The research team, led by Shaohong Xu and colleagues, built a simplified but rigorous experimental system: casein, the predominant protein in milk, was mixed with glucose at a fixed concentration and incubated at 90 degrees Celsius for up to 24 hours. Into this mixture they added either sodium dihydrogen phosphate, abbreviated MSP, or disodium hydrogen phosphate, DSP, at low and high doses of 10 and 100 millimolar. Crucially, the pH of every sample was adjusted to 7.0 before the reaction began, a design choice that allowed the researchers to isolate the intrinsic chemical effects of the phosphate species and ionic strength from the well-known influence of acidity itself. Samples were then pulled at eight time points, from half an hour to a full day, and interrogated with an arsenal of analytical techniques.

The most visually dramatic result came from simple colorimetry. After 24 hours of heating, the browning index of the untreated control casein reached about 28 units. Adding low-dose MSP slashed that figure to roughly 4.5, producing a nearly white sample, while high-dose MSP still kept browning well below the control at about 17 units. DSP did the opposite: low-dose DSP pushed the index to about 41, and high-dose DSP sent it soaring to nearly 222, an eightfold increase over the control, accompanied by a deep reddish-brown hue. The explanation lies in acid-base chemistry. MSP is a weakly acidic phosphate that pulls the local reaction environment toward lower pH values unfavorable to the Maillard cascade, whereas DSP, a weakly alkaline salt, nudges the local pH upward and thereby facilitates the initial attack of glucose on the protein’s amino groups.

Spectroscopic measurements traced the reaction’s progress through its intermediate and advanced stages. Ultraviolet absorbance at 294 nanometers, a proxy for early Maillard intermediates such as furfurals and reductones, rose steadily in all samples over 24 hours, but the 100 millimolar phosphate groups, both MSP and DSP, accumulated significantly more intermediates than the control throughout the run. Absorbance at 420 nanometers, which tracks the colored melanoidin pigments of the reaction’s late stage, told a complementary story: every phosphate-supplemented sample browned faster than the control, and the effect was clearly concentration-dependent, with the high-dose groups reaching the highest pigment levels. Even the low-dose groups, though weaker, remained measurably above the control, hinting that ionic strength itself can redirect reaction pathways and blunt pigment formation efficiency.

Beneath the color changes, the phosphates were quietly remodeling the protein itself. Dynamic light scattering revealed that the untreated control casein underwent dramatic particle growth during glycation, a signature of aggregation and conformational unfolding. Phosphate-treated samples, by contrast, showed far gentler increases in particle size, and the effect scaled with dose: 100 millimolar phosphate consistently yielded smaller particles than 10 millimolar. This mirrors earlier observations in meat and dairy systems, where phosphates reduce protein diameter and boost solubility through charge shielding and dispersion mechanisms. In practical terms, phosphate addition kept the glycated protein dispersed rather than clumped, a property that also improved water solubility and emulsifying capacity, traits highly prized in beverage and encapsulation applications.

The salts also unmasked the protein’s reactive chemistry. Using the OPA assay to quantify free amino groups, the researchers found that at the very start of the reaction, before any glycation had proceeded, all phosphate-treated samples displayed significantly higher free amino content than the control, with the high-dose DSP group recording the highest value. This indicates that phosphate pretreatment exposes lysine and arginine residues that are normally buried inside the folded protein, handing the glucose molecule more accessible docking sites. Over the first two hours, the phosphate groups showed dynamic shifts, with some samples consuming free amino groups early while the high-dose MSP group sustained elevated levels, demonstrating persistent reactive capacity. Phosphate, in other words, acts not merely as a dispersant but as a molecular chaperone of sorts, rearranging the protein to make it more reactive.

Circular dichroism spectroscopy confirmed that this rearrangement was structural and remarkably fast. Far-UV spectra collected at one, two and 16 hours showed that glycated samples shifted from a highly ordered, beta-sheet-rich conformation toward a more flexible, disordered state. Alpha-helix content rose modestly from about 6 percent in the control to 8 or 9 percent in treated samples, while parallel beta-sheet structure plummeted by 10 to 15 percentage points, and beta-turn and random coil fractions climbed correspondingly. Strikingly, the secondary structure proportions changed by less than 2 percent across the three time points within each sample, meaning the major conformational overhaul was essentially complete within the first hour of heating and then held steady. The loosened, open architecture of the high-dose phosphate samples aligns neatly with their higher free amino exposure and faster glycation kinetics.

To map exactly where glucose and its reactive descendants attached, the team turned to proteomics, digesting the glycated casein with trypsin and analyzing the resulting peptides by nano-scale liquid chromatography coupled to an Orbitrap mass spectrometer. They catalogued glycation sites, carboxymethylation, carboxyethylation, pyrraline, and the hydroimidazolone derivatives of glyoxal and methylglyoxal on lysine and arginine residues. After one hour, the MSP-treated samples showed markedly fewer detectable modification sites than the control, particularly for glucosylation and oxidation, while the DSP samples carried as many or more sites, especially for carboxymethylation and carboxyethylation. By four hours the picture shifted: MSP’s site counts rose steeply, suggesting its early inhibitory grip weakens with time, whereas some DSP markers declined, implying dynamic conversion or masking of modified residues. The authors caution that these counts reflect detectable site distribution rather than absolute glycation extent, since the analysis was not based on peptide-level quantification.

Perhaps the most commercially consequential findings concern flavor. An electronic nose fitted with ten sensors for compound classes ranging from aromatics to sulfides showed that after one hour, the control and high-dose DSP samples emitted the strongest volatile signals, while the MSP groups, especially the low-dose one, yielded the weakest. Gas chromatography-ion mobility spectrometry sharpened the picture: the untreated sample reached normalized intensity values of 100 for aldehydes and alcohols such as hexanal and 1-hexanol, evidence of amino acid degradation and Strecker degradation pathways, whereas high-dose MSP dramatically suppressed pentanal, 2-heptanone and ethyl propanoate. DSP-treated samples, meanwhile, maintained aldehyde, ketone and ester signals comparable to or above the control. Because the model system contained no lipids, these volatiles arose purely from protein-side chemistry, making the contrast especially clean.

Taken together, the study recasts phosphate salts as active, selective regulators of the Maillard reaction rather than inert processing aids. At high concentrations, both salts accelerate glycation by curbing aggregation, exposing amino groups and loosening protein structure, yet they diverge sharply downstream: MSP restrains early glycation and oxidative modification and suppresses aldehyde and ketone formation, supporting flavor stability, while DSP promotes browning and advanced glycation end product accumulation with little effect on the volatile profile. For manufacturers of processed cheese, milk powders and heat-treated dairy formulations, the message is that the choice between these two chemically similar salts is a choice between two different chemical futures for the product, one browner and more aromatically active, the other paler and more flavor-stable. The work offers a mechanistic roadmap for exploiting that divergence deliberately, turning a longstanding empirical art of dairy formulation into a matter of precise molecular control.

Subject of Research: Effects of sodium phosphate salts on the Maillard glycation of casein in dairy systems

Article Title: Effects of sodium dihydrogen phosphate (MSP) and disodium hydrogen phosphate (DSP) on the glycation of casein (CN)

Article References: Xu, S., Hu, X., Sun, Y., Huang, X., Zhou, Z., Han, L., Zhang, Y., Zhang, J., Gao, Y., Wang, L., & Qin, D. (2026). Effects of sodium dihydrogen phosphate (MSP) and disodium hydrogen phosphate (DSP) on the glycation of casein (CN). Food Chemistry: X, 39, Article 104621. https://doi.org/10.1016/j.fochx.2026.104621

Image Credits: AI Generated

DOI: 10.1016/j.fochx.2026.104621

Keywords: Maillard reaction, casein, glycation, phosphate salts, dairy processing, browning, food chemistry, protein structure, volatile compounds, flavor stability, processed cheese, mass spectrometry

Nepal offers an unusually instructive setting for this kind of analysis. Although the country contributes just 0.08 percent of global greenhouse gas emissions, its industrial sector consumes 20 percent of national energy and produces 40 percent of the country’s net carbon emissions. Manufacturing is the largest contributor to both. Yet Nepal’s electricity grid is dominated by hydropower, giving it a carbon intensity of just 0.068 kilograms of CO2-equivalent per kilowatt-hour—a figure roughly 35 times lower in lifecycle terms than coal-fired electricity. That combination of an inefficient industrial base and an exceptionally clean grid creates what the researchers describe as a rare opportunity: electrifying fossil-fueled industrial heat in Nepal delivers far deeper emissions cuts than the same retrofit would in countries reliant on coal or natural gas, where studies have shown boiler electrification can sometimes increase emissions.

The research team, led by Adity Sapkota and colleagues, selected two representative facilities from each sector, deliberately choosing plants with contrasting energy profiles. The dairy facilities ran around the clock on grid electricity supplemented by diesel and biomass, processing between roughly 2,100 and 18,900 tons of milk products annually. The plastic plants produced high-density polyethylene pipes using almost exclusively electrical power, while the metal facilities cast aluminum utensils—one with an electric induction furnace, the other with fossil-fueled reverberatory and annealing furnaces burning waste oil, LPG, and diesel. Over the 2024/25 base year, the team deployed calibrated three-phase power quality analyzers, clamp meters, infrared thermometers, and thermal imaging cameras, logging electrical loads at hourly intervals and cross-checking results against twelve months of utility bills to within a 10 percent deviation.

The baseline measurements exposed substantial efficiency gaps. Nepalese dairy plants consumed 0.22 to 0.25 kilowatt-hours per kilogram of product—better than the national average of 0.3 to 0.58, but still two to four times higher than international best practice of 0.056 to 0.12. In the metal sector, the contrast was starker still: the fossil-fueled aluminum plant recorded a specific energy consumption of 9.17 kilowatt-hours per kilogram, far above the 1.65 to 5.69 range reported internationally, while its electrically driven counterpart performed at 1.18, better than comparable facilities abroad. Thermal efficiency testing revealed why. The dairy boilers operated within normal industrial ranges at 80 to 82 percent efficiency, but the oil-fired melting furnace managed only 21 percent and the LPG-fired annealing furnace a mere 17 percent, meaning most of the fuel’s energy escaped as waste heat rather than reaching the metal.

Motor systems emerged as a universal weakness. Across the 164 motors audited, average loading ranged from 52 percent in the metal facility to 64 percent in dairy—well below the 60 percent threshold at which motor efficiency and power factor begin to decline sharply. In the plastic plants, 60 percent of motors ran underloaded, and in the metal plant the figure reached 85 percent. The consequences were visible in the numbers: the extruder drive motors in the plastic facilities consumed 0.42 to 0.55 kilowatt-hours per kilogram, three to five times the benchmark range, because oversized motors churned at low load. Using the US Department of Energy’s MEASUR tool, the team calculated that upgrading motors to higher-efficiency units yields diminishing returns past a saturation point—95 percent efficiency for dairy and metal, 91 percent for plastic—beyond which replacement costs outweigh incremental savings.

The study then applied a three-tiered scenario framework to each facility: process optimization, electrification of thermal systems, and renewable energy integration. Under the first scenario, insulating steam lines and installing a desuperheater on the refrigeration system of the large dairy plant could recover 690 megawatt-hours annually, about 15 percent of total energy, and cut boiler fuel demand by 30 percent, saving roughly $100,000 per year. In the fossil-fueled aluminum plant, preheating combustion air with recuperators promised fuel savings of 43 percent, while preheating the charge material added another 25 percent—a combined 68 percent fuel reduction from relatively conventional engineering measures. In the plastic plants, where waste heat opportunities are inherently limited, insulating extruder barrel heaters and preheating polymer feedstock delivered a more modest 3 to 5 percent of facility energy.

Electrification produced the study’s most dramatic results. Replacing the diesel boiler at the large dairy plant with a 96 percent efficient electric boiler would pay for itself in six months and save $164,000 annually, while cutting facility emissions by up to 85 percent. Yet the same retrofit at the smaller dairy plant, which burns inexpensive firewood, yielded negative savings because wood and electricity cost nearly the same in Nepal—a finding the sensitivity analysis confirmed was robust even to a 20 percent rise in wood prices. In the metal sector, electrifying the inefficient melting and annealing furnaces could save nearly 60 percent of total facility energy and more than 90 percent of emissions, though the melting furnace’s financial case proved fragile, turning negative at discount rates above 8 percent. The lesson, the authors note, is that electrification’s viability hinges on the cost of the fuel being displaced.

Solar photovoltaic integration told a different story across the sectors. Hybrid systems pairing rooftop solar with lithium iron phosphate battery storage achieved renewable penetration of 15 to 90 percent depending on the facility, but battery capital and replacement costs accounted for more than half of total system expense, pushing the levelized cost of electricity to between $0.04 and $0.17 per kilowatt-hour. Only one facility, a plastic plant, recorded an LCOE below Nepal’s grid tariff of $0.068 per kilowatt-hour, and most hybrid configurations showed negative net present value with indefinite payback periods. Strip out the batteries, however, and the economics transform: PV-only systems achieved an LCOE of $0.02 per kilowatt-hour, repaid their capital within five years at every facility, and delivered positive NPV across the board. The battery remains technically necessary to replace diesel backup during grid instability, creating a gap between technical need and financial reality that the authors argue only concessional financing or capital subsidies can close.

Taken together, the results deliver a message that resists uniform technology prescription. Fossil-fuel-dependent dairy and metal plants achieved their largest energy and emissions reductions through heat recovery and electrification, while the electrically driven plastic facilities gained most from solar integration, offsetting up to 65 percent of grid dependence. The modeled emissions cuts of 50 to 90 percent from electrification vastly exceed what comparable retrofits achieve on fossil-dominated grids, underscoring that industrial decarbonization strategy must be matched to the carbon intensity of the electricity system. The authors caution that their findings rest on two facilities per sector from a single industrial cluster, with modeled rather than verified post-implementation outcomes, and they call for broader multi-facility studies. But the policy implications travel well beyond Nepal: mandatory audit programs, sector-specific benchmarks, targeted financing for capital-intensive retrofits, and grid investment to handle rising industrial demand are all prerequisites for turning audited potential into real-world emission cuts in developing economies.

Subject of Research: Cross-sectoral energy auditing and scenario-based decarbonization assessment of dairy, plastic, and secondary aluminum manufacturing facilities in Nepal

Article Title: Cross-sectoral energy audit and scenario-based decarbonization assessment of manufacturing industries in Nepal: A comparative study of dairy, plastic, and metal sectors

Article References: Sapkota, A., Paudel, S., Joshi, A., & Adhikari, B. (2026). Cross-sectoral energy audit and scenario-based decarbonization assessment of manufacturing industries in Nepal: A comparative study of dairy, plastic, and metal sectors. Results in Engineering, 32, Article 113191. https://doi.org/10.1016/j.rineng.2026.113191

Image Credits: AI Generated

DOI: 10.1016/j.rineng.2026.113191

Keywords: energy audit, industrial decarbonization, Nepal, electrification, solar photovoltaics, waste heat recovery, specific energy consumption, dairy processing, aluminum manufacturing, plastic extrusion, greenhouse gas emissions, energy efficiency

The review, authored by Rina Yu, Sin-Young Park, Prabhathma Yasasvi Rathnayake, and colleagues at Chungnam National University, Kongju National University, and the Korea Institute of Materials Science, systematically compares how different ultrasound systems and thermal conditions inactivate microbes in milk and milk-derived drinks. The authors frame their analysis around a simple but consequential observation: the antimicrobial power of ultrasound varies enormously depending on the equipment configuration, the processing parameters, and, crucially, how much heat is generated or deliberately added during treatment. By sorting the literature into three processing modes, cavitation-driven non-thermal ultrasound, ultrasound with natural temperature rise, and thermally assisted ultrasonic treatment, the review provides one of the clearest pictures yet of where sound-based pasteurization stands on the path from laboratory bench to dairy plant floor.

The physics behind ultrasonic pasteurization is striking. A transducer converts electrical energy into acoustic energy, sending longitudinal pressure waves through the liquid. These waves create alternating regions of compression and rarefaction, and in the rarefaction phase the liquid is literally torn apart, forming microscopic bubbles. At sufficiently high acoustic amplitudes, these bubbles undergo inertial cavitation: they expand rapidly and then collapse violently. The collapse generates localized hotspots with temperatures estimated to reach up to 5,500 degrees Celsius and pressures up to 50,000 kilopascals, conditions that exist for only fractions of a microsecond but are enough to wreak havoc on nearby microorganisms. The asymmetric collapse of bubbles produces shockwaves, microjets, and microstreaming currents that physically batter bacterial cell walls and membranes, tearing open structures that would otherwise protect the cell.

But the physical assault is only half the story. The extreme conditions inside collapsing bubbles also split water vapor into hydrogen and hydroxyl radicals, reactive oxygen species that penetrate bacterial cells through membrane pores and attack intracellular biomolecules. Hydroxyl radicals can cleave the DNA double helix, induce base modifications, and trigger lipid peroxidation in the phospholipid bilayer by reacting with polyunsaturated fatty acids. The result is oxidative degradation of proteins, lipids, polysaccharides, and nucleic acids, culminating in cell death. A related phenomenon, sonoluminescence, in which collapsing bubbles emit light across a broad spectrum, can further amplify microbial inactivation when a photocatalytic sonosensitizer is present, because the emitted light excites the sensitizer and generates additional reactive species. Together, these mechanical and chemical mechanisms make cavitation a genuinely multi-pronged antimicrobial weapon rather than a single-mode killer.

The review emphasizes that not all ultrasound equipment delivers this weapon equally well. Probe-type systems, in which a sonotrode is immersed directly in the sample, concentrate energy intensely at the tip and deliver the highest power intensity. Bath-type systems, which use sandwich transducers mounted on tank walls and rely on water as a coupling medium, suffer from attenuation of the ultrasound in the water, resulting in power intensity roughly one hundred times lower than probe systems. Both configurations irradiate from a single direction, producing non-uniform energy distribution within the treated volume. Continuous-flow systems, a newer development, address this weakness by circulating the product through a treatment zone, and some cylindrical designs generate ultrasonic energy in a 360-degree pattern, giving circulating milk stronger and more uniform exposure. These systems also allow operators to tune flow rate and number of treatment cycles alongside the usual power, amplitude, and frequency settings, a flexibility that matters greatly for industrial scale-up.

The experimental record assembled in the review shows how strongly outcomes depend on thermal conditions. Under controlled room-temperature conditions, where cooling systems or ice baths suppress heating, ultrasound alone achieves moderate inactivation. Mudgil and colleagues found that treating camel milk with probe-type ultrasound at 160 watts and 20 kilohertz for ten minutes reduced total aerobic bacteria by approximately 4.16 log CFU per milliliter, Staphylococcus species by 3.40 log, and lactic acid bacteria by 1.50 log. Chouliara’s group reported roughly 2 log reductions in total viable and psychrotrophic counts in milk after sixteen minutes at 200 watts and 24 kilohertz without added heat. In a Kinnow whey beverage, fifteen minutes of 400-watt, 20-kilohertz treatment cut total aerobic bacteria by about 1 log and molds and yeasts by 1.61 log. These are meaningful reductions, but they fall short of what regulators demand.

When the natural temperature rise of ultrasound is allowed to accumulate rather than suppressed, the numbers improve dramatically. Treating raw milk with probe-type ultrasound at 19 kilohertz and 475 watts for 158 seconds raised the temperature to 54 degrees Celsius and reduced mesophilic bacteria by about 2.6 log and lactic acid bacteria by 2.1 log. More strikingly, Shamila-Syuhada and colleagues showed that raw milk treated at 200 watts and 24 kilohertz for fifteen minutes reached 60 degrees Celsius at the higher amplitude tested, and at that point reductions of approximately 8 log CFU per milliliter were recorded for Staphylococcus aureus, Listeria monocytogenes, Salmonella Typhimurium, E. coli, Pseudomonas fluorescens, and two Lactobacillus species. Scudino’s team demonstrated the same principle through energy density: 1 kilojoule per milliliter raised raw milk to only 34 degrees Celsius with no detectable bacterial reduction, 3 kilojoules per milliliter reached 55 degrees Celsius and achieved a 1.8 log reduction, and 5 kilojoules per milliliter pushed the temperature to 76 degrees Celsius, delivering a 4 log reduction in just over four minutes. In chocolate milk, an energy density of 3 kilojoules per cubic centimeter at 400 watts and 19 kilohertz produced a 3.56 log reduction with a final temperature of only 42 degrees Celsius.

Thermally assisted ultrasound, combining acoustic cavitation with deliberately applied mild heat, offers perhaps the most pragmatic route to regulatory compliance. Van Hekken and colleagues applied continuous-flow ultrasound at dual frequencies of 16 and 20 kilohertz and 1,200 watts to raw milk held at 54 degrees Celsius for fourteen minutes, achieving reductions of 3.36 log in total mesophilic bacteria and 4.88 log in psychrotrophic bacteria, whereas the same treatment at 42 degrees Celsius showed no bactericidal effect at all. In human milk, bath-type ultrasound at 60 degrees Celsius reduced Staphylococcus aureus by approximately 4.58 log, while treatment at 20 degrees Celsius had no effect. The synergy arises because mild heat weakens the protective function of the bacterial cell envelope and increases cavitation efficiency, making cells simultaneously easier to rupture mechanically and more vulnerable to radical attack.

Yet the review is candid about the obstacles standing between these promising numbers and commercial reality. Under the Codex Alimentarius, any validated milk pasteurization technology must achieve at least a 5 log CFU per milliliter reduction of non-spore-forming pathogenic bacteria, and only a handful of ultrasound studies have crossed that threshold using ultrasound alone. Pushing intensity high enough to meet the standard risks damaging the product: ultrasound-generated radicals promote lipid oxidation and create volatile compounds responsible for metallic, burnt, and rubbery off-flavors in treated milk. There are also safety concerns specific to the equipment itself, since probe erosion can release metallic particles into the product and ultrasound accelerates electrochemical corrosion of stainless steel in the presence of chlorides. The authors argue that the future lies in continuous-flow systems suitable for large-scale processing, hurdle combinations of ultrasound with mild heat, pulsed electric fields, ultraviolet treatment, or natural antimicrobials, and real-time digital process control that can hold both microbial safety and sensory quality within tight tolerances.

What emerges from the review is not a verdict but a roadmap. Ultrasound is safe, non-toxic, relatively inexpensive to build, and well suited to liquid foods, and its antimicrobial mechanisms are now well characterized at the cellular level. The decisive variable is heat: whether it is suppressed, harvested, or deliberately supplied determines whether ultrasound is a gentle quality-preserving treatment or a genuine pasteurization technology. As consumer demand grows for fresh-flavored, minimally processed dairy, and as outbreaks linked to pasteurization failures continue to surface, the pressure to validate sound-based alternatives will only intensify. The next few years of equipment engineering and regulatory data generation will determine whether the dairy industry’s next pasteurizer hums rather than hisses.

Subject of Research: Ultrasonic pasteurization of milk and milk-based beverages using different ultrasound systems and thermal conditions

Article Title: A review of ultrasonic pasteurization in milk and milk-based beverages using different ultrasound systems and thermal conditions: from mechanistic insights to regulatory challenges

Article References: Yu, R., Park, S.-Y., Rathnayake, P. Y., Yeo, S. E., Nam, C., Cho, H. U., Baek, K. H., & Yong, H. I. (2026). A review of ultrasonic pasteurization in milk and milk-based beverages using different ultrasound systems and thermal conditions: from mechanistic insights to regulatory challenges. Food Science of Animal Resources, 46(1), Article 90. https://doi.org/10.1007/s44463-026-00105-5

Image Credits: AI Generated

DOI: 10.1007/s44463-026-00105-5

Keywords: ultrasound, pasteurization, milk, dairy, acoustic cavitation, food safety, microbial inactivation, non-thermal processing, reactive oxygen species, continuous-flow ultrasound, foodborne pathogens, dairy processing