Identification of oat (<Emphasis Type="Italic">Avena sativa</Emphasis>) and buckwheat (<Emphasis Type="Italic">Fagopyrum esculentum</Emphasis>) proteins and their prolamin fractions using two-dimensional polyacrylamide gel electrophoresis

Total (non-fractionated) kernel proteins and the prolamin fraction (soluble in 75% ethanol) were extracted from oat (Avena sativa) var. Flämingstern kernel and from buckwheat (Fagopyrum esculentum) var. Kora kernel. As for buckwheat, extraction was effective only after kernel dehulling which allowed the removal of tannins and phenolic compounds that form complexes with proteins during extraction. The extracted proteins were analyzed using two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Gels of the prolamin fractions of oat and buckwheat were used as reference gels in order to detect prolamins on gels of total kernel proteins. The occurrence of 26 and 29 spots corresponding to prolamins was found on gels of total oat proteins and on gels of total buckwheat proteins, respectively. The electrophoretic images of oat and buckwheat prolamins revealed organized subregions containing spots with similar isoelectric points (pI) and various molecular weights (MW), mostly on oat prolamin gels and spots of similar molecular weights with various isoelectric points, mostly on buckwheat prolamin gels. Such organized subregions can be used as identifiers for the occurrence of prolamin fractions in total proteins (particularly as regards buckwheat proteins).     

Development of a nucleic acid lateral flow immunoassay for simultaneous detection of <Emphasis Type="Italic">Listeria</Emphasis> spp. and <Emphasis Type="Italic">Listeria</Emphasis><Emphasis Type="Italic">monocytogenes</Emphasis> in food

We present a new nucleic acid lateral flow immunoassay (NALFIA) for the assessment of listeria contamination. The detection procedure starts with enrichment of sample in Half Fraser broth (24 h). Following isolation of DNA, a duplex PCR is performed with two labelled primer sets, one generic and directed to a specific sequence of the gene encoding 16S rRNA from Listeria spp. and the other specific and directed to a part of the prfA gene encoding the central virulence gene regulator from the food pathogen Listeria monocytogenes (3.5 h). The PCR solution is directly added to the one-step assay device and the appearance of a grey/black line is indicative of the presence of specific amplicons (max 15 min). In all tests performed, the method correctly identified L. monocytogenes and strains of Listeria spp. PCR material of over 20 food samples was tested by NALFIA. The method proved to be useful for the detection of L. monocytogenes in different kinds of food samples.     

Antioxidant capacity and total phenolics of <Emphasis Type="Italic">Cyphostemma digitatum</Emphasis> before and after processing: use of different assays

In the framework of standardisation of new healthy food sources, this paper aimed to study the total phenolics and the antioxidant power of Cyphostemma digitatum (Vitaceae) in water and ethanol extracts, using 96-well micro plates with BMG FLUOstar Optima micro plate reader. Total phenolics by Folin–Ciocalteu method in the water extracts were significantly lower after processing, decreasing from 1.41 ± 0.06 g GAE/100 g in the raw leaves to 0.80 ± 0.08 g GAE/100 g in the processed sample; the ethanol extract revealed the same trend with higher values, decreasing from 1.95 ± 0.03 to 1.56 ± 0.12 g GAE/100 g. The antioxidant capacity was elucidated by four methods: TEAC, DPPH, FRAP and ORAC. No or very weak correlations were found between antioxidant assays and total phenolics; this confirms that the antioxidant capacity could be attributed to other molecules. The ORAC assay proved to be more powerful than the other assays; it showed 103.3 ± 2.5 mmol/100 g Trolox equivalents in the raw leaves ethanol extract and 91.9 ± 3.0 mmol/100 g in the processed sample. ORAC assay showed the opposite for the water extract where the antioxidant capacity increased from 16.7 ± 0.2 to 41.7 ± 2.7 mmol/100 g Trolox equivalents after processing, which could be attributed to new water-soluble compounds generated in the consumed form.     

Purification and characterization of antioxidative peptides derived from rice bran protein hydrolysates

Rice bran protein fraction (RBPF)—albumin, globulin, glutelin and prolamin were hydrolyzed with proteases M, N, P, S and pepsin under their optimal conditions for 24 h. Hydrolysates of various hydrolysis periods were collected and subjected to peptide mapping and the antioxidative activity measured by the 2,2-Azino-bis-3-ethylbenzothiazoline-6-sulfonic Acid (ABTS) method. Protease M hydrolysates showed high degree of hydrolysis (DH), but low antioxidative activity. On the contrary, pepsin hydrolysates showed low DH with high activity. Albumin and globulin hydrolysates had higher DH values, but lower values for glutelin and prolamin. The globulin hydrolysate (Opep2) from 2 h-pepsin hydrolysis was separated by using three consecutive purification steps with RP-HPLC. Nineteen antioxidative peptides were isolated and their amino acid sequences were determined by a gas-phase protein sequencer and MALDI-TOF mass spectrometry. These peptides were composed of 6–30 amino acid residues with molecular masses ranging from 670–3,611 Da. Tyr-Leu-Ala-Gly-Met-Asn had the highest antioxidative activity among them.     

Effects of pretreatments on colour alterations of litchi during drying and storage

The objective of this research was to study the effect of osmotic pretreatment with combined anti-browning agents (acid, glycerol and/or trehalose) on the colour characteristics of dried litchi after drying and during 5 months of storage compared to samples without pretreatment. The pretreated samples showed good inhibition of polyphenol oxidase activity when compared with the control, while the total phenolic contents in the dried products were not reduced. The results demonstrated that water activity, lightness difference, chroma, degree of browning (DB), and 5-hydroxymethylfurfural values of all pretreated samples increased, while hue angle decreased with storage time. Samples pretreated with glycerol showed the best potential for browning retardation, followed by glycerol combined with trehalose, and trehalose, respectively. In addition, the colour parameters were used to calculate the luminescence values, representing the data in grey scale, which were correlated with a non-enzymatic browning index. The results showed grey value could be adequately used to represent the DB of dried litchi with r ² value of 0.92.     

Structural modification of soy protein by 13-hydroperoxyoctadecadienoic acid

To reveal the role of primary products of lipid peroxidation during soy protein oxidation process, oxidative modification of soy protein by 13-hydroperoxyoctadecadienoic acid (13-HPODE) generated by lipoxygenase-catalyzed oxidation of linoleic acid was investigated in this article. Incubation of soy protein with increasing concentration of 13-HPODE resulted in generation of protein carbonyl derivatives and loss of protein sulfhydryl groups. Circular dichroism spectra indicated that exposure of soy protein to 13-HPODE led to loss of α-helix structure. Effect of oxidation on tertiary structure was demonstrated by surface hydrophobicity and tryptophan fluorescence. Surface hydrophobicity gradually decreased, accompanied by loss and burial of some tryptophan residues. The results of surface hydrophobicity and tryptophan fluorescence implied that aggregation was induced by oxidation. Size exclusion chromatogram indicated that the extent of aggregation was increased in a 13-HPODE dose-dependent manner. Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that non-disulfide linkages were involved in aggregate formation, and β-conglycinin was more vulnerable to 13-HPODE than glycinin.     

Effects of suni-bug (<Emphasis Type="Italic">Eurygaster</Emphasis> spp.) damage on size distribution of durum wheat (<Emphasis Type="Italic">Triticum durum</Emphasis> L.) proteins

Wholemeal samples were obtained from five durum wheat cultivars at two different bug (Eurygaster spp.) damage levels (medium and high damage). The samples were incubated (60 and 120 min) and used in size exclusion high performance liquid chromatography (SE-HPLC) analyses. The results showed that the amount of larger polymeric protein (TP1) and smaller polymeric protein (TP2) obtained from total (sodium dodecyl sulfate soluble) proteins decreased significantly in the bug-damaged samples, while the amount of total larger monomeric proteins (TP3) increased. The polymeric/monomeric protein ratio of all cultivars decreased at 60 min of incubation with increasing damage level. For all cultivars, the ratio of unextractable polymeric protein (UPP%) significantly decreased at 60 min of incubation except cv. Diyarbakir. The results suggested that bug protease caused depolymerization and/or disaggregation of polymeric proteins to lower their average molecular size. The changes in protein structure as determined using SE-HPLC supported by the decreases in gluten content and gluten index values which decreased with suni-bug damage. Deteriorative effects of bug damage on durum wheat quality were found to be quite similar to those on bread wheats.     

Steroid biosynthesis in the whelk, Buccinum undatum

Cell-mediated immunity (CMI) to homologous spermatozoal antigens was studied in sixty-two males following vasectomy of a duration of 1-10 years. A group of twenty-two normal, fertile non-vasectomized males was also included in the study. The inhibition in the leucocyte migration test (LMT), in the presence of spermatozoal antigen, was taken as an index of CMI. Twenty of the sixty-two vasectomized males (32.2 percent) showed a positive LMT reaction. When the results were analysed with reference to the duration of vasectomy, it was noted that four cases each (22.2 percent), showed a positive LMT reaction in the groups 0-2 years, and 3.5 years. On the other hand twelve cases gave a positive reaction in the group 6-10 years (46.1 percent). It appears that the incidence of CMI to spermatozoa increases with the duration in vasectomy.     

The subgenus Persicargas (Ixodoidea: Argasidae: Argas). 26. Argas (P.) arboreus: effect of photoperiod on diapause induction and termination

The anthelmintic efficacy of fenbendazole (methyl 5-(phenylthio)-2-benzimidazole carbamate) was tested in sheep against standardised strains of Hcaemonchus contortus and Trichostrongylus colubriformis, known to be resistant to thiabendazole (LD90 for thiabendazole against H ontortus was 200 mg/kg bodyweight and against T colubriformis was 150 mg/kg). Fenbendazole at dose rates of 5, 10 and 20 mg/kg per os reduced total worm counts in H contortus infected sheep by 66, 90 and 100 per cent respectively, with similar reductions recorded for worm egg outputs. For the thiabendazole resistant strain of T colubriformis, fenbendazole reduced total worm counts in infected sheep by 4, 44 (40-48), 79 (75-83), 96 and 100 per cent at dose rates of 5, 10, 20, 40 and 80 mg/kg per os. Significant suppression of worm-egg production by thiabendazole resistant T colubriformis was obtained with fenbendazole at dose levels of 5 mg/kg and above. The implications of these results are discussed in the light of the increasing occurrence of strains of trichostrongylid nematodes resistant to currently available benzimidazole anthelmintics.     

Advanced Modeling of Food Convective Drying: A Comparison Between Artificial Neural Networks and Hybrid Approaches

In the present paper, three different approaches are proposed to model the convective drying of food. The performance of thin-layer, pure neural network and hybrid neural model is compared in a wide range of operating conditions, with two different vegetables, available either as cylinders or as slabs with different characteristic dimensions. It was found that the thin-layer model was adequate to describe food drying behavior, but it could be applied only as a fitting procedure. Pure neural models gave accurate predictions in some situations, but exhibited poor performance when tested outside the range of operating conditions exploited during their development. Finally, it was shown that hybrid neural models, formulated as a combination of both theoretical and neural network models, are capable of offering the most accurate predictions of system behavior with average relative errors never exceeding 10%, even in operating conditions unexploited during the definition of the neural part of the model. The results obtained proved that the hybrid neural paradigm is a novel and efficient modeling technique that could be used successfully in food processing, thus allowing drying process optimization to be achieved, and efficient and fast on-line controllers to be implemented.