Laccase-aided protein modification: Effects on the structural properties of acidified sodium caseinate gels

Trametes hirsuta laccase (EC 1.10.32) alone was not able to cross-link proteins effectively unless high dosages were used. Incorporation of ferulic acid enhanced the formation of intermolecular cross-links. Cross-linking was more effective when the reaction was carried out at 45 °C rather than at room temperature. Size exclusion chromatography showed that ferulic acid monomers disappeared from the solution in the presence of laccase. Force at rupture point of the caseinate gels treated with laccase without ferulic acid was not significantly different from the control, while stronger gels were achieved when ferulic acid was present. Rheological measurements showed that laccase treatment together with ferulic acid resulted in higher G′ values than the control. Gels were analyzed with confocal laser scanning microscope. A finer network was observed when the enzyme was used together with ferulic acid. Slight proteolytic activity resulted in a negative effect on the gel firmness and microstructure when laccase was used without ferulic acid.     

Chemical composition,antioxidative activity and cell viability effects of a Siberian pine (Pinus sibirica Du Tour) extract

Siberian pine (Pinus sibirica Du Tour) seeds, commonly known as cedar nuts, are ascribed a number of medicinal properties. In this study, we report the qualitative–quantitative composition, antioxidant activity and cell viability-related properties of a defatted aqueous-acetone-soluble P. sibirica seed extract. The total phenolic and total tannin contents were estimated at 266 ± 3.9 mg gallic acid/g and 115 ± 7.8 mg tannic acid/g, respectively. Reverse-phase chromatographic analysis of the crude extract indicated the presence of a chromatographic hump indicative of the presence of proanthocyanidins. After acid hydrolysis, the presence of hydroxylated benzoic and cinnamic acids, flavanones and flavan-3-ols was confirmed. After thiolysis, (+)-catechin was identified as more abundant than (−)-epicatechin, suggesting that this molecule was the main terminal unit of the proanthocyanidins within this extract. The extract demonstrated iron(III)-reductive (AscAE = 650 ± 5.10 μmol ascorbic acid/g) and iron(II) chelating (EC₅₀ = 20.1 ± 2.1) activities and the ability to scavenge 1,1-diphenyl-2-picrylhydrazyl (IC₅₀ = 257 ± 2.36 μg/ml) and hydroxyl (IC₅₀ = 338 ± 6.49 μg/ml) free radicals. When the effects of P. sibirica extract were assessed in a tumourigenic SH-SY5Y neuroblastoma cell line, it was found that the cell viability was diminished in the presence of P. sibirica extract (0.2–1.0 mg/ml), as indicated by decreased membrane integrity (LDH assay) and mitochondrial metabolic activity (MTT assay), but the level of p53 protein was not changed (Western blot).     

Effects of transglutaminase, tyrosinase and freeze-dried apple pomace powder on gel forming and structure of pork meat

Effects of microbial transglutaminase (mTG), mushroom tyrosinase and an apple powder containing transglutaminase (TG) and polyphenol oxidase (PPO) on the structure of industrial pork meat homogenate were studied. Apple powder and mTG both increased the value of storage modulus (G′). Mushroom tyrosinase was not able to affect gel forming with the used dosages and treatment conditions. All the enzymes studied were able to improve gel hardness of unheated meat homogenate at 4 °C to a certain extent. In gel hardness measurements added cysteine affected positively on the apple powder—treated pork meat and negatively on mTG—and tyrosinase-treated meat. Surprisingly cysteine addition nullified also the action of mTG. Hence powdered apple pulp, a recovered co-product of an industrial process, may contain suitable enzyme activities for food protein stabilization.     

Antioxidant, pro-oxidant and cytotoxic properties of parsley

Parsley (Petroselinum crispum) leaves were macerated with a mixture of methanol: water: acetic acid to produce a crude extract which was then defatted with (40°-60°) petrol. Antioxidant activity of the extract was evaluated using a battery of in vitro assays, viz., iron(iii) reduction, iron(ii) chelation and free radical scavenging assays. Evaluation of the pro-oxidant activity of the extract was based upon its effects upon DNA fragmentation and protein carbonylation. Cytotoxicity and apoptotic effects of the extract were determined in non-cancerous CV1-P fibroblast and cancerous A375 melanoma cells using MTT and LDH tests and caspase 3-like activity assay. The highest concentration, 2.0 mg ml(-1), decreased the viability of both cell lines, however, the cancerous melanoma cells were slightly susceptible to the effects. The observed cytotoxicity was not due to the caspase 3 activity. In conclusion, the toxicity might be explained by the pro-oxidative activity of components within the extract against proteins and/or DNA but it is not related to caspase 3-dependent apoptosis within cells.     

Unbalanced magnetic pull induced by arbitrary eccentric motion of cage rotor in transient operation. Part 2: Verification and numerical parameter estimation

Eccentric rotor motion of an electric motor induces an unbalanced magnetic pull. This eccentricity force can be described using a simple parametric model with physical parameters. This model allows an arbitrary rotor motion and transient operation. This paper presents an effective method to estimate the parameters from simulation results of electromagnetic fields. Further, the numerical results verify the form of the proposed parametric model in steady-state operation.     

THE IDENTIFICATION OF CARBONYL COMPOUNDS IN BEER

Carbonyl compounds were separated from bottom-fermented lager beer by extraction with a diethylether-pentane mixture and precipitation from the extract with 2,4-dinitrophenylhydrazine. The diketones, diacetyl and 2,3-pentanedione, were identified as bishydrazones by thin-layer chromatography with benzene-petroleum ether-ethyl acetate (34:5:1) as solvent and Silica Gel HF₂₅₄ as adsorbent. For the identification of the aldehydes, the hydrazone precipitate was treated with ozone in formic acid solution and the aldehydes were determined as their corresponding carboxylic acids by iso-thermal gas chromatography on a NEGS column. Aldehydes were found in the following order of magnitude: acetaldehyde, isobutyraldehyde, isovaler- and/or opt.act.valeraldehyde (2-methylbutyraldehyde), valeraldehyde and butyraldehyde.     

Potato peeling costreams as raw materials for biopolymer film preparation

Potato peel mass is a costream produced in large quantities by the food industry. Its availability and the presence of starch (46%), pectin, and cellulose make it a potential renewable raw material for polymer products. In this study, biopolymer films were produced from potato peel mass and glycerol. High‐pressure homogenization (HPH) and HPH combined with heat treatment were investigated as pretreatment technologies before film casting. HPH‐treated potato peel mass yielded biopolymer films with similar barrier and mechanical properties as films prepared from pure potato starch, including complete impermeability to grease. Additional heat treatment of the peel mass enhanced starch gelatinization, resulting in improved barrier properties and smoother surface topography of the films. Films with similar appearance and quality were also obtained from starch‐free potato peel mass, indicating that potato fiber rich in pectin and cellulose is likewise a suitable material for biopolymer film preparation after HPH treatment. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42862.     

Cytotoxicity of curcumin,resveratrol and plant extracts from basil,juniper, laurel and parsley in SH-SY5Y and CV1-P cells

The health-promoting effects of natural phenolic compounds are attracting growing interest. In this study, we tested four plant extracts, namely basil, juniper, laurel and parsley, and two well-known pure phenolic compounds of natural origin, curcumin and resveratrol, for their possible cytotoxic effects in vitro. AraC was used as an apoptotic reference compound. The pure compounds were studied in two cell lines, SH-SY5Y neuroblastoma and CV1-P fibroblast cells, and the plant extracts in SH-SY5Y cells. Cytotoxicity was examined by MTT and LDH assays, and the molecular mechanisms by Western blot analysis of p53 protein in cells. Juniper extract decreased the cell viability and increased the amount of p53 in SH-SY5Y cells at lower concentrations than did other plant extracts, and its effects on the amount of p53 in cells were comparable to the treatment with 50 μM AraC. The actions of curcumin and resveratrol were dependent on the concentration and cell line. Curcumin decreased the cell viability and increased the amount of p53 in SH-SY5Y cells more effectively than in CV1-P cells. The comparison between the results of AraC and pure curcumin showed a similar effect on the amount of p53. Our results indicate a potential role of plant extracts and plant-derived compounds as health-promoting food constituents, as well as candidates for drug development.