Siyah havuç (Daucus carota) posa ve kabuğunun polifenol kapasitesinin ve in vitro biyoyararlılığının incelenmesi

Carrots belong to the Apiaceae family; which is one of the most consumed vegetable in the world. Although orange colored carrots are common, black carrots have recently gained interest especially as a natural food colorant due to their high heat, light and pH stability. Black carrots (Daucus carota) originate from Turkey and the Middle and Far East, where they have been cultivated for at least 3000 years. They have an attractive bluish-purple color with high levels of anthocyanins. Black carrot is usually consumed after processing into various products, such as concentrate, jams and juices. As a result of processing, large amounts of by-products including peel and pomace are generated. These by-products are usually disposed, both in environmental and economic terms. Several literature studies proved that by-products of different fruit and vegetables contain high levels of total phenolics, flavonoids, anthocyanins and antioxidant capacity. However, there is no study on black carrot by-products; peel and pomace. In this study the aim is to investigate characterization and in vitro bioaccessibility of polyphenols of black carrot and its by-products. This study is performed on industrial waste materials that will also provide information about the effect of processing. For the experimental setup of the in vitro gastrointestinal digestion, pepsin, pancreatic enzymes and intestinal bacteria were used. Total phenolic, total anthocyanin and total antioxidant capacities and polymeric color were determined by a spectrophotometer. For the identification and quantification of phenolic metabolites high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography-electrospray ionization mass spectrometry (UPLC-ESI-MS) were used. Statistical differences between samples were evaluated by one-way ANOVA (p<0.05). Five major anthocyanin pigments; two non-acylated (cyanidin-3-xylosylglucosyl galactoside and cyanidin-3-xylosylgalactoside) and three acylated with sinapic acid (cyanidin-3-sinapoylxylosylglucosylgalactoside), ferulic acid (cyanidin-3-feruloyl xylosylglucosylgalactoside) and p-coumaric acid (cyanidin-3-p-coumaroylxylosyl glucosylgalactoside) were investigated. In the group of phenolic acids; neochlorogenic acid, cryptochlorogenic acid, chlorogenic acid caffeic acid, ferulic acid were determined. After in vitro digestion, a decrease in the content of neochlorogenic, cryptochlorogenic and chlorogenic acid were observed, whereas an increase in the content of caffeic and ferulic acid was found. Significantly lower amounts of total anthocyanins were present in the stomach (26%-49%), small intestine (20%-38%) and colon (18%-47%). Similarly, total phenolics in the stomach (29%-57%), small intestine (48%-73%) and colon (45%-64%) were also lower than undigested total phenolic content. During colonic digestion, acylated anthocyanins were converted into their parent anthocyanins as a result of microbial activity. The proportional production of major SCFAs after 24 hours were observed for pomace and peel samples. Among all four antioxidant capacity methods performed in this study (ABTS, DPPH, FRAP and CUPRAC), DPPH, CUPRAC and FRAP assays showed similar trends of decrease or increase. CUPRAC resulted in the highest antioxidant capacity for undigested black carrot (17426.1 mg TE/100 g dw); whereas it was measured 7198.7 mg TE/100 g dw with DPPH, 9257.2 mg TE/100 g dw with FRAP and 2489 mg TE/100 g dw with ABTS. In total, the CUPRAC assay gave the highest and DPPH assay the lowest values for each sample. In overall, the current study highlighted black carrot and its by-products as valuable health promoting sources.