Extraction, Quantification, and Characterization of Phenolics Extracted with the Aid of Sonication from Rice Bran

Abstract

Phenolics are phytochemicals extensively distributed among plants that have been receiving great deal of attention for their functionality. Rice bran is a good source of phenolics, especially hydroxycinnamates. Although chemicals are commonly employed to isolate phenolics, the use of physical treatments such as sonication is still limited. This study was conducted to optimize a procedure to isolate phenolics from rice bran using sonication as a preextraction treatment. Sonication was optimized by varying output, time, and temperature. Extraction was optimized by varying solvent, extraction time, temperature, and sample‐to‐solvent ratio. After an optimum procedure was established, HPLC analyses were conducted to identify and quantify the major individual phenolic acids extracted. The optimum conditions for extracting phenolics from rice bran were sonication with water (1:100 sample‐to‐solvent ratio) for 1 min; output intensity of 10; holding at ambient temperature; and autoclave treatment for 20 min at 121°C. This procedure extracted 8.85 ± 0.18 mg of phenolics/g of dried rice bran. Benzoic, p‐coumaric, and trans‐ferulic acids were the major phenolics identified in the extract. The proposed procedure will be valuable in obtaining phenolics for increasing product functionality such as lipid oxidation inhibitors in food systems.

Extraction, optimisation and characterisation of phenolics from Thymus vulgaris L.: phenolic content and profiles in relation to antioxidant, antidiabetic and antihypertensive properties

“…The ACE‐inhibitory activities of the extracts varied significantly with the maximum value of ACE‐inhibitory activity obtained in methanol extracts at 40 °C for 6 h (88.78%). Lower ACE activities were seen at higher temperatures of 50–60 °C after the 6‐h extraction or after the 8 h at all tested temperatures, which is explainable by observations showing that the use of markedly higher temperatures for more prolonged periods can destroy the chemical structure of biologically active compounds leading to decreased bioactivities (Onofre & Hettiarachchy, ).…”

Optimization of Phenolic Content, Antioxidant, and Inhibitory Activities of α-Glucosidase and Angiotensin Converting (AC) Enzymes fromZingiber officinaleZ.

“…generally showed no significant variations with temperature and time of extraction; however, the highest total phenolic content was observed with extraction at 60ºC for 1 h. Likewise, the optimum temperature for extraction of phenolic compounds has previously been noted to be 60ºC in olive cake [23] and rice. [30] Hodzic et al [31] has reported that raising the temperature of extraction increases the extractability of phenolic compounds from rice, rye, oats, buckwheat, barley, wheat, and corn. Onofre and Hettiarachchy [30] showed that the phenolic yield from rice bran increased with a longer time of extraction at 95°C.…”

“…[30] Hodzic et al [31] has reported that raising the temperature of extraction increases the extractability of phenolic compounds from rice, rye, oats, buckwheat, barley, wheat, and corn. Onofre and Hettiarachchy [30] showed that the phenolic yield from rice bran increased with a longer time of extraction at 95°C. As the time of extraction increased from 0.5 to 1 h, the content of extracted phenolic compounds was shown to increase in rice bran.…”

“…As the time of extraction increased from 0.5 to 1 h, the content of extracted phenolic compounds was shown to increase in rice bran. [30] Jensen et al [28] also found that the extraction temperature and time increased the total content of phenolic compounds in red grapes. In the present study, however, an increase in extraction time ranging from 1 to 8 h at all the tested temperatures was not associated with an increase in extraction of phenolics from ginger.…”

The effect of infrared stabilisation on B vitamins, phenolics and antioxidants in rice bran

“…Both the free and bound extracts were analysed for total phenol content, antioxidant capacity and phenolic acids as the majority of phenolic compounds, many of which also possess antioxidant activity, are bound covalently to the cell wall as the structural components of cellulose, lignin and proteins (Adom & Liu, ; Pérez‐Jiménez & Saura‐Calixto, ). Onofre & Hettiarachchy () stated that more than 70% of the phenolics in rice bran are cross‐linked to carbohydrates in the cell wall matrix. Owing to be the dominant phenolic acid in cereals, total phenol content was evaluated as ferulic acid equivalents.…”