Hydrothermal treatments of rice starch for improvement of rice noodle quality

Impact of Maturity of Malay Cherry (Lepisanthes alata) Leaves on the Inhibitory Activity of Starch Hydrolases

Aqueous extracts of young (7-day-old) Malay cherry (Lepisanthes alata) leaves were incorporated into wheat and rice flours to evaluate their inhibitory activities against α-amylase and α-glucosidase. HPLC-ESI/MS² results showed that the active components in young leaves were proanthocyanidins with lower mean degrees of polymerisation (≤10). The IC₅₀ of the aqueous extracts of young leaves were 2.50 ± 0.03 and 12.91 ± 0.29 µg/mL, against α-amylase and α-glucosidase, which make them less active compared to the mature leaves. In contrast, total proanthocyanidins in aqueous extracts decreased as the leaves matured, indicating that the compounds in the mature leaves have much higher activity. However, there was no significant difference in the digestibility of wheat noodles incorporated with the aqueous extracts from either young or mature leaves. Interestingly, with regard to rice noodles, their digestibility was mostly reduced by incorporating aqueous extracts of young leaves compared to using mature leaves.

Studies on effect of temperature and time on textural and rheological properties of starch isolated from traditional rice cultivars of Kashmir (India)

In the present study, the effect of storage temperature and time on the textural and rheological properties of starch gels from seven different rice cultivars having higher amylose content than the hybrid rice varieties were evaluated. Water solubility and swelling power increased with every 10C increase in temperature due to granule swelling and solubilization of starch wherein the maximum solubility was found in starch of Koshkari rice cultivar (0.721 to 13.50) and swelling power in starch of Zag rice cultivar (3.688 to 10.806). However, syneresis in the analyzed rice starch gels had shown a fluctuating trend for each individual cultivar at different storage periods in which the cultivars Zag had shown the highest values of syneresis during storage (4.123 to 4.957%). In the texture profile analysis of starch gel of these cultivars, Mushki Budgi had the highest value of hardness (0.723N), gumminess (36.262) and chewiness (31.056). The turbidity values of gelatinized starch suspensions from different rice cultivars increased progressively during the first 4 days of storage followed by a decrease in the 5th day coupled with slight increase in the 6th day. The highest turbidity was found in Zag ranging from 1.47 to 1.67 during refrigerated storage after 6 days. The rheological analysis revealed that Zag indicated the highest value of TG' (76.96C) whereas cultivars Koshkari and Mushki Kandi had shown the lowest value of TG' (74.34C) upon heating cycle.

PRACTICAL APPLICATIONS

Rheological properties of starch are affected by amylose contents, lipid contents, branch chain length distribution of amylopectin. The starch from different varieties depicted variable textural and rheological properties at various time: temperature combinations. No research has been reported to explore the effect of time and temperature on the textural and rheological properties of starch isolated from these traditional rice cultivars. The starches from traditional rice cultivars (native or indigenous rice cultivars of a region) indicated novel characteristic as compared to other cultivars in terms of their higher amylose content, starch yield, purity, clarity, solubility, syneresis, turbidity, and rheology. The novelty of this research was to exploit the desirable properties of starch obtained from traditional rice cultivars that had better characteristics than the hybrid varieties. This in turn led the various agencies to motivate the farmers to encourage their cultivation, provide an essential platform to scientists to inherit their valuable characteristics.

Bioactives-retained non-glutinous noodles from nixtamalized Dent and Flint maize

Nixtamalization is a well-known pre-treatment technique in the tortilla industry. Nixtamalized maize (nixtamal) is known for its modified physicochemical as well as nutritional attributes. In the present study, two types of nixtamalization processes (traditional and ecological) were employed for the development of whole-grain-maize-based noodles using Dent and Flint maize genotypes. Results showed that ecological nixtamalization had resulted in better cooking and textural qualities of noodles compared to the one prepared traditionally. Dent maize noodles from traditional and ecological nixtamalization had lower retention of phenolics (40 and 64%, respectively) whereas, Flint maize noodles retained 50 and 66% phenolics, respectively. Dent maize noodles had undergone phenolics loss of 5-6% on cooking while those of Flint maize lost only 2%. Ecological nixtamalization maintained the pH of the cooking liquor within an acidic-neutral range and yielded noodle with higher retention of phenolics whereas, the traditional process negatively affected the antioxidant compounds and their properties.

Overview on the General Approaches to Improve Gluten-Free Pasta and Bread

The use of gluten-free products is increasing since a growing number of people are suffering from celiac disease and thereby need gluten-free diet. Gluten is responsible for the visco-elastic characteristics of wheat-based products; therefore, its lack makes the gluten-free products not similar to wheat-based product, with scarce textural properties. This reason constitutes the major industrial limitation. Thus, obtaining good-quality gluten-free products represents a technological challenge. This review reports the main strategies adopted to produce high quality gluten-free pasta and bread. They are mainly obtained by the utilization of specific ingredients (hydrocolloids, proteins or enzymes) to be incorporated into the standard formulation or the adoption of proper technological variables that can enhance above all the functional properties, the texture and the taste.

Changes in crystal structure and physicochemical properties of potato starch treated by induced electric field

The effects of induced electric field (IEF) on the crystal structure and physicochemical properties of potato starch were investigated by subjecting identically treated control and electrically-modified samples to the same temperature history. Additionally, a method of combining IEF with heating for efficient modification of native polymer was also proposed. Results showed that the application of IEF at an electric voltage of 75V has a statistically significant effect on starch gelatinization and pasting properties, especially when combined with heating at 50°C. After treatment by the combination method for 96h, the gelatinization temperatures increased, which can be explained by the slight increase in the ratio of 1044/1015cm(-1) and relative crystallinity. Furthermore, IEF reduced granular swelling and therefore contributed to decreasing the peak, breakdown, and setback viscosity of potato starch. This study explores the potential of IEF as innovative technology for starch modification.

Impact of acid and oxidative modifications, single or dual, of sorghum starch on biodegradable films

The objective of this study was to evaluate the effects of acid and oxidation modifications on sorghum starch, as well as the effect of dual modification of starch on the physical, morphological, mechanical, and barrier properties of biodegradable films. The acid modification was performed with 3% lactic acid and the oxidation was performed with 1.5% active chlorine. For dual modification, the acid modification was performed first, followed by oxidation under the same conditions as above. Both films of the oxidized starches, single and dual, had increased stiffness, providing a higher tensile strength and lower elongation when compared to films based on native and single acid modified starches. However, the dual modification increased the water vapor permeability of the films without changing their solubility. The increase in sorghum starch concentration in the filmogenic solution increased the thickness, water vapor permeability, and elongation of the films.

Potato starch oxidation induced by sodium hypochlorite and its effect on functional properties and digestibility

The effects of different concentrations of sodium hypochlorite (active chlorine content at 0.1, 0.2, 1.0, 2.0, 3.0, and 4.0 g/100 g) on the properties of potato starch (PS) were investigated by determining the morphological, physicochemical, crystallinity, pasting, gel texture and digestive properties. The starch granules of PS oxidized with high oxidant concentrations caused cracks and pores, and oxidation mainly acts on the amorphous regions of the starch granules. As the sodium hypochlorite concentration increases, the carbonyl content, carboxyl content, solubility, and pasting temperature of PS increased, as measured using a Rapid Visco Analyser (RVA). The swelling power, breakdown, setback, and peak and final viscosities decreased according to the RVA (P<0.05). The gel strength increased under low-intensity oxidative treatments and decreased under high-intensity oxidative treatments. Oxidative treatment decreased the digestibility of gelatinized potato starch. The slowly digestible starch and resistant starch contents increased significantly, while the rapidly digestible starch content decreased after the oxidation modification (P<0.05). Overall, PS oxidation with sodium hypochlorite improved the functional characteristics of starch and decreased starch digestibility.

Changes in physicochemical properties and in vitro digestibility of common buckwheat starch by heat-moisture treatment and annealing

Heat-moisture treatment (HMT) and annealing (ANN) were applied in the test to investigate how they can affect the physicochemical properties and in vitro digestibility of common buckwheat starch (CBS). In the practice, these two modification methods did not change typical 'A'-type X-ray diffraction pattern of CBS. However, the gelatinization temperature, amylose content, and relative crystallinity increased and peak viscosity value and gelatinization enthalpy of CBS declined significantly. Both the solubility and swelling power, which were temperature dependent, progressively decreased along with the treatments. Remarkable increase in slowly digested starch and resistant starch level was found at the same time. Besides, the decreases of rapidly digested starch and total hydrolysis content by using HMT were greater than by using ANN. The results indicated that the ANN and HMT efficiently modified physicochemical properties and in vitro digestibility of CBS and were able to improve its thermal stability, healthy benefits and application value.