Investigating the bioaccesibility of antioxidants in red fruits commonly consumed in Turk

In this context, the bioaccesibility of phenolic compounds and the antioxidant capacity of the dried fruits such as Black raisins, Plums, Cornelian cherries and Cranberries which are specific to Turkey and frequently consumed by Turkish people, have been determined. For this purpose, in-vitro digestion analysis were carried out, the antioxidant and polyphenolic compounds were determined after and before the intestinal digestion and the stability of these compounds during the digestion were examined by carring out in-vitro systems. This study aimed that to fill the gap in the literature about the bioaccesibility of the polyphenolic contents and antioxidants by working in-vitro digestibility studies, of some kinds of the dried fruits which are known to have high quantities of the phenolic and antioxidant compenents and special to our country. Analysis were carried out in triplicate and it was planned to determine the stability of the antioxidant compenents after in-vitro digestion of the intestinal digestion level. Total phenolic content has been determined by Folin-Ciocalteu method and for antioxidant capacity, DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-Azino-di-[3-ethylbenzthiazoline sulfonate (6)]), FRAP (Ferric ion reducing antioxidant power) and CUPRAC (Cupric reducing antioxidant capacity) methods have been used. Anthocyanin determinations were carried out by pH differential method and Flavonoid assays were carried out according to colorimetric assays. Additionally, in-vitro digestion methods were carried out in the laboratory environment by using the gastric and intestinal enzymes, bile salts and digestion fluids which have been chemically synthesized. In-vitro digestion analysis were done in 3 major stages, firstly the oral digestion, secondly the gastric digestion and the thirdly the intestinal digestion. In this study, stability and bioaccessibility of phenolic compenents and antioxidants were performed on the basis of post-intestinal digestion. According to this study; the results of phenolic compenents of black grape, plum, cornelian cherry and cranberry as the initial values and after the gastro-intestinal digestion are; 634±79 mg GAE/100g-418±15 mg GAE/100 g, 416±40 mg GAE/100-653±19 mg GAE/100, 1082±46 mg GAE/100g-984±62 mg GAE/100 g, 314±45 mg GAE/100 g-338±48 mg GAE/100 g respectively. The initial and after the digestion of total flavonoid values of black grape, plum, cornelian cherry and cranberry are; 200±7 mg CE/100 g-72±8 mg CE/100 g, 125±5 mg CE/100 g-132±15 mg CE/100 g, 274±13 mg CE/100 g -174±26 mg CE/100 g, 92±6 mg CE/100 g-23±6 mg CE/100 g respectively. To determine the monomeric anthoycanin values, it can be seen clearly that anthocyanin values are very unstable in the gastro-intestinal conditionals while they are replaced in dried fruits as a compenent. Here are the initial values and after the digestion values of monomeric anthocyanins for black grape, plum, cornelian cherry and cranberry respectively; 9,9±0,4 mg anthocyanin/100 g-4,7±0,3 mg anthocyanin/100 g, 1,1±0,1 mg anthocyanin/100 g-0,7±0,0 mg anthocyanin/100 g, 4,4±0,3 mg anthocyanin/100 g- 2,6±0,0 mg anthocyanin/100 g, and 1,2±0,0 mg anthocyanin/100g-0,6±0,0 mg anthocyanin/100 g. To determine the stability of the antioxidant capacities of these four samples, four different antioxidant capacity determination methods have been applied which are ABTS, DPPH, CUPRAC and FRAP. For ABTS the initial and after-digestion values of the four samples are; 156,6±2,5 µ mol TEAC/100g-213,1±0,4 µ mol TEAC/100g, 123,1±2,9 µ mol TEAC/100g-216,5±0,7 µ mol TEAC/100g, 124,0±1,8 µ mol TEAC/100 g-222,9±1,1 µ mol TEAC/100 g ve 121,0±2,5 µol TEAC/100 g-215,7±0,4 µ mol TEAC/100 g for black grape, plum, cornelian cherry and cranberry respectively. According to the results, ABTS values are enhanced for all of the samples after the digestion process. For DPPH the initial values of the four samples are; 133,3±3,7 µ mol TEAC/100 g, 127,0±2,0 µ mol TEAC/100 g, 144,4±1,9 µ mol TEAC/100 g and 133,3±1,5 µ mol TEAC/100 g for black grape, plum, cornelian cherry and cranberry respectively. DPPH values after the gastro-intestinal digestion process are; 127,4±5,7 µ mol TEAC/100 g, 135,5±1,6 µ mol TEAC/100g, 218,0±13,6 µ mol TEAC/100 g ve 141,3±3,2 µ mol TEAC/100 g for black grape, plum, cornelian cherry and cranberry respectively. According to the DPPH results, it can be seen that the bioaccesibility of the antioxidant compenents in dried fruits are very high. The initial values and after the digestion values of CUPRAC for black grape, plum, cornelian cherry and cranberry are; 120,6±1,2 µ mol TEAC/100g-163,9±1,4 µ mol TEAC/100g, 124,2±1,5 µ mol TEAC/100g-161,2±0,4 µmol TEAC/100g, 352,2±0,8 µ mol TEAC/100 g-383,0±0,3 µ mol TEAC/100 g ve 91,5±1,0 µ mol TEAC/100g-78,5±4,3 µ mol TEAC/100 g respectively. CUPRAC values of black grape, plum and cornelian cherry enhanced after the gastro-intestinal digestion but for a little amount of CUPRAC value of cranberry are degraded. FRAP values for black grape, plum, cornelian cherry and cranberry as the initial values and after the digestion values are; 26,9±1,2µmol TEAC/100 g-15,2±1,5 µmol TAEC/100g, 39,5±2,8 µ mol TEAC/100 g-3,8±1,2 µ mol TEAC/100 g, 103,3±1,1 µ mol TEAC/100 g-72,0±2,6 µ mol TEAC/100 g ve 15,2±1,1 µ mol TEAC/100 g-6,4±1,6 µ mol TEAC/100 g respectively. FRAP values are degraded after the digestion process for all the four samples. The reason between the stabilities of the antioxidant compenents of all the dried fruit samples after the digestion process has been explained in the research and data part. Key Words: Antioxidants, Bioaccesibility, Bioavailability, Phenolic compenents,In-vitro digestion