Characterization of total antioxidant capacity and (poly)phenolic compounds of differently pigmented rice varieties and their changes during domestic cooking

Honey contains important bioactive compounds (enzymes, phenolic compounds, vitamins, and minerals) with several positive health effects for humans. In the study six types of honey (acacia, rape, floral, multi flower, forest, and honeydew honeys), of Czech and Slovak origin, were evaluated for bioactive compounds by means of color, polyphenols and antioxidant capacity analyses. The brightest color of honeys, the lowest values measured spectometrically, had acacia and rape honeys, followed by floral, and darker multi flower and forest honeys, and honeydew honeys. Polyphenols (PP) amount, determined by spectrophotometric method with Folin-Ciocalteu reagent, was highest for the darkest honeydew honeys, followed by multi flower and forest honey, brighter floral honeys, and rape and acacia honey. Honeys polyphenols were in the range from 54.0 to 254.2 mg GAE.100g-1. The total antioxidant capacity (TAC) was analyzed by spectrometric methods with ABTS and DPPH reagents. Antioxidant capacity values are in agreement with the PP contents order. They were highest also for honeydew honeys (59.2 - 89.6 and 73.1 - 118.7 mg TE.100g-1), followed by multi flower (66.0 and 56.7 mg TE.100g-1) and forest honey (56.0 and 49.1 mg TE.100g-1), then floral honeys (33.0 - 49.2 and 27.8 - 38.7 mg TE.100g-1) and the lowest values for rape (19.0 and 28.1 mg TE.100g-1) and acacia (15.5 and 11.3 mg TE.100g-1) honey. A positive correlation between color, PP amount and TAC was evaluated for analyzed honeys. Darker honey samples showed higher values of phenolic compounds and antioxidant potential, therefore they belong to the honey types with higher amount of bioactive compounds such as antioxidants.

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The Total Antioxidant Capacity and the Total Phenolic Content of Rice Using Water as a Solvent

International Journal of Food Science ◽

10.1155/2021/5268584 ◽

2021 ◽

Vol 2021 ◽

pp. 1-6

Author(s):

C. Priyanthi ◽

R. Sivakanesan

Keyword(s):

Antioxidant Capacity ◽

Total Antioxidant Capacity ◽

Phenolic Content ◽

Condensed Tannin ◽

Reducing Power ◽

Total Phenolic ◽

Anthocyanin Content ◽

Tannin Content ◽

Rice Varieties ◽

Total Antioxidant

Background. The present study evaluates the antioxidant properties of some Sri Lankan red rice varieties using water extracts. Methods. Water extracts of rice varieties Attakkari, Bg2907, and Bg407 were used in this study. The total antioxidant capacity was measured by ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, and reducing power assays. The total phenolic content (TPC), total flavonoid content (TFC), monomeric anthocyanin, and condensed tannin contents were measured by Folin-Ciocalteu, aluminium chloride, pH differential, and vanillin assays, respectively. Results. It was observed that mean FRAP, DPPH, reducing power, TPC, TFC, monomeric anthocyanin content, and condensed tannin content were in the range of 0.561 ± 0.113 to 0.695 ± 0.077 mmol / 100 g fresh weight (FW), 26.07 ± 3.08 to 53.66 ± 7.61 mg / mL FW , 33.49 ± 4.105.14 to 40.81 ± 3.65 mg / mL , 0.676 ± 0.078 to 0.900 ± 0.057 mg tannic acid equivalent (TAE)/g, 5.36 ± 0.75 to 6.38 ± 0.82 mg TAE / g FW , 0.0202 ± 0.005 to 0.0292 ± 0.009 mg / g FW , and 0.078 ± 0.015 to 0.104 ± 0.017 mg TAE / g FW , respectively. Significant differences were observed in DPPH, reducing power, and TPC among rice varieties ( p < 0.05 ). Rice variety Attakkari had the highest total antioxidant capacity (TAC), scavenging activity, reducing power, TPC, TFC, monomeric anthocyanin content, and condensed tannin content followed by Bg2907 and Bg406. Conclusion. Total phenolic compounds, total flavonoid, and condensed tannin are the major antioxidants in all three varieties of rice while the monomeric anthocyanin is only a minor antioxidant.

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