Ryszard Zadernowski

Protein precipitating capacity of condensed tannins of beach pea, canola hulls, evening primrose and faba bean

Abstract Condensed tannins (CT) from beach pea, Cyclone canola hulls, evening primrose and faba bean were extracted into 70% (v/v) aqueous acetone. The lyophilized extracts were then purified on a Sephadex LH-20 column using first 95% ethanol as a mobile phase for elution of non-tannin phenolics and then 50% aqueous acetone to elute CT. Condensed tannins isolated from beach pea possessed shorter polymer chains than those isolated from canola hulls, evening primrose or faba bean. Bovine serum albumin (BSA) was effectively precipitated by beach pea CT at pH values between 3.5 and 5.0. CT of canola hulls, evening primrose and faba bean precipitated BSA at pH 4.0–5.0. A statistically significant ( P =0.0001) linear relationship existed between the amount of tannin-protein complex formed and the amount of CT added to the reaction mixture. The slopes of these lines indicated that evening primrose CT were the most effective protein precipitants, followed by canola hulls, faba bean and beach pea CT. Based on the amount of gelatin and BSA required to inhibit 50% of dye-labelled BSA-CT complex precipitation, gelatin was 10 times more effective as a precipitation inhibitor than unlabelled BSA.

Protein-binding and antioxidant potential of phenolics of mangosteen fruit (Garcinia mangostana).

Phenolics were extracted from mangosteen fruit parts with 70% (v/v) aqueous acetone. The yield of crude extracts of phenolics (CP) ranged from 5.8% to 7.9%. The total phenolics (TPH) content ranged from 9.3mg to over 250mg of gallic acid equivalents per g of extract in the edible aril and skin, respectively. The formation of phenolic-protein complexes was assayed by both the dye-labelled bovine serum albumin (BSA) and the fluorescence quenching methods. Phenolics from peel and rind displayed a strong protein-precipitating potential. On the other hand, phenolics from edible aril exhibited greater affinity for BSA, as determined by the fluorescence quenching assay. The static quenching was the dominant mode of quenching of BSA fluorescence by mangosteen fruit phenolics. Mangosteen phenolics occupied two binding sites on BSA molecules located most likely in or near both tryptophan residues in the BSA molecule acting as an intrinsic fluorescence probe.

Amaranth Seeds and Products – The Source of Bioactive Compounds

Abstract In recent years, new products obtained from amaranth seeds have entered the food market including expanded “popping” seeds and flakes. Lipids and biologically-active substances dissolved in these products are susceptible to changes. Additionally, due to the fact that fat quality has high dietary importance, there is a need to conduct detailed quality and quantity studies on the lipid composition of Amaranthus cruentus. For the samples under analysis, protein, fat, starch and ash content were determined. Fatty acids and sterols were analysed by gas chromatography. The analysis of tocopherols and squalene content was carried out with the application of high-performance liquid chromatography coupled with photodiode array and fl uorescence detectors (HPLC-DAD-FLD). Protein, fat and starch content did not change during seed processing. However in the case of tocopherols, the total tocopherol content was 10.6 mg/100 g for seeds, while in “popping” and in flakes it was reduced by approximately 35%. The squalene content ranged from 469.96 mg/100 g for seeds to 358.9 mg/100 g for flakes. No significant differences were observed in the fatty acid profile of seeds and products, but differences were observed in the sterol content.

Characteristics of Biologically-Active Substances of Amaranth Oil Obtained by Various Techniques

Amaranth seeds and their main product amaranth oil are a rich source of bioactive substances. The non-saponifi able substances which accompany lipids include: squalene, tocopherols, sterols and others. The aim of the study was to compare the content of squalene, tocopherols and phytosterols in amaranth oils obtained by various techniques. The oil was extracted from seeds (Amaranthus cruentus) with the use of supercritical fl uid extraction (SFE), extraction with a chloroform/methanol mixture and expeller pressing. Contents of squalene and tocopherols were determined with high performance liquid chromatography (HPLC) method. The content of sterols in oils was determined by gas chromatography coupled with mass spectrometry (GC-MS). The highest squalene content was found for the oil obtained as a result of supercritical CO2 extraction (6.95 g/100 g of oil). A lower content of squalene was noted in the oil extracted with organic solvents and in cold-pressed oil - 6.00 and 5.74 g/100 g of oil, respectively. The amaranth oils were characterised by a signifi cant content of tocopherols. The oil obtained as a result of fl uid extraction was characterised by the highest content of tocopherols (131.7 mg/100 g of oil). A dominating homologue (40%) was β-tocopherol. Also the same sample was characterised by the highest content of sterols (2.49 g/100 g of oil). In all samples the predominating sterol was sum of α-spinasterol and sitosterol, which accounted for 45%, 56% and 53% of total analysed sterols for the oil obtained from SFE, from extraction with solvents and from cold pressing, respectively.