Alicia E. Bevilacqua

Partial least squares correlations between sensory and instrumental measurements of flavor and texture for Reggianito grating cheese

Abstract Visual, manual and oral texture descriptors for Reggianito grating cheese were correlated with parameters obtained from an instrumental compression test. Aroma and flavor descriptors were correlated with organic acid concentrations. Linear partial least squares regression was used for the multivariate correlations and proved to be a useful tool. Measurements were done between 30 and 290 days of ripening time. Strain at breaking point was the instrumental texture parameter which best correlated with sensory descriptors: negatively wth visual, manual and oral fracturability; and positively with manual elasticity. Sensory hardness was related to instrumental hardness although the correlation coefficients were not high. Total flavor and aroma intensity were well correlated with propionic acid, suggesting this acid could be a flavor indicator for this type of cheese. Uric and orotic acids changed during ripening yet remained below sensory threshold values.

Optimization of the flocculation stage in a model system of a food emulsion waste using chitosan as polyelectrolyte

The influence of different factors on the dose of chitosan necessary to neutralize electrical charge and to get flocculation in a model system of a sunflower oil/ water emulsion was analyzed. These factors included: ionic strength, pH, size of the drops in the emulsion, concentration of oil and surfactant and type of emulsifier (sodium dodecyl and tetradecyl sulfate). Results showed that the increase of NaCl concentration reduces the dose necessary to produce destabilization and flocculation. The longer the surfactant chain length the greater the chitosan dose to reach zero charge. pH variation did not show any influence on the chitosan dose necessary to flocculate the colloidal system. Increasing globule size led to lower chitosan doses to reach flocculation. A linear relationship between initial values of colloidal charge and electrophoretic mobility was established, allowing the prediction of the optimum dose of chitosan as polyelectrolyte to be applied for the treatment of food emulsion wastes.

Freezing low moisture Mozzarella cheese: changes in organic acid content

Abstract Vacuum-packaged low moisture Mozzarella cheese samples were ripened both by the traditional method at 4°C and after subjecting the samples to a freeze (−20°C)–thaw (4°C) cycle before ageing. Nine organic acids (formic, pyruvic, orotic, uric, lactic, acetic, citric, propionic and butyric) were analyzed each week by high performance liquid chromatography. There was no significant effect of the freeze–thaw cycle on the variations in organic acids content. They were only affected by ripening time. Each organic acid presented a characteristic pattern of change during ripening. Discriminant analysis classified cheeses according to their age.

Effect of processing conditions on the hardness of cooked beef

Abstract Changes in meat tenderness that occur during cooking are generally associated with heat-induced alterations of the components (collagen and myofibrillar proteins) of the primary structure of the muscle tissue. Heat transfer during the cooking process and the related textural changes were simulated numerically in irregular domains by integrating both the differential equation for unsteady state heat conduction and the temperature-dependent kinetic equation that corresponds to textural changes of the cooked meat. A code employing a boundary-fitted grid method was implemented in a numerically conservative form (control volume formulation). The proposed model was verified experimentally on irregularly shaped pieces of beef. The effects of heat transfer coefficient, temperature of the cooking medium, and size of the meat piece on the hardness distribution and average final hardness of the cooked product were studied. When the temperature of the cooking medium was above 85 °C the average hardness was always high, regardless of processing time, even for small pieces of meat. Conversely, low temperatures produce a more tender product, although on large beef cuts this advantage is overcome because of the long cooking times required.

Optimisation of the design parameters in an activated sludge system for the wastewater treatment of a potato processing plant

Abstract Aerated biological reactors at a laboratory scale, fed continuously with a model wastewater system, were used to obtain design parameters of an activated sludge process for the wastewater treatment of a potato processing plant. Experiments were performed using different dilution rates ( D ) ranging between 0.01 and 0.13 h −1 to determine parameters such as: maximum specific microbial growth rate ( μ max ), saturation constant ( K s ), coefficient of microbial decay ( k d ) and true biomass yield ( Y X/S ). Design parameters were calculated from the mass balances of substrate consumption and biomass production under steady state, considering a Monod-type equation to represent the effect of substrate concentration on biomass production rate. The values of Y X/S and k d were obtained from the linear plot of q S (specific rate of substrate consumption) vs. D . Experimental data regression led to Y X/S =0.45 gVSS/g COD and k d =0.024 h −1 . By non-linear regression of q S vs. substrate concentration ( S S ) data the following values were obtained μ max =0.09 h −1 and K s =0.006 g/l. Critical dilution rate was also calculated; it corresponds to the D value for which the cells of a reactor operating under such conditions are destroyed or are eliminated from the system at the same rate than they are produced.

Rheological behaviour of Reggianito Argentino cheese packaged in plastic film during ripening

The effect of plastic film packaging (BK1, Grace) was analysed during ripening of hard cheese (Reggianito Argentino). Cheeses packaged 30 and 45 days after manufacture were compared with traditionally ripened cheeses. The values of soluble and nonprotein nitrogen were determined. No significant differences were found among the three cheese lots in spite of the slightly higher average water content of packaged cheeses. Hardness, breaking force and strain at breaking point were analysed. Packaged cheeses exhibited less hardness and lower breaking force values. Relaxation curves were used to analyse the visco-elastic behaviour. The visco-elastic parameters, (elastic modulus and viscosities) were obtained using the generalized Maxwell model. Results showed that traditionally ripened cheeses were harder and less elastic than packaged cheeses. The relationships between the texture parameters (hardness, breaking force and strain at breaking point) and both the percentage of water-soluble nitrogen compounds and water content variations were mathematically modelled.

Dietary Fiber and Availability of Nutrients: A Case Study on Yoghurt as a Food Model

© 2012 Dello Staffolo et al., licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Dietary Fiber and Availability of Nutrients: A Case Study on Yoghurt as a Food Model

Chitosan Interaction with Iron from Yoghurt Using an In Vitro Digestive Model: Comparative Study with Plant Dietary Fibers

The objective of this work was to investigate the interaction of chitosan with iron from yoghurt by an in vitro gastrointestinal tract model. Taking into account that chitosan is a polysaccharide included in fiber definition by Codex Alimentarius; chitosan behavior was studied and compared with different plant fiber (wheat, bamboo, apple, psyllium and inulin) behaviors, in the same in vitro conditions. Ferrous sulfate was added to yoghurts with each type of fiber. The gastric environment was simulated with HCl (pH 1.0–2.0). The duodenal environment was simulated with NaHCO3 (pH 6.8–7.2) and a dialysis tubing cellulose membrane. Results showed that chitosan had the highest iron retention percentages (53.2% at 30 min; 56.8% at 60 min) interacting in a more pronounced manner with iron than the plant fibers used in this work.