BIOACCESSIBILITY OF PHENOLIC COMPOUNDS AND FATTY ACIDS IN WHOLE AND GROUND CHIA SEEDS AND SPROUTS

Chia seeds and sprouts contain high amounts of phenolic compounds, dietary fibers, proteins, and polyunsaturated fatty acids. However, despite their nutritional composition, consuming these whole foods does not mean that their nutrients and bioactive compounds will be released in the gastrointestinal tract. This study aimed to evaluate the effects of grinding and germination on the phenolic compounds, fatty acids, and antioxidant capacity of chia seeds subjected to in vitro gastrointestinal digestion (IVGD). Whole chia seeds (WC), ground chia seeds (GC), whole chia sprouts (WCS), and ground chia sprouts (GCS) were subjected to simulated in vitro gastrointestinal digestion using the INFOGEST 2.0 protocol. Total phenolic content (TPC) was determined using the Folin–Ciocalteu method, while phenolic profiles were characterized by HPLC-DAD and antioxidant activity was assessed using DPPH (1,1-diphenyl-2-picrylhydrazyl free radical), ABTS (Trolox equivalent antioxidant capacity), and FRAP (Ferric-reducing antioxidant potential method) assays before and after IVGD. After digestion, the ground samples (GC and GCS) showed the highest values of total phenolic compounds, antioxidant capacity, and fatty acids when compared to their respective whole samples (WC and WCS). The total phenolic compounds reached 7.00 mg gallic acid equivalents/g (GC) and 8.76 mg gallic acid equivalents/g (GCS), compared to 4.40 mg gallic acid equivalents/g (WC) and 2.57 mg gallic acid equivalents/g (WCS). In the evaluation of antioxidant capacity, GC and GCS showed higher values in the FRAP (40.38 and 38.62 µmol ferrous sulfate/g), ABTS (79.98 and 74.99 µmol Trolox equivalent/g), and DPPH (63.36 and 51.51 % antioxidant activity) assays, compared to WC and WCS (FRAP: 2.85 and 11.53 µmol ferrous sulfate/g; ABTS: 57.40 and 47.98 µmol Trolox equivalent/g; DPPH: 39.27 and 42.11 % antioxidant activity, respectively). Furthermore, rosmarinic acid was detected only in ground samples (GC or GCS), while the rosmarinic acid 3-O-glycoside and caffeic acid were detected only in the ground seeds after digestion, indicating that processing can facilitate the release or transformation of phenolic compounds during gastrointestinal digestion. Regarding the lipid content, values of 6.33 g/100 g were obtained for GC and 5.36 g/100 g for GCS, while WC and WCS showed only 0.19 g/100 g. This result demonstrates that the physical structure of the seed can limit the release of lipids. On the other hand, omega-3 was identified in all samples, although its quantity decreased in the sprouts, suggesting that germination can modify the lipid profile due to the metabolic changes associated with vegetative development. It is concluded that, under the evaluated conditions, grinding was a more determining factor than germination in improving the bioaccessibility of phenolic compounds and fatty acids in chia seeds.

Acknowledgments: This work was supported by CAPES (Finance Code 001) and FAPERJ (Grant No. E-26/211.830/2021).