This research studied the impact of planting location and cooking time
periods of (5, 10, 15, 20 and 40 minutes) on the antioxidant effect, and on the
total Phenols and Flavonoids contents using five different samples of Syrian
onions. The results
showed that the total Phenols, total Flavonoids and
antioxidant activity contents were between (279-583)mg/100g dry wt, (80-180)mg/100g dry wt, and (60-75%) respectively. In addition, boiling for
different periods resulted in increased total Phenols from (383 to789)mg/100g
dry wt and in total Flavonoids from (124 to 205)mg/100g dry wt as well as an
increase of (77% to 88%) of antioxidant activity as measured using the DPPH
method.
Total polyphenols (TP), total flavonoids (TF) and (-)-epigallocatechin gallate
((-)-EGCG) were determined in five commercial tea infusions by continuous
infusion method, using the ratio 20g of tea to 1L of water at 85±5 °C and
brewing time between 5-180 min.
Functional foods are similar to conventional food and demonstrate beneficial effects
beyond their nutritional value. These effects are attributed to the presence of functional
ingredients. Functional ingredients can either be found naturally in a c
ertain food or added
to it. There’s a number of functional food products available in the market. For example,
natural functional juices containing polyphenols. The aim of this study is to determine total
phenolic content and antioxidant activity in some local functional juices. Total phenolic
content was determined according to Folin- Ciocalteu method. The highest in content was
mulberry juice, while the lowest was red grape juice. The best conditions for eliminating
ascorbic acid were also determined which were heating for
30 min at 75°C. Antioxidant activity was subsequently determined using potassium
ferricyanide. The highest in phenolic content among the studied juices were the highest in
antioxidant activity. Thus a strong correlation was found between total phenolic content
and antioxidant activity.
Total Polyphenol was studied in olive leaves collected from Lattakia area
(AlQurdaha zone), where Phenolic compounds were extracted from dry Olive leaves by
using two extraction methods: maceration and Ultrasonic Device. By the both two methods
a
study was carried out on the extraction solvent concentration effect where the extraction
was done by using the mixture of Ethanol-Water with different percentages (60,70,80
%). As well, The extraction temperature effect was studied at the both methods at (20,30,
40°C); in addition to the study of the extraction time effect.
At the method of Maceration Extraction, the total polyphenols amount was studied in
dry olive leaves after extraction during different times (24,48,72 h). While at the Ultrasonic
Extraction the times were (10,20,30 min).
The study showed that the highest amount of phenolic compounds were existed in
dry olive leaves which were extracted by Ultrasonic Waves with the concentration of the
solvent ethanol-water 80%, temperature of 40°C, and with an extraction time of 20min.
