The research, conducted by Yao Zhang and Xia Zhou, began with a simple observation: plant proteases such as papain and bromelain have long been used to tenderize meat, and sodium phytate has been studied on its own as an antioxidant, but nobody had systematically tested the two together in cooked beef. The authors hypothesized a synergy. Ficin, the cysteine protease that makes up roughly 12.31 percent of the protein in fig latex, attacks myofibrillar and connective tissue proteins, physically softening the meat. Sodium phytate, or inositol hexaphosphate, operates on an entirely different axis: it is a powerful chelator that sequesters pro-oxidant metal ions such as ferrous iron and copper, the very catalysts that drive lipid peroxidation and metal-catalyzed protein cross-linking during thermal processing. If both mechanisms held, the combination should outperform either agent alone.

To test this, the team sourced hind limb muscles—the semimembranosus and biceps femoris—from six independent Chinese Yellow cattle aged 24 to 30 months, chilled for 48 hours post-mortem in line with standard industrial practice. The muscles were trimmed and cut into uniform five-centimeter cubes, then marinated at 4 degrees Celsius in a two-to-one water-to-additive mixture with gentle agitation. In the first optimization round, cubes were immersed in fig latex solutions ranging from 0 to 30 grams per kilogram for 120 minutes before being boiled for one hour and subjected to Warner-Bratzler shear force testing on a texture analyzer. Shear force declined steadily as latex concentration rose, bottoming out at 42.05 newtons at 20 grams per kilogram; higher doses offered no further benefit, a classic plateau that fixed the enzymatic component of the formula.

The second round layered sodium phytate onto that optimal latex base, testing concentrations from 50 to 300 milligrams per kilogram. The result was striking. At 200 milligrams per kilogram of phytate, shear force plummeted to 19.15 newtons—less than half the value achieved with fig latex alone and far below the untreated control, which exceeded 36 newtons. Two-way analysis of variance with an interaction term confirmed what the numbers suggested: a statistically significant synergistic interaction between the two additives. The authors are careful to note that the mechanism behind this extra tenderization remains preliminary. Phytate-mediated chelation of iron and copper plausibly suppresses the metal-catalyzed cross-linking that hardens muscle proteins during cooking, but the study did not directly quantify protein cross-links or structural changes, so this explanation awaits confirmation by techniques such as SDS-PAGE, protein carbonyl and sulfhydryl assays, collagen solubility measurements, and microscopy.

Chemical characterization of the latex revealed why it is such a rich bioactive package. Beyond ficin, whose specific proteolytic activity measured 85.62 units per milligram, the exudate contained 6.18 milligrams of phenolics per gram, 2.82 milligrams of flavonoids per gram, and 1.49 milligrams of vitamin C per gram, along with citric and malic acids, tannins, saponins, terpenoids, and coumarins. The phenolics, flavonoids, and ascorbic acid act as chain-breaking antioxidants and free-radical scavengers, while the organic acids and tannins contribute antimicrobial potential, though the study did not experimentally test antibacterial activity. All latex came from a single harvest batch in Jiangsu Province to limit natural variability—an honest acknowledgment that fig latex is inherently inconsistent from season to season and batch to batch, a hurdle any industrial application will have to clear.

Marination time proved to be a delicate variable. When beef cubes were soaked in the optimal 20 grams per kilogram of fig latex, shear force fell from 58.16 newtons at time zero to 24.25 newtons after 120 minutes, and a 24-member trained panel rated overall liking at a remarkable 8.8 on a nine-point hedonic scale—its peak. But here the story takes a counterintuitive turn: when sodium phytate was added and shear force dropped further to 19.15 newtons at the same marination time, liking scores fell to 5.9. The panel, reflecting Chinese culinary preferences for braised beef with moderate chewiness in the 24-to-30-newton range, found the ultra-tender meat pasty and mushy. The authors suggest that processors could tune phytate levels to market taste—lower doses for consumers who prize some bite, higher doses for Western markets accustomed to very soft meat—though they caution that these preferences are culturally specific and may not generalize.

On the oxidation front, the dual treatment delivered a clean win. Thiobarbituric acid reactive substances, the standard proxy for lipid peroxidation, fell to 0.24 micromoles per gram in the combined treatment, a 33.3 percent reduction from the untreated control value of 0.36 micromoles per gram. Sodium phytate alone reduced TBARS dose-dependently from 0.35 to 0.24 micromoles per gram across its tested range, consistent with its known ability to block Fenton-driven radical production by tying up iron and copper. The authors propose a division of labor: phytate chelation likely dominates the early initiation stage of oxidation, while fig polyphenols terminate radical chain propagation later in storage. They are candid, however, that the experimental design could not quantitatively separate these two contributions, and that sequential reagent addition or selective functional masking experiments would be needed to decouple them.

The storage trial put the formula to its most practical test. Treated cubes, vacuum-packed and refrigerated at 4 degrees Celsius, maintained significantly lower shear force and TBARS values than controls across ten days, with day-10 TBARS at 0.28 micromoles per gram. Sensory scores for the treated samples stayed above the consumer rejection threshold of 5.0 for the entire period, while untreated controls dropped below that line by day six, at which point control sampling was discontinued. Because ficin is a heat-labile enzyme that is almost certainly inactivated during the one-hour boil, the authors attribute the lasting tenderness to proteolytic modifications made before cooking rather than any ongoing enzymatic activity—a subtle but important mechanistic point. The persistent quality advantage instead reflects the structural changes ficin imparted during marination, phytate’s sustained metal chelation, and the radical-scavenging capacity of the latex phenolics.

The study’s limitations are clearly flagged: no microbiological data, no direct molecular evidence for the proposed mechanisms, a laboratory scale of operation, and a single harvest of latex. Real-world adoption will also require answers on raw material standardization, regulatory approval, production cost, batch consistency, and the allergenicity of fig latex, a substance known to cause reactions in some individuals. Still, the core finding stands as an appealing proof of concept. Two natural, inexpensive, food-grade agents—one scraped from the skin of an unripe fig, the other a staple of grain chemistry—can jointly make cooked beef dramatically more tender, measurably more resistant to oxidative rancidity, and acceptable to consumers for days longer than untreated meat. For small and medium meat processors who cannot afford high-pressure equipment, sous-vide lines, or gamma irradiation, and who face mounting consumer pressure to drop synthetic preservatives in favor of clean-label ingredients, that combination may prove hard to resist.

Subject of Research: Synergistic use of fig latex and sodium phytate to improve tenderness and oxidative stability of cooked beef

Article Title: Synergistic tenderization and oxidative stabilization of cooked beef by combined fig latex and sodium phytate

Article References: Zhang, Y., & Zhou, X. (2026). Synergistic tenderization and oxidative stabilization of cooked beef by combined fig latex and sodium phytate. Food Chemistry: X, 39, Article 104475. https://doi.org/10.1016/j.fochx.2026.104475

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104475

Keywords: fig latex, sodium phytate, ficin, meat tenderization, lipid oxidation, TBARS, shear force, cooked beef, clean-label preservatives, antioxidants, food chemistry, refrigerated storage

Researchers at Yanbian University in China worked with rump steaks from 36-month-old Yanbian Yellow Cattle, cut from the biceps femoris muscle within 24 hours of slaughter. The steaks, vacuum-packed and weighing roughly 250 grams each, were divided into four treatment groups drawn from the same carcass. One control group was held at 4 degrees Celsius. The others were rapidly frozen in a minus 30 degrees Celsius freezer until their core temperatures reached minus 0.5 degrees Celsius, representing supercooling with little or no ice formation; minus 5 degrees Celsius, representing sub-freezing with partial ice formation; or minus 18 degrees Celsius, representing deep-freezing with complete freezing. Each group was then packed with six pre-frozen gel ice packs in alternating layers, wrapped in an insulating bag, sealed inside an EPS box, and placed in an incubator at 25 degrees Celsius for 48 hours to simulate a realistic summer delivery.

Temperature logging confirmed the scenario the team wanted to reproduce. During the first 15 hours, while the ice packs melted, the core temperature of all pre-cooled groups stayed below zero. Thereafter, temperatures gradually rose, reaching between minus 1.7 and 3.3 degrees Celsius at the delivery stage depending on the treatment. Sampling continued through five days of subsequent refrigerated storage at 4 degrees Celsius, but only while total volatile basic nitrogen, a spoilage marker, remained below the strict threshold of 20 milligrams per 100 grams. The deep-frozen and sub-frozen groups crossed that limit prematurely, a first hint that their quality was deteriorating faster than the others.

Color told the most visible part of the story. Surface color is the attribute consumers weigh most heavily when buying meat, and it depends on the balance between bright red oxymyoglobin and brown metmyoglobin. At the frozen stage, the deep-frozen steaks actually looked best, showing the highest redness values and the highest lightness, the latter reflecting ice-crystal damage that pushed free water to the surface and increased light scattering. But appearances deceived. Once the parcels warmed during simulated distribution, redness in the deep-frozen group fell fastest, and its metmyoglobin content climbed to the highest level of any group during refrigerated storage. The supercooled group, by contrast, showed the slowest decline in redness, the smallest rise in lightness and yellowness, and consistently low metmyoglobin accumulation, indicating that avoiding ice formation preserved both pigment stability and the endogenous antioxidant environment that protects it.

Texture measurements reinforced the pattern. Deep-frozen steaks were initially the most tender, with a shear force of about 82.65 newtons compared with 123.56 newtons for the refrigerated control, because ice crystals physically disrupted the muscle fibers. Yet after the temperature rise of distribution, shear force in the deep-frozen and sub-frozen groups spiked sharply to 142.37 and 132.36 newtons respectively, a hardening attributed to drip loss, fiber shrinkage, and protein denaturation. Later, both groups softened excessively as structural degradation took over, with the deep-frozen group falling to roughly 53 newtons by 72 hours after delivery. The myofibril fragmentation index, a measure of proteolytic breakdown, surged in the frozen groups after distribution, consistent with freeze-thaw damage releasing lysosomal enzymes such as cathepsins, while the supercooled group showed a gradual, orderly increase reflecting normal aging.

The molecular core of the study lay in the myofibrillar proteins, the structural scaffold that governs water-holding capacity and tenderness. These proteins are acutely sensitive to reactive oxygen species: oxidation converts amino acid side chains to carbonyls, unfolds the native alpha-helical structure, exposes hydrophobic groups buried inside the molecule, and drives cross-linking and aggregation. Carbonyl content rose in all pre-cooled groups during pre-cooling itself, showing that even the phase transition imposes oxidative stress. But after distribution the groups diverged dramatically. By 72 hours after delivery, carbonyl content in the deep-frozen group had reached 2.610 nanomoles per milligram and the sub-frozen group 2.287, while the supercooled group sat at only 1.357, close to the refrigerated control.

Surface hydrophobicity, measured by bromophenol blue binding, painted the same picture of unfolding and aggregation. Deep-frozen and sub-frozen samples already showed markedly elevated hydrophobicity before shipping, and values climbed steeply for every group once distribution began. Protein solubility, meanwhile, fell fastest in the deep-frozen group, dropping from 14.043 to 8.791 over 72 hours after delivery, a rate of decline roughly 80 percent faster than the supercooled group’s. Fourier transform infrared spectroscopy of the amide I band added a structural dimension: after distribution, alpha-helix content in the deep-frozen group collapsed from 56.21 percent to 11.25 percent while beta-sheet, a conformation associated with intermolecular aggregation, jumped to 50.19 percent. The supercooled group retained far more ordered structure, with 23.34 percent alpha-helix and only 18.55 percent beta-sheet at the same stage.

Sensory panels of ten trained assessors, evaluated against ISO 8586 standards, confirmed what the instruments recorded. Scores for meat color, fat color, wetness, and firmness declined most rapidly in the deep-frozen and sub-frozen groups after distribution, and by 72 hours after delivery those groups offered little remaining quality. The supercooled steaks maintained relatively high appearance scores, stable wetness, and acceptable firmness for the longest period, translating the molecular advantages into a longer window of consumer acceptability. The pH trajectory mirrored the biochemical sequence: stable and mildly acidic early on, rising near 6.8 as endogenous proteases released alkaline nitrogen compounds, then falling again as psychrotrophic spoilage bacteria presumably produced organic acids in the later stages.

The study’s central insight is the causal chain it draws from pre-cooling state to protein stability to final quality. Deep-freezing buys a larger thermal reserve and a briefly better initial appearance, but the ice crystals it creates, followed by melting and recrystallization during the warm ride, rupture cell membranes, release pro-oxidants and proteolytic enzymes, and set off a cascade of moisture exudation, pigment oxidation, carbonylation, unfolding, and aggregation. Supercooling at minus 0.5 degrees Celsius threads a needle: it supplies enough cold reserve to blunt the thermal shock of passive distribution while sidestepping the phase transition and its physical damage entirely. For the EPS box and ice pack systems that dominate fresh meat e-commerce, the authors conclude, supercooled pre-cooling is the strategy most likely to deliver beef that still looks, feels, and tastes the way the shopper expects, and the findings offer cold-chain planners a molecularly grounded rationale for rethinking how far down the thermometer a shipment should go before it leaves the warehouse.

Subject of Research: Effects of supercooling, sub-freezing, and deep-freezing pre-cooling on beef quality and myofibrillar protein stability during EPS-based e-commerce distribution

Article Title: Effects of supercooling, sub−freezing, and deep−freezing pre−cooling on color, pH, shear force, sensory quality, and myofibrillar protein properties of beef during expanded polystyrene−based distribution

Article References: Effects of supercooling, sub−freezing, and deep−freezing pre−cooling on color, pH, shear force, sensory quality, and myofibrillar protein properties of beef during expanded polystyrene−based distribution. (n.d.). https://doi.org/10.1007/s44463-026-00083-8

Image Credits: AI Generated

DOI: 10.1007/s44463-026-00083-8

Keywords: beef, supercooling, sub-freezing, deep-freezing, pre-cooling, cold chain, e-commerce distribution, myofibrillar proteins, protein oxidation, meat color, shear force, sensory quality