The study, published in Food Science of Animal Resources, set out to optimize high-pressure processing, or HPP, for wild deer loins. HPP is a non-thermal preservation technology that subjects vacuum-packed food to uniform hydrostatic pressure, inactivating microorganisms and enzymes at low temperatures without the sensory and nutritional damage caused by sterilization or pasteurization. The technique is already used commercially on juices, guacamole and deli meats, but its effects depend heavily on the food matrix. Moderate pressures between 300 and 400 megapascals achieve partial microbial reduction while better preserving raw meat quality, whereas pressures above 500 megapascals kill more microbes but can wreck colour and texture. Finding the sweet spot for venison was the goal of Beatriz García-Béjar, Almudena Soriano and colleagues at the University of Castilla-La Mancha, working with the Castilla y León Agricultural Technological Institute.

The raw material came from 16 male Iberian red deer shot during montería hunts in the province of Ciudad Real at the end of the hunting season. Each animal was eviscerated and inspected by a veterinarian in the field, hung in a refrigerated truck and aged for two days at 4 to 5 degrees Celsius before the loins — the longissimus thoracis et lumborum muscles — were extracted. Each left loin was halved and vacuum-packed, with one half kept as an untreated control and the other processed on an industrial Hiperbaric Wave 6000/135 unit, a 135-litre vessel calibrated annually and fitted with alarms that interrupt the cycle if pressure or temperature drifts. Treatments were applied on the fifth day after death, and all analyses were completed one week after slaughter, giving a realistic picture of how the technology would perform in a commercial workflow.

In the optimization phase, the team tested six pressure-time combinations: 350, 450 and 550 megapascals, each for either 3 or 6 minutes, with biological replicates from different animals. Initial bacterial counts hovered around 6 log colony-forming units per gram. The heaviest treatment, 550 megapascals, delivered the biggest microbial kill, reducing viable mesophilic aerobic bacteria by more than 2 log units — roughly 99.5 percent. Treatments at 350 and 450 megapascals still achieved reductions greater than 1 log unit, corresponding to about 94.9 to 96.8 percent. Interestingly, processing time on its own and the pressure-time interaction had no statistically significant effect on bacterial reduction, suggesting that pressure, not duration, is the dominant lever. But the price of brute force became obvious the moment the researchers looked at the meat itself.

Colour is the single most important quality cue for raw meat, and HPP left a visible fingerprint. Control loins bloomed to a bright red after 45 minutes of exposure to oxygen, as myoglobin converted to oxymyoglobin. Treated samples turned a pinkish-brown, and the effect intensified with pressure. Instrumental measurements confirmed the shift: lightness and yellowness values rose across all treatments, while redness dropped significantly from the 450 megapascal, 6-minute condition onward. The mechanism is well understood — myoglobin begins to denature at pressures of 400 megapascals and above, altering the way muscle absorbs and reflects light. A trained sensory panel of four experts with more than 25 years of experience each, working under ISO consensus-profiling protocols, agreed: aroma and tenderness were unaffected, but adhesiveness increased and red colour faded, with the worst damage at 550 megapascals, where colour intensity fell by two to three points on a three-point scale.

Based on this trade-off, the researchers selected 350 megapascals for 6 minutes as the best compromise and put it through a tougher test. Four loins from different animals were deliberately chosen because their high microbial loads reflected particularly poor hygiene during field handling — a worst-case scenario, though not fully representative of the wider population. The results were striking. Mesophilic aerobic bacteria fell by 99.97 percent, from about 7.9 to 4.4 log CFU per gram. Enterobacteriaceae dropped by 99.98 percent, and Escherichia coli by 99.99 percent, plunging from 7.8 to 2.1 log CFU per gram. Staphylococcus spp. counts were cut by 99.99 percent, and neither Salmonella spp. nor Listeria spp. could be detected in treated samples, with absence confirmed in 25-gram portions. Notably, no Staphylococcus aureus was found in any sample, treated or not.

The microbiology behind these numbers is revealing. Gram-negative bacteria such as E. coli and the Enterobacteriaceae are known to be more pressure-sensitive than gram-positive species, whose cross-linked peptidoglycan cell walls provide structural armour. Yet even the gram-positive Staphylococcus spp. in this study collapsed under treatment, a sensitivity the authors attribute to variability in baro-resistance and to the stage of the cell cycle. Rod-shaped bacteria also tend to be more vulnerable than spherical cocci, which helps explain the dramatic elimination of Listeria. The data also hinted that the treatment works harder on dirtier meat: samples starting at 8 log CFU per gram lost 99.97 percent of their bacteria, while cleaner samples starting at 6.1 log CFU per gram lost 94.9 percent. For a sector where carcass contamination ranges from below 2 to over 6 log CFU per square centimetre depending on field practices, that scalability matters.

Crucially, the gentler treatment left the meat’s chemistry largely intact. pH rose only slightly and non-significantly, moisture content was unchanged at around 76 percent, and cooking losses were statistically identical between treated and control loins at roughly 28 to 31 percent. Drip loss during 48 hours of refrigerated storage was actually lower in the pressurized meat, indicating improved water-holding capacity — a potential commercial bonus. The sensory story, however, had a twist. In a triangle test with 14 expert tasters following ISO 4120 protocols, panellists could reliably distinguish raw treated venison from raw controls, citing colour and tactile texture in every case. But once the loins were grilled to an internal temperature of 72 degrees Celsius, the differences vanished: the panel could no longer tell treated from untreated meat. Thermal denaturation of muscle proteins and surface browning reactions appear to homogenize whatever HPP changed, meaning consumers would never notice on the plate.

To understand what pressure actually does to muscle, the team turned to cryo-scanning electron microscopy, freezing samples in liquid nitrogen and imaging them with a field-emission microscope. The treated loins showed clearly defined separation between myofibrils — a subtle structural loosening that likely underlies the increased adhesiveness the panellists noted and the textural differences detected in raw samples. Similar disruption of sarcomere continuity has been reported in myofibrils exposed to 300 megapascals. The authors are careful to frame the work as preliminary: only four loins were used in the validation assay, and larger datasets are needed to confirm the findings and to test whether HPP extends shelf life. Still, the message is compelling. A 6-minute treatment at 350 megapascals can eliminate Salmonella and Listeria and slash bacterial loads by up to 99.99 percent in heavily contaminated wild venison, while leaving pH, moisture and cooked eating quality untouched. For a growing game meat industry operating outside the hygiene controls of conventional slaughterhouses, that combination of safety and subtlety could be exactly what it takes to bring wild deer from the hunting field to the supermarket shelf — and finally to the fork — with confidence.

Subject of Research: Optimization of high-pressure processing conditions for microbial reduction and quality preservation in wild venison

Article Title: Preliminary optimization and quality assessment of high-pressure processing for venison preservation

Article References: García-Béjar, B., González-Fernández, J. L., Alarcón, M., Delgado, B., Peinado, C., & Soriano, A. (2026). Preliminary optimization and quality assessment of high-pressure processing for venison preservation. Food Science of Animal Resources, 46(1), Article 109. https://doi.org/10.1007/s44463-026-00117-1

Image Credits: AI Generated

DOI: 10.1007/s44463-026-00117-1

Keywords: high-pressure processing, venison, game meat, food safety, microbial reduction, Salmonella, Listeria, E. coli, meat colour, sensory analysis, cryo-SEM, water-holding capacity

Moshe H. Azachi and Zeev Wiesman compared two commercially available products that could hardly be more different in structure: an Angus beef burger and a soy-based vegan burger. Both were cooked in an air fryer to an internal temperature of 72 degrees Celsius, then probed with an arsenal of techniques including low-field time-domain nuclear magnetic resonance (TD-NMR), cryogenic scanning electron microscopy, texture profile analysis, and a trained sensory panel. The question was deceptively simple: could measurements of the water inside the burger, taken before anyone chewed it, explain which one would taste juicier?

The answer hinged on a subtle but crucial distinction in physics. When a burger is chewed, the teeth compress and fracture a hydrated soft material, generating pressure gradients that squeeze fluid through interconnected pathways. This mechanically driven serum release is what food scientists increasingly regard as the true proximal driver of perceived juiciness. Molecular self-diffusion, by contrast, is the spontaneous, thermally driven jiggling and translational motion of individual water molecules, measured by pulsed-field-gradient NMR in a completely undeformed sample. The two processes are physically distinct, but the researchers hypothesized they might share common structural determinants: the size of water-filled domains, the connectivity of the aqueous network, tortuosity, interfaces, and the strength of water-protein interactions.

The first surprise came from the moisture numbers. The beef burgers started with 68.05 percent water and the soy burgers with 62.61 percent, a difference that did not reach statistical significance. During cooking, the beef patties lost far more mass, shedding 35.73 percent of their weight compared with 21.21 percent for the soy burgers, and shrank nearly twice as much in diameter. By conventional food-science logic, the soy burger should have been the juicier product: it held onto its water more tenaciously. Instead, the opposite happened. A panel of thirteen trained assessors, scoring five juiciness-related attributes on a ten-point scale, rated the beef burger dramatically higher on every single one, from first-bite juiciness to sustained juiciness, rate of juice release, and mouthcoating. The composite Sensory Juiciness Index came to 7.46 for beef versus 5.00 for the soy burger, a difference the authors report as highly significant.

The decisive instrumental signal came from the NMR diffusion measurements. Using a 20 MHz Bruker Minispec mq20 and the classic Stejskal-Tanner pulsed-field-gradient sequence, the team measured an apparent water self-diffusion coefficient in both the interior and the cooked outer layer of each burger. The beef interior showed the highest value, 1.03 by ten to the minus nine square meters per second, while the soy burger’s outer region showed the lowest, just 0.36 by ten to the minus nine. At the whole-burger level, beef averaged 1.030 and soy 0.704 by ten to the minus nine square meters per second, a difference with a p-value below 0.001. In both products, diffusion decreased from the moist interior toward the dehydrated surface, but the formulation gap dwarfed the regional one.

What makes this result conceptually important is what did not differentiate the burgers. Transverse relaxation times, the T2 values that reflect local molecular environments and confinement, told a murkier story. The longest relaxation components exceeded roughly 300 milliseconds in both matrices and did not differ significantly, and the mean long-T2 values at the parent-burger level were statistically indistinguishable. The soy burger’s outer layer was especially instructive: it combined a comparatively long mono-exponential T2 with a very low diffusion coefficient, demonstrating that water molecules can be locally mobile yet still encounter severe barriers to longer-range displacement. Relaxation and diffusion, in other words, probe different aspects of the water state and cannot be used interchangeably.

Cryogenic scanning electron microscopy provided visual context. The researchers flash-froze small sections from the interior and outer regions of each cooked burger, fractured them under cryogenic conditions, etched them, and imaged them with an in-lens detector at around minus 120 degrees Celsius. The beef samples revealed a heterogeneous architecture of irregular pore-like and hydrated domains with apparently greater continuity, while the soy matrix appeared denser and more homogeneous, with thicker solid regions and lower apparent connectivity, especially in the cooked outer layer. This qualitative morphology paralleled the spatial ordering of the diffusion coefficients, though the authors are careful to note that pore size, mesh dimensions, tortuosity, and three-dimensional connectivity were not quantified, so the structural explanation remains a hypothesis rather than a demonstrated mechanism.

Texture told a similarly incomplete story. The beef burgers were numerically harder and chewier than the soy burgers, though these differences did not reach significance with only three independent parent burgers per formulation, and only cohesiveness differed significantly. The juiciness gap therefore cannot be reduced to a simple soft-versus-hard distinction. What the study does support is a multiscale framework: food architecture shapes the pre-deformation molecular state of water, which TD-NMR can measure non-destructively; during mastication, deformation generates pressure gradients that drive macroscopic serum displacement through whatever pathways the architecture permits; and that released serum lubricates the mouth, producing the sensation of juiciness. The intermediate links in this chain, the actual serum flux and oral lubrication, were not measured here and remain testable propositions for future work.

The authors are equally candid about the limits of their evidence. Because the sensory ratings and the NMR measurements were obtained from separate experimental units rather than matched observations from the same parent burgers, no within-sample correlation between diffusion and juiciness could be calculated. The findings represent concordant formulation-level contrasts, not proof of causation. The study also compared only one commercial beef product and one commercial soy product, so it establishes a contrast between two matrices rather than a universal law of animal versus plant. An exploratory Water Accessibility Index, defined as the ratio of diffusion to relaxation, showed a significant difference between formulations but remains an empirical, unit-dependent descriptor pending external validation.

Even so, the implications for food designers are concrete. Strategies aimed solely at maximizing water-holding capacity or minimizing cooking loss may be fundamentally insufficient: a highly hydrated matrix can still taste dry if its architecture strongly restricts the redistribution of fluid during chewing. The design objective, the authors argue, is not simply to trap water but to retain it through manufacture and cooking while making an appropriate fraction available at the moment of mechanical deformation. Variables such as protein-network organization, domain connectivity, structural anisotropy, lipid distribution, and protein-polysaccharide interactions all become levers worth pulling. And because TD-NMR diffusion is rapid and non-destructive, it could serve as a screening tool that predicts, before a single taste test, whether a reformulated plant-based patty has the architectural prerequisites for a genuinely juicy bite.

Subject of Research: Water self-diffusion measured by TD-NMR in cooked beef and soy-based burger matrices and its relationship to sensory juiciness

Article Title: Water self-diffusion differentiates two protein-based burger matrices with contrasting sensory juiciness

Article References: Azachi, M. H., & Wiesman, Z. (2026). Water self-diffusion differentiates two protein-based burger matrices with contrasting sensory juiciness. Current Research in Food Science, 13, Article 101562. https://doi.org/10.1016/j.crfs.2026.101562

Image Credits: AI Generated

DOI: 10.1016/j.crfs.2026.101562

Keywords: water self-diffusion, TD-NMR, plant-based meat analogues, juiciness, food microstructure, soy protein, beef burgers, sensory evaluation, serum release, Cryo-SEM, food oral processing, water-holding capacity