EFFECTS OF THERMAL PROCESSING ON WILD BLUEBERRY ANTHOCYANINS AND THEIR ABSORPTION, METABOLISM, DISTRIBUTION AND EXCRETION IN SPRAGUE-DAWLEY RAT

Anthocyanins (ACN) bioavailability and metabolism were not well established. Moreover, ACN are labile compounds and deteriorate during storage. Thus, the degradation kinetics of ACN contained in wild blueberry (WB) powder stored at 25, 42, 60 and 80 °C for 49 days and total antioxidant activity (TAA) were evaluated. Then, we investigated WB ACN adsorption, metabolism, distribution in the plasma, liver, brain, and their excretion in urine and feces in rats fed a WB-enriched diet (24±5 mg/day of ACN) for 4 and 8 weeks. At last, we evaluated ACN transformation by human and rat microflora from stomach, small intestine and colon. Anthocyanins in WB were 1.8±0.1 mg/100 mg powder. The product maintains the content of ACN and TAA longer (up to 130 days) at 25°C; however, storage at 4 °C represents the best way to delay decay. Anthocyanin profile in biological sample significantly increased in urine and not in feces after 8 weeks on the WB diet compared to that in 4 weeks. No ACNs were detected in the controls. ACN metabolites were detected in the plasma, urine, feces, and tissues, but the urinary excretion of hippuric acid increased significantly after 4 and 8 weeks of WB consumption. Thus, ACN are metabolized by the intestinal microflora to respective phenyl-alkyl acids, which can be further metabolized to benzoic acid. In conclusion, ACN are bioavailable in rats, and the extent of their metabolism and excretion is based on diet duration. The colon bacteria showed the highest catabolic activity against ACN, indeed about 84% degradation in the first six hours of incubation. The amount of the formed phenolic acid reached up to a maximum of 40 % of the parent compound, suggesting the occurrence of ACNs degradation pathways not yet identified.