Relationship between the structure,physicochemical properties and in vitro digestibility of rice starches with different amylose contents

The in vitro digestibility and molecular and crystalline structures of rice starches (Long-grain, Arborio, Calrose, and Glutinous) differing in amylose content were investigated and the relationship between the structure and in vitro digestibility of starch was studied. Long-grain showed the highest amylose content (27.2%), whereas Glutinous showed the lowest amylose content (4.2%). Long-grain had the highest average amylopectin branch chain length (18.8) and proportion (8.7%) of long branch chains (DP ≥ 37), and the lowest proportion (26.9%) of short branch chains (DP 6–12). Among the non-waxy rice starches (Long-grain, Arborio, and Calrose), Calrose had the lowest average chain length (17.7) and the lowest proportion (7.1%) of long branch chains (DP ≥ 37). The relative crystallinity of rice starch followed the order: Glutinous (33.5%) > Calrose (31.4%) > Arborio (31.0%) > Long-grain (29.9%). Long-grain had the highest gelatinization temperature and the lowest gelatinization temperature range, whereas Glutinous showed the highest gelatinization temperature range and gelatinization enthalpy. Arborio had the highest melting enthalpy for amylose–lipid complex among the tested rice starches. Pasting temperature, setback, and final viscosity increased with increasing amylose content, whereas the peak viscosity and breakdown showed negative correlations with amylose content. The rapidly digestible starch (RDS) content of the tested rice starches followed the order: Glutinous (71.4%) > Calrose (52.2%) > Arborio (48.4%) > Long-grain (39.4%). Contrary to this, the slowly digestible starch (SDS) and resistant starch (RS) contents showed an opposite trend compared to RDS. Digestibility (RDS, SDS, and RS) of the rice starches was significantly correlated (p ≤ 0.05) with amylose content, proportions of DP 6–12 and DP 13–24, relative crystallinity, intensity ratio (of 1047 cm⁻¹ to 1022 cm⁻¹ from Fourier transform infrared spectroscopy), swelling factor, amylose leaching, onset temperature of gelatinization, gelatinization temperature range, gelatinization enthalpy, pasting temperature, peak viscosity, breakdown, setback, and final viscosity.     

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.     

Starch characteristics of dry peas (Pisum sativum L.) grown in the USA

Starch samples from seven major dry pea (Pisum sativum L.) cultivars grown in North Dakota, US was isolated and their physicochemical properties investigated. The objective of the study was to establish the basic foundation of advanced research on physical and chemical modification to improve the functionality of dry pea starches grown in the region. Isolated starch samples were analysed by high performance size exclusion chromatography (HPSEC). Amylose percentages were in the range of 32.2–41.1%. Granules were elliptical or spherical with smooth surfaces based on microscopic analysis. Starch samples had similar gelatinisation transition temperatures and displayed ‘C patterns’. The swelling factors of dry pea starches influenced by temperature were determined at 10° intervals between 50 and 90 °C with continuous mixing. The pasting profiles were studied using a rapid visco analyzer (RVA), which exhibited different pasting profiles. This study indicated that dry pea cultivars grown in the region possess starch with different physicochemical characteristics.     

Structural characteristics and in vitro digestibility of Mango kernel starches (Mangifera indica L.)

Structural characteristics and digestibility of starches isolated from the kernels of two mango cultivars (Chausa and Kuppi) were studied and compared with those of a commercial normal corn starch. Mango kernel starches showed an A-type X-ray diffraction pattern, with relative crystallinities of 35.4% and 38.3%, respectively for Kuppi and Chausa cultivars. The structural characterisation obtained, using high performance size exclusion column chromatography connected to multi-angle laser light scattering and refractive index detectors (HPSEC-MALLS-RI), revealed that the mango kernel starches had lower molecular weight (M_w) and radius of gyration (R_g) of amylopectin and amylose compared to those of corn starch. The M_w of amylopectin for Chausa and Kuppi starches were 179 × 10⁶ and 140 × 10⁶ g/mol, respectively. The amounts of readily digestible starch (RDS) and slowly digestible starch (SDS) were lower for mango kernel starch than those of corn starch. Resistant starch (RS) contents in the mango kernel starches (75.6% and 80.0%, respectively) were substantially higher than those of corn starch (27.3%). The glycemic index (GI) values for mango kernel starches were 48.8 and 50.9 (for Chausa and Kuppi, respectively), whereas that of corn starch was 74.8, indicating that the mango kernel starch granules were highly resistant to digestion with significant contents of RS.     

Physicochemical characterization of sweet potato starches popularly used in Chinese starch industry

Physicochemical properties of starches isolated from 11 sweet potato cultivars popularly used in Chinese starch industry were studied. Moisture, protein, ash, lipid and phosphorus content of the starches varied from 3.86 to 6.52%, 0.28 to 0.75%, 0.10 to 0.47% and 0.00 to 0.02%, respectively. Amylose content varied between 13.33 and 26.83%. The starches differed in their mean granule sizes, particle size distribution, and susceptibility to pancreatin hydrolysis. Swelling power and solubility ranged from 13.46 to 26.13 g/g and 8.56 to 18.77%, respectively. Higher retrogradation tendency was observed in pastes of starches of high amylose content. Gelatinization temperature and enthalpy ranged from 55.54 to 69.11 °C and 6.40 to 11.89 J/g, respectively. Pasting properties including peak viscosity (134–255 BU), breakdown viscosity (91–162 BU), setback viscosity (26–112 BU), peak time (5.97–7.03 min) and pasting temperature (67.20–73.00 °C) varied significantly among the sweet potato starches. Pearson's correlation analysis showed that phosphorus content of the starches had substantial effect on their swelling power (r = 0.70, p ≤ 0.05) showing positive correlations. There was significant positive correlation between swelling power and solubility of the starches (r = 0.64, p ≤ 0.05). Thermal and pasting parameters also showed significant correlations.     

Use of multivariate techniques in studying the flour making properties of some CMD resistant cassava clones

High quality cassava flour (HQCF) is one of the primary products of raw cassava root that has continued to find wider food application in Nigeria. In this study, some 43 newly developed cassava mosaic disease (CMD) resistant clones of cassava were screened based on some physical (flour yield, bulk density, and tri-stimulus colour characteristics (L^∗, a^∗, b^∗, Chroma and Hue)), chemical (moisture, protein, ash, starch, amylose, sugar contents, TTA, pH, and cyanogenic potential), functional (water and oil absorption capacities, water solubility, swelling power, least gelation capacity, diastatic activity, percent damaged starch, and alkaline water retention), and pasting properties. One-way analysis of variance (ANOVA) showed that all properties measured varied significantly (P < 0.001). The flours had a wider range of starch content (65–88%), amylose content (13–23%), water absorption capacity (136–224%), diastatic activity (128–354 mg maltose), peak viscosity (77–328 RVU), final viscosity (56–217 RVU), and trough (32–152). Due to the peculiarity of the experimental data generated, two protocols of applying multivariate statistical techniques were evaluated for discriminating the cassava clones. By first applying principal component analysis (PCA), followed by cluster analysis (CA) and finally, discriminant function analysis (DFA) of the experimental data, it was possible to achieve about 87% correct classification of the cassava clones. The final viscosity and diastatic activity of the flours were found to be the most important variables for classifying the cassava clones.     

Milling behavior of hulled barley and its thermal and pasting properties

Eight commonly grown Indian hulled barley cultivars were studied for their dehusking, pearling, physico-chemical, β-glucan, pasting and thermal behavior. Milling of the hulled barley at 14% moisture significantly lowered the dehusking and pearling time as compared to milling at 10% moisture content. The extraction rate ranged from 55.05% to 62.35% and significantly (p < 0.05) differed among the cultivars. Particle size distribution of flours was significantly different among the cultivars with flour from RD-2552 and RD-2035 cultivars having the most even particle size distribution. The colour difference (ΔE) was not significantly different among cultivars. The extractable β-glucan content varied from 1.93% to 3.81% among the cultivars and was highest in PL-172. The final pasting viscosity was significantly different among cultivars while the pasting temperature did not vary significantly. The enthalpy (ΔH) of gelatinization of barley flour varied from 4.45 to 7.08 J/g and gelatinization temperature (T_p) varied from 64.23 to 66.26 °C.     

Characterization of new starches separated from different Chinese yam (Dioscorea opposita Thunb.) cultivars

The starches separated from four different Dioscorea opposita Thunb. cultivars were investigated for morphological, thermal, crystal, and physicochemical properties, such as amylose content, swelling power, solubility and water-binding capacity properties. Amylose content of D. oppositastarches from different cultivars ranged from 20.74% to 25.94%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round to oval or elliptic. The mean particle diameter of starches ranged from 23.39 to 26.87 μm. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). T_o, T_p and T_c varied from 73.6 to 74.8, 78.8 to 81.0, and 83.3 to 87.2 °C, respectively. D. opposita cv. Jinchengerhao starch showed the highest ΔH_gel values (12.48 J/g) while D. opposita cv. Baiyu starch showed the lowest values (8.413 J/g). The crystal type of starches separated from different D. opposita cultivars was a typical C_B-type pattern. The degrees of crystallinity of the four D. opposita cultivars starches were about 50.52%, 32.99%, 33.57% and 36.16%, respectively.     

Physicochemical,thermal and pasting properties of starch separated from γ-irradiated and stored potatoes

The morphological, thermal and pasting properties of starch separated from potatoes of three varieties (Kufri Chandramukhi, Kufri Jyoti and Kufri Chipsona-2), treated either with CIPC (isopropyl N-(3 chlorophenyl) carbamate) or γ-irradiation (Co⁶⁰, 0.1 and 0.5 kGy) and subsequently stored at 8, 12 and 16 °C for 90 days, were studied. Scanning electron microscopy (SEM) showed the presence of oval and irregular shaped starch granules with a diameter range of 15–16 μm. Mean granule size of starch separated from potatoes stored at 12 °C ranged from 18–25 μm and irradiation treatment resulted in an increase in the proportion of small size granules. The irradiation of potatoes with 0.5 kGy resulted in starch with significantly lower peak-, trough- and breakdown-viscosity as compared to starch from potatoes treated with either CIPC or 0.1 kGy irradiation. The irradiation of potatoes with 0.5 kGy caused a significant increase in setback and pasting temperature. Pasting temperature of starch was observed to vary with the storage temperature. Starch separated from potatoes stored at higher temperature showed lower pasting temperature and vice versa. The starch from potatoes stored at 8 °C showed higher peak-, trough- and breakdown-viscosity and lower setback. Peak viscosity increased and swelling volume decreased with increase in storage temperature. FTIR spectra showed that the starch from irradiated potatoes displayed a significant decrease in the intensity of the C–H stretch region between 2800 and 3000 cm⁻¹, which was observed to be irradiation dose-dependent, and higher with 0.5 than 0.1 kGy. However, a slight broadening of O–H stretch (3000–3600 cm⁻¹) in starches from irradiated potatoes was observed. The spectral changes caused by γ-irradiation were apparent in the O–H stretch (3000–3600 cm⁻¹), C–H stretch (2800–3000 cm⁻¹) and bending mode of water (1600–1800 cm⁻¹).     

Pasting behaviour, textural properties and freeze-thaw stability of wheat flour-crude malva nut (Scaphium scaphigerum) gum system

The effect of replacement of crude malva nut gum (CMG) at 0%, 2.5%, 5%, 7.5% and 10% w/w on pasting behaviour, textural properties and freeze-thaw stability of wheat flour was investigated. Replacement of wheat flour by CMG significantly elevated (p < 0.05) the peak viscosity (128-669 RVU), hot paste viscosity (77-363 RVU), breakdown (51-306 RVU) and final viscosity (157-557 RVU) of wheat flour pastes. Pasting temperature (59-85 °C) of the flour decreased with increasing CMG content. The textural parameters including hardness, springiness, cohesiveness, gumminess and chewiness of the mix gels decreased with higher level of CMG. Freeze-thaw stability measurement revealed that wheat gel mixtures containing higher level (7.5% and 10%) of CMG decreased syneresis more than 80% after 3 freeze-thaw cycles, when compared to non-CMG sample. The rate of syneresis depended on CMG concentration and number of freeze-thaw cycles. The results demonstrated that higher viscosity, softer texture and lower syneresis of wheat gel could be attained using CMG.     

Correlation between astaxanthin amount and a* value in fresh Atlantic salmon (Salmo salar) muscle during different irradiation doses

The amount of astaxanthin and a* value changes in fresh Atlantic salmon light and dark muscle during cold storage was studied for different e-beam doses (0, 1, 1.5, 2 and 3 kGy). Astaxanthin (mg/kg muscle) and a* value decreased with increasing irradiation dose for both fresh light and dark muscle. The level of irradiation dose gave high correlation between a* value and amount of astaxanthin. The reason for the change in colour or decrease in a* value of Atlantic salmon during irradiation could be due to the destruction of astaxanthin. The amount of astaxanthin and a* value of 1 kGy treated salmon fillets were not significantly different (p > 0.05) from that of the control but significantly different (p < 0.05) from other irradiation treatments. The colour (a* value) of salmon muscle was related to the content of astaxanthin, which decreased as irradiation increased. The amount of astaxanthin in light muscle was three to five times greater than dark muscle. This study demonstrated that irradiating salmon fillets at 1 kGy, can be successfully used and leads to no significant change in colour and amount of astaxanthin.     

Anthocyanins and hydroxycinnamic acids of Lambert Compact cherries (Prunus avium L.) after cold storage and 1-methylcyclopropene treatment

Sweet cherries cv. Lambert Compact were treated with 1-methylcyclopropene (1-MCP) at 0, 180 and 360 nL/L for 2 h at 25 °C and then stored at 2–4 °C in refrigerator. Their quality was measured after 12 days of storage in terms of the contents of total and individual anthocyanins and hydroxycinnamic acids, occurrence of rot, and colour change. Colour change was monitored at three day intervals during storage in the CIE L*, a*, b* colour space. 1-MCP did not retard colour change. The contents of total and individual anthocyanins and hydroxycinnamic acids showed no correlation with the colour behaviour of the cherries. All cherries lost their initial shiny red colour on storage, regardless of the treatment. 1-MCP reduced sweet cherry rot at the highest concentration used (360 nL/L) – only 6% were rotten after 12 days in the refrigerator. This differed significantly (P < 0.05) from untreated fruits and those treated with 180 nL/L 1-MCP which resulted on average in 14 and 20% rot (not statistically different P < 0.05), respectively. The occurrence of rot was shown to be correlated with anthocyanin accumulation, (R = 0.62, P < 0.10). The profile of individual anthocyanins and hydroxycinnamic acids in sweet cherry was not affected neither by cold storage nor 1-MCP treatment.     

Genotypic diversity in physico-chemical,pasting and gel textural properties of chickpea (Cicer arietinum L.)

Twenty chickpea cultivars were evaluated for genetic diversity in seeds (physical, hydration and cooking), flours (composition, pasting and gel textural) and starch (swelling, thermal, amylose content and amylopectin structure) properties. Frequency distribution and principal component analysis revealed significant differences among the cultivars studied. Pasting temperature, peak viscosity, breakdown, final viscosity and setback of flours ranged from 75.0 to 87.1 °C, 564 to 853 cP, 32 to 123 cP, 573 to 969 cP, and 84 to 185 cP, respectively. Amylose content of starch ranged from 28.26% to 52.82%. Amylopectin unit chains of DP 6–12, 13–18, 19–24 and 25–30 ranged from 36.2% to 43.25%, 36.44% to 38.68%, 14.86% to 18.22% and 4.95% to 6.9%, respectively. To establish the relationships between different properties Pearson correlation coefficients (r) were computed. Cluster analysis for grain and flour characteristics was also done to see the association between chickpea cultivars.     

Composition,molecular structure,and physicochemical properties of starches from two grass pea (Lathyrus sativus L.) cultivars grown in Canada

The morphology, molecular structure and physicochemical properties of starches from two cultivars (NC8A97, Lath 96) of grass pea (Lathyrus sativus L.) were examined. In both cultivars, starch granules were irregular to oval to round to elliptical shaped, with smooth surfaces. No significant differences was observed between the cultivars with respect to mean granule diameter (26.3–27.3 μm), mean granule length (32–34.5 μm), amylose content (37.95–38.30%), bound lipid content (0.08%), amylopectin chain length distribution, average chain length (19.2) and X-ray diffraction pattern (‘C’ type). However, NC8A97 and Lath 96 starches differed significantly with respect to the degree of crystallinity (Lath 96 > NC8A97), B-polymorphic content (Lath 96 > NC8A97), granular swelling (NC8A97 > Lath 96), extent of amylose leaching (NC8A97 > Lath 96), peak viscosity (Lath 96 > NC8A97), shear stability (Lath 96 > NC8A97), set-back (NC8A97 > Lath 96) and susceptibility towards enzyme and acid hydrolysis (NC8A97 > Lath 96). The results showed that physicochemical properties of the grass pea starches were influenced by the extent of interaction between starch chains (Lath 96 > NC897) in the amorphous regions, amount of crystallites (NC8A97 > Lath 96) and crystallite heterogeneity (NC8A97 > Lath 96).     

Free and bound total phenolic concentrations,antioxidant capacities,and profiles of proanthocyanidins and anthocyanins in whole grain rice (Oryza sativa L.) of different bran colours

To study the polyphenols in whole grain rice varying in bran colour, the total phenolics, flavonoids and antioxidant capacities of the solvent-extractable (Free) and cell-wall bound (Bound) fractions and the profiles of proanthocyanidins and anthocyanins were determined. Red and purple bran rices had significantly higher total (sum of Free- and Bound-) phenolic (PC) and flavonoid (FC) concentrations and antioxidant capacities than light-coloured bran rice or other cereals (P < 0.05), due to their higher concentrations of proanthocyanidins and anthocyanins, respectively. The concentrations of the Bound-PC and FC accounted for approximately half of the total PC and FC in the light-coloured bran rice, but were lower than those in purple and red bran rice (P < 0.05). High correlations were found between the concentrations of total phenolics and the three antioxidant capacity assays except for those in the bound fraction when related to iron chelating capacity. The concentrations of proanthocyanidins in red bran rice was 1.27 mg/g and its composition was 6.5%, 33.5%, 30.6% and 29.4% of 1–3, 4–6, 7–10 mers, and polymer (>10 mers), respectively. Cyanidin-3-glucoside was the predominant anthocyanin and peonidin-3-glucoside was the second highest; the profiles varied between purple bran cultivars. Whole grain rice differing in bran colour contained unique polyphenol subgroups, which have been proposed to positively impact human health.     

Studies on the physicochemical,morphological, thermal and crystalline properties of starches separated from different Dioscorea opposita cultivars

The physicochemical, morphological, thermal and crystal properties of the starches separated from four different Dioscorea opposita Thunb. cultivars (Taigu, Ribenbai, Wenxi and Zhongbowen) were studied. Amylose contents of D. opposita Thunb. starches from different cultivars ranged from 21.17% to 25.00%. The shape of starch granules separated from different D. opposita Thunb. cultivars varied from round or oval to elliptic or caky. The surface of the starch granules appeared to be smooth without any fissures. The average particle diameter of starches from different D. opposita Thunb. cultivars ranged from 25.90 to 28.06 μm. The transition temperatures (T_o, T_p and T_c) and enthalpy of gelatinization (ΔH_gel) were determined using differential scanning calorimetry (DSC). T_o, T_p, T_c and ΔH_gel of D. opposita Thunb. starches ranged from 73.1 to 73.9, 77.6 to 80.4, 82.1 to 85.9 °C and 6.548 to 12.13 J/g, respectively. The crystal type of starches separated from different D. opposita Thunb. cultivars was a typical C-type pattern. The relative degree of crystallinity of the four D. opposita Thunb. cultivars starches were about 38.79%, 39.88%, 41.67% and 49.03%, respectively.     

Phenolic compounds in strawberry (Fragaria x ananassa Duch.) fruits: Composition in 27 cultivars and changes during ripening

Phenolic compounds in fruits of 27 cultivars of strawberry (Fragaria x ananassa Duch.) grown in Norway were characterised and quantified by HPLC-DAD-MSⁿ. Total phenolic content, calculated as the sum of the individual compounds, varied 2.3-fold among cultivars, i.e., from 57 to 133 mg/100 g of fw. There were significant differences among cultivars in concentration of all phenolic compounds. The highest variation between cultivars was found for cinnamoyl glucose (0.6-24.9 mg/100 g of fw). Concentration of anthocyanins, the most abundant class of phenolic compounds in the majority of the cultivars, varied from 8.5 to 65.9 mg/100 g of fw. Flavan-3-ols (11-45 mg/100 g of fw) and ellagitannins (7.7-18.2 mg/100 g of fw) contributed on average 28% and 14% to total phenolic contents in the strawberry cultivars, respectively. In three cultivars harvested at three stages of ripeness, anthocyanins and cinnamic acid conjugates were the compounds most affected by ripening. The anthocyanin profile for the individual cultivars was only slightly affected by ripening and growing conditions.     

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.     

Amaranthus hypochondriacus and Amaranthus caudatus germplasm: Characteristics of plants,grain and flours

In the present study, the plant, grain and flour characteristics of 48 Amaranthus hypochondriacus and 11 Amaranthus caudatus lines are reported. A. hypochondriacus grains had a higher thousand kernel weight (0.62–0.88 g), a creamish yellow colour (L∗ = 61.38–68.29, b∗ = 5.26–6.8 and a∗ = 19.71–23.84), whereas A. caudatus grains had a lower thousand kernel weight (0.46–0.70 g) and a reddish-brown colour (L∗ = 47.1–51.2, b∗ = 11.82–14.02 and a∗ = 7.72–13.29). The A. caudatus lines had a higher protein content, fat content and tendency for retrogradation, and lower α-amylase activity as compared to A. hypochondriacus lines. The Amaranthus lines with higher a∗-values and lower thousand kernel weight, L∗- and b∗-values, had a higher fat, crude fibre and protein content. The correlation of fat and crude fibre content with the thousand kernel weight, L∗-, a∗- and b∗-values, was significant. The A. hypochondriacus lines showed higher pasting temperature, and lower peak viscosity, breakdown and setback, as compared to the A. caudatus lines. The result reflected that the lines with higher α-amylase activity showed a lower peak viscosity, breakdown, final viscosity and gel hardness, and a higher pasting temperature.     

Antioxidant properties of different cultivars of Portulaca oleracea

Methanolic extracts of six cultivars of Portulaca oleracea were analyzed for their total phenol content (TPC) using the Folin–Ciocalteu method. The antioxidant activity was measured using the 1,1-diphenyl-2-picrylhydrazyl, ferric-reducing antioxidant power (FRAP) and β-carotene bleaching (BCB) assays. The iodine titration method was used to determine the ascorbic acid content (AAC). The TPC of the cultivars of P. oleracea ranged from 127 ± 13 to 478 ± 45 mg GAE/100 g of fresh weight of plant. There was good correlation between the TPC value and its AEAC, IC₅₀ and FRAP values (r² > 0.9) for all the cultivars. The AAC for the cultivars ranged from 38.5 ± 0.6 to 73.0 ± 17.5 mg/100 g. The TPC value of the common variety PO1, was the lowest compared to the ornamental cultivars (PO2–PO6). The BCB assay showed that all cultivars were capable of inhibiting lipid peroxidation and the inhibition power did not correlate with TPC value.