Investigation into the Physicochemical and Textural Properties of an Iron-Rich 3D-Printed Hybrid Food.

In the context of dietary transition, blending animal-source protein with plant-source protein offers a promising way to exploit their nutritional complementarity. This study investigates the feasibility of formulating an iron-rich hybrid food product blending plant-source and animal-source protein ingredients for iron-deficient populations. Using a commercial 3D-food printer, two different-shaped products composed mainly of pork and chicken liver and red lentils were designed. After baking at 180 °C with 70% steam, the 3D-printed products were packed under two different modified atmospheres (MAP): O2-MAP (70% oxygen + 30% carbon dioxide) and N2-MAP (70% nitrogen + 30% carbon dioxide) and stored at 4 °C. pH, water content, aw, lipid oxidation, heme iron and non-heme iron contents and textural properties were measured after 0, 7, 14 and 21 days in storage. After 21 days in storage, the 3D-printed hybrid products had an iron content of around 13 mg/100 g, regardless of the product form and packaging method. However, O2-MAP products showed significant (p < 0.05) time-course changes from day 0 to day 7, i.e., an increase in lipid oxidation, a decrease in heme iron content and an increase in product hardness, gumminess and chewiness. This work opens prospects for developing hybrid food products that upvalue animal by-products.

Effect of dry salt versus brine injection plus dry salt on the physicochemical characteristics of smoked salmon after filleting.

Smoked fish fillets are pre-salted as a food conservation and quality preservation measure. Here we investigated biochemical and sensory aspects of smoked salmon fillets. Left-side salmon fillets were dry-salted while the right-side fillets underwent a mixed salting method consisting of an injection of saturated brine followed by surface application of dry salt. After 6 h of salting, all the fillets were smoked. At each step of the process, quality was evaluated using instrumental measurements (pH, color, texture, water content, salt content, aw), and lipid distribution was visualized by MRI. Mixed-salted fillets had a higher salt content than dry-salted fillets and variability in salt distribution was dependent on the salting process. However, these variations had no effect on pH, color or texture, which showed similar values regardless of salting method. Fatty areas had a lower salt content due to slower diffusion of aqueous salt solutions through them. Mixed salting speeds up the salting of the muscle without significantly affecting the quality traits of the salmon fillet.

Development of a 3D Printer for the Manufacture of Functional Food Protein Gels.

The use of additive manufacturing is growing in multiple sectors, including food, and its scientific and technological challenges form the subject of much ongoing research. One current hurdle is the implementation of the 3D printing process for meat protein matrices. This article gives an overview of the various 3D printers used to study the printability properties of foods and presents the development of a 3D printer designed to print food protein gels. Printhead development (flow rate and temperature control) and the modifications made to the printing plate (temperature control) are described and discussed in relation to the constraints highlighted in a first prototype. A second, developed prototype was characterized and validated. This last phase showed perfect control of the prototype in the purging of the extrusion system, the flow rate, the calibration and the displacement of the printhead, along with the temperatures at both printhead and plate. A study of the printed gels also revealed good repeatability of the printed gel geometry and pointed to new ways to improve the process. In the near future, the protein gels that will be printed from this prototype will serve as a base for texturizer-free functional foods for people with chewing difficulties.

Physicochemical and microbiological characteristics of El-Guedid from meat of different animal species.

El-Guedid is an Algerian traditional meat-based product that is prepared from red meats. It belongs to the wide diversity of salted/dried meat products. This study described the physicochemical and microbiological properties of different products from four animal origins and during all the conservation. Results indicated that these products were mainly characterized by a low moisture with an average decrease of water content between 15.6% and 16.3% for all the samples, and a decrease in water activity ranging from 0.66 to 0.68, while the salt content ranged from 8.8 to 19.3%. A decrease in pH values oscillated from (6.3-6.4) to reach (5.2-5.5) at T0 and T365 consecutively, in all the samples. Microbial analyses revealed the absence of pathogenic bacteria such as Listeria and Salmonella but the sporadic contamination by Staphylococcus aureus up to one month of ripening. Lactic acid bacteria and coagulase negative staphylococci were the dominant populations in El-Guedid with Leuconostoc mesenteroides, Lactobacillus sakei, and Staphylococcus saprophyticus as the main species identified. All these populations decreased along the process and reached low levels (2 log CFU/g) at the end of storage (365 days). The drastic drying of El-Guedid led to safe traditional meat product that could promote its production.

Simulation of the gastric digestion of proteins of meat bolus using a reaction-diffusion model.

A reaction-diffusion mathematical model has been developed to predict the gastric digestion of meat proteins. The model takes into account pepsin diffusion and proton diffusion in bolus particles and the pH buffering capacity of meat. The computations show that the size of bolus particles and the change in gastric pH have a substantial effect on the percentage of protein digested in the stomach and that the pH buffering capacity of meat has to be accounted for to properly calculate the gastric digestibility of meat. The intensity of surface transfers between stomach fluid and bolus particles has a significant impact on protein digestibility, whereas the variation in pepsin content in the stomach between individuals appears to have little effect on protein digestibility. From a nutritional standpoint, the simulations show that meat protein digestibility is high under normal physiological stomach conditions. However, in a situation where masticatory capacity, hydrochloric acid secretion and gastric motor function performances are reduced, such as with advancing age, protein digestibility rapidly decreases, ultimately leading to near-zero digestibility value in the stomach in extreme cases.

Relation between crust development and heterocyclic aromatic amine formation when air-roasting a meat cylinder.

The meat crust that develops during cooking is desired by consumers for its organoleptic properties, but it is also where heterocyclic aromatic amines (HAs) are formed. Here we measured HAs formation during the development of a colored crust on the surface of a beef meat piece. HAs formation was lower in the crust than previously measured in meat slices subjected to the same air jet conditions. This difference is explained by a lower average temperature in the colored crust than in the meat slices. Temperature effects can also explain why colored crust failed to reproduce the plateauing and decrease in HAs content observed in meat slices. We observed a decrease in creatine content from the center of the meat piece to the crust area. In terms of the implications for practice, specific heating conditions can be found to maintain a roast beef meat aspect while dramatically reducing HAs content.

Quantitative study of the relationships among proteolysis, lipid oxidation, structure and texture throughout the dry-cured ham process.

Temperature, salt and water contents are key processing factors in dry-cured ham production. They affect how proteolysis, lipid oxidation, structure and texture evolve, and thus determine the sensory properties and final quality of dry-cured ham. The aim of this study was to quantify the interrelationships and the time course of (i) proteolysis, (ii) lipid oxidation, (iii) five textural parameters: hardness, fragility, cohesiveness, springiness and adhesiveness and (iv) four structural parameters: fibre numbers, extracellular spaces, cross section area, and connective tissue area, during the dry-cured ham process. Applying multiple polynomial regression enabled us to build phenomenological models relating proteolysis, salt and water contents to certain textural and structural parameters investigated. A linear relationship between lipid oxidation and proteolysis was also established. All of these models and relationships, once combined with salt penetration, water migration and heat transfer models, can be used to dynamically simulate all of these phenomena throughout dry-cured ham manufacturing.

Analysis of the juice and water losses in salted and unsalted pork samples heated in water bath. Consequences for the prediction of weight loss by transfer models.

This study has analyzed the effect of different factors on variation of meat weight due to juice loss, and variation of water content of pork samples heated in a water bath. The weight loss (WL) was influenced by initial water content of raw meat which can be connected to meat pH, muscle type, and by pre-salting. WL was also influenced by sample thickness and by nature of the surrounding fluid. These effects were significant at 50°C and in thinner samples but decreased as meat temperature and sample thickness increased. WL showed no significant difference in response to prior freezing, applying a surface constraint during heating or varying meat salt content from 0.8 to 2.0%. The results were interpreted from literature knowledge on protein denaturation, contraction and, transport phenomena. Reliably predicting WL from water content variation during heating hinges on taking into account the loss of dry matter and the possible effects of meat pH, sample size or surrounding fluid.

Towards models for the prediction of beef meat quality during cooking.

Heating of beef muscles modifies the water content, the micronutrient content and the colour of beef meat. Juice expelling and loss of water soluble micronutrients were predicted by combined transfer-kinetics models. Kinetics modeling and crust formation are needed to progress toward a reliable prediction of HAAs formation. HAAs formation in uniformly heated beef meat slices was compared with the values issued from the kinetic models developed in literature in liquid systems. The models of literature were adapted to meat slices but the parameter values were different from those determined in liquid systems. Results in meat slices were confronted to the HAAs formation at the surface of bigger meat pieces subjected to air roasting conditions. The transposition of the results from the meat slices towards the bigger meat pieces was not direct because the formation of HAAs was affected by the thickening of the crust and the migration of precursors.

Combined heat transfer and kinetic models to predict cooking loss during heat treatment of beef meat.

A heat transfer model was used to simulate the temperature in 3 dimensions inside the meat. This model was combined with a first-order kinetic models to predict cooking losses. Identification of the parameters of the kinetic models and first validations were performed in a water bath. Afterwards, the performance of the combined model was determined in a fan-assisted oven under different air/steam conditions. Accurate knowledge of the heat transfer coefficient values and consideration of the retraction of the meat pieces are needed for the prediction of meat temperature. This is important since the temperature at the center of the product is often used to determine the cooking time. The combined model was also able to predict cooking losses from meat pieces of different sizes and subjected to different air/steam conditions. It was found that under the studied conditions, most of the water loss comes from the juice expelled by protein denaturation and contraction and not from evaporation.

Dynamic MRI and thermal simulation to interpret deformation and water transfer in meat during heating.

Understanding and controlling structural and physical changes in meat during cooking is of prime importance. Nuclear magnetic resonance imaging (MRI) is a noninvasive, nondestructive tool that can be used to characterize certain properties and structures both locally and dynamically. Here we show the possibilities offered by MRI for the in situ dynamic imaging of the connective network during the cooking of meat to monitor deformations between 20 and 75 °C. A novel device was used to heat the sample in an MR imager. An MRI sequence was developed to contrast the connective tissue and the muscle fibers during heating. The temperature distribution in the sample was numerically simulated to link structural modifications and water transfer to temperature values. The contraction of myofibrillar and collagen networks was observed at 42 °C, and water began to migrate toward the interfascicular space at 40 °C. These observations are consistent with literature results obtained using destructive and/or nonlocalized methods. This new approach allows the simultaneous monitoring of local deformation and water transfer, changes in muscle structure and thermal history.

Synchronous front-face fluorescence spectroscopy coupled with parallel factors (PARAFAC) analysis to study the effects of cooking time on meat.

In this study, the potential of synchronous front-face fluorescence coupled with chemometrics has been investigated for the analysis of cooked meat. Bovine meat samples (thin slices of 5 cm diameter) taken from Longissimus dorsi muscle were cooked at 237 degrees C for 0, 1, 2, 5, 7, and 10 min under control conditions. Synchronous front-face fluorescence spectra were collected on meat samples in the excitation wavelength range of 250 to 550 nm using offsets (Delta lambda) of 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, and 160 nm between excitation and emission wavelengths. The synchronous fluorescence landscape containing 360 spectra was analyzed using PARAFAC. The best PARAFAC model presented 2 components since core consistency values for the first 2 components were 100% and the explained variance was 67.98%. The loading profiles of 1st and 2nd components had an optimal Delta lambda of 70 and 40 nm, respectively, allowing to determine the excitation (exc.) and emission (em.) maxima wavelengths of 1st (fluorescence band at about exc.: 340 to 400/em.: 410 to 470 nm, and peak at exc.: 468/em.: 538 nm) and 2nd (exc.: 294 nm/em.: 334 nm) components. As the loading profile of the 1st component of PARAFAC was assigned to Maillard-reaction products formed during cooking, the profile of the 2nd component corresponded with the fluorescence characteristics of tryptophan residues in proteins. Loadings and scores of the PARAFAC model developed from the synchronous fluorescence spectra enabled to get information regarding the changes occurring in meat fluorophores during cooking of meat at 237 degrees C from 0 to 10 min.

Effects of steam and lactic acid treatments on inactivation of Listeria innocua surface-inoculated on chicken skins.

Effectiveness of combined steam (10 and 60 s, 70 degrees C and 98 degrees C) and chemical treatments, using concentrated solutions of lactic acid (1 and 30 min, 5% and 10% lactic acid), on the inactivation of Listeria innocua inoculated on the surface of chicken skins have been studied. Surviving bacteria on the skin were enumerated immediately after treatment, and after 7 days of storage at 4 degrees C. The most effective treatment was the combination of steam of 98 degrees C and 10% lactic acid with its immediate efficacy being mainly attributed to the applied heat treatment. However, after 7-day storage, the treatment's effectiveness was mainly due to the applied acid treatment, which prevented growth of the bacteria that survived the heat treatment. Milder treatments (70 degrees C steam, 5% lactic acid) revealed a genuine synergy between the heat and acid treatments, paving the way for an effective means of reducing bacterial load on the surface of poultry without affecting the product's "raw" appearance.