Pierre-Sylvain Mirade

Fish industry operators have to process fish that arrive at various postmortem times. Postmortem time constrains processing and impacts product quality, safety, and economic value. The objective identification of biomarkers is desirable to predict the postmortem day of aging and this requires a comprehensive longitudinal characterisation of postmortem aging. We analysed the postmortem aging process in trout over a 15-day window. Quantitative physicochemical measurements (pH, colour, texture, a_w, proteolysis, and myofibrillar protein solubility) performed on the same fish over time revealed the levels of protein denaturation, solubility, and pH, among other parameters, change very little when assessed by conventional chemical methods. Histological analyses were performed on thin sections and revealed fibre ruptures after 7 days of storage on ice. Ultrastructures were observed by transmission electronic microscopy (TEM) and revealed that sarcomere disorganisation occurred more often after 7 days of storage. Label-free FTIR micro-spectroscopy combined with a SVM model accurately predicted the postmortem time. Spectra-based PC-DA models also enable the identification of biomarkers corresponding to Day 7 and Day 15 postmortem. This study provides insights on postmortem aging and raises prospects for the rapid assessment of trout’s freshness status from label-free imaging.

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, a_w, 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.

This study investigated the effect of combining tumbling and sous-vide cooking processes on the tenderness, cooking losses and colour of bovine Semitendinosus (ST) muscles sampled from Charolais-breed cows. Half of the ST muscles were tumbled for 12 h with a compression rate of 40%. All muscle samples, whether tumbled or not, were then sous-vide cooked at 50 °C, 60 °C or 80 °C for 1 h or 4 h. After cooking, we measured the shear forces (SF), cooking losses, total water content and the main colour characteristics of pre-tumbled and non-tumbled meat pieces. Pre-tumbled meat pieces had 20% lower SF values than non-tumbled meat pieces, regardless of the cooking conditions applied. All meat pieces cooked at 50 °C had significantly higher (p < 0.05) SF values and lower (p < 0.05) cooking losses than meat pieces cooked at 60 °C or 80 °C. Pre-tumbled meat pieces showed significantly lower cooking losses (p < 0.001) than non-tumbled meat pieces. Applying the tumbling process before cooking led to an increase in meat colour lightness values (p < 0.001), and the colour parameters were significantly affected (p < 0.05) by temperature, cooking time, and temperature × cooking time interaction. Combining a 12-h tumbling process with cooking at 60 °C appears to provide the best compromise between increasing meat tenderness and limiting cooking losses.

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.

Tenderness is a major factor in consumer perception and acceptability of beef meat. Here we used a laboratory tumbling simulator to investigate the effectiveness of the tumbling process in reducing the toughness of raw beef cuts. Twelve Semitendinosus beef muscles from cows were tumbled according to four programs: T1 (2500 consecutive compression cycles (CC), for about 3 h), T2 (6000 CC, about 7.5 h), T3 (9500 CC, about 12 h), and T4 (13,000 CC, about 16 h). The effect of tumbling on the toughness of raw meat was assessed using compression tests (stresses measured at 20% and 80% of deformation ratios) and microscopic observations made at the periphery and centre of meat samples, and compared against non-tumbled controls. Longer tumbling times significantly reduced the stresses measured at 20% and 80% compression rates, which reflected the toughness of muscle fibres and connective tissue, respectively. At the microscopic level, longer tumbling times led to reduced extracellular spaces, increased degradation of muscle structure, and the emergence of amorphous zones. A 12-h tumbling protocol ultimately makes the best compromise between the process time demand and toughness reduction in beef Semitendinosus meat pieces.

A mathematical model predicts the gastric digestion of meat proteins and quantifies the impacts of physiological factors on digestibility.