Grapefruit | Chemistry Review

GENERAL INFO

Grapefruit (Citrus paradisi) was discovered in Barbados in the 18th century. Many botanists think the grapefruit was the result of a natural cross breeding which occurred between the orange and the pomelo, a citrus fruit that was brought from Indonesia to Barbados in the 17th century. Its current name alludes to clusters of the fruit on the tree, which often appear similar to grapes.

NUTRITIONAL INFO

Grapefruit is very low in calories (42 Kcal/100g). It is rich in dietary insoluble fiber pectin, which promote intestinal health and reduce blood cholesterol levels. It is a good source of vitamin A (about 1150 IU per 100g) and Vitamin C (about 52% of DRI) which are important for skin health and immune system. Grapefruit is very rich in potassium. Potassium is an important component of cell and body fluids, helps controlling heart rate and blood pressure. 

It contains bioactive compounds such as naringenin, beta-carotene, xanthin and lutein. Studies suggest that these compounds have antioxidant properties and are essential for vision. Red varieties of grapefruits are especially rich in the most powerful flavonoid and lycopene. Studies have shown that lycopene protects skin damage from UV rays, and offers protection against prostate cancer. It contains moderate levels of B-complex group of vitamins such as folate, riboflavin, pyridoxine, and thiamin in addition to some resourceful.

NARINGENIN: THE MOST ABUNDANT BIOACTIVE IN GRAPEFRUIT

Grapefruit is one of the best sources of the flavonoid and naringenin. It is a primary bioactive compound in grapefruit. 100 g of grapefruit contains on average 30-40 mg of naringenin (compared to 15 mg in oranges and 3mg in limes and cherry tomatoes). Only 15-25% of the naringenin is absorbed in the GI.

Naringenin Health Benefits:

Strong antioxidant activities (important for cellular health)

Reduce inflammatory processes in the body. Prevention and treatment for type 2 diabetes. May help in prevention of certain types of cancer (ex: colon cancer, lung cancer). Helps increase good cholesterol and lower bad cholesterol (important for cardio-vascular health. May help to slow down the spread of Hepatitis C virus. 

Naringenin was shown to improve insulin signaling and sensitivity thus promoting the cellular actions of insulin in adult male rats. This is research showing the potential of naringenin on Metabolic Syndrome and Diabetes.

  

If you currently take medications, consult with your doctor before making grapefruit a part of your diet!

As little as 200 ml (7 fluid ounces) of grapefruit juice has been found to interact with some medications making them harmful.

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Types of Titration

 

1. Aqueous Titration: 

 

Neutralization Reaction or Acid-Base Titration: It involves the titration of either acid with base (pH increases) or base with acid (pH decreases). It is of two types:

• Acidimetry: It is a measurement of the quantity of base by titration with a suitable standard acid (example: potassium hydrogen phthalate, oxalic acid, benzoic acid)

• Alkalimetry: It is a measurement of the quantity of acid by titration with suitable standard bases.  

Examples of Aqeous Titration of Organic Compound:

Titration of Monoprotic Organic Acids with NaOH (strong Base)

 

• Titration of benzoic acid with NaOH

• Titration of acetic acid with NaOH

2. Oxidation-Reduction Titration:

 

Example: Determination of Vitamin C Concentration by Titration (Redox Titration Using Iodine Solution)

Organic Compounds which generate free radical ions:

Compounds which does not contain electroactive substituents (Cation generation)

• Aromatic Hydrocarbons example: except benzene, radicals ions have been obtained from diphenyl and stilbene

• Heterocyclic compounds example: nitrogen heterocylces example pydridazine, tetrazine

Compounds contating electroactive substituents (Anion generation)

• Quinone

• Aromatic carbonyl compounds

• Carboxylic acid derivative

• Amines

• Nitrile
 

Electrochemical Methods in Organic Chemistry are used for:

• Oxidation and Reduction of organic compounds

3. Non-Aqueous Titration

       • Neither weak nor weak base can be easily titrated in aqeous solution due to dual behaviour of water as competing acid or base. The simple solution to this problem is to replace water as solvent. Hence, this type of titation is designed as non-aqeous titarion.

  

Acidimetry in Non-aqueous Titrations: It can be further sub-divided into two heads, namely:

•Titration of primary, secondary and tertiary amines with standard perchloric acid , and

• Titration of halogen acid salts of bases. 

Alkalimetry in Non-aqueous Titrations: titration of acidic substances

•Factors for performing non-aqeous titration: If

•Reactant is insoluble in water,

•Reactant is reactive with water 

Factors: for performing non-aqeous titration: If

•Reactant is insoluble in water,

•Reactant is reactive with water

Solvents Examples: Glycerin, Polyethelene glycol, alcohol

 Measuring the Endpoint or Equivalence of a Titration

 

•Indicator:

•pH Indicators

•Potentiometer

•pH meter

•Conductivity

•Color change

•Isothermal titration calorimeter

•Thermometric titrimetry

•Spectroscopy

•Amperometry

 

 Application

 

Particular Uses of TItration for Estimation Organic Compounds

Acid–base titrations

 

•In biodiesel: waste vegetable oil (WVO) must be neutralized before a batch may be processed. A portion of WVO is titrated with a base to determine acidity, so the rest of the batch may be properly neutralized. This removes free fatty acids from the WVO that would normally react to make soap instead of biodiesel. 

•Kjeldahl method: a measure of nitrogen content in a sample. Organic nitrogen is digested into ammonia with sulfuric acid and potassium sulfate. Finally, ammonia is back titrated with boric acid and then sodium carbonate. 

•Acid value: the mass in milligrams of potassium hydroxide (KOH) required to titrate fully an acid in one gram of sample. An example is the determination of free fatty acid content.

•Saponification value: the mass in milligrams of KOH required to saponify a fatty acid in one gram of sample. Saponification is used to determine average chain length of fatty acids in fat.

•Ester value (or ester index): a calculated index. Ester value = Saponification value – Acid value.

•Amine value: the mass in milligrams of KOH equal to the amine content in one gram of sample.

•Hydroxyl value: the mass in milligrams of KOH corresponding to hydroxyl groups in one gram of sample. The analyte is acetylated using acetic anhydride then titrated with KOH.

Redox titrations

•Vitamin C: Also known as ascorbic acid, vitamin C is a powerful reducing agent. Its concentration can easily be identified when titrated with the blue dye l.

Miscellaneous

•Karl Fischer titration: A potentiometric method to analyze trace amounts of water in a substance. A sample is dissolved in methanol, and titrated with Karl Fischer reagent. The reagent contains iodine, which reacts proportionally with water. Thus, the water content can be determined by monitoring the potential of excess iodine.

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