Physicochemical and structural characterization of resistant starch isolated from Vigna unguiculata

Effects of heat treatment at different moisture of mung bean flour on the structural, gelation and in vitro digestive properties of starch

Effects of heat treatment (100 °C) at different moisture content (13-70 %) on the structural, gelation and digestive properties of starch in real mung bean flour (MBF) systems are investigated. The results showed that the structural destruction of the starch, the starch-lipid complexion and starch-protein interaction were promoted with increasing moisture content. The starch-protein interaction was mainly driven by hydrophobic interaction forces, leading the increase of total phase transition enthalpy. Even though starch retained ordered structure after heating at 50 %-70 % moisture, the typical pasting curve almost disappeared. The less leached amylose to construct the continuous phase, and more flexible amylopectin swollen granules dispersed in the matrix may weakened the viscoelasticity of the gels. As a result, two distinct gel textures were presented: soft solids with good water-binding capacity (below 30 %) and pasty fluids (above 40 %). Starch-lipid/protein interactions were demonstrated to retard the digestion rate of starch during MBS gelatinization according to the two-stage first-order kinetic and LOS (logarithm of the slope) models.

The effects of different hydrocolloids on lotus root starch gelatinization and gels properties

In this study, xanthan gum (XG), sodium alginate (SA), guar gum (GG), and gum Arabic (GA), were used to modify Lotus root starch (LRS). The incorporation XG, SA, and GG significantly (p < 0.05) influence the swelling power (SP) of LRS, among which the 1.5 % of XG exhibited the highest value of 25.84 g/g at 90 °C. Gelatinization analysis revealed that XG raised the final viscosity (FV) and lowered the breakdown (BD), while SA significantly increased peak viscosity (PV) and BD. Furthermore, GG and GA exhibited a substantial reduction in setback (SB). The incorporation of XG, SA, and GG enhanced the rheological and structural properties (e.g., gel strength and elasticity) of LRS. Particularly, XG demonstrated a more prominent effect, while GA exhibited an opposite trend. Moreover, the structural analyses revealed that hydrophilic colloids have no impact on the functional group and crystal structure of the LRS. However, complex system exhibited the more stable hydrogen bonding. The addition of 1.5 % XG exhibited the most stable hydrogen bonding and highest water binding affinity. Overall, the results demonstrated the effect of different hydrophilic colloids on LRS, offering a theoretical basis for LRS applications and novel insights for the use of starches and hydrocolloids.

Isolation, Structural Characteristics Analysis of a Vigna unguiculata Polysaccharide VUP80-3 and Its Protective Effect on GES-1 Cells In Vitro

Cowpea (Vigna unguiculata) is one of the main edible legume vegetables in China, and it can improve spleen and stomach function. A polysaccharide component (VUP80-3) has been isolated from V. unguiculata in this study. The average molecular weight of VUP80-3 is 6.43 × 10⁴ Da, and the main monosaccharide group is glucose. The mass ratio of monosaccharide groups in the polysaccharide was glucose:galactose:arabinose:rhamnose:xylose:mannose:fucose = 152.36:24.50:16.53:8.13:1.26:0.97:0.82. NMR analysis showed that VUP80-3 has →4)-α-D-Galp (1→ and →4)-α-D-Glcp(1→ main chain and →3,4)-β-D-Glcp(1→, →4,6)-α-D-Glcp(1→ branch chains, and the terminal sugar is α-D-Glcp(1→. Biological activity test results showed that VUP80-3 at 1000 μg·mL^-1 significantly increased the activity of ethanol injured GES-1 cells (p < 0.01) and significantly reduced reactive oxygen species (ROS) in ethanol injured GES-1 cells and inflammatory factors (IL-8, IL-1β and TNF-α,) in GES-1 cells. This compound also reduced the apoptosis rate (p < 0.05), thereby significantly reducing the oxidative damage caused by ethanol in GES-1 cells. Therefore, VUP80-3 is a potential drug to protect the gastric mucosa from damage.

Functional properties and in vitro starch digestibility of infrared-treated (micronized) green banana flour

BACKGROUND

The consumption of green banana flour (GBF) products has been linked to reduced glycemic index (GI) and low risk of type 2 diabetes and obesity. The purpose of this study was to investigate the effect of micronization (high-intensity infrared heating method) on the molecular, microstructure and in vitro starch digestibility of five GBF cultivars grown in South Africa. The GBF was micronized at three surface temperatures (90, 120 and 150 °C for 30 min) and the in vitro starch digestibility was determined with Megazyme kits.

RESULTS

Micronization at the highest temperature (150 °C) increased the swelling power by 6.00% in all five GBF cultivars when compared to control (unmicronized GBF). Micronization slightly reduced the resistant starch (RS) of the GBF cultivars by up to 8.63%. The FHIA-01 cultivar showed the highest RS (86.50%), whereas Grande Naine - 150 °C cultivar had the lowest RS (76.00%). Both micronized and control GBF exhibited similar X-ray diffraction patterns with all cultivars and at all micronization temperatures. Similarly, the functional properties of the GBF were not altered by micronization when observed with Fourier transform infrared spectroscopy. Scanning electron microscopy showed changes in the surface morphology of starch granules after micronization and these were dependent on temperature.

CONCLUSION

Overall, micronization at 120 °C showed the best improvement in functional properties of GBF and this makes it suitable for potential application for the manufacture of instant breakfast products, baked goods and pasta. In addition, the micronized GBF cultivars retained high RS, suggesting potential health benefits for people with diabetes and obesity. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Infrared heating under optimized conditions enhanced the pasting and swelling behaviour of cowpea starch

Native starches are not suitable for industrial use and must be modified for improved functionality. In this study, the effect of moisture preconditioning and infrared heating time on physicochemical properties of cowpea starch was investigated using a two-factor central composite rotatable design. Factors (moisture levels:10-40 g/100 g starch and infrared heating time:10-60 min) with their corresponding α mid-point values resulted in 13 experimental runs. Selected functional and pasting properties were determined as response variables. Starch samples produced under optimized conditions were compared with corn starch and their physicochemical properties determined. Except for pasting temperature, cowpea starch prepared using the optimal conditions (moisture: 46.21 g/100 g starch, dry basis and heating time of 32.88 min) had higher functional and pasting properties compared with the native cowpea starch. Infrared heating significantly reduced the gelatinization temperatures of cowpea starch but did not significantly change that of the corn starch. The crystallinity and double-helical order structure of moisture conditioned cowpea starch also reduced after modification. Cowpea starch showed a bigger granule size, higher swelling power but lower water absorption capacities and pasting properties compared with the control. The infrared heating process is a novel and promising modification method for improving the swelling properties of starch.

Extraction and characterization of starch from Yard-long bean (Vigna unguiculata (L.) Walp. ssp. unguiculata cv.-gr. sesquipedalis)

Vigna unguiculata subsp. sesquipedalis is an important derivative cultivar of cowpea planted widely in China, and popularly known as "Yard-long bean". There is lack of research about the structural characterization and physicochemical aspects of carbohydrate content in Yard-long bean seeds. Thus, the present study aimed to evaluate structures, thermal and technological properties of Yard-long bean seeds starch (YSS). The starch contains little of ash, protein and total fiber meanwhile amylose content of 37.52%. The shapes of the starch granules obtained from field emission scanning electron microscopy (FESEM) were oval to semi-elliptical with little granules occurring in agglomerated structures clusters, and volume median diameter of granules ranged from 10.5 μm to 12.5 μm. The initial gelatinization temperature of YSS was 73.86 °C, peak temperature was 80.59 °C and final 88.53 °C. Solubility index (SI, 3.43% at 90 °C) and swelling power (SP, 6.62 g/g at 90 °C) were observed with low volume, which corroborated with the C-type structure shown by X-ray diffraction (XRD) and high crystallinity degree. The extraction of YSS can be feasible, and it has suitable properties for use in the food industry.

Physicochemical and functional properties of native and modified agave fructans by acylation

Native agave fructans were modified by an acylation reaction with lauric acid. Native and modified fructans were characterized using NMR, FTIR and various physicochemical and functional properties at different pHs were evaluated. NMR and FTIR spectra demonstrated the incorporation of lauric acid in the molecular structure of fructans. Modified agave fructans exhibited a color, moisture and water activity similar to native fructans, but properties such as solubility, swelling capacity, emulsifying activity and foam capacity were significantly modified by the acylation reaction mainly when the samples were analyzed at different pHs. The thermogram of the acylated fructans evidenced significant changes in thermal properties when compared with native fructans and acylated fructans were able to form micellar aggregates. In general, modified fructans showed improved functional properties in comparison with native fructans representing an important opportunity to improve the functionality of the foods in which it is incorporated.