A preliminary study about the influence of high hydrostatic pressure processing in parallel with oak chip maceration on the physicochemical and sensory properties of a young red wine.

The influence of high hydrostatic pressure (HHP) processing in parallel with oak chip maceration on the physicochemical and sensory properties of a young red wine was investigated preliminarily. Wines were treated by HHP at 250, 450 and 650MPa for up to 45min and French oak chips (5g/L) were added. HHP enhanced the extraction of phenolics from oak chips. The phenolic contents and antioxidant activity of the wine increased after HHP processing in the presence of oak chips. Meanwhile, the anthocyanin content and wine color intensity decreased in the first 5min of pressure treatment and then increased gradually. The multivariate analysis revealed that "pressure holding time" was the key factor affecting wine physicochemical characteristics during HHP processing in the presence of oak chips. Furthermore, oak chip maceration with and without HHP processing weakened the intensities of several sensory attributes and provided the wine with an artificial taste.

Nutritional properties of tubers of conventionally bred and transgenic lines of potato resistant to necrotic strain of Potato virus Y (PVYN).

The potential effect of genetic modification on nutritional properties of potatoes transformed to improve resistance to a necrotic strain of Potato virus Y was determined in a rat experiment. Autoclaved tubers from four transgenic lines were included to a diet in the amount of 40% and compared with the conventional cv. Irga. The experiment lasted 3 weeks and special attention was paid to nutritional properties of diets, caecal metabolism and serum indices. Genetic modification of potato had no negative effect on the chemical composition and nutritional properties of tubers, ecosystem of the caecum, activity of serum enzymes and non-specific defence mechanism of the rats. Obtained results indicate that transgenic potato with improved resistance to PVY(N): line R1F (truncated gene coding for PVY(N) polymerase in sense orientation), R2P (truncated gene coding for PVY(N) polymerase in antisense orientation), and NTR1.16 (non-translated regions of PVY(N) genome in sense orientation) are substantial and nutritional equivalence to the non-transgenic cultivar. Tubers of transgenic line NTR2.27 (non-translated regions of PVY(N) genome in antisense orientation) increased the bulk of caecal digesta and the production of SCFA as compared to tubers of the conventional cultivar and the other transgenic clones. Taking into account some deviations, it seems reasonable to undertake a long-term feeding study to confirm the nutritional properties of tubers of transgenic lines.

Annealing of normal and mutant wheat starches. LM, SEM, DSC, and SAXS studies.

Structure and thermodynamic properties of native and annealed wheat starches with different amylose content (from 1.5% to 39.5%) have been studied by high-sensitivity differential scanning microcalorimetry (HSDSC), small-angle X-ray diffraction (SAXS), light (LM), and scanning electron microscopy (SEM). Starch morphology, the values of the melting cooperative unit, the thickness of crystalline lamellae and the size of amylopectin clusters as well as thermodynamic parameters characterizing surface of the face side in starch crystals were determined. Some suppositions based on different physical approaches are used for a discussion of the results concerning structural reorganization of starches on different levels of macromolecular organization.

Structural parameters of amylopectin clusters and semi-crystalline growth rings in wheat starches with different amylose content.

Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) were used to investigate the internal structure of wheat starch granules with different amylose content. Different approaches were used for treatment (interpretation) of SAXS data to assess the values of structural parameters of amylopectin clusters and the size of crystalline and amorphous lamella in different wheat starches. The average values of the semi-crystalline growth rings thickness in starches have been determined and the relationship between structural characteristics and thermodynamic melting parameters is discussed.

Influence of cooking and microwave heating on microstructure and mechanical properties of transgenic potatoes.

The transgenic potato clones of cultivar Irga with improved resistance to a necrotic strain of potato virus Y (PVY(N)) were subjected to heat treatment in order to determine their technological quality. The technological quality was determined on the basis of differences between mechanical properties of unmodified potato and transgenic clones during cooking and microwave heating. The compression test was applied in order to evaluate the mechanical resistance of raw, cooked and microwave-treated potatoes. Compression resistance was expressed by fracture stress F (kPa), fracture strain D (mm/mm), and Young modulus E (kPa). The differences in microstructure of potato tubers (unmodified and modified) were investigated using scanning electron microscopy (SEM). The observed differentiation in the mechanical properties of heat-treated potatoes was less connected with genetic modification but most of all with a kind of the process used. The heat processes caused a distinct decrease in mechanical resistance in all the examined tubers. However, the process of microwave heating resulted in more significant changes in mechanical properties of tubers than cooking. Deformation of parenchyma cells during cooking was directly connected with starch, gelatinisation and gel formation. Microwave heating affected significantly cellular water evaporation which resulted in intercellular failure, collapsing of cells, and limitation of starch gelatinisation.