Dr Serge Mabeau Applied Research Center for plant breeding, biotechnology and quality.

Transcription

1 FAV Health 2005 Quebec City, August Dr Serge Mabeau Applied Research Center for plant breeding, biotechnology and quality. Specialised on main vegetable crops from Western France : Cauliflower, broccoli, artichoke, tomato, onion, shalot, potato

2 Antioxidant activity of extracts of artichoke and by-products Mrs Odile Chodosas, Dr Michel Surbled, Archimex, Vannes Dr Serge Mabeau, Mrs Céline Baty, BBV, St Pol de Léon Dr Pierre Métra, Lareal, Vannes Dr Christophe Chesné, Proclaim, Rennes

3 General objectives of the group : - Better knowledge of food composition with respect to health - Preparation of plant extracts with high antioxidant activity - Selection of the best extracts for further industrial implementations - Comparison between 2 methods of analysis of antioxidant activity

4 Content : results on artichoke - Raw material - Extraction methods - Extraction yield - Extract composition - Measure of antioxidant activity (ORAC) - Comparison of ORAC and Pholasin methods

5 Plant material Abundant and economically important crops in Western France : artichoke (cauliflower and buckwheat) Focus on by-product Simple extraction procedures

6 Frozen artichoke industrial process «solid» byproducts Peeling Bleaching Bleaching water Deep-freezing Storage

7 Antioxidant compounds from artichoke : polyphenols Cynaroside Caffeic acid Isorhoifolin Chlorogenic acid Cynarin Narirutin

8 Artichoke solid products / by-products Ethanol/water Extraction Filtration Solid products : simple extraction procedures Evaporation ethanol Freeze drying Extraction liquid-liquid Ethyl acetate «Raw extract» Organic fraction Aqueous fraction Solvant evaporation Freeze drying «Enriched extract»

9 Bleaching effluents : freeze drying

10 Polyphenol extraction yield Mg / kg of starting raw material mg/kg wet matter Byproducts A : Byproducts A : Byproducts B : Artichoke heart : Bleaching raw extract enriched extract raw extract raw extract effluents Chlorogénic acid Narirutin Cynarin A Cynarin E Cynaroside Isorhoifolin Caffeic acid

11 Polyphenol composition of artichoke extracts content (g/100 g dry extract) 40,0 35,0 30,0 25,0 20,0 15,0 10,0 5,0 cynarin A isorhoifolin narirutin cynaroside caffeic acid cynarin E chlorgenic acid 0,0 Byproducts A : raw extract Byproducts A : enriched extract Byproducts B : raw extract Artichoke heart : raw extract Bleaching effluents

12 Correlation between HPLC and Folin - Ciocalteu methods for total polyphenol measure total plyphenols (g/100 g) Bleaching effluents Byproducts A : raw extract Byproducts A : enriched extract Byproducts B : raw extract Artichoke heart : raw extract 0 HPLC Folin Ciocalteu

13 Measure of antioxidant activity Principle of ORAC method : reaction in a spectrophotometer cuvette Reference method (first published in 93) Free radicals produced by AAPH (added at time zero) Destroy fluorescein Antioxidant in the mixture prevent this destruction Measure every 100 seconds

14 Measure of antioxidant activity Quantification = area under the curve Result expressed as micromole equivalent Trolox per kg

15 Antioxidant activity (ORAC method) and polyphenol content (HPLC) of artichoke extracts ORAC (µmoles TE/g) total polyphenols g/100g Bleaching effluentsbyproducts A : raw Byproducts A : Byproducts B : raw Artichoke heart : extract enriched extract extract raw extract measured Orac total polyphenols HPLC

16 Artichoke extracts : polyphenol content (HPLC) allows the prediction of antioxidant activity (ORAC) R 2 = Orac (µmoles TE/100 g) total polyphenols HPLC (g/100g)

17 Comparison between measured ORAC values and calculated ORAC value as the sum of individual polyphenol contributions Orac (µmoles TE/g) caffeic acid cynarin A isorhoifolin narirutin cynaroside cynarin E chlorgenic acid measured Orac Bleaching effluents Byproducts A : raw extract Byproducts A : enriched extract Byproducts B : raw extract Artichoke heart : raw extract

18 Correlation between measured ORAC values and calculated ORAC value as the sum of individual polyphenol contributions calculated ORAC (µmoles TE/g) y = x R 2 = measured ORAC (µmoles TE/g)

19 Measure of antioxidant activity Principle of Pholasin method : reaction in a spectrophotometer cuvette Pholasin = photo-protein of the marine mollusc Pholas dactylus Emits light in presence of free radicals and other reactive oxygen species Superoxide generated in situ (time zero, «solution B») Antioxidants in the mixture lower the luminescence Pro-oxidants enhance it Quantification = percent reduction (or increase) of peak luminescence Result expressed as micromole equivalent Trolox per kg

20 Measure of antioxidant activity : comparison between Pholasin and ORAC methods for artichoke extracts y = x R 2 = Pholasin (µmoles TE/g) Orac (µmoles TE/g)

21 Comparison between Pholasin measured values and calculated Pholasin value as the sum of individual polyphenol contributions y = x R 2 = calculated Pholasin (µmoles TE/g) measured Pholasin (µmoles TE/g)

22 Conclusion Antioxidant activity of artichoke extracts compared favourably to reference extracts Possibility of upgrading by-products from the industry (nutraceutical or «regular food» market) Potential of the Pholasin method for antioxidant activity measurement

23 Work under progress (to be completed by late 2005) Comparative work on : - Artichoke, cauliflower : products and industrial by-products - Buckwheat kernel (Polygonum fagopyrum) - Green tea (reference)

24 Thank you for your attention!