Türkiye'ye özgü yöresel bir pancar çeşidinde ve atıklarında fenolik madde profilinin, antioksidan kapasitesinin ve biyoyararlılığın belirlenmesi

Consumption of vegetables is considered as a traditional healthy diet because of the numerous nutrient substances they possessed. The health promoting action of fruits and vegetables has been attributed to the presence of phytochemicals, vitamins and enzymes, as well as other minerals and fibers. These compounds have strong protective effects against major disease risks including cancer and cardiovascular diseases due to their rich potential as antioxidants. Polyphenols are present in fruits and vegetables in great abundance as powerful antioxidants in addition to the other constituents. Plants bearing polyphenols and other phytochemicals with antioxidant potential are gaining attention of researchers gradually. Beetroot (Beta vulgaris L.) contains water-soluble nitrogen-containing pigments called as betalains as well as polyphenolics compounds. Betalains are known to have antioxidant, antimicrobial, antiviral, antiproliferative, anti-inflammatory, hepatoprotective, and anti-cancer activities. Due to these excessive health-promoting effects, new betalain-containing food products are of interest. A local red beet variety native to Turkey has been investigated for the first time including fleshes (BVf) and peels (BVp). The experiments were carried out to three different biological replicates which were harvested at different times from various farms. The results of all assays indicated statistically significant differences between the batches and between peel and flesh samples. Peel samples showed higher values than flesh samples according to all assays performed. Phenolic profile was analyzed using UFLC-MS/MS. Similar chromatogram patterns of phenolic acids were observed for peel and flesh samples; contents differed depending on batches. As a result, the presence of chlorogenic acid, ferulic acid, syringic acid, vanillic acid and 4(p-)hydroxybenzoic acid were detected in both types of extract (BVp and BVf) at different concentrations. However, caffeic acid and rutin were present only in trace amounts. Notably, chlorogenic and ferulic acid was the major phenolic constituents for BVp samples whereas ferulic acid was the only major phenolic in BVf samples in contrast with red beetroot, which contains 4-hydroxybenzoic acid as the major phenolic acid. The phenolic acid composition was seen different from the red beet and sugar beet. The decreasing order of individual phenolic acids in peels was as follows: ferulic acid, chlorogenic acid, syringic acid, 4(p-)hydroxybenzoic acid, vanilic acid. On the other hand, the decreasing order of individual phenolic acids in fleshes was as Ferulic acid, syringic acid, vanilic acid, 4(p-)hydroxybenzoic acid, chlorogenic acid. In regards to the total antioxidant capacity methods, CUPRAC assay gave higher responses than the DPPH assay in accordance with the literature, although the antioxidant capacity of this beetroot variety was not as high as red beetroot. Total phenolic content was in a similar range with the reported values for red beetroot. DPPH Free Radical Scavenging Capacity and CUPRAC Cupric Reducing Antioxidant Capacity assays were performed to determine the antioxidant capacity and the total phenolic content was determined via Folin-Ciocalteu method. The bioaccessibility of phenolics from both flesh and peel parts was assessed by in vitro gastro-intestinal digestion procedure that simulates the physiochemical and biochemical changes that occur in the gastrointestinal tract. Since in vivo studies on humans and animals are not preferred due to the limitations such as complexity, expensiveness and ethical reasons, in vitro digestion assays provide rapid and simple methods to evaluate phytochemical stability in food matrices. Results from in vitro digestion demonstrated that differences in bioaccessibility of polyphenolics between the batches were significant and the reduction of TPC in peel samples is greater than in fleshes. In other words, the bioaccessibility of phenolics in fleshes is greater than the bioaccessibility of phenolics in fleshes. Additionally, phenolic acids were found to be stable in gastric digestion due to acidic conditions. However, their recoveries become lowered in IN fractions representing the compound passed into serum. The UFLC-MS/MS detection was done on phenolic acids from PG, IN and OUT fractions of GI digestion. Notably, no peak could be detected in IN, OUT and PG fractions for the 4(p-)hydroxybenzoic acid. Furthermore, the total betalain content was quantified spectrophotometrically and expressed as the sum of red-violet (betacyanin -BC) and yellow-orange (betaxanthin -BX) pigments. BX and BC of peel samples were found as 1.6 ± 0.01 mg g-1 indicaxanthin equivalent and 0.9 ± 0.01 mg g-1 betanin equivalent whereas 0.3 ± 0.05 mg g-1 indicaxanthin equivalent and 0.9 ± 0.01 mg g-1 betanin equivalent for flesh samples, respectively.Total betalain content of this beetroot variety was found as 2.5 mg/ g for peels and 1.2 mg/ g for fleshes, lower than the red beetroot.