Physiochemical,Pasting, and Thermal Properties of Starch Isolated from Different Barley Cultivars

Starches from eight different barley cultivars were isolated and evaluated for their physiochemical, thermal, and pasting properties. The amylose content varied significantly among cultivars and ranged from 21.0 to 28.3%. The majority of the starch granules were of the B-type (20 to 40 μm) in size and accounted for 50.5 to 61.6% of the total granules. The starch gel from RD-2052 showed the highest firmness (0.55 N). The pasting behavior of starch varied significantly; the PL-172 cultivar showed the highest peak viscosity (2622 cP) while it was lowest for RD-2035 (1913cP). The time to peak of pasting properties exhibited a significant (p ≤ 0.05) negative correlation with water solubility index (r =??0.74). The pasting temperature showed a significant (p ≤ 0.05) positive correlation with water binding capacity (r = 0.73) and significant negative correlation with water solubility index (r =??0.82). The highest enthalpy of gelatinization (ΔH) was exhibited by DWR-28 cultivar (4.9 J/g). Amylose content showed a significant (p ≤ 0.01) negative correlation with ΔH (r =??0.90). A significant (p ≤ 0.01) positive correlation was observed between gelatinization temperature range and water binding capacity of starch (r = 0.85).     

Extrusion of Hulled Barley Affecting β-Glucan and Properties of Extrudates

Grits from eight different hulled barley cultivars were subjected to extrusion cooking on a twin screw extruder, and the effect of extrusion variables (temperature and moisture) on β-glucan and physicochemical properties was evaluated. The highest bulk density was observed for extrudates extruded at 150 °C and 20% moisture (low temperature high moisture, LTHM) while the highest expansion was observed for the extrudates extruded at 150 °C and 15% moisture (low temperature low moisture). Extrusion reduced the lightness (L*) of the extrudates and the highest decrease observed for LTHM extrudates. Increasing the feed moisture decreased water solubility index (WSI) significantly while increasing the extrusion temperature significantly increased WSI. The high temperature high moisture (HTHM) extrudates exhibited the highest water absorption capacity. The total β-glucan content was not affected by extrusion cooking, but a significant increase in soluble β-glucan was observed with the highest in high temperature low moisture extrudates. The ratio of soluble to insoluble β-glucan varied from 0.7 to 1.5 in the control barley, but after extrusion cooking, the ratio was changed from 1.2 to 3.1. The β-glucan extractability increased by up to 8% after extrusion with extrudates from HTHM showing the highest extractability. The extent of starch gelatinization varied from 80% to 100% upon extrusion, and the highest was observed in HTHM extrudates. A significant decrease in the peak and final viscosity of the extrudates at all the extrusion conditions was observed.     

In vitro starch digestibility,expected glycemic index,and thermal and pasting properties of flours from pea,lentil and chickpea cultivars

In vitro starch digestibility, expected glycemic index (eGI), and thermal and pasting properties of flours from pea, lentil and chickpea grown in Canada under identical environmental conditions were investigated. The protein content and gelatinization transition temperatures of lentil flour were higher than those of pea and chickpea flours. Chickpea flour showed a lower amylose content (10.8–13.5%) but higher free lipid content (6.5–7.1%) and amylose–lipid complex melting enthalpy (0.7–0.8 J/g). Significant differences among cultivars within the same species were observed with respect to swelling power, gelatinization properties, pasting properties and in vitro starch digestibility, especially chickpea flour from desi (Myles) and kabuli type (FLIP 97-101C and 97-Indian2-11). Lentil flour was hydrolyzed more slowly and to a lesser extent than pea and chickpea flours. The amount of slowly digestible starch (SDS) in chickpea flour was the highest among the pulse flours, but the resistant starch (RS) content was the lowest. The eGI of lentil flour was the lowest among the pulse flours.     

The utilisation of barley middlings to add value and health benefits to white breads

The beneficial health effects of β-glucan, a major non-starch polysaccharide in barley, have become the focus of much attention in recent years, with the incorporation of barley fractions into baked products being a growing area in the development of healthier food products. In this study, flour formulations, doughs and breads were produced using the “middling” fraction (M) of wholegrain (WM) and pearled (PM) barley in different ratios (15%, 30%, 45% and 60% middlings with wheat flour). A 100% wheat formulation was used as a control. The protein content differed significantly (P < 0.01) between formulations (i.e. the amount of barley middlings substituted for flour) but did not differ significantly between WM and PM formulations of the same inclusion level. Starch pasting properties were significantly affected by the increased inclusion of barley middlings (BM) into the formulation. Fundamental dough rheology of the samples also showed significant differences between doughs made from different BM levels, with doughs containing BM having increased firmness, decreased resistance to extension and decreased elasticity. Bread quality was not significantly affected by the addition of up to 30% BM, the loaf volume and textural properties in particular of breads up to 30% BM inclusion were of a suitable standard when compared to the control. Both fibre and β-glucan content of the breads was increased significantly with the inclusion of BM; inclusion of BM at a 30% level increased the fibre and β-glucan contents, respectively.     

Tocol and β-glucan levels in barley varieties and in pearling by-products

In order to verify a different genotype potential in barley varieties, in terms of tocols and β-glucans, and to demonstrate that pearling by-products have interesting amounts of these bioactive compounds, their content was investigated in 36 barley varieties and in the pearling by-products of a commercial hulled barley stock. The β-glucan content ranged from 2.64 g/100 g dw (dry weight) for Vanessa to 8.05 g/100 g dw for Ludine, with an average value of 3.95 g/100 g dw and 50% of the compounds were in the range between 3.45 and 4.36 g/100 g dw. The total tocol amount ranged from 50.3 mg/kg dw (Ladoga) to 88.6 mg/kg dw (Maggiodoro), with a mean value of 69.1 mg/kg dw and with most genotypes (50%) having a content between 62 and 75 mg/kg dw. Adagio and Sabel were the best source of vitamin E activity, expressed as Tocopherol Equivalents. In the pearling by-products there was no enrichment of β-glucans, on the contrary, a seven and a fivefold increase was observed for tocopherols and tocotrienols, respectively.     

Antioxidant and polyphenol oxidase activity of germinated barley and its milling fractions

Eight different hulled barley cultivars were evaluated before and after germination for total phenolic content (TPC), antioxidant activity (AOA) and polyphenol oxidase (PPO) activity. Germination for 12 h significantly decreased the TPC in whole flour (WF), bran (B) and refined flour (RF), however, further increase in germination to 24 h significantly increased the TPC in the fractions. Germination for 12 h duration significantly increased the AOA for WF, B and RF and further increase in germination to 24 h significantly increased the AOA in all the barley cultivars tested. A strong positive correlation was observed between AOA and TPC. Upon germination for 12 h the polyphenol oxidase activity of WF, B and RF significantly decreased by 13.31–59.22, 1.93–59.46 and 7.08–45.87%, respectively, however, the PPO activity increased upon germination for 24 h. The highest level of TPC and AOA was observed in the bran fraction of all the barley cultivars.     

Effect of extrusion conditions on resistant starch formation from pastry wheat flour

Pastry wheat flour was extruded under various conditions of feed moisture (20%, 40%, and 60%) and screw speed (150, 200, and 250 rpm), at constant barrel temperature profile (40, 60, 80, 100, and 120 °C, feed port to exit die). The extruded samples were stored at 4 °C for 0, 7, or 14 days, at which times resistant starch (RS) formation was analyzed. Thermal and pasting properties of extruded samples stored for 14 days were analyzed using a differential scanning calorimeter and rapid visco analyzer (RVA), respectively. The RS content increased after extrusion compared to non-extruded pastry wheat flour. High significant positive correlations of feed moisture (P < 0.01) and storage period (P < 0.05) with RS formation were observed. The RS derived from extrusion and storage showed higher thermal stability with decreasing feed moisture and screw speed. Statistically significant differences in pasting properties were observed with feed moisture or screw speed. In particular, the setback value from RVA of the sample was significantly increased with increasing feed moisture. These results indicate that feed moisture and storage time were both important factors for the formation of RS from pastry wheat flour during extrusion.     

Physicochemical properties of five cocoyam (Colocasia esculenta and Xanthosoma sagittifolium) starches

Physicochemical properties of starches of five cocoyam cultivars were evaluated. CIE L^*, a^*, b^* colour parameters of corm and starches were measured. Amylose, pasting and functional properties of the starches were investigated using colourimetric, Rapid Visco-Analyser and standard methods respectively. Cocoyam starches were white in colour as shown by L^* (84.83–88.65), a^* (+0.01–+1.19), and b^* (+15.33–+16.54) values. Starch granule sizes varied significantly in length (6.47–13.63 μm) and width (5.36–8.45 μm), while amylose content ranged from 11.55% (NCe002) to 33.77% (NXs001). Peak (49.09–141.96 RVU), breakdown (49.09–141.96 RVU), final (189.79–327.42 RVU) viscosities, pasting temperature (84.53–88.75 °C) and time (4.55–4.97 min) varied significantly (p < 0.05) among cultivars. Also, water absorption capacity (21–36%), pH (4.8–5.3), gelling point (60.5–69.5 °C), foam capacity (4.46–18.28%), bulk density (0.14–1.15 g/mL) and swelling power (2.31–10.09) varied significantly (p < 0.05) among the cultivars. Average yield of the starches varied significantly from 10.03 (NCe001) to 18.61% (NXs001).     

Differences in viscosity and textural properties of selected barley cultivars as influenced by pearling and cooking

Viscosity and texture are important attributes not only in determining quality of barley but also in delivering health benefits of barley products. The present study aimed at investigating viscosity and textural properties of nine barley cultivars selected for their compositional differences and economic importance to Canada. The cultivars were pearled to varying degrees to obtain whole grain and three pearled barley fractions named commercial, pot and white pearl. Increasing pearling time resulted in higher peak, trough, setback and final viscosity compared with whole grain flours. The hulless cultivars tested, tended to have lower trough, final and setback viscosities than the hulled ones. The waxy cultivars exhibited higher breakdown viscosities than normal cultivars. Viscosity at 37 °C of two cooked barley cultivars having extreme glycemic index (GI) values were significantly different. In other words, cooked Celebrity cultivar (low GI) had higher viscosity than AC Klink cultivar (high GI). Significant differences in maximum force and shearing work were also observed between cultivars. On the contrary to viscosity, both force and work decreased as pearling time increased. The study showed that some barley cultivars such as Celebrity fractions may hold a promise for the development of barley as a functional food ingredient or rice substitute.     

Effect of feeding corn, hull-less or hulled barley on fermentation by mixed cultures of ruminal microorganisms

Increased demands for corn grain warrant the evaluation of alternative grain types for ruminant production systems. This study was conducted to determine the effects of hulled and hull-less barley (Hordeum vulgare L.) cultivars compared with corn (Zea mays L.) as an alternative grain type on fermentation in cultures of mixed ruminal microorganisms. Three continuous fermentors were fed 14 g of dry feed per day (divided equally between 2 feedings) consisting of alfalfa (Medicago sativa L.) hay pellets (40% of dry matter) and 1) ground corn, 2) hulled barley, or 3) hull-less barley concentrate (60% of dry matter) in each fermentor. Following an adaptation period of 5 d, culture samples were taken at 2 h after the morning feeding on d 6, 7, and 8 of each period for analysis. A second run of the fermentors followed the same treatment sequence to provide replication. Culture pH was reduced with corn (5.55) and did not differ between barley cultivars (average pH 5.89). Total volatile fatty acid concentration and acetate to propionate ratio were not different across grain type or barley cultivar with the exception of greater total volatile fatty acid concentrations with hull-less barley. Corn produced less methane (14.6 mmol/d) and ammonia-N (7.3 mg/100 mL) compared with barley (33.1 mmol/d and 22 mg/100 mL, respectively); methane was greater with hull-less barley but ammonia-N concentration was similar between the 2 barley cultivars. Hull-less barley had greater digestibility compared with hulled barley, and corn had reduced digestibility compared with barley. Concentrations of C18:0 were greater and those of C18:1 and C18:2 lesser in cultures fed hulled and hull-less barley compared with corn. Our data indicate that grain type and barley cultivar have an impact on ruminal fermentation. The lesser starch concentration of barley minimized the drop in culture pH and improved digestibility.     

Some properties of corn grains and their flours I: Physicochemical,functional and chapati-making properties of flours

The variability in physical (1000 kernel weight and bulk density) and mechanical (rupture force) properties of grains from different Indian corn varieties (African tall, Ageti, Early composite, Girja, Navjot, Parbhat, Partap, Pb sathi and Vijay) were studied. The functional (colour, gelatinization, retrogradation and pasting) and chapati-making properties of flours milled from corn varieties were evaluated. African tall flour showed the highest enthalpy of gelatinization (ΔH_gel), peak-, trough-, breakdown-, final-, and setback viscosities, and L^∗ (84.4) value and resulted in chapaties with higher extensibility (5.76 mm) and of light colour. African tall flour, with the lowest protein content, showed the lowest grain rupture force. Amylose content and hardness of starch gel from African tall were found to be the lowest among all corn varieties. Girja flour, with the lowest transition temperatures and ΔH_gel, showed the lowest extensibility of chapaties made from it. Pearson correlations between physical and textural properties of corn grains and the functional properties of their flours were established. Rupture force of corn grain and protein content of flour showed a negative correlation with peak viscosity of flour (r = −0.917, and −0.863, p < 0.01). The protein content of flours was negatively correlated with L^∗ (r = −0.759, p < 0.01) value and positively with b^∗ (r = 0.635, p < 0.01) value. Pasting temperature of flours showed a significant negative correlation with peak, trough, breakdown, final and setback viscosities (r = −0.836, −0.846, −0.778, −0.871, and −0.847, respectively, p < 0.01). Pearson correlation was also established between the grain and starch properties. Rupture force of corn grains was positively correlated with the amylose content of starch (r = 0.950, p < 0.01).     

Effects of two barley β-glucan isolates on wheat flour dough and bread properties

The effects of wheat flour fortification with two different molecular weight barley β-glucan isolates (1.00 × 10⁵, BG-100 and 2.03 × 10⁵, BG-200) on the rheological properties of dough and bread characteristics, using flours from two wheat cultivars that differ in their breadmaking quality, have been examined. The farinograph water absorption of doughs and the moisture content and water activity of the breads increased with increasing β-glucan content; the β-glucan isolate with the higher molecular weight (BG-200) exerted a greater effect than did BG-100. The addition of β-glucans to the dough formula increased the development time, the stability, the resistance to deformation and the extensibility of the poor breadmaking quality doughs, as well as the specific volumes of the respective breads, exceeding even that of the good breadmaking cultivar. Furthermore, the colour of the bread crumbs got darker and their structure became coarser, whereas the bread crumb firmness decreased with increasing level of β-glucan addition. Generally, the BG-200 was more effective in increasing the specific bread volume and reducing the crumb firmness, especially when used to fortify the poor breadmaking quality flour. The results further indicate a requirement for optimisation of the fortified doughs (level and molecular size of the β-glucan) to maximise bread quality attributes (loaf volume, texture, and staling events).     

Comparative study of the functional,thermal and pasting properties of flours from different field pea (Pisum sativum L.) and pigeon pea (Cajanus cajan L.) cultivars

Physicochemical, functional, thermal and pasting properties of flours from field pea (LFP-48 and PG-3) and pigeon pea (AL-15 and AL-201) cultivars were determined and related to each other using Pearson correlation and principal component analysis (PCA). Field pea flours (FPF) were significantly (P < 0.05) different from pigeon pea flours (PPF) in their lower ash and higher fat and protein contents. FPF also exhibited higher L^∗, ΔE value, water solubility index (WSI), oil absorption capacity (OAC), foaming capacity (FC) and lower a^∗, b^∗ value, water absorption index (WAI) and water absorption capacity (WAC) in comparison to PPF. FPF differed significantly from PPF in exhibiting lower transition temperatures (T_o, T_p, T_c), enthalpy of gelatinization (ΔH_gel), peak height index (PHI) and higher gelatinization temperature range (R). PCA showed that LFP-48 and PG-3 flours were located at the far left of the score plot with a large negative score, while the AL-15 and AL-201 flours had large positive scores in the first principal component. Several significant correlations between functional, thermal and pasting properties were revealed, both by Pearson correlation and PCA. Pasting properties of the flours, measured using the rapid visco analyzer (RVA), also differed significantly. PPF were observed to have higher pasting temperature (PT), peak viscosity (PV), trough viscosity (TV), breakdown (BV), final viscosity (FV) and lower setback viscosity (SV) as compared to FPF.     

Thermal properties and resistant starch content of green banana flour (Musa cavendishii) produced at different drying conditions

The objective of this research was to verify the effect of drying conditions on thermal properties and resistant starch content of green banana flour (Musa cavendishii). The green banana flour is a complex-carbohydrates source, mainly of resistant starch, and quantifying its gelatinization is important to understand how it affects food processing and the functional properties of the flour. The green banana flour was obtained by drying unripe peeled bananas (first stage of ripening) in a dryer tunnel at 52 °C, 55 °C and 58 °C and air velocity at 0.6 m s⁻¹, 1.0 m s⁻¹ and 1.4 m s⁻¹. The results obtained from differential scanning calorimetry (DSC) curves show a single endothermic transition and a flow of maximum heating at peak temperatures from (67.95 ± 0.31) °C to (68.63 ± 0.28) °C. ANOVA shows that only drying temperature influenced significantly (P < 0.05) the gelatinization peak temperature (Tp). Gelatinization enthalpy (ΔH) varied from 9.04 J g⁻¹ to 11.63 J g⁻¹ and no significant difference was observed for either temperature or air velocity. The resistant starch content of the flour produced varied from (40.9 ± 0.4) g/100 g to (58.5 ± 5.4) g/100 g, on dry basis (d. b.), and was influenced by the combination of drying conditions: flour produced at 55 °C/1.4 m s⁻¹ and 55 °C/1.0 m s⁻¹ presented higher content of resistant starch.     

Storage stability and pasting properties of hydrothermally treated pearl millet flour

Hydrothermal treatment (30 ± 2% moisture and steaming at 1.05 kg m^?2 for 0, 10, 15, 20 and 25 min) was given to whole and pearled pearl millet grains. Flour obtained after each treatment was evaluated for physical, functional and pasting properties. Flour obtained from steamed before pearling (SBP, 20 min) and steamed after pearling (SAP, 15 min) grains exhibited no lipase activity and acceptable physical, functional and pasting properties. Significant (P ≤ 0.05) reduction (28.65%) was observed in total phenol content after pearling. Tannins content of control flour was 120.3 ± 2.15 mg, and a reduction of 25.2% and 16.5% was observed after 20 and 15 min of steaming in SBP and SAP samples, respectively. Significant (P ≤ 0.05) increase in bulk density, functional properties and decrease in pasting properties of treated flour samples was observed with increase in duration of steaming. Selected flour samples (SBP, 20 min and SAP, 15 min) were found acceptable for 50 days when stored in polyethylene pouches (75 μ) at ambient conditions (15–35 °C).     

Cross-linking of corn starch with phosphorus oxychloride under ultra high pressure

To investigate the effect of UHP treatment on the cross-linking reaction, normal corn starch was subjected to UHP-assisted reaction with a single addition level of POCl₃, at varied pressure levels ranging from 0.1 to 400 MPa. Swelling power, gelatinization, and pasting properties were assessed for all native and cross-linked starches. UHP-assisted reaction achieved a 12.5% level of conventional reaction time. UHP-assisted POCl₃ starch derivatives, reacted at 100–400 MPa, exhibited reduced swelling powers and gelatinization properties relative to that at 0.1 MPa, though both attributes did not possess any tendency depending on pressure levels. UHP-assisted POCl₃ reaction generated pasting viscosity profiles similar to those observed for conventional cross-linked starches. Pasting viscosity profiles were significantly different among various UHP treatments, though no trends were present. At 400 MPa, the UHP-assisted POCl₃ starch derivative revealed pasting viscosity profiles most similar to those of the conventional POCl₃ starch derivative.     

Effects of hull-less barley flour and flakes on bread nutritional composition and sensory properties

Barley is a desirable food ingredient, with health benefits provided by a β-glucan fibre fraction. A hull-less barley flour and flakes were incorporated into white and wholegrain wheat bread in quantities usually applied in practice. The breads were evaluated for nutritional composition and sensory properties and compared to standard products as controls. The supplemented breads were high in fibre, zinc and selenium content. It was estimated that a 300-gram daily portion of such breads could meet up to 40% of dietary recommended intakes for selenium and 70–75% of recommended daily values for β-glucan. Regarding sensory quality, the only significant differences (p < 0.05) were higher taste and lower volume in the white supplemented breads and lower crumb elasticity in the white bread made with barley flour. Hull-less barley can substantially contribute to an adequate intake of selenium and β-glucan. In addition, supplemented breads were not found to pose a significant risk, with regard to excessive intakes of heavy elements (Pb, Cd, As).     

Tocol Composition and Supercritical Carbon Dioxide Extraction of Lipids from Barley Pearling Flour

Samples of whole grain and 35% pearling flour of 20 different barley varieties grown in Alberta were analyzed for their lipid contents. Total lipid contents of whole grains were within 1.9% to 3.0% (w/w), whereas those of the 35% pearling flour were 4.3% to 7.9%. Lipids of 35% pearling flour fraction of Tercel barley were extracted using supercritical carbon dioxide (SC‐CO₂) at different pressures (24, 45, and 58 MPa) and temperatures (40 and 60 °C) for 3 h. Lipid recoveries of 73% to 97% were achieved using SC‐CO₂ extraction under different operational conditions. Tocol contents and compositions of whole grain, 35% pearling flour, and SC‐CO₂ extracts were analyzed using HPLC. Tocol content of the whole grain was 53.8 to 124.9 μg/g and that of the pearling flour was 195 to 363 μg/g of flour. The hulless barley varieties were higher in tocols, with waxy, double waxy and Tercel varieties having the highest levels (P < 0.05). The ratios of total tocotrienols to total tocopherols varied within 1.6 to 3.9 range. Tocol concentrations of SC‐CO₂ extract fractions varied from 1171 to 4391 μg/g extract depending on the operational conditions. Barley oil is a good natural source of different tocol isomers rich in tocotrienols.     

Some properties of corn starches II: Physicochemical,gelatinization, retrogradation,pasting and gel textural properties

The physicochemical, thermal, pasting and gel textural properties of corn starches from different corn varieties (African Tall, Ageti, Early Composite, Girja, Navjot, Parbhat, Partap, Pb Sathi and Vijay) were studied. Amylose content and swelling power of corn starches ranged from 16.9% to 21.3% and 13.7 to 20.7 g/g, respectively. The enthalpy of gelatinization (ΔH_gel) and percentage of retrogradation (%R) for various corn starches ranged from 11.2 to 12.7 J/g and 37.6% to 56.5%, respectively. The range for peak viscosity among different varieties was between 804 and 1252 cP. The hardness of starch gels ranged from 21.5 to 32.3 g. African Tall and Early Composite showed higher swelling power, peak, trough, breakdown, final and setback viscosity, and lower ΔH_gel and range of gelatinization. Pearson correlations among various properties of starches were observed. Gelatinization onset temperature (T_o) was negatively correlated to peak-, breakdown-, final- and setback viscosity (r = −0.809, −0.774, −0.721 and −0.686, respectively, p < 0.01) and positively correlated to pasting temperature (r = 0.657, p < 0.01). ΔH_gel was observed to be positively correlated with T_o, peak gelatinization temperature and (T_p) and gelatinization conclusion temperature T_c (r = 0.900, 0.902 and 0.828, respectively, p < 0.01) whereas, it was negatively correlated to peak- and breakdown- (r = −0.743 and −0.733, respectively, p < 0.01), final- and setback viscosity (r = −0.623 and −0.611, respectively, p < 0.05). Amylose was positively correlated to hardness (r = 0.511, p < 0.05) and gumminess (r = 0.792, p < 0.01) of starch gels.     

Carotenoid contents of extruded and non-extruded sweetpotato flours from Papua New Guinea and Australia

Carotenoid contents of extruded and non-extruded flours of Papua New Guinean and Australian sweetpotato cultivars were studied, using spectrophotometry and high performance liquid chromatography (HPLC). The cultivars differed (p < 0.05) in their total carotenoid and β-carotene contents, and the Original Beauregard cultivar had the highest total carotenoid and β-carotene contents among the cultivars. The spectrophotometry (84–1720 μg/g solids) method generally over-estimated the total carotenoid content compared to the more specific HPLC (23–355 μg/g solids) method. Extrusion significantly (p < 0.05) decreased the ΔL^∗ Hunter colour values, while the Δa^∗, Δb^∗, total colour change (ΔE), chroma (CR), and browning indices (BI) increased. With the extruder and screw configuration used, extrusion at 40% moisture and 300 rpm screw speed retained carotenoid maximally at more than 80%. This study reports, for the first time, carotenoids of flours from south Pacific sweetpotato cultivars, and carotenoid retention during extrusion.