Physicochemical Properties of Caribbean Sweet Potato (Ipomoea batatas (L) Lam) Starches

The proximate compositions and physicochemical properties of 21 Caribbean sweet potato (Ipomoea batatas (L) Lam) starches were investigated. Proximate composition, amylose, reducing and non-reducing sugars were determined using standard methods. Swelling power and solubility were evaluated and pasting properties of the starches were determined using Rapid Visco Analyzer. Moisture (8.0–12.4%), protein (0.0–0.2%), ash (0.1–0.5%), and reducing (0.3–2.3%) and non-reducing sugar (0.1–0.2%) contents of starches were significantly different (P < 0.05) among the cultivars. Amylose content varied significantly between 12.8–21.3%. Swelling power and solubility ranged between 7.8–31.1% and 1.5–9.6%, respectively. Pasting properties such as peak viscosity measured in Rapid Visco Units (143.2–288.8 RVU), breakdown viscosity (29.4–162.6 RVU), and setback viscosity (15.0–78.8 RVU), pasting temperature (73.5–87.7 °C) and time to pasting temperature (3.6–4.5 min) varied significantly among the cultivars. Breakdown viscosity was poorly correlated with final viscosity attained (r = − 0.0507, P < 0.05); however, pasting temperature was correlated (r = 0.479, P < 0.05) with setback viscosity. The variability observed in the physicochemical properties of the starches was related to specific requirements for use in the production of noodles, pasta, and inclusion in bread and weaning food formulations.     

Physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand

This research aimed to study physicochemical properties and in vitro digestibility of flours and starches from taro cultivated in different regions of Thailand, that is, Kanchanaburi (KB), Chiang Mai (CM), Phetchaburi (PB) and Saraburi (SB). Taro starches were extracted from taro flours using either water or alkaline extraction. The taro flours had significantly (P ≤ 0.05) larger particle size, higher pasting and gelatinisation temperatures, and resistant starch content but lower total starch content, whiteness (L* value), paste viscosities and clarity than their corresponding extracted starches. All the taro starches exhibited polygonal and irregular granules and gave A-type X-ray diffraction pattern. The alkaline-extracted taro starches had significantly (P ≤ 0.05) higher extraction yield, total starch content, L* value, pasting and gelatinisation temperatures, and paste clarity but lower granular size, amylose content, resistant starch content, paste viscosities and relative crystallinity than their water-extracted counterparts.     

Properties of Starch Separated From Ten Mung Bean Varieties and Seeds Processing Characteristics

Starch samples from ten mung bean cultivars grown in china were isolated, and their morphology, physicochemical, thermal, and pasting properties were evaluated. The objectives of the study were to investigate the starch properties and processing characteristics of different mung bean varieties, and to establish the basic foundation of improving the functionality of mung beans and their starch grown in the region. The mung bean starches showed the kidney-shaped, elliptical, small spherical and dome-shaped granules, and the starches granule size varied between 5 and 40 μm. Total starch content, amylose content, solubility, and swelling power ranged from 54.73% to 57.99%, 40.44% to 41.82%, 13.72% to 17.67%, and 17.27% to 20.55%, respectively. The pasting properties were determined using a rapid visco analyzer, and various mung bean starches exhibited different pasting profiles. Different starches differed in transition temperatures (T _o, T _p, and T _c), gelatinization temperature range (ΔT _r), and enthalpy of gelatinization (ΔH) according to differential scanning calorimeter analysis. Hydration coefficient, degree of gelatinization, and hardness of mung bean varieties ranged from 51.97% to 84.46%, 62.99% to 95.11%, and 26.07 N to 112.11 N, respectively. This study indicated that starches separated from different mung bean cultivars possess different physicochemical characteristics, and various mung beans cultivars showed diverse processing properties.     

Structures and Functional Properties of Starch From Seeds of Three Soybean (Glycine max (L.) Merr.) Varieties*

Structures and functional properties of starch from high‐protein, lipoxygenase‐free and low‐linolenic acid soybean variety seeds collected 20 d prior to harvest were investigated. Soybean starches exhibit C_B‐type X‐ray diffraction patterns, and granule diameters were very small (0.7 to 4 µm). Soybeans, 20 d prior to harvest contained 10.9–11.7% starch (dry basis). Apparent amylose content was 19–22% and absolute amylose content was 11.8–16.2%. Amylopectin weight‐average molar mass ranged from 5.1 to 11.3×10⁸ g/mol. Amylopectin average branch chain‐length, determined by anion‐exchange chromatography with an amyloglucosidase post‐column and pulsed amperometric detector, was very short relative to other starches (20.4–20.9). Onset gelatinization temperature ranged from 52–54°C, and ΔH was 12–13 J/g. Paste viscosity was low relative to other starches, especially peak (81–93 RVU) and final (93–106 RVU) viscosity. The apparent amylose content of the low‐linolenic acid soybean starch was significantly higher than that of high‐protein soybean starch, and absolute amylose content of low‐linolenic acid soybean starch was significantly higher than that of lipoxygenase‐free soybean starch. Based on our results, investigations on whether soybeans with different fatty acid oil composition have different starch structures would be worthwhile. Field replicates for each soybean variety exhibited high variation in starch characteristics, with further differences in starch structures and functional properties likely to be determined once variation is minimized.     

Multi‐scale structural and digestion properties of wheat starches with different amylose contents

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc‐like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high‐amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm^?1 following the gel storage suggested the molecules of HAWS are more readily to re‐associate and re‐organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.     

Physicochemical Properties of Pin Oak (Quercus palustris Muenchh.) Acorn Starch

Physicochemical properties of acorn (Quercus palustris) starch were studied. Acorn starch granules were spherical or ovoid, with diameters ranging from 3–17 μm. Acorn starch exhibited A‐type X‐ray diffraction pattern, an apparent amylose content of 43.4% and absolute amylose content of 31.4%. Relative to other A‐type starches, acorn amylopectin had a comparable weight‐average molar mass (3.9×10⁸ g/mol), gyration radius (288 nm) and density (16.3 g mol⁻¹nm⁻³). Average amylopectin branch chain‐length corresponded to DP 25.5. Onset gelatinization temperature was 65.0°C and peak gelatinization temperature was considerably higher (73.7°C). The enthalpy change of gelatinization was very high compared to non‐mutant starches (20.8 J/g). An amylose‐lipid thermal transition was not observed. Starch retrograded for 7 d at 4°C had very high peak melting temperature (54.2°C) relative to other A‐type starches. Final (260 RVU) and setback (138 RVU) viscosity of an 8% acorn starch paste was high relative to other starches and pasting temperature was 71.5°C.     

Fundamental and Derived Properties of Yam (Dioscorea Spp.) Starch Powders and Implications in Tablet and Capsule Formulation

A comparative investigation of the fundamental and derived properties of starches from some species of yam (Dioscorea spp.) was conducted with a view to establishing their suitability as excipients in tablet and capsule formulations. Variations were observed in the mean granular diameter of the starches obtained from the different Dioscorea species. Granular diameter ranged from 5.4 µm (Chinese yam) to 34.5 µm (Round leaf yellow yam). Chinese yam and Bitter yam had the highest specific surface area (625.91 m²/kg and 258.76 m²/kg, respectively) while Round leaf yellow yam and Negro yam had the lowest (117.4 m²/kg and 154.34 m²/kg, respectively). Chinese yam had the lowest granular volume (6.00 µm³), surface area (5.67 µm²) and granule surface‐mean diameter (6.74 µm), while Round leaf yellow yam had the largest mean granular diameter, highest granular volume (35.2 µm³), surface area (34.8 µm²) and granule surface mean diameter (35.88 µm). Particle size distribution plots of Chinese yam, Round leaf yellow yam and Negro yam displayed a Gaussian size distribution pattern while Bitter yam displayed a negatively skewed distribution. The variations observed in the granular size and shape may influence the observed derived properties of the starches.     

Physicochemical properties of acetylated starches from some Indian kidney bean (Phaseolus vulgaris L.) cultivars

Starches separated from four kidney bean cultivars were modified by acetylation to reduce retrogradation and increase gel stability and compared with respective native starches (data of native starch reported by Wani et al., 2010 ). Acetylation was carried out by treating starches with 0.04 and 0.08 g of acetic anhydride per gram of starch dry weight basis (dwb) at 25 °C and pH between 8.0 and 8.5. The extent of acetylation increased proportionally with the concentration of acetic anhydride used. The pasting curves of 10.7% starch determined by Rapid Visco Analyzer at 160 rpm showed that acetylation decreased the setback viscosity values by 0.64–34.58% and pasting temperature by 4.4–9.2 °C when compared with the native starch. Differential scanning calorimetry observations also revealed significant (P ≤ 0.05) decrease in gelatinisation temperature of acetylated starches than the corresponding native starches. Hardness of starch gels varied between 14.3 and 44.0 g, which was significantly (P ≤ 0.05) lower than the corresponding native starch gels.     

Composition and properties of starches from Virginia‐grown kabuli chickpea (Cicer arietinum L.) cultivars

Composition and properties of seeds and starches from five Virginia‐grown kabuli chickpea cultivars were investigated. The seeds had the average weight of 4.48 g per 10 g and volume of 641.2 mm³, and were rich in carbohydrate with starch as a principal constituent (59.2–70.9%). Resistant starch accounted for 7.7–10.4% of the total starch content. The composition and properties of the starches among the five cultivars were significantly different (P ≤ 0.05). All starches had a C‐type crystalline structure. The degree of crystallinity ranged from 21.1% to 27.4%, gelatinisation temperature from 7.97 to 11.2 °C and gelatinisation enthalpies from 2.18 to 3.76 J g^?1, and water absorption capacities from 90.7% to 117.5%. Different shapes and granule sizes were observed. Molecular weight of amylopectin was in the range of 6.35 × 10⁸–11.6 × 10⁸ Da. Cultivar ‘HB‐14’ was superior to the other cultivars, when combining larger seed size, higher resistant starch level and better properties.     

Micellar properties of OSA starch and interaction with xanthan gum in aqueous solution

Octenyl succinate (OSA) modified starches are used, as emulsifiers and stabilizers, in many food, cosmetics and pharmaceutical products. The aim of this study was to determine critical micellar concentration (CMC) of two different octenyl succinate modified waxy corn starches at 25 °C, and to examine possibility of their interactions with xanthan gum in aqueous solution. The CMC was determined by viscometry, conductometry, surface tension and dye solubilization. The CMC values for two OSA starches (OS1 and OS2) varied from 0.050 to 0.088 g/100 cm³ and from 0.041 to 0.081 g/100 cm³ respectively, depending on applied technique. The same techniques were used for investigation of the interactions between OSA starch and xanthan gum. The addition of xanthan gum decreases the specific viscosity and increases surface tension and the CMC values compared to the single OSA starch solutions.     

Characterizations of starches isolated from five different Dioscorea L. species

The physicochemical, morphological and crystal structure characterization of the starches separated from rhizomes of Dioscorea opposita Thunb. Dioscorea alata Linn., Dioscorea nipponica Makino, Dioscorea bulbifera Linn. and Dioscorea septemloba Thunb. were studied and compared. Amylose content varied between 13.58% and 20.05%. Water-binding capacity, swelling power, solubility and total starch content of starches differed significantly. Scanning electron micrographs revealed that the surface was smooth or rough, the granules were oval to spherical and the size was obviously different. D. nipponica displayed A-type pattern. D. opposita D. alata, D. septemloba and D. bulbifera starches all exhibited C-type crystal. While the crystallinity degree of the starches separated from the five species were about 33.90%, 37.63%, 43.11%, 32.06% and 53.35%, respectively. The gelatinization transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) and peak height index (PHI) were determined. D. OT, D. AL and D. BL starches showed the higher enthalpy of gelatinization. Pasting viscosity of D. OT and D. BL starches were much higher than others. The five plants could be separated into two groups: D. OT, D. AL and D. BL; D. ST and D. NM.     

The effect of starch isolation method on physical and functional properties of Portuguese nut starches. II. Q. rotundifolia Lam. and Q. suber Lam. acorns starches

A new starch was isolated from fruits of two acorn species, Quercus rotundifolia and Quercus suber by alkaline (A3S) and enzymatic (ENZ) methods and physical and functional properties were studied. The isolation method induced changes in most of those properties in the isolated starches, mainly in resistant starch content, syneresis, pasting, thermal and rheological properties. Isolated acorn starches presented high amylose content (53–59%) and resistant starch content (30.8–41.4%). Acorn starches showed limited and similar solubility values and swelling power values, showing a gradual increase from 60 °C to 90 °C. The pasting temperatures ranged from 67.5 to 72.0 °C and pastes did not present breakdown, which is suggestive of a high paste stability of acorn starches during heating. At ambient temperature the turbidity and syneresis values were low, but when held at freezing temperatures the syneresis significantly increased. Thermal analysis revealed that the acorn starches easily undergo transition phenomena as shown by the low T_o and enthalpy values (4.1–4.3 J/g), these effects were more evident in starches isolated by ENZ method. Pastes are more elastic than viscous and form strong gels after cooling. Q. suber starch was shown to be more sensitive to the effect of isolation method. Generally, starch isolated by enzymatic method presented less interesting functional properties, since this isolation procedure greater affected the raw structure of starches.     

Thermal and Pasting Properties of Acid‐treated Rice Starches

The physicochemical properties of acid‐treated rice starches were investigated. Rice starches were treated with hydrochloric acid at different acid concentrations and hydrolysis times. The pasting properties were tested using a Rapid Visco Analyser, and gelatinization and retrogradation properties using a differential scanning calorimeter. The results showed that acid concentration had a more pronounced effect on degree of polymerization (DP) and viscosity than hydrolysis time. The onset, peak and conclusion temperatures of gelatinization were increased significantly with hydrolysis time, while the gelatinization enthalpy (ΔH_G) was decreased. In addition, there was an increase in the gelatinization temperature range with longer hydrolysis time. After storing gelatinized starches at 4°C for 7 days, the transition temperature and enthalpy (ΔH_R) to melt retrograded amylopectin did not change significantly. Additionally, the temperature and enthalpy transition for melting amylose‐lipid complex of all gelatinized and retrograded starches were in the same range.     

Chemical and Physical Properties of Kiwifruit (Actinidia deliciosa) Starch

Chemical and physical properties of kiwifruit (Actinidia deliciosa var. ‘Hayward’) starch were studied. Kiwifruit starch granules were compound, irregular or dome‐shaped with diameters predominantly 4–5 µm or 7–9 µm. Kiwifruit starch exhibited B‐type X‐ray diffraction pattern, an apparent amylose content of 43.1% and absolute amylose content of 18.8%. Kiwifruit amylopectins, relative to other starches, had low weight‐average molecular weight (7.4×10⁷), and gyration radius (200 nm). Average amylopectin branch chain‐length was long (DP 28.6). Onset and peak gelatinization temperatures were 68.9°C and 73.0°C, respectively, and gelatinization enthalpy was high (18.5 J/g). Amylose‐lipid thermal transition was observed. Starch retrograded for 7 d at 4°C had a very high peak melting temperature (60.7°C). Peak (250 RVU), final (238 RVU) and setback (94 RVU) viscosity of 8% kiwifruit starch paste was high relative to other starches and pasting temperature (69.7°C) was marginally higher than onset gelatinization temperature. High paste viscosities and low pasting temperature could give kiwifruit starch some advantages over many cereal starches.     

Effect of peeling and unpeeling on yield,chemical structure,morphology and pasting properties of starch extracted from three diverse potato cultivars of Pakistan

The current study investigates the comparison and quality characteristics of starches isolated from potatoes using different processing methods from three commercial varieties: Lady Rosetta, Asterix and Challenger, for the first time in Pakistan. The analysis of variance revealed that starch yield significantly (P < 0.05) depended on total solids, peeling (12.7%, 12.0% and 12.0%) and unpeeling (15.0%, 14.0% and 14.0%) of potatoes compared to potato varieties for Lady Rosetta, Challenger and Asterix, respectively. Moreover, pasting properties, protein content, redness and yellowness were increased in those starches isolated without peeling while carbohydrates and lightness were increased in peeled potato starches. Furthermore, Fourier-transform infrared spectroscopy analysis revealed that protein (1200–1400 cm⁻¹) was present in starch extracted without peeling. Besides, scanning electron microscopy analysis revealed oval-shaped starch granules with no impurities in peeled potato starch. The findings suggest the suitability of peeling process for obtaining a high-quality pure starch.     

Cell Wall Degrading Enzymes and Proteases Improve Starch Yields of Sorghum and Maize

The effects of a commercial cell‐wall‐degrading enzyme (CWDE) complex and/or commercial protease on yield and quality of starch extracted from white regular sorghum (RSOR), white waxy sorghum (WSOR) and yellow maize (YMZ) were determined. A bifactorial experiment with a level of confidence of P<0.05 was performed to study the effect of CWDE and/or protease addition to coarsely ground grains for 4 h after 20 h of regular SO₂ steeping of whole kernels. Calcium oxide (CaO) or lactic acid were used to adjust the pH solution to 5.5 prior to grinding. YMZ yielded the highest amount of starch, whereas RSOR gave higher starch yield than WSOR. All enzyme treatments significantly (P<0.05) improved starch yields. Protease alone and CWDE plus protease treatments were the most effective treatments in terms of starch yields. These enzyme treatments allowed the recovery of more than 90% of the starch. The two types of sorghum starches contained higher amounts of residual protein and ash when compared with maize starch. The various enzymes treatments did not affect starch composition or Visco Analyser properties of each type of kernel. As expected, the WSOR starch had lower pasting temperature and retrogradation when compared with the regular starches.     

Effect of Cross‐linking with Epichlorohydrin on the Properties of Cassava (Manihot esculenta Crantz) Starch

Cassava starch was cross‐linked with epichlorohydrin (EPI) at 45°C for 2 h in three different media which include water, water in the presence of a phase transfer catalyst (PTC) and N,N‐dimethylformamide (DMF). The products were characterized by determining their physicochemical, thermal and retrogradation properties. In aqueous medium, the use of a PTC, tetrabutylammonium bromide (TBAB) produced derivatives with higher degree of cross‐linking than those prepared without the use of the catalyst. The degree of cross‐linking was found to be higher using the same concentration of EPI when the reaction was carried out in DMF. At low levels of cross‐linking, the peak viscosity of the cross‐linked starches increased in comparison to that of the native starch. With increasing degree of cross‐linking, the peak viscosity showed a significant reduction. The swelling volume, solubility and light transmittance of the starch pastes were lower for the modified starches. The cross‐linked starches showed slightly reduced values for the gelatinization temperatures, T_onset, T_peak and T_end. The enthalpy of gelatinization of the modified starches increased with increase in the degree of cross‐linking. The modified starches exhibited higher water‐binding capacities (WBC) than the native starch; but with increase in the degree of cross‐linking, there was a gradual decrease in WBC. The in vitro alpha amylase digestibility of the modified starches decreased gradually with increase in the level of cross‐linking.     

Prediction of the Glass Transition Temperature on Extruded Waxy Maize and Rice Starches in Presence of Glycerol

Polymer science approach has shown to be useful to understand the structural complexity of food systems. This work looks at the effect of glycerol (5%, 10%, and 20% (dry weight basis)) on the glass transition temperature (Tg) of a starchy matrix determined by DSC and its prediction using Ten-Brinke–Karasz equation. Waxy maize starch (WMS) and rice starch (RS) systems were prepared by thermomechanical extrusion. A decrease in Tg, from ∼170 to ∼25 °C, was detected for both starches (0% glycerol) when the moisture increased from 5% to 25% (wet weight basis (wb)). When glycerol was added, a further decrease in Tg was obtained. Tg was reduced from 120 to 60 °C and 45 °C for 10% and 20% glycerol, respectively, at a moisture content of 10% (wb). A direct comparison between starches with similar composition showed equal Tg (P > 0.05). The modeling for the control samples (0% glycerol) gave a ΔCp ∼ 0.4 Jg⁻¹ K⁻¹ for WMS and RS and ∼1.9 Jg⁻¹ K⁻¹ for water. These values can be explained by the well-known Tg dependence on degree of polymerization and molecular weight. When the glycerol concentration was increased, an increase was observed, ΔCp ∼ 0.6 Jg⁻¹ K^−1, for both starches and ∼2.8 Jg⁻¹ K⁻¹ for water. This behavior would indicate an overestimation in the plasticizing effect of glycerol due to the possible occurrence of polyol-rich fractions in the extruded samples.     

The effects of blackcurrant and strawberry powder on the physicochemical and in vitro glycaemic response of starches derived from sweet potato (Ipomoea batatas) and potato (Solanum tuberosum)

Phenolic compounds have been shown to deliver numerous health benefits. Research has also shown that starch and phenolic compounds interact. This study aimed to investigate the effects of blackcurrant and strawberry powder on the physicochemical and in vitro predicted glycaemic response of sweet potato and potato starches. Sweet potato, or potato, starches were mixed with 0%, 5%, 10% and 15% (w/w) of blackcurrant, or strawberry, powder, to form blackcurrant and strawberry-enriched starch pastes. The results showed that enrichment with 5%, 10% and 15% blackcurrant or strawberry powder for sweet potato and potato starch significantly altered the pasting viscosity and colour profiles (P < 0.05), increased the phenolic content and antioxidant activities of starch pastes (P < 0.05). Blackcurrant or strawberry powders mixed with sweet potato or potato starches reduced amount of reducing sugar released during in vitro digestion. Addition of 15% blackcurrant powder for the starch exerted stronger in vitro antioxidant and hypoglycaemic properties than that of 15% strawberry powder. Collectively, these findings suggested that addition of blackcurrant or strawberry powder into sweet potato and potato starches manipulated the hypoglycaemic property of pastes.     

Effects of different types of potato resistant starches on intestinal microbiota and short-chain fatty acids under in vitro fermentation

The prebiotic effects of potato resistant starches RS1, RS2, RS3a, RS3b and RS4 were studied using simulated gut fermentation in vitro. The intestinal microbial composition was significantly changed by resistant starch (RS) after 24-h fermentation. All RSs (P < 0.05) decreased the ratio of Firmicutes/Bacteroidetes (F/B), and RS2 exhibited the lowest value of 0.95 ± 0.07. The relative abundance of Bifidobacterium was significantly increased by RS4, whereas Megamonas and Prevotella were promoted by RS2. Further, RS4 produced the highest levels of acetate (138.34 µM), whereas RS2 produced the highest levels of propionate (41.45 µM) and butyrate (21.65 µM). However, Bifidobacterium did not promote the production of propionate or butyrate, even though it was proficient in fermenting RS. Megamonas and Prevotella were positively associated with the higher production of propionate and butyrate. Here, different RSs played key roles in promoting intestinal health, and RS2 especially showed more abundant probiotic functions.