Carola Cappa

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.

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).

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.