An Enzyme Often Used in Laundry — Lipase

1) What lipase does in the laundry

A detergent lipase is used mainly to treatgrease / oily stains. Its typical reaction is to hydrolyse cooking oils and fats (mostly triglycerides, TAG) intofatty acids + glycerol(and some mono- / diglycerides), so the oil soil is more easily emulsified, dispersed and rinsed away by the surfactant in the bath.NCBE Reading+1

An industry background: the history of lipase being added to laundry products can be traced to the early 1990s。NCBE Reading

2) The mechanism: why “hydrolysing first” makes it easier to wash

Common reasons oil soil is hard to wash are:

• The oil film is hydrophobic and adheres strongly to the fibre surface

• Oil soil is often mixed with dust / carbon black / pigment, forming a compound soil that is still harder to emulsify

Lipase’s role is first to cut the “large-molecule fats” into components that are more hydrophilic / more readily form an interfacial structure (fatty acids and the like), so that afterwards:

1. The surfactant more readily coats / emulsifies them

2. The oil soil more readily leaves the fibres and enters the water phase

Teaching materials also especially point out:Emulsification increases the surface area of the fat, and the reaction is faster(in essence this is control of the “contact area”).NCBE Reading

• Fats (triglycerides) are non-polar and strongly resist water; but the fatty acids that are cut out become, in an alkaline environment, a “fatty-acid salt (soap).” This is not only hydrophilic; it even has a cleaning action of its own.

• In plain language: Lipase does not only cut the oil into pieces; it turns “oil that is hard to wash” into “soap that can help wash the clothes.”

• Its value for deodorising:

• A rancid-oil smell (rancidity): Many garments look clean after a wash, but after sitting for a long time have a “rancid oil smell,” because deep grease was not washed out and has oxidised. Lipase can go deep into the fibres and break down this deep oil; it is aspecific remedy for removing an aged oil smell.

3) The stain types it is most suited to

The stains lipase is most a match for are usually “fats that can be hydrolysed,” or compound stains that contain oil, for example:

• Cooking oil, salad oil, frying oil, animal and vegetable fats(a typical example: salad oil)NCBE Reading

• Sebum / oily soil on collars and cuffs(sebum contains lipids and wax esters; in practice it often needs to be paired with a surfactant and other enzymes)

• Oil-phase residues of oil-based cosmetics / sunscreens and the like(usually a compound system of grease + pigment + wax / polymer; lipase is mainly responsible for the oil-phase part)

4) Wash conditions: how to set pH, temperature and time reasonably

pH: most laundry lipases are designed to be “usable from neutral to alkaline”

Taking the teaching materials for Lipex (a laundry lipase preparation) as an example, it is effective underneutral-to-alkalineconditions, and takes the region around pH 10as representative of its best performance.NCBE Reading
Academic, research-type “detergent-candidate lipases” also often show a design direction ofan alkaline optimum activity, and stability at pH 8–11.Frontiers

Temperature: a low-temperature wash is possible, but there is still an “optimum temperature zone”

The same Lipex teaching material shows it can work at 4–50 °C(and notes that at still lower temperatures it can still act but needs longer).NCBE Reading
Some detergent-candidate lipase studies also often place the optimum temperature around 40–50°C, and aim to keep relatively high activity at 30–70°C.Frontiers

Time and contact: a thick oil soil should first be “broken up / wetted open”

The enzyme must contact the substrate to be effective. For heavy grease, a more stable approach common in practice is:

• First wet the oil film open with detergent / warm water, to reduce adhesion

• Then let the lipase act in the bath (extending the contact time is more effective than “only raising the concentration”)

• About time:

• A practical pain point: The speed of lipase’s action is usually, compared with protease,slower。

• A suggested SOP: If you meet “chef’s whites” or “massage-shop towels,” a **pre-soak** of at least 20–30 minutes is suggested. Relying only on the 15-minute main wash of a washer’s standard cycle, the lipase has often not finished cutting before it is drained away.

• About contact:

• An interface problem: The enzyme is in the water, the oil is on the fibres, and oil and water do not mix.

• A suggested SOP: For heavy grease, a small amount of **emulsifier (surfactant)** must first be added and stirred with water, so the surface of the grease “opens,” and only then can the enzyme get in.

5) The logic of pairing with other enzymes / ingredients

(A) With a surfactant: they are not mutually exclusive; they “divide the work and add to each other”

Lipase cuts the fat smaller; the surfactant is responsible foremulsifying / dispersing and carrying awaythe oil phase after it has been cut smaller. So “hydrolyse first, then emulsify” is the typical synergistic logic.NCBE Reading

(B) With protease / amylase / mannanase: dealing with compound stains is still more critical

Real stains are often a mixture: grease + protein + starch + thickening gum (for example sauces, desserts, cosmetic residues). Detergent-enzyme review chapters also place proteases, amylases, cellulases, lipases, mannanasesand the like side by side as commonly used classes, reflecting a formula approach of “each doing its own job.”Springer

(C) Points to watch on “stability” in a liquid wash and a powder wash

Taking suppliers’ public descriptions as an example:

• Powder detergents: high temperature, humidity, and long-term contact with a bleach system may make enzyme activity decline over time

• Liquid detergents: enzyme stability is related to pH, water content, polyols in the formula, and (sometimes) a strategy of inhibiting / protecting against proteasenovonesis.com
  Cationic surfactants (fabric softener): Although the softener is generally added only at the end, if in the pre-wash stage an auxiliary that contains a cationic ingredient is mixed in, it may inhibit lipase activity (it depends on the enzyme type, but an anionic / non-ionic formula is usually safer).
  

6) Effects on materials, and limits

Lipase acts mainly onfats, and does not directly hydrolyse the fibre itself; but the following two classes should still be written clearly on a website:

• Technical fabrics / coated fabrics with a special surface finish: oil soil may embed itself in the coating’s microstructure, and needs to be paired with temperature, a surfactant and a thorough rinse; it is suggested that you first do a small-area test.

• Protein fibres such as silk and wool: the real high risk usually comes from “protease,” not lipase. If your formula is a multi-enzyme system, the risk management for silk and wool should be assessed on the enzyme combination as a whole (especially protease).Springer

7) Safety and occupational health: what lipase (and all enzymes) most need to be managed for is “sensitisation by inhalation”

The risk-assessment guide for enzymes in professional cleaning points out: enzyme protein as a whole is usually not highly toxic, and can biodegrade quickly, but itis a known respiratory sensitiser. If the enzyme becomes an inhalable particle in the form of dust or mist, it may lead to a risk of occupational allergy, so the focus of control is “avoiding the generation of inhalable dust / aerosols” and good ventilation / engineering controls.media.acihq.org+1
The ILO’s occupational-hazard materials also mention: if, in the detergent-manufacturing process, there is exposure to enzyme-containing dust, it may cause a respiratory allergic reaction, and in serious cases may lead to asthma.International Labour Organization

Practical suggestions for a shop / factory (can be put in an SOP)

• Prefer a low-dust form (a liquid, granulated / coated enzyme)

• When dosing, avoid pouring powder so that dust rises, and avoid high-pressure spraying that causes atomisation; if necessary, use local extraction

• Wear eye protection / gloves according to the SDS, and avoid inhaling dust or mistmedia.acihq.org+1

8) The environmental side: why lipase is often seen as a “tool for lowering the burden on a formula”

The risk-assessment guide for cleaning enzymes mentions that an enzyme can, bylowering the use temperature that is needed, substituting the function of some stronger ingredients, and itselfbiodegrading quickly and completely, help to improve the formula’s sustainability and environmental-safety profile.media.acihq.org+1

9) “A one-sentence version of the key points”

• Lipase = a hand that cuts fats: it hydrolyses fats such as cooking oil and sebum into components that are more readily emulsified, and raises degreasing efficiency.NCBE Reading

• Neutral-to-alkaline is more favourable; a low temperature can also be used but may need longer。NCBE Reading+1

• The safety focus is to avoid inhaling dust / mist (the risk of respiratory sensitisation)。media.acihq.org+1