1. Université Mouloud Mammeri de Tizi Ouzou Physicochemical and antioxidant proprieties of dates syrup: A comparaison between commercial syrups and syrups from second grade dates (Phoenix dactylifera L.) In this work, we tried to evaluate the physicochemical parameters, phytochemicals and the antioxidant activity of syrups obtained from the powdered and unground dates (Phoenix dactylifera L.), and those of two commercial date syrups (Al Faiza and Al Fateh). Physico- chemical measurements indicated that total sugars were predominant in all syrups. Al Faiza syrup was characterised by the high reducing sugars content (24.04 ± 0.80%), contrary to Al Fateh syrup (9.61 ± 0.13%). pH values of the studied syrups are ranged from 5.30 ± 0.01 to 4.07 ± 0.01 and the high value is enrigistred by syrups from the second grade dates, they were about 5.30 ± 0.01 and 5.24 ± 0.01 for the powdred and the unground fruits, respectively. A part from Al Fateh syrup, content of vitamine C is hight in both products and all syrups have found to be poor in carotenoids. Commercial syrups have shown the highest content of total phenolics, flavonoids, flavonols, anthocyanins and condensed tannins. They have also exhibited the highest radical scavenging activity of DPPH and reducing power, but the prepared syrups from second grade dates have exhibited the highest scavenging activity of ABTS radical. The obtained results suggest that dates syrup is an important source of natural antioxidants. Key words: Dates, Phoenix dactylifera, commercial syrups, physico-chemicals, antioxidants The date palm has played an important role in the day-to-day life of the people for the last 7000 years (Chandrasekaran & Bahkali, 2013), It plays a vital role in economic production with the date and its by-products (Abbès et al., 2013). The date syrup is a natural food by-product extracted from dates (Abbès et al., 2013), it can be made with all varieties of dates and preferably those of secondary quality (El-ogaidi, 1987). The antioxidant activity of date fruits from Algeria has been reported (Benmeddour et al., 2012), but to the best of our knowledge, there is no study about an Algerian dates syrup. The results obtained in this study support the conclusion that:  The physicochemical properties of the different syrups varie from syrup to an other;  The highest amounts of phenolic compounds and carotenoids is found in the two commercial syrups;  The best content of vitamine C is detected in the prepared syrups from the powder and unground fruits;  Commercial syrups have exhibited the best antiradical scavenging activity of DPPH and reducing power;  The highest antiradical scavenging effect of ABTS radical is observed by the syrups from the second grade dates "Mech Degla or Kentichi »;  The high antioxidant potential of the two commercial syrups was demonstrated and could used as a good sources of antioxidants. Lynda Arkoub-Djermoune a,b, Lila Boulekbache-Makhlouf a, Khodir Madani a a Laboratoire de Biomath é matique, Biophysique, Biochimie, et Scientom é trie, Facult é des Sciences de la Nature et de la Vie, Université A/Mira de Bejaia, Algérie. b Universit é de Tizi Ouzou, Facult é des Sciences Biologiques et des Sciences Agronomiques, Laboratoire 3BS, Algerie. Email: lynda_arkoub@yahoo.fr Tél: 05 55 22 20 63lynda_arkoub@yahoo.fr Abbès F., Bouaziz M. A., Blecker C., Masmoudi M., Attia H., Besbes S., 2011. Date syrup: effect of hydrolytic enzymes (pectinase/cellulase) on physico-chemical characteristics, sensory and functional properties. LWT-Food Science and Technology 44: 1827-1834. Abbès F., Kchaou W., Blecker C., Ongena M., Lognay G., Attia H., Besbes S., 2013. Effect of processing conditions on phenolic compounds and antioxidant properties of date syrup. Industrial Crops and Products 44 : 634-642. Benahmed D. A., Amrani M., Azouaou M., Damir A., Benamara S., 2011. Possibilité de fabrication d’un jus naturel à base d’un sirop de dattes communes et d’un extrait de spiruline et jus de citron naturel. Powder Technol 208: 725-730. Benmeddour Z., Mehinagic E., Meurlay D.L., Louaileche H., 2013. Phenolic composition and antioxidant capacities of ten Algerian date (Phoenix dactylifera L.) cultivars: A comparative study. Journal of Functional Foods 5: 346-354. Chandrasekaran M., Bahkali A. H., 2013. Valorization of date palm (Phoenix dactylifera) fruit processing by-products and wastes using bioprocess technology–Review. Saudi journal of biological sciences 20: 105-120. El-Nagga E., Abd El–Tawab Y., 2012. Compositional characteristics of date syrup extracted by different methods in some fermented dairy products. Annals of Agricultural Sciences 57: 29-36. Table 1 Physico-chemical propreties of different syrups syrups Values are averages ± standard deviation of triplicate analysis; different letters in same column indicate significant difference (p b>c>d. syrups Table 2 Antioxidant contents of different syrups Values are averages ± standard deviation of triplicate analysis; different letters in same column indicate significant difference (p b>c>d. The vitamin C content expressed as milligram Ascorbic Acid Equivalent per 100g of the extract (mg AAE/100g Ext);carotenoid content as milligram β-Carotene Equivalent per 100 g of the extract (mg βCE/100g Ext); polyphenol and content as milligram Gallic Acid Equivalent per 100g of the extract (mg GAE/100g Ext ; flavonoid as milligram Quercetine Equivalent per 100 g of the extract (mg QE/100g Ext); flavonol and anthocyanin content expressed as milligram Quercietine 3-Glucoside Equivalent per 100g of the extract (mg Q3GE/100g Ext) and the condensed tannin as milligram Cyanidine Equivalent per 100 g of the extract (mg CE/100g Ext). Table 3 Antioxidant power of different syrups Values are averages ± standard deviation of triplicate analysis; different letters in same column indicate significant difference (p b>c>d. Fig. 1. Antioxidant activity of the different syrups. Values are averages ± standard deviation of triplicate analysis; different letters in same column indicate significant difference (p b>c>d. The antioxidant activity expressed as milligram Trolox Equivalent per gramm of the extract (mg TE/g Ext). Results and discussion Conclusion Refvererences The result of acidity, pH, total sugar and reducing sugar are shown in Table 1. The pH values of the different date syrups are significantly different (p  0.05). The pH of commercial syrups are slightly lower than those prepared from powder and unground dates. The commercial syrups are more acidic than those prepared in the laboratory. Our results are proximate (2.10 and 3.36%) to that reported by Benahmed et al. (2011). The commercial syrups exhibit the highest levels of phenolic compounds, they are about 622.04 ± 1.12 mg GAE/100 g Ext for Al Faiza, and 414.29 ± 0.42 mg GAE/100 g Ext for Al Fateh. On the other hand, syrup from ungroud dates gives the best yield (205.81±1.12 mg GAE/100 g Ext). The highest levels of flavonoid were observed in commercial syrups (Al Fateh and Al Faiza) with a rate of 51.32 ± 1.68 mg QE/100 g Ext and 64.15 ± 0.37 mg QE/100 g Ext, respectively; followed by syrups prepared from powder dates (48.02 ± 0.37 mg QE/100 g Ext) and unground dates (19.92 ± 1.53 mg QE/100 g Ext). The best yields of flavonol were obtained with commercial syrups. Concerning the prepared syrup, the best rate of flavonol is obtained for syrup prepared from unground dates with a value of 12.70 ± 0.14 mg Q3GE/100 g Ext, followed by the syrup prepared with a powder dates (11.56 ± 0.08 mg Q3GE/100 g Ext). AL Fateh syrup extract gives the best content of anthocyanin but no difference has been detected in the content of Al Faiza syrup and that prepared in the laboratory from the powder dates. The highest values ​​of proanthocyanidin were observed in the commercial syrups. There is no significant differences between syrups prepared with unground dates (3.97±0.03 mg CE/100 g Ext) and that of Al Faiza. No studies have been reported about the content of condensed tannin in dates syrup. Objectives Introduction The antioxidant content of the different syrup dates are shown in the Table 2. The highest level of vitamin C is obtained from syrups prepared in the laboratory and the lowest content is found in the commercial syrup Al Fateh. The carotenoid contents of the different syrups dates are ranged from 1.91± 0.20 mg βCE/100 g Ext to 2.44 ± 0.02 mg βCE/100 g Ext (Table 2). Abbès et al. (2011) reported that the carotenoid contents of syrups date are between 0.013 and 0.215 mg βCE/100 g Ext, which are largely lower than those obtained in this study. Physicochemical parameters Antioxidant content Abstract Antioxidant activity The antiradical activity of the different syrup extracts expressed as mg Trolox Equivalent per gram of the sample are presented in Figure 1.  DPPH The results shows that the best yields are exhibited by commercial syrups (16.10 ± 0.24 mg TE/g Ext and 13.38 ± 0.21 mg TE/g Ext for Al Fateh and Al Faiza, respetively) with an IC 50 value of 7.77 ± 0.10 mg/mL for Al Fateh and 8.97 ± 0.11 mg/mL for Al Faiza) (Table 3). The syrup prepared from the powder dates gives a good activity (IC 50 = 13.74 ± 0.13 mg/mL), followed by that obtained from unground fruits (IC 50 of 15.71 ± 0.10 mg/mL). Abbès et al. (2013) have obtained an IC 50 value of 18.84 mg/mL for syrups of the same variety (Kentichi).  ABTS The scavenging activity against ABTS free radical of the different syrup extracts are ​​ranged from 21.48 ± 0.05 mg TE/g Ext to 32.17 ± 0.05 mg TE/g Ext (Fig. 1) and the best yields were obtained with syrups prepared with unground dates (32.17±0.05 mg TE/g Ext) with an IC 50 of 1.10 ± 0.00 mg/mL (Table 3), followed by Al Faiza syrup (22.78±0.24 mg TE/g) with an IC 50 of 3.01 ± 0.04 mg/mL and that of powder date with an IC 50 of 3.13 ± 0.01 mg/mL (Table 3). No difference has been detected between the antiradical activity of the syrup from the powder dates (21.78±0.08 mg TE/g Ext) and that of the commercial syrups (Al Fateh) which is about 21.48 ± 0.05 mg TE/g Ext.  Determination of the physicochemical proprieties in the syrup obtained from dates with low quality and hard texture ("Mech Degla" or "Kentichi") under two forms (powder and unground) and those of two commercial syrups (Al Fateh and Al Faiza) produced in Algeria;  Determination of the phytochemicals contents (phenolic compounds, vitamine C, carotenoids);  Evaluation of the antioxidant activity.  The reducing power The reducing power is expressed by the reducing capacity "RC 0.5 " (Table 3), which corresponds to the concentration of products giving an absorbance of 0.5. A lower RC 0.5 correspond to a higher reducing activity. The results shows a high reducing power for commercial syrups. The Figure 1 show that the best yields were obtained with syrup extracted from powder fruits (19.81±0.12 mg TE/g Ext), followed by that of Al Faiza syrup (13.87±0.11 mg TE/g Ext). The lowest content is found in Al Fateh syrup and unground dates syrup (7.13±013 mg TE/g Ext and 2.85±0.05 mg TE/g Ext, respectively). All differences in the obtained results and those reported in the literature can be explained by the differences of the variety used and/or the extraction methods. Syrup from powder dates gives the best yield of total sugars compared to that of unground dates. For the commercial syrups, the yield of total sugars are higher with a value of 26.99 ± 0.75% (Al Faiza syrup) and 23.84 ±1.65% (Al Fateh syrup) No difference has been detected in the reducing sugar content of the syrup prepared from the powdred dates and that prepared from unground dates. Their levels in commercial syrups are 9.61 ± 0.13% and 24.04 ± 0.80% for Al Fateh and Al Faiza, respectively. Université M’hamed Bougara, Boumerdès, Laboratoire de Recherche Technologie Alimentaire (LRTA) Séminaire national sur la Biodiversité, l’environnement et la Sécurité Alimentaire (20 et 21 Octobre 2015)