Izvorni znanstveni članak
Influence of Jam Processing Upon the Contents of Phenolics and Antioxidant Capacity in Strawberry fruit (Fragaria ananassa × Duch.)
Branka Levaj
; Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Danijela Bursać Kovačević
orcid.org/0000-0002-6829-6472
; Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Martina Bituh
orcid.org/0000-0002-3596-8383
; Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Verica Dragović-Uzelac
; Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia
Sažetak
Seven cultivars of strawberry (Diamante, Elsanta, Honeoye, Madeleine, Marmolada, Miranda and Miss) were analyzed for total phenols (TP), total flavonoids (TF), total nonfl avonoids (TN), total anthocyanins (TA) and antioxidant capacity (AC) before and after low sugar jam production to evaluate their changes after thermal processing. The content of TP, TF and TN were determined according to the Folin-Ciocalteu assay. Anthocyanins were determined by spectral method based on the bisulfite bleaching of monomeric anthocyanins. The antioxidant capacity was evaluated by ,2-diphenyl-1-picrylhydrazil radical (DPPH). Fresh fruits had total phenolics ranging from 251.97 to 713.06 mg gallic acid equivalent GAE/g of dry weight. In all investigated samples, fresh strawberries and jams, nonflavonoids were predominant phenols. Cultivar Honeoye had the highest amounts, while cultivar Miss had the lowest amounts of TP and TN. Cultivar Miranda had TF in the highest concentrations, while the lowest concentrations were found in cultivar Marmolada. TA for investigated cultivars was 63.55-177.71 mg Cy-3-G/100 d.w. with strong differences among cultivars. On the basis of dry weight the processing and heating during jam making generally decreased the contents of TP for 37-70 %. During processing, cultivar Madeleine
showed the greatest stability of TP, TN and TF, while cultivar Elsanta showed the greatest anthocyanins stability. In comparison with
fresh strawberry fruit, whose antioxidant capacity were in the range of 0.23 mmol TE/kg f.w. to 0.67 mmol TE/kg f.w., the jams also represent a noticeable source of antioxidant compounds, even considering the lower content of phenolic compounds, with the antioxidant capacity of 0.20 mmol TE/kg f.w. to 0.62 mmol TE/kg f.w.
Hence, the obtained results showed that besides fresh strawberry fruit, the strawberry jams also possess noticeable content of important bioactive compounds with considerable antioxidant capacity.
Ključne riječi
Fragaria x ananassa Duch.; strawberry; phenolics; anthocyanins; jam; antioxidant capacity
Hrčak ID:
82765
URI
Datum izdavanja:
6.6.2012.
Posjeta: 3.873 *