Key Takeaways 

• Hydrogenation adds hydrogen to unsaturated compounds under controlled temperature and pressure. 
• In food manufacturing, hydrogenation changes oils to improve oxidative stability, shelf life, and texture.
• Partial hydrogenation may form industrial trans fats and has largely been phased out. 
• Full hydrogenation produces little to no industrial trans fats and is still in use.
• Food manufacturers still need a dependable supply of high-purity hydrogen. 
• Hydrogen can be delivered or generated on-site through water electrolysis. 
• The CO₂ emissions associated with electrolytic hydrogen depend on the electricity used. 
• Stargate Hydrogen supplies industrial electrolysers needed for producing hydrogen.

Hydrogenation is an established food manufacturing process, but manufacturers are reassessing how they obtain the irreplaceable hydrogen required. 

For more than a century, food hydrogenation has helped producers control the stability, texture, and melting properties of edible oils. The process is still used in the production of bakery fats, confectionery ingredients, frying fats, fillings, coatings, and other specialty products. 

Public discussion about trans fats has sometimes created the impression that hydrogenation has been prohibited. That is incorrect. Regulations address industrially produced trans fats, which are mainly associated with partial hydrogenation. Full hydrogenation is still an accepted process and produces little to no industrial trans fats. 

The chemistry has not changed. Hydrogen gas still reacts with unsaturated bonds on the surface of a catalyst. Process engineers still control temperature, pressure, mixing, catalyst loading, and reaction time to achieve a defined product specification. 

What is changing is the upstream hydrogen supply. 

Delivered hydrogen remains suitable for many plants, but manufacturers are also assessing on-site hydrogen production. Water electrolysis gives a facility the possibility to produce hydrogen where it is consumed, using electricity and water as inputs. 

This creates a direct link between two questions: 

1. What is hydrogenation? 

2. Where does the hydrogen come from? 

The first question concerns food chemistry and other major chemical industries. The second concerns plant design, utilities, logistics, procurement, and long-term supply security. 

What exactly is Hydrogenation? 

Hydrogenation is a chemical reaction in which hydrogen is added to an unsaturated molecule, normally with the help of a catalyst. 

In edible oil hydrogenation, hydrogen reacts with carbon-carbon double bonds in fatty acids. The reaction reduces the degree of unsaturation and changes the physical and chemical behaviour of the oil. 

A typical hydrogenation process includes: 

• Refined vegetable oil 
• Hydrogen gas 
• A nickel catalyst 
• A stirred reactor 
• Controlled temperature and pressure 
• Catalyst filtration 
• Further refining or fat modification 

The degree of reaction depends on the required product. A manufacturer may want greater oxidative stability, a higher melting point, a firmer texture, or a particular solid-fat profile. 

Hydrogenation is also used in pharmaceutical, chemical, and refining applications, but food hydrogenation requires close control because taste, texture, nutritional composition, and regulatory compliance all affect the finished product. 

The Chemistry Behind Hydrogenation 

Hydrogenation converts some or all carbon-carbon double bonds into unsaturated fatty acids into single bonds. 

Vegetable oils consist mainly of triglycerides. Each triglyceride holds three fatty acid chains attached to a glycerol backbone. 

Fatty acids can be: 

• Saturated, containing only carbon-carbon single bonds 
• Monounsaturated, containing one carbon-carbon double bond 
• Polyunsaturated, containing two or more carbon-carbon double bonds 

Common unsaturated fatty acids include oleic, linoleic, and linolenic acid. Common saturated fatty acids include palmitic and stearic acid. 

Double bonds are more susceptible to oxidation than single bonds. When oxygen reacts with unsaturated oils, it can initiate reactions that produce rancid flavours, odours, colour changes, and declining product quality. 

During hydrogenation, hydrogen gas is introduced into a reactor containing oil and a finely dispersed catalyst. The catalyst provides an active surface where hydrogen molecules separate into hydrogen atoms. Those atoms then react with the double bonds in the fatty acid chains. 

The catalyst speeds up the reaction but is not intended to remain in the final oil. It is removed by filtration after the required degree of hydrogenation has been reached. 

The Role of the Nickel Catalyst in Hydrogenation

Nickel is commonly used because it combines strong catalytic activity with established industrial handling methods. 

Nickel catalysts are widely applied in edible oil hydrogenation because they offer: 

• Suitable reaction activity 
• Commercial availability 
• Established process experience 
• Reasonable cost 
• Recoverability through filtration 

Catalyst conditions affect reaction rate, selectivity, and hydrogen consumption. Contaminants in the oil or hydrogen stream may reduce catalyst activity, so feed preparation and hydrogen purity require proper control. 

Temperature, Pressure and Mixing 

Hydrogenation performance depends on controlled contact between hydrogen, oil, and catalyst. 

Temperature affects reaction speed and selectivity. Hydrogen pressure affects the amount of hydrogen available to the liquid phase. Mixing controls gas dispersion and contact with the catalyst. 

Operators also monitor: 

• Catalyst concentration 
• Oil composition 
• Reaction time 
• Hydrogen flow 
• Heat removal 
• Degree of unsaturation (iodine value) 
• Finished fat properties 

These variables are adjusted together. A change in pressure or mixing may alter the rate at which hydrogen reaches the catalyst, while temperature changes can affect both reaction speed and product composition. 

Why Vegetable Oils Are Hydrogenated 

Vegetable oil hydrogenation is used to improve stability and create fats with defined processing and melting properties. 

Untreated vegetable oils are suitable for many products, but they do not always provide the required shelf life, structure or temperature response. 

Oxidative Stability and Shelf Life 

Hydrogenation reduces the number of oxidation-sensitive double bonds. This can improve resistance to rancidity and help a product retain its intended flavour and quality during storage. 

Greater oxidative stability may support: 

• Longer distribution periods 
• More predictable product quality 
• Reduced spoilage and waste 
• Better performance during frying 
• Greater resistance to heat and oxygen exposure 

Shelf life depends on many factors, including packaging, antioxidants, storage temperature, light exposure and oil composition. Hydrogenation is one method available to formulators when greater stability is required. 

Melting Point and Texture 

As an oil becomes more saturated, its melting behaviour changes. The product may become semi-solid or solid at room temperature. 

This property is useful in: 

• Bakery shortenings 
• Margarine formulations 
• Cream fillings 
• Confectionery coatings 
• Icings 
• Wafer fillings 
• Frying fats 
• Plant-based products 

The goal is rarely to make a fat as hard as possible. Manufacturers usually need a defined melting curve that supports processing, storage, mouthfeel and consumption. 

Speciality Fats and Edible Oil Refining 

Hydrogenation often forms one part of a wider edible oil refining and modification route. 

Depending on the feedstock and final specification, the process may include: 

• Degumming 
• Neutralisation 
• Bleaching 
• Deodorisation 
• Fractionation 
• Hydrogenation 
• Interesterification 
• Blending 

Manufacturers combine these methods to produce speciality fats with specific solid-fat content, melting behaviour and stability. 

Partial vs Full Hydrogenation 

Partial and full hydrogenation differ in how far the reaction proceeds and in their potential to form industrial trans fats. 

Partial Hydrogenation 

Partial hydrogenation leaves some unsaturated bonds in the oil. During the reaction, part of the natural cis configuration may change into a trans configuration. 

This is how industrially produced trans fatty acids can form. 

Partially hydrogenated oils were historically used because they offered good texture, stability and processing performance. They were common in shortenings, margarines, baked goods, frying fats and packaged foods. 

Health evidence led authorities to restrict industrial trans fats. The World Health Organisation identifies partially hydrogenated oils as a major source of industrially produced trans fats and supports measures that remove them from the food supply. 

Full Hydrogenation 

Full hydrogenation continues until nearly all unsaturated double bonds have reacted. 

Because very few double bonds stay, the final fully hydrogenated fat has little to no industrial trans fats. It is generally hard and has a high melting point. 

That hardness often makes direct use impractical. Food manufacturers may therefore combine fully hydrogenated fats with liquid oils through blending or interesterification. 

These methods allow formulators to create the required texture and melting profile without relying on partially hydrogenated oils. 

Hydrogenation and Trans Fat Regulations 

Hydrogenation is not banned. Regulations limit industrial trans fats in food. 

Commission Regulation (EU) 2019/649 sets a maximum of 2 grams of trans fat, other than trans fat naturally occurring in animal fat, per 100 grams of fat in food intended for final consumers or retail. It also includes information requirements for certain business-to-business food supplies above that level. 

The regulation does not prohibit hydrogenation as a process. It controls the amount of trans fat in the food supply. 

This distinction matters for plant owners and EPC teams. Existing full hydrogenation assets may remain relevant, provided the resulting products meet applicable composition, quality and labelling requirements. 

Myth vs Fact about Hydrogenation 

Where Does Hydrogen Come From? 

Most industrial hydrogen is still produced from fossil fuels, while water electrolysis accounts for a much smaller share. 

Hydrogen must be separated from compounds that contain it. Major production routes include: 

• Steam methane reforming 
• Coal gasification 
• By-product recovery 
• Water electrolysis 

The International Energy Agency reported that global hydrogen production reached 97 million tones in 2023, with less than 1% classed as low-emissions production. 

For a food plant, the relevant choice is often between delivered hydrogen and local generation. 

Delivered hydrogen may suit low or intermittent consumption. On-site hydrogen production may become more attractive where demand is steady; transport is difficult, storage creates constraints, or supply security is a concern. 

Producing Hydrogen with Electrolysis 

Water electrolysis uses electricity to split water into hydrogen and oxygen. 

The overall reaction is: 

2H₂O → 2H₂ + O₂ 

In simple terms, hydrogen forms at the cathode and oxygen forms at the anode. The gases are separated, treated as needed, and directed to storage or the process. 

For food hydrogenation, the hydrogen may be compressed, buffered, and supplied to the reactor through the plant's gas distribution system. 

Oxygen is produced as a by-product. Its use depends on site demand, purity, integration costs, and local economics. 
 
If you want to learn all about electrolysis for hydrogen production, read the first article of Stargate’s Hydrogen blog: The basics of Hydrogen production 

What Is an Alkaline Electrolyser? 

An alkaline electrolyser system has at its core one or more electrolyser Stacks, filled with an alkaline electrolyte, commonly potassium hydroxide (KOH), to support ion transfer during water splitting. 

Alkaline electrolysis has a long industrial operating history and is used in systems ranging from smaller installations to multi-megawatt hydrogen production plants. 

A complete industrial electrolysis system normally includes: 

• Electrolyser stacks 
• Gas separation 
• Power conversion 
• Water treatment 
• Cooling 
• Controls and safety systems 
• Gas purification where required 
• Compression and storage where required 

 
If you want to know more about Alkaline electrolyser Stacks and System, read the following article: Alkaline Electrolysers 101 

Electricity Source and Emissions 

Electrolysis does not automatically produce zero-carbon hydrogen. 

There are no direct carbon dioxide emissions from the electrolyser stack, but the overall emissions depend on how the electricity is generated. 

The IEA states that emissions from electrolytic hydrogen depend on the electricity source. Electricity with a high carbon intensity can result in substantial upstream emissions, while renewable or other low-emission power can reduce them. 

For this reason, project assessments should examine the actual power supply rather than assuming that all electrolytic hydrogen has the same environmental profile. 

Benefits of On-Site Hydrogen Production 

On-site electrolysis can improve control over supply, logistics, and production planning. 

Potential benefits include: 

• Reduced dependence on road deliveries 
• Greater supply security 
• Local production at the point of use 
• High hydrogen purity 
• Adjustable production 
• Modular expansion 
• Compatibility with renewable electricity 
• Support for industrial decarbonisation plans 

These benefits depend on site conditions. Electricity price, operating hours, water availability, storage requirements, maintenance strategy and financing all affect feasibility. 

Delivered hydrogen and on-site electrolysis are therefore not universal substitutes for one another. 

 
If you want to know more about the pros and cons of on-site hydrogen production, read the following article: Centralised vs Distributed Hydrogen Production Systems 

Hydrogen Purity 

Hydrogen purity can affect catalyst performance, process control and product consistency. 

Food hydrogenation systems may set limits for contaminants such as: 

• Oxygen 
• Moisture 
• Carbon monoxide 
• Carbon dioxide 
• Sulphur compounds 
• Hydrocarbons 
• Nitrogen 

The required specification depends on the catalyst, reactor, food process and quality system. There is no single purity value that applies to every hydrogenation plant. 

Engineering teams should define both the total hydrogen purity and individual contaminant limits. A headline purity percentage alone may not describe whether the gas is suitable for the catalyst and process. 

The hydrogen production and purification system should be designed against the plant's documented gas specification. 

If you want to know more about hydrogen purity, read the following article: How pure is pure enough? 

Why is Stargate Hydrogen the ideal partner? 

Stargate Hydrogen is a European electrolyser technology company developing industrial hydrogen production systems for infrastructure and energy resilience projects.  

The company deploys its alkaline electrolysers, which are free from precious metals, in energy-intensive industries that are transitioning away from grey hydrogen, such as refining, ammonia, methanol, e-methane and steel.  

With IPCEI status, the company is among a select group backed by the European Union to deliver large-scale cross-border projects that support innovation, sustainability, and Europe’s industrial competitiveness. 
  

Stargate Hydrogen is backed by committed investors such as Repsol, and trusted by clients including Fortum, Utilitas, ABB, and Rockfin, among many others across Europe, Turkey, and India. 
  

Stargate’s Hydrogen products are tested by independent institutions, providing customers with additional performance assurance. The products are CE certified and fully comply with "Made in Europe" requirements. 

In parallel, Stargate Hydrogen actively develops breakthrough technologies, including ceramic-based electrodes, allowing customers to deploy proven technology today while accessing firsthand the performance of tomorrow. 
  

By prioritising robustness, transparency, and hands-on partnership, Stargate Hydrogen eliminates technical uncertainty and enables confident electrolyser deployment from pre-FEED through commissioning and beyond. 

For food manufacturers, Stargate Hydrogen's position is upstream of the hydrogenation process. Its equipment can produce hydrogen for industrial users that require an on-site supply. 

The company's Gateway platform is a containerised 1 MW alkaline electrolyser system designed for outdoor installation. Stargate states that the system supports dynamic operation, pre-FEED and FEED activities, and hydrogen purity above 99.999% with the specified purification configuration. 

For EPC companies and plant owners, Stargate's stated offering includes: 

• Alkaline electrolyser technology 
• Containerised outdoor systems 
• High-purity hydrogen production 
• Dynamic operation 
• Modular project development 
• Pre-FEED and FEED support 
• Documentation for project integration 
• Maintenance and after-sales support 
• On-site serviceability 
• Long-term technical cooperation 

Stargate Hydrogen provides technology for producing hydrogen. The food manufacturer or its process technology partner is still responsible for the hydrogenation plant, edible oil process, and finished product specification. 

Conclusion 

Hydrogenation is still in industrial use because it provides functions that many food products still require. 

It can improve oxidative stability, extend shelf-life, and modify the melting behaviour of edible oils. Food manufacturers continue to require high-purity hydrogen. The main change is taking place upstream, where companies are reconsidering how that hydrogen should be sourced. 

Delivered hydrogen remains suitable for many sites. On-site hydrogen production through industrial electrolysis offers another route, particularly for plants seeking greater control over supply, logistics, purity, and future expansion. 

Hydrogenation has not changed. The way hydrogen is produced is changing. 

Stargate Hydrogen supplies modular alkaline electrolysers for industrial hydrogen production and supports projects through pre-FEED, FEED, integration, and after-sales activities. 

Contact Stargate Hydrogen to discuss whether the Gateway electrolyser is suitable for your hydrogen demand, site conditions, and food hydrogenation project.