Mara Lucisano

Influence of Psyllium, sugar beet fibre and water on gluten-free dough properties and bread quality

Celiac patients generally have a low intake of protein and fibre attributed to their gluten-free (GF) diet. To satisfy the increasing demand for healthier products, this research focused on the effects of the supplementation of Psyllium (P) and sugar beet fibre (SB) on the mixing and leavening behaviour of gluten-free doughs. Four doughs, having different consistencies that made them suitable to be poured into moulds or to be shaped, and their corresponding breads were evaluated. The results obtained suggested that a lower consistency is preferred to assure good dough performances during leavening, in particular when ingredients having a high water affinity are included into the recipe. Both P and SB improved the workability of the doughs, but P played a central role on GF bread development, thanks to its film forming ability, and evidenced a more effective antistaling effect, thanks to its high water binding capacity.

Macromolecular interactions and rheological properties of buckwheat-based dough obtained from differently processed grains.

The physicochemical properties of the protein and starch fractions of flour obtained from buckwheat grains that were previously dehulled or puffed after dehulling were investigated. Dehulling removed most of the nonprotein, nonstarch components of the grain, without affecting the chemical and structural features of the protein and starch components, as made evident by microstructural and spectroscopic measurements. Puffing resulted in extensive modifications of the interprotein network as well as in most of the properties of the buckwheat starch. Flours obtained from dehulled or puffed after dehulling grains were blended with 60-80% wheat flour and tested for their dough-making ability. Blends containing dehulled and puffed buckwheat flours gave dough of much lower quality than dehulled, but had water-holding properties that may be of interest for the shelf life of baked products.

Performance of a series of novel N-substituted acrylamides in capillary electrophoresis of DNA fragments

DNA separations by capillary electrophoresis in viscous solutions of novel polymers, made with Ω-hydroxyl, N-substituted acrylamides (notably N-acryloyl amino propanol, AAP and N-acryloyl amino butanol, AAB) are evaluated. Whereas in standard poly(acrylamide), at 6% concentration, the theoretical plate number (N) does not exceed 500 000, in 6% poly(AAP) N reaches 922 000 and in 6% poly(AAB) N values as high as 1 200 000 are obtained. Also, copolymers of AAP and AAB give N values in excess of 1 million plates. The two novel monomers (AAP and AAB) remain extremely stable during alkaline hydrolysis and display very good hydrophilicity, while being devoid of the noxious habit of auto-polymerization and auto-reticulation exhibited by the previous monomer of this series (N-acryloyl amino ethoxy ethanol). The reasons for such a good performance of the Ω-substituted acrylamide derivatives could be that their polymers may form hydrogen bonds via their distal -OH group during DNA separation.

Minimisation of instrumental noise in the acquisition of FT-NIR spectra of bread wheat using experimental design and signal processing techniques

Spectral resolution (R) and number of repeated scans (S) have a significant effect on the S/N ratio of Fourier transform-near infrared (FT-NIR) spectra, but the optimal values of these two parameters have to be determined empirically for a specific problem, considering separately both the nature of the analysed matrix and the specific instrumental setup. To achieve this aim, the instrumental noise of replicated FT-NIR spectra of wheat samples was modelled as a function of R and S by means of the Doehlert design. The noise amounts in correspondence to different experimental conditions were estimated by analysing the variance signals derived from replicate measurements with two different signal processing tools, Savitzky–Golay (SG) filtering and fast wavelet transform (FWT), in order to separate the “pure” instrumental noise from other variability sources, which are essentially connected to sample inhomogeneity. Results confirmed that R and S values leading to minimum instrumental noise can vary considerably depending on the type of analysed food matrix and on the different instrumental setups, and helped in the selection of the optimal measuring conditions for the subsequent acquisition of a wide spectral dataset.

Physical and structural changes induced by high pressure on corn starch, rice flour and waxy rice flour

The impact of high pressure (HP) processing on corn starch, rice flour and waxy rice flour was investigated as a function of pressure level (400MPa; 600MPa), pressure holding time (5min; 10min), and temperature (20°C; 40°C). Samples were pre-conditioned (final moisture level: 40g/100g) before HP treatments. Both the HP treated and the untreated raw materials were evaluated for pasting properties and solvent retention capacity, and investigated by differential scanning calorimetry, X-ray diffractometry and environmental scanning electron microscopy. Different pasting behaviors and solvent retention capacities were evidenced according to the applied pressure. Corn starch presented a slower gelatinization trend when treated at 600MPa. Corn starch and rice flour treated at 600MPa showed a higher retention capacity of carbonate and lactic acid solvents, respectively. Differential scanning calorimetry and environmental scanning electron microscopy investigations highlighted that HP affected the starch structure of rice flour and corn starch. Few variations were evidenced in waxy rice flour. These results can assist in advancing the HP processing knowledge, as the possibility to successfully process raw samples in a very high sample-to-water concentration level was evidenced. INDUSTRIAL RELEVANCE This work investigates the effect of high pressure as a potential technique to modify the processing characteristics of starchy materials without using high temperature. In this case the starches were processed in the powder form - and not as a slurry as in previously reported studies - showing the flexibility of the HP treatment. The relevance for industrial application is the possibility to change the structure of flour starches, and thus modifying the processability of the mentioned products.

Development of a Type I gluten‐free sourdough

The aim of this study was the setting up of a gluten‐free sourdough from selected lactobacilli and yeasts isolated from a traditional wheat‐based Type I sourdough. A gluten‐free matrix was inoculated with Lactobacillus sanfranciscensis and Candida humilis, fermented to pH 4·0, and constantly propagated for ten times. A stable association between micro‐organisms was observed from the second refreshment with mean values of 9·08 ± 0·25 log CFU g−1 for lactobacilli and 7·81 ± 0·07 log CFU g−1 for yeasts. In order to have a good workability of the dough, a 230 BU consistency was considered. Rheofermentographic indices remained constant over the ten refreshments, showing an average value of 23·2 mm dough height in about 7·5 h. The CO2 production and retention volumes reached average values of 1430 and 1238 ml respectively. The microbiological and technological data obtained highlighted that a GF sourdough was effectively developed.

Shelf life extension of whole-wheat breadsticks: Formulation and packaging strategies

The aim of this study was the shelf life extension of whole-wheat breadsticks through the addition of a rosemary extract and packaging under nitrogen. Shelf life was studied at four temperatures (20, 27, 35, 48°C) for up to 200 storage days. The minimal changes observed in moisture, water activity and texture of the samples, coupled with the high peroxide values (13-539meqO2/kgfat) measured at the end of storage, and the exponential increase of hexanal concentrations (up to 13-34mg/kg) confirmed that quality decay of whole-wheat breadsticks is mainly associated to lipid oxidation. The kinetic study of oxidation development and the consumer sensory acceptance determined by the survival analysis demonstrated that the rosemary extract addition yields a 42% shelf life extension, higher than that observed using nitrogen in the package (24-29%). The combination of the formulation and packaging strategies gave the best result (83% shelf life extension at 25°C).

On the nature and the practical relevance of the molecular modifications induced in wheat proteins by high pressure treatment

Abstract Modifications induced by the combined application of pressure (up to 800 MPa) and temperature (up to 80° C) were studied on wet and dry semolina, and on fresh pasta as such and after cooking. Rheological and immunochemical properties of the treated products were investigated, along with parameters indicating the extent of protein denaturation. No modification occurs in semolina treated at less than 45% water, below 60°C/800MPa for 10min. Egg noodles prepared from pressure/heat treated semolina had increased protein digestibility and low recognition by anti-gliadin antibodies either before or after cooking. The same effects were observed in heat/pressure treated pasta, but were lost upon subsequent cooking, although we found decreased immunochemical reactivity after heat/pressure treatment of cooked pasta. No sensory difference was found between cooked and pressure-treated semolina products.

Gluten-Free Bread : Influence of Sourdough and Compressed Yeast on Proofing and Baking Properties

The use of sourdough is the oldest biotechnological process to leaven baked goods, and it represents a suitable technology to improve traditional bread texture, aroma, and shelf life. A limited number of studies concerning the use of sourdough in gluten-free (GF) breadmaking have been published in comparison to those on traditional bread. The aim of this study was to compare the properties of GF breads obtained by using a previously in-lab developed GF-sourdough (SD), compressed yeast (CY; Saccharomyces cerevisiae) or their mixture (SDCY) as leavening agents; more specifically, it aims to confirm the findings of a previous studies and to further improve (both in terms of recipe and process) the features of the resulting GF breads. Dough pH and rheological properties were measured. Fresh and stored breads were characterized for weight, height, specific volume, crust and crumb color, moisture, water activity, crumb hardness, and porosity. The combination SDCY was effective in improving bread volume and softness when compared to SD only. Furthermore, SD- and SDCY-crumbs exhibited a less crumbly behavior during storage (69 h, 25 °C, 60% of relative humidity) in comparison to CY-breads. This study confirms the positive effect of SD in GF breadmaking, in particular when used in combination with CY.

A new micro-baking method for determination of crumb firmness properties in fresh bread and bread made from frozen dough / Entwicklung eines Mikrobackversuches zur Evaluierung der Krumeneigenschaften von frischen Broten und Broten aus vorgegarten Tiefkühlteiglingen

Summary In general, micro-baking tests are used to determine the baking quality when only low amounts of test flour are available, for example, in grain breeding. Several micro-methods are described in literature, but none of them allows the determination of bread crumb texture parameters. Therefore, a micro-baking procedure that offers this option was developed, and it was also evaluated for bread made from pre-fermented frozen doughs. In this procedure, Rapid Visco Analyser (RVA) sample cans were used as baking pans. To examine the capability of this procedure, three wheat flours with different starch properties were chosen. The obtained breads were analyzed with respect to specific loaf volume, crust color and bread crumb firmness. Additionally, a storage test (0-5 days) was performed to determine the crumb firming parameters by kinetics of the Avrami equation. The obtained specific bread volumes revealed significant differences between the flours and the coefficients of variation ranged between 4.2 and 5.5%. Crumb firmness measurement was able to identify significant differences within the samples. The obtained data on firming kinetics reflected the expected properties of samples with different starch properties. Overall, this work demonstrated the feasibility of crumb property measurement on breads on a micro-scale.