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Buckwheat starch was subjected to cycles of high pressure-cooling (P-CC) or autoclaving-cooling (A-CC) combined with pullulanase debranching to determine changes in resistant starch (RS) content, digestibility, rheological properties and microstructure. Native buckwheat starch had 11.9 g/kg of RS, while the highest RS content (58.7 g/kg) was reached after A-CC and 6 h of pullulanase treatment. Among the P-CC samples, the highest RS content (43.3 g/kg) was obtained after treatment with 600 MPa/9 min and 6 h pullulanase debranching. The digestibility of the starch samples was negatively correlated with RS content and its highest values were noted for native and P-CC 200 MPa preparations subjected to 2 and 16 h of pullulanase treatment (95.18–95.35%). Buckwheat starch A-CC preparations after 6 h of pullulanase treatment exhibited the lowest digestibility (85.87%). Rheological analysis of 6% starch pastes showed that all investigated samples demonstrated a non-Newtonian flow, pseudoplastic properties and thixotropy. The Ostwald de Waele rheological model was very well fitted to the flow curves of the investigated pastes (R2>0.98). Both P-CC and A-CC reduced the consistency coefficient (K) and thixotropy values, while the flow behavior index (n) was increased only after P-CC treatment. The P-CC and A-CC treatment resulted in starch granule breakdown and porous gel structure formation, differing in surface properties.

The distribution of a fraction of soluble dietary fibre (1,3)(1,4)-β-D-glucans was depicted in selected Polish oat grains (Avena sativa L.). Localisation of β-glucans within the grains was visualised by the light microscopy with Calcofluor white as a fluorescence agent. The content of β-glucans varied in samples from 3.08% d.m. to 5.04% d.m. Analysis of distribution of (1,3)(1,4)-β-D-glucans showed that the localization of β-glucans varied between various cultivars and lines. It was demonstrated that the total content of (1,3)(1,4)-β-D-glucans in oat kernels had an effect on their distribution. All the lines and cultivars tested displayed the greatest accumulation of (1,3)(1,4)-β-D-glucans in the cells of the subaleurone layer. With increase in the levels of β-glucans in high-glucan oat cultivars and lines, a tendency was observed towards their greater accumulation in the central parts of the kernel. It makes oat grain particularly suitable for the production of wholemeal foods. It is important not only to focus on increasing the content of β-glucans, but also to investigate molecules distribution in the seed. It was also demonstrated that Dukat cultivar was characterised by an especially valuable triple aleurone layer, which makes this cultivar predestined for further breeding studies as an extremely valuable carrier of genetic information.

Summary: The effect of high hydrostatic pressure (HHP) (450–550–650 MPa/5–10–15 min) on the carotenoid profile of purées obtained from commercial tomato varieties (Maliniak, Cerise, Black Prince and Lima) was investigated. The carotenoids profile was analysed using high performance liquid chromatography (HPLC‐DAD). Photochemiluminescence (PCLACL), ferric‐reducing antioxidant power (FRAP) and cyclic voltammetry (CV) assays were used to determine the antioxidant capacity of the lipophilic extracts. The results demonstrated that at certain processing conditions, HHP distinctly enhanced antioxidant capacity of the studied material. A significant reduction in lycopene and β‐Carotene concentration was observed for all the HHP‐treated purées. In contrast, lutein found in the purée extracts of Cerise and Black Prince tomatoes was slightly affected at 550 MPa/5 min and 650 MPa/5 min. Among all the carotenoids studied, lutein strongly and significantly affected PCLACL and CV parameters. In contrast, lycopene had a negligible effect on the examined parameters. [ABSTRACT FROM AUTHOR]

Buckwheat starch was subjected to cycles of high pressure-cooling (P-CC) or autoclaving-cooling (A-CC) combined with pullulanase debranching to determine changes in resistant starch (RS) content, digestibility, rheological properties and microstructure. Native buckwheat starch had 11.9 g/kg of RS, while the highest RS content (58.7 g/kg) was reached after A-CC and 6 h of pullulanase treatment. Among the P-CC samples, the highest RS content (43.3 g/kg) was obtained after treatment with 600 MPa/9 min and 6 h pullulanase debranching. The digestibility of the starch samples was negatively correlated with RS content and its highest values were noted for native and P-CC 200 MPa preparations subjected to 2 and 16 h of pullulanase treatment (95.18-95.35%). Buckwheat starch A-CC preparations after 6 h of pullulanase treatment exhibited the lowest digestibility (85.87%). Rheological analysis of 6% starch pastes showed that all investigated samples demonstrated a non-Newtonian fl ow, pseudoplastic properties and thixotropy. The Ostwald de Waele rheological model was very well fi tted to the fl ow curves of the investigated pastes (R2>0.98). Both P-CC and A-CC reduced the consistency coeffi cient (K) and thixotropy values, while the fl ow behavior index (n) was increased only after P-CC treatment. The P-CC and A-CC treatment resulted in starch granule breakdown and porous gel structure formation, differing in surface properties. [ABSTRACT FROM AUTHOR]

Size exclusion chromatography with triple detection as well as infrared spectroscopy studies of commercially available pyrodextrins proved that these molecules are characterized not only by significantly lower molecular mass, in comparison to that of native starch, but also by increased branching. Therefore, pyrodextrins adopt a very compact structure in solution and show Newtonian behavior under shear in spite of their molecular masses of tens of thousands Daltons. The results also indicate that 50% reduction of digestibility of pyrodextrins is, to a minor extent, caused by formation of low-molecular color compounds containing carbonyl functional groups. The main reason is, as postulated in the literature, transglycosidation that leads to decreased occurrence of α-1,4-glycoside bonds in the molecular structure. In the process of dextrinization starch also undergoes changes in supermolecular structure, which, however, have no influence on digestibility. Likewise, the effect of formation of low-molecular colorful compounds containing carbonyl groups is not crucial. [ABSTRACT FROM AUTHOR]

The aims of this study were to: (1) evaluate the effect of each stage of HACD + MWVD on the drying kinetics and quality parameters of blueberries, including color, overall appearance, mechanical and physical attributes, and rehydration potential; (2) select proper combination order and conversion point of HACD + MWVD to minimize physicochemical changes and maintain high quality of blueberries. The results were compared with HACD and MWVD alone. A linear equation produced a good fit to data describing the drying kinetics of the constant or first falling rate period, whereas the Henderson and Pabis model was a good fit for the dataset describing the second falling rate period. The color changes induced in berries by HACD + MWVD were limited (ΔE*ranged from 3.08 ± 2.25 to 3.65 ± 2.28) in comparison with HACD (ΔE*ranged from 7.90 ± 2.29 to 8.21 ± 1.77). HACD + MWVD contributed to the achievement of significantly lower values of hardness, chewiness, and gumminess in blueberries, compared to HACD. Multi-stage HACD + MWVD with hot air predrying at 80°C until the achievement of the moisture content of 1.95 ± 0.05 kg · kg−1db caused the lowest shrinkage of blueberries. Blueberries dried by multi-stage HACD +MWVD with hot air predrying at 80°C until the achievement of moisture content of 1.95 ± 0.05 kg · kg−1db were characterized by the highest rehydration potential, in terms of moisture content, rehydration ratio, and water gain; i.e., 4.15 ± 0.02 kg · kg−1db, 4.02 ± 0.05 g · g−1db, 4.07 ± 0.01 g · g−1db, respectively. [ABSTRACT FROM AUTHOR]