granules with a slightly rough and porous surface were observed and a rough and porous surface was increased with increasing hydrolyzed time. The X-ray diffraction patterns of native flour showed A-type configuration, which hydrolyzed flour showed almost 0% crystallinity indicated that both amorphous and crystalline structures of starch were simultaneously hydrolyzed by α-amylase.
Abstract: This work was conducted to improve the level of
resistant starch (RS) in a rice noodle using unripe banana flour and to
investigate the effect of substitution of unripe banana flour for rice
flour on the physical properties of rice noodle. In order to prepare
rice noodles, the unripe banana flour were replaced the rice flour
with different degrees of substitutions including 0, 20, 40, 60, 80, and
100%. The results indicated that substitution of unripe banana flour
was significantly affected the viscosity properties of noodle flour,
color, cooking loss, RS and total starch content of noodle. It was
found that the noodle prepared from 100% unripe banana indicated
the greatest changes on the viscosity properties and color profiles. It
also showed the highest values of cooking loss (2.53%), tensile
strength (129.03%), and RS content (13.15%).
Abstract: Four different colors of cowpeas (Vigna unguiculata)
(black, white, red and black/white speckled) and red kidney bean
(Phaseolus vulgaris) were used to evaluate proximate compositions,
starch content, and pasting properties. There were no significant
differences of moisture, protein, ash, fat, and carbohydrate contents
of all bean types. The kidney bean had significantly lower amounts of
total starch and solubilized starch compared to those of other
cowpeas (p ≤ 0.05), whereas the red cowpea and red kidney bean had
highest content of resistant starch (9-10%). Decortication indicated
no significant effect on the proximate compositions of all samples,
but it significantly decreased the resistant starch content in cowpeas
and increased the solubilized starch and total starch content in all
types of cowpeas. The highest values of pasting properties, generally
observed in flours obtained from black and black/white speckled
cowpea.
Abstract: Banana is one of the most consumed fruits in the tropics and subtropics. Brazil accounts for about 9% of the world banana production. However, the production losses are as high as 30 to 40% and even much higher in some developing countries. The green banana flour is a complex carbohydrate source, including a high total starch (73.4%), resistant starch (17.5%) with functional properties. Gamma irradiation is considered to be an alternative method for food preservation. It has been performed due to the need of extending the shelf - life of foods, whilst maintaining their safety and avoiding one of the main concerns: the nutrient loss. In this work data about on the effects of ionizing radiation on the physicochemical analysis (carbohydrate, proteins, lipids, alimentary fiber, moistures and ashes) of Brazilian functional products (biscuits and bread) of the green banana pulp are presented. The caloric value was calculated. No significant difference was observed between the samples of irradiated and non – irradiated green banana biscuits with the following determinations: carbohydrates, proteins, alimentary fiber and ashes. Only a small significant difference was found in lipids (macronutrients). The results of physical chemical analysis of the irradiated and non- irradiated green banana bread non- irradiated showed no significant difference with the following determinations: carbohydrates, lipids (macronutrients), moisture, ashes and caloric value. A small difference was found in proteins (macronutrients). Irradiation of functional products (biscuits and bread) with doses of 1 and 3kGy maintained their original macronutrients content, showing good radioresistance.
Abstract: Mung bean starches were subjected to heat-moisture treatment (HMT) by different moisture contents (15%, 20%, 25%, 30% and 35%) at 120Ôäâ for 12h. The impact on the yields of resistant starch (RS), microstructure, physicochemical and functional properties was investigated. Compared to native starch, the RS content of heat-moisture treated starches increased significantly. The RS level of HMT-20 was the highest of all the starches. Birefringence was displayed clear at the center of native starch. For HMT starches, pronounced birefringence was exhibited on the periphery of starch granules; however, birefringence disappeared at the centre of some starch granules. The shape of HMT starches hadn-t been changed and the integrity of starch granules was preserved for all the conditions. Concavity could be observed on HMT starches under scanning electronic microscopy. After HMT, apparent amylose contents were increased and starch macromolecule was degraded in comparison with those of native starch. There was a reduction in swelling power on HMT starches, but the solubility of HMT starches was higher than that of native starch. Both of native and HMT starches showed A-type X-ray diffraction pattern. Furthermore, there is a higher intensity at the peak of 15.0 and 22.9 Å than those of native starch.