Elwira Worobiej

Antioxidant activity and chemical difference in fruit of different Actinidia sp.

Abstract The present research aimed at evaluating the vitamin C, total phenolic content (TPC), phenolic compounds, carotenoids, and chlorophyll contents, as well as antioxidant activity (AAC) of six Actinidia species fruit. Vitamin C, phenolic compounds, carotenoids and chlorophylls were measured using high-performance liquid chromatography. TPC was determined using the Folin–Ciocalteau reagent, and AAC using 2,2-diphenyl-1-picryl hydrazyl (DPPH) assay. The highest concentrations of vitamin C and TPC were found for Actinidia kolomikta fruit (1008.3 and 634.1 mg/100 g fresh weight [FW], respectively). Among phenolic compounds, seven phenolic acids and three flavonoids were identified. The 2,5-dihydroxybenzoic acid prevailed in A. kolomikta (425.54 mg/100 g FW), while tannic acid dominated in other species (4.63–100.43 mg/100 g FW). The largest amounts of chlorophylls and carotenoids were identified as Actinidia macrosperma (4.02 and 2.09 mg/100 g FW, respectively). The AAC of fruit extracts decreased in the order of A. kolomikta > Actinidia purpurea > Actinidia melanandra > A. macrosperma > Actinidia arguta > Actinidia deliciosa according to the DPPH assay.

Chemical composition and starch digestibility in flours from Polish processed legume seeds

The study was undertaken to determine the effect of various treatments, i.e. cooking after soaking, freezing after cooking and storage at a low temperature (-18°C, 21days), and autoclaving, of Polish cultivars of bean, pea and lentil seeds on the chemical composition and starch digestibility of the resultant flours. The cooking of seeds caused a significant decrease in contents of ash (by 11-48%), polyphenols (by 10-70%) and protein (to 19%) in flours made of bean. In addition, analyses demonstrated significantly decreased contents of resistant starch, RS (by 61-71%) and slowly digestible starch, SDS (by 56-84%). Storage of frozen seeds resulted in insignificant changes in the chemical composition, and in increased contents of both RS and SDS. The flours produced upon the autoclaving process were characterized by similar changes in the contents of ash and protein as in cooked seeds, yet losses of polyphenols were lower and, simultaneously, contents of RS and SDS were higher. All the analyzed flours were shown to be characterized by a reduced content of amylose in starch, which might have affected its digestibility. This was indicated by a strict negative correlation reported between the value of the starch digestion index (SDRI) and amylose content of starch (r=0.84, p>0.05).

Effect of Sterilization Process and Storage on the Antioxidative Properties of Runner Bean

In this study, we investigated the effect of standard preservation of bean seeds on changes in contents and activity of their selected components: dry matter, ash, different forms of nitrogen, composition of protein fractions; total phenolics and condensed tannins; ability to chelate iron(II) ions; antiradical activity against ABTS•+ and DPPH•; and capability for inhibiting autoxidation and enzymatic oxidation of linoleic acid. The conducted technological process caused various changes in contents of nitrogen forms and partial loss of phenolic compounds. The antiradical and antioxidative activity of the extracts decreased significantly, while an increase was observed in their ability to chelate Fe(II). These changes were due to the migration of active compounds to the brine, and to their structural transformations and degradation. Longer storage of the sterilized product caused restoration of part of the antiradical activity of the seeds.

Effect of hydrothermal modifications on properties and digestibility of grass pea starch

This study aimed to investigate functional and thermal properties and digestibility of grass pea starch, and provide information on the effect of hydrothermal modifications - annealing (ANN) and heat-moisture treatment (HMT) on the physico-chemical characteristics of the starch and digestibility, especially after processing (cooking, storage after cooking and freezing). After heat treatment, especially after cooking and storage at a temperature of -18 °C, the total content of slowly digestible starch and resistant starch in grass pea starch was high, which may indicate its great tendency for retrogradation. The HMT and ANN modifications of grass pea starch caused changes in its crystalline structure and increased integrity of its granules, which in turn resulted in a lower swelling power and amylose leaching, however this effect was more pronounced upon HMT which contributed to starch polymorphic type transformation from C to A. Despite greater resistance of granules of modified starches to swelling during cooking their suspensions, after cooking these starches were characterized by a higher predicted glycemic index than the non-modified ones. A similar content of resistant starch determined in modified and non-modified gelatinized starches stored at lowered temperatures indicates that starch modifications, HMT in particular, cause no changes in its susceptibility to retrogradation.