Περιγραφή
Quantitative Determination of total polyphenols in edible oils, wine and food
Description
The antioxidant capacity of polyphenols plays an important role in the stability of olive oil, as there is a correlation between the amount of total polyphenols and resistance to oxidation. Polyphenols have a protective effect on the cells of the human body because they oppose
the negative effects of free radicals. These polyphenols in olive oil act as natural antioxidants. The amount of polyphenols decreases during olive oil extraction, so the test can be used to optimize the processing.
Olive oil is rich in polyphenols, which form its “polar fraction” and prevent its self-oxidation, thus giving it its excellent thermal stability and contributing to its characteristic aroma and taste. The main ones are: tyrosol, hydroxytyrosol, oleuropein and protocatechuic, gallic,
vanillic, vanillic, p-hydroxybenzoic, syringic, 4-hydroxyphenyl acetate, omavanillic, quinamic, o-coumaric, p-coumaric, caffeic, ferulic and sinoacetic acids. The main antioxidants of olive oil are considered to be tocopherols, the main representative being alpha-tocopherol, and phenolic compounds.
Vitamin E with its parent compound tocol consists of two series of compounds: tocopherols and tocotrienols. The tocopherols are divided into a-tocopherol, b-tocopherol, c-tocopherol, and d-tocopherol, while the tocotrienols are divided into a-, b-, c-, and d-tocotrienol. The total
biological activity of vitamin E is mainly due to the presence of αtocopherol. It is the alpha-tocopherol that exerts the greatest biological activity in the human body and is the reference for the action of the other forms of vitamin E.
All tocopherols are natural antioxidants of oils, since they have an antioxidant activity that increases from a to d. The stability of olive oil to oxidation is largely due to the presence of tocopherols, which are easily oxidised.
A-tocopherol is traditionally considered the main antioxidant in olive oil. It constitutes about 90% of all tocopherols and normally ranges from 100 to 300 ppm (Blekas et al., 1995; Psomiadou and Tsimidou, 1998). c-Tocopherol constitutes about 8% of all tocopherols in olive oil, while b-, d-tocopherols are only present in trace amounts (Andrikopoulos et al., 1989). Vitamin E is an important natural antioxidant of oils, since it inhibits the oxidation of their fatty substances (triglycerides), and protects olive oil from peroxidation and the free radical propagation
mechanism.
Package contents: 1 x 5 ml R1а, 3 x 17 ml R1b, 1 x 7.5 ml R2
Number of tests: 50 tests
Ref.: 89001
Shelf life: 24 months from date of manufacture
Storage & Stability: 2-8°C
Sample collection instructions
No preparation of olive oil sample is required.
Preparation of reagents
*WR1: Mix 100 μl R1a with 1000 μl R1b and shake gently for 3 seconds
R1а – Mixing with R1b is required
R1b – Mixing with R1a is required
R2 – Ready for use
Procedure
– Wavelength: 700 nm on the Electra m2 Unified Analyzer
– Temperature: 30°C (25°C – 37°C)
– Method: FIXED TIME
– Fitting: LINEAR
– Select the T.PPS parameter from the test menu
– ZERO: WR1 500 uL. + 10 uL. deionized water, Press OK.
– ADD REAGENT R1 : WR1: 500 uL. Press OK.
– ADD SAMPLE: 10 uL.Press OK.
– Wait 180 seconds.
– Measurement of absorbance A1. ADD REAGENT R2: 150 uL. Press OK.
– Wait 300 seconds.
– Absorbance measurement A2.
DA = A2-A1 (total polyphenol concentration expressed in mg/l.)
Note: A 5-point calibration of 0, 125, 250, 500, 1000 (mg/l) is recommended.
Reference values
Linearity: 0-1000 mg/l.
Note: For samples that the analyzer gives you an UPPER LIMIT value, then you should dilute your sample with OLIVE OIL DILUTOR (Ref. 89377, sold separately by MenidiMedica Biotech Greece) in a ratio of 1:1 or 1:5 and multiply the result given by the analyzer by 1 or 5.
Safety measures
The components of elean morian polyphenols pose no health risk when used in accordance with standard laboratory practices and the procedures in this insert.
For further safety instructions, refer to the Safety Data Sheet (SDS).
Notes
A 4-level calibration kit is available by MenidiMedica Biotech Greece (Recommended for calibration on automatic instruments).
