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The main limitation of salting is its extended processing time, mainly caused by the slow diffusion of salt into the muscle tissue. The diffusion process can be accelerated by different technologies such as moderate electric fields (MEF) and CO2-laser microperforations. The main objective of this research was to evaluate the implementation of a combined MEF-CO2-laser-microperforation treatment on the acceleration of the salting process in Atlantic salmon (Salmo salar) and its influence on the effective diffusion coefficient (Deff). Salmon fillets were cut in cylinders. Microperforations at 50 and 100% depth into salmon tissue were produced axially with a 100 W CO2 laser. For MEF treatment an electric field strength of 1 V/cm was used. Salt concentrations along time were analyzed through Fick’s second law and anomalous diffusion models, considering a finite cylindrical geometry. As a result, treatment with micropores-MEF achieved a salt concentration of 3.5% after 4 h, while the control required 12 h to reach the same salt concentration. When both technologies were simultaneously applied, both Deff and final equilibrium salt concentration were increased, thus resulting in a significant reduction in salting time. The mathematical analysis showed good fit through the anomalous, presenting a sub-diffusive (α

A simple method to study the diffusion of a probe molecule into muscle tissue, which considers real composite architecture and anisotropy, was proposed. An anisotropic diffusion study of methylene blue (MB) as a probe molecule into the composite muscle tissue of salmon (Salmo salar) was performed using an image-processing technique. The concentration profile was determined in the middle sagittal plane by considering the muscle fiber orientation angle (θ). The mean value of the angle was θ = 31 ± 1.2°, and the fractional anisotropy values showed an anisotropic behavior for all samples tested. The presence of the discontinuity between muscle and connective tissue was characterized by the distribution coefficient. The simulation using the generalized minimum residual method iterative solver in COMSOL Multiphysics™ software described the anisotropic condition of the tissue with root mean square values of less than 27%. Significant differences were found in effective diffusion coefficient values between the muscle and connective tissue at 2 °C (p-value

Free fatty acid (FFA) release from the in vitro digestion of an emulsion-filled gel using three different particle size distributions and its modeling using the Weibull function and Gallagher–Corrigan model were investigated. To produce the emulsion-filled gel, an oil/water mix was prepared and blended with sodium alginate to finally produce small calcium alginate gel cubes. Three different particle size area distributions were generated by comminuting the cubes applying 5, 10, and 15 cycles of compression/shearing. The particles were intestinally in vitro digested, and the fraction of FFA released was calculated and analyzed using the Weibull function and Gallagher–Corrigan model. The FFA release showed a sigmoidal behavior for the three particle distributions; the Weibull function did not show a good fit. The Gallagher–Corrigan model presented a good fit to the FFA data, reinforced with a random error distribution. The model parameters were able to explain the kinetic processes related to both surface emulsion release and emulsion release by matrix dissolution. In addition, some parameters were linearly correlated (R2 > 0.99) with particle size, which established a relationship between particle size and the kinetics of release attained during the first stage of the digestion curve.

A proteolytic susceptibility index was proposed to evaluate the reaction performance of different food by-products with subtilisin. Whey, salmon muscle and feather keratine were hydrolyzed at the same peptide bond concentration at 50 °C and pH 8.0 with different subtilisin concentrations. The logarithmic equation P = 1/b ln(abt+1) was fitted to estimate the kinetic constants a and b. The a/b ratio was proposed as a proteolytic susceptibility index, which was correlated with the chemical structure and conformation of protein sources in increasing order of feather keratin, salmon muscle and whey proteins with corresponding a/b values of 0.1, 8.2 and 14.4 mM2/min, respectively. The methodology proposed in this work can be used to evaluate the proteolytic susceptibility of different protein by-products to different proteases and to evaluate the changes in proteolytic susceptibility after treatment.

Freeze-dried berry fruits are generally consumed as they are, whole and without peeling or cutting, as the conservation of their original shape and appearance is often desired for the final product. However, usually, berries are naturally wrapped by an outer skin that imparts a barrier to vapor flow during freeze-drying, causing berry busting. Photo-sequence, experimental, and theoretical methodologies were applied to evaluate the application of CO2 laser microperforations to blueberry skin. Under the same set of freeze-drying conditions, blueberries with and without perforations were processed. The results showed that the primary drying time was significantly reduced from 17 &plusmn, 0.9 h for nontreated berries to 13 &plusmn, 2.0 h when nine microperforations per berry fruit were made. Concomitantly, the quality was also significantly improved, as the percentage of nonbusted blueberries at the end of the process increased from an average of 47% to 86%. From a phenomenological perspective, the analysis of the mass transfer resistance of nontreated fruits, in agreement with reported studies, showed a Type II curvature, with a sharp decrease at low time, followed by a linear increase. In contrast, blueberries with nine perforations depicted a Type III regime, with a saturation curvature toward the time axis. It was demonstrated that CO2-laser microperforation has high potential as a skin pretreatment for the freeze-drying of blueberries.

The objective of this research was to explore the advantages of apple slices dehydration (cv. Granny Smith) using a Refractance Window (RW) with and without osmotic dehydration as pretreatment and compared with conventional hot‐air drying considering the quality attributes such as color and texture. For pretreatment, the apple slices were osmotically dehydrated and coupled to a moderate electric field (9.3 V/cm) using a sucrose solution (45°Brix) at 40°C until an Aw = 0.95 was achieved. Then, apple slices (with and without pretreatment) were dehydrated using RW at 55, 75, and 95°C and compared with conventional hot‐air drying at 55°C as a control. The results showed that with dehydration using RW, both with and without pretreatment at 95°C, it was possible to achieve a similar quality of apple slices when compared with conventional hot‐air drying at 55°C, but with a significant reduction in processing time. Additionally, the dehydration process using RW presented anomalous diffusion behavior on apple slices with an α > 1. PRACTICAL APPLICATIONS: Refractance Window (RW) is a technology used for dehydration of fruit and vegetables slices and pulp based on the refractance properties of wet materials. RW has reported promising results in processing time reduction as compared with conventional dehydration methods. In addition, the quality of the end products by RW is higher as compared with conventional drying methods. In this research, we have showed that the final product (dehydrated apple slices) using RW attained quality values (color and texture) similar to those obtained with osmotic dehydration (OD) coupled with moderate electric field (MEF)/hot‐air drying. However, the time spent by RW (50 min) was much lower than OD coupled with MEF/hot‐air drying (240 min). Then, the main advantage of RW is the capacity to dehydrate fruit and vegetables materials using temperatures around 100°C, which allow both, reduce processing time and also attain high‐quality retention.

The aim of this work was to validate a mathematical model and evaluate hydrolysis of salmon muscle proteins by Alcalase in batch reactor. The inhibition constants were correlated with conversion and temperature thus improving dramatically the agreement between model predictions and experimental hydrolysis time courses. The standard operation in batch reactor consisting in pre-heating, isothermal stage and inactivation of enzyme was evaluated through simulation of different operational strategies based on increasing temperature gradients. Operational conditions were 7.5%(w/w) protein, 1 g/l Alcalase and different temperatures from 50 °C to 73 °C. The optimal temperature for the standard process was 68 °C with a processing time of 41 min. Different operational strategies, included temperature profiles, resulted in longer operation times. The standard process was the best reactor performance due to the maximization of the enzyme efficiency.