16 Questions
What is the primary factor that influences the yield of phenolics extracted from different plant samples?
Type of plant and its active compounds
Which solvent is most effective for extracting phenolics from sorghum leaf?
Water
What is the effect of increasing extraction time and temperature on analyte solubility?
It promotes analyte solubility, but also leads to degradation of phenolics
What is the optimal extraction time and temperature for extracting phenolics from canola meal?
2 min at room temperature
Which of the following solvents is not commonly used for extracting phenolics?
Hexane
What is the effect of enzymatic oxidation on plant phenolics during extraction?
It degrades or undergoes undesirable reactions
Which of the following plant samples requires 80% aqueous ethanol for optimal extraction of phenolics?
Wheat bran
What is the role of the number of repeat extractions of the sample in influencing the yield of phenolics?
It is a critical parameter in optimizing the extraction of phenolics
What is the primary reason for determining the optimum solvent-to-sample ratio in phenolic extraction?
To minimize solvent input and saturation effects
What is the purpose of adding enzymes during phenolic extraction?
To hydrolyze linkages between phenolics and other sample elements
What is the primary advantage of using acidic hydrolysis in phenolic extraction?
It promotes the extraction of bound phenolics
What is the common form in which phenolic acids exist in plants?
In a free, esterified, or glycosylated form
What is the purpose of treating the extract with 4 M HCl during phenolic acid extraction?
To reduce the pH of the extract to 2-3
What is the effect of a pH of 4-5 on catechins and their isomers?
It enhances their stability
What is the purpose of using ethyl acetate during phenolic acid extraction?
To separate the phenolic fraction from the rest of the extract
What is the effect of sample matrix and particle size on phenolic extraction?
They strongly influence phenolic extraction
Study Notes
Extraction of Phenolic Compounds
- Complete extraction of phenolic compounds is a critical step after sample preparation
- Extraction techniques employ solvents, which can be organic or inorganic
Factors Influencing Phenolic Extraction
- Extraction time, temperature, solvent-to-sample ratio, and the number of repeat extractions affect the yield of phenolics
- Optimum recovery of phenolics varies depending on the type of plant and its active compounds
- Solvent type and choice influence the yields of phenolics extracted
Examples of Solvent Choices
- Water is effective for extracting phenolics from sorghum leaf
- 80% aqueous ethanol is effective for extracting phenolics from wheat bran
- 50% aqueous ethanol is more efficient than pure or 50% aqueous forms of methanol and acetone for extracting phenolics from Potentilla atrosanguinea
- Pure methanol and 80% aqueous acetone are effective for extracting phenolics from Vitis vinifera wastes and sunflower meal, respectively
Importance of Time and Temperature
- Increasing time and temperature promote analyte solubility but can degrade or cause undesirable reactions in plant phenolics
- Optimum extraction time and temperature for canola meal is 2 min at room temperature
Other Key Parameters
- Solvent-to-sample ratio affects the recovery of phenolics, with an optimal ratio of 60:1 reported for a two-stage procedure
- Sample matrix and particle size influence phenolic extraction, with phenolics potentially binding to other sample elements
- Acidic and alkaline hydrolysis can be used to isolate phenolics from plants and plant products, promoting stability in the extract
Specific Classes of Phenolic Compounds
- Phenolic acids exist in a free, esterified, or glycosylated form in plants
- Free phenolic acids can be extracted using 70% ethanol at room temperature followed by centrifugation
- Bound or esterified phenolic acids can be extracted by removing free phenolic acids and lipid using 70% ethanol and hexane, respectively
Learn about the common techniques used to extract phenolic compounds, including the influence of parameters like extraction time and solvent type on the yield of phenolics. Discover how the optimum recovery of phenolics varies from one sample to another.
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