Science in the box

Fresh smelling clothes as the sign of a laundry job well done
People connect certain smells to specific functions. This leaves the perfumer with the challenge of matching the right scent to the right product. For instance we associate almond with soft skin whereas lemon is linked to degreasing. And while we accept pine in floor cleaners we reject it in fabric softeners. Some smells we find inherently repulsive even one-day-old babies faces react to the odour of fish and rotten eggs but most of our responses to smells are learned.

Some perfumes are valued all over the world. Others, such as lavender, have particularly strong connotations in certain countries. For instance, the French associate lavender with hot summer vacations in Provence whereas in the UK lavender is associated with relaxation, comfort and femininity. Another example is the long established Savon de Marseille soap which is liked a lot by Southern European countries like France and Spain because it reminds them of old traditions.

Consumers feel freshness delivered by perfumes on laundry is very important
In Southern European countries this is particularly significant (in France and Italy the figure is as high as 90%) but even in Northern Europe (Germany, the U.K., the Netherlands, and the Nordic countries), where perfume is typically less important, laundry freshness is still a major consideration (importance varies from 70 to 80%). People interpret fresh-smelling clothes as the sign of a laundry job well done. When you ask consumers what they want in laundry detergents, the resounding answer is longer lasting freshness after washing clothes, after drying and above all in the wardrobe and in-wear. In fact, when clothes don’t smell fresh and clean, people feel the need to re-wash.
The role of the perfumer
A perfumer needs to be able to identify thousands of smells and know how to classify and recognize them. At P&G, most of the perfumers start out as trained chemists who then spend approximately three years learning the art and science behind creating a fragrance. To help them refine their skills, they also spend time training in external perfume houses. P&G’s perfumers need to combine all their skills when designing a product. They have to be able to select and blend the individual notes of the perfume, all at the right level, so that the perfume and the product form a compatible whole that will not degrade.

It is no easy task though. So this is where P&G brings in its innovative technologies.

Throughout history, perfumes have reflected the interests of society. The first scents were created out of plant and animal extracts. In ancient civilizations they were used in religious ceremonies, in medicines, as cosmetics and as gifts. Today’s perfumes contain a huge range of ingredients to give a dazzling range of fragrances. Fashions change but the purposes behind perfumes remain constant.

With thousands of raw ingredients to choose from, a perfumer needs talent and an excellent memory when creating a fragrance. As the fragrances in today’s laundry products can be just as complex as the fine fragrances created in prestigious perfume houses, P&G’s perfumers are using the same skills. P&G perfumers work with a smaller palette of ingredients, ones that will not break down during the wash cycle. But out of the 3,000 ingredients available, they use no less than 1,000. Each finished fragrance contains 30 to 200 ingredients. Compare this with the average fine fragrance, which contains a blend of 10 to 100 ingredients or even the most complex perfumes worn today, containing many hundreds of ingredients.

Perfume notes
Try describing a smell. Perfumers learn the language of perfumery by using the fragrance pyramid system, based on how quickly the ingredients evaporate. Borrowing from music terminology, each individual scent is called a note. The perfumes themselves are a skilful blend of top, middle and base notes. The top perfume notes evaporate the fastest, creating the fragrances first brief impression. This is what you smell when opening a bottle of laundry liquid or fabric softener. Perfumers typically describe them as green, fresh and citrus. The core character of the scent comes from the middle or heart notes, which develop later and form the body of the fragrance. You experience that when you take the laundry out of the washing machine. These can be floral, spicy or fruity. Later the perfume releases the base or dry down notes, the most substantive ingredients. They can smell musky, woody, warm, mossy and so on. These are the fragrance notes that will make your laundry smell fresh when it is ready to wear.
The Fragrance Pyramid

Facts and Figures
• The perfume industry is comparatively small, selling about 10.5 billion euros worth of perfume raw materials annually.
• Worldwide, P&G is the largest perfume house with 35 expert perfumers.
• The Fabric and Home Care and Beauty Care divisions alone use 400 different types of perfumes.
• P&G has perfume manufacturing facilities in Germany, the U.S. and Mexico, which produce 40,000 tons of perfumes a year.
• Depending on their make-up, fragrances can cost from just $2 per kg to a staggering $8,000 per kg.
• Common perfume levels in laundry products are between 0.2 and 1.5%. This means that typically there is less than 1g of perfume in the wash solution. With the subsequent rinses and the drying, this leaves only a small amount of perfume on the garments to make them smell fresh.

So how do we identify all those myriad smells that we encounter every day? It all starts when odour molecules of whatever you are smelling hit your nose. These volatile molecules (meaning they evaporate easily) drift up the nasal passages to a postage-stamp-sized area of nerve cells lying just below the eyes (the olfactory epithelium).

Each nerve cell is covered in minute hairs that each play host to one type of the 1,000 or so sensors known as odour receptors. The human nose contains several million odour receptors. Odour receptors are quite picky; they have different shapes each designed to hook up with a certain shape odour molecule like a lock and key. So some odour receptors will respond to cut grass molecules and others will respond to freshly baked bread. When the odour molecule hits the right receptor this triggers the neurons in your nose to send a signal to the olfactory bulb in the very front of the brain. The signals are relayed from the olfactory bulb to the brains higher olfactory cortex, triggering patterns of activity in the cortex corresponding to certain smells and to the limbic system, which generates emotional feelings. One pattern of signals will mean coffee, another aftershave.

P&G regularly surveys consumers about the sort of fragrance they want on their laundry products. When testing the variants of a fragrance, we ask consumers to smell products directly from the container as well as washed items. P&G then goes further, inviting people to use new detergents in their homes. How does the fragrance perform over the wash cycle? What is it people want from laundry detergents and fabric softeners? Careful listening is one step on the path to designing the perfect perfume. Time and again, consumers say that what they want is more staying power for the fresh smell on fabrics. Consumers feel that the freshness factor drops with each stage in the laundry cycle. Ideally they want the fragrance to keep on working, especially at two key points or moments of truth when storing clothes and when wearing them. A wardrobe full of fresh-smelling clothes is enjoyable. Wearing such clothes boosts confidence and gives pleasure.

Getting the ingredients to keep working in our clothes after drying and in-wear is a tricky challenge for our perfumers. This depends on the ingredients staying power. For instance, how well does it withstand heat and water plus detergent, or sunlight, if hung outside to dry will it dissolve away or evaporate? When clothes are washed, water and detergent carry away the more soluble parts of the fragrance, and when clothes are dried perfume ingredients evaporate. In conventional perfumes, this mainly leaves some of the heavier ingredients (the base perfume notes) on the fabric, giving the clothes their traditional fresh smell. The challenge at P&G is to extend the range of perfume ingredients that stay longer on the fabric leaving a noticeable fresh scent.

Traditionally, higher levels of perfume were used in the laundry detergent to boost freshness on dry clothes. The downside was that the scent of the detergent itself became too strong and turned people off. This led to the search for more balanced compositions that made the level of fresh smell pleasant during all stages of the laundry process.

One exciting development in P&G perfume science is pro-perfumes. The pro-perfume technology works like an anchor that retains the perfume that is otherwise washed off the fabrics. The freshness releases slowly over time and magically materialises on your clothes when it is needed. Researchers are currently extending the range of freshness characters delivered by pro-perfumes. In just 10 years P&G has filed more than 100 perfume patents, many of them relating to the delivery of longer lasting freshness on dry laundry.


Another breakthrough in perfume delivery is controlled freshness release via encapsulation of substantive perfume particles. Here the freshness is locked up in microcapsules that slowly dissolve in the wash, releasing it on damp and dry laundry.

P&G has also created a fabric softener, Lenor Stayfresh, which helps to neutralize unpleasant smells. The key ingredient, cyclodextrin, works by hooking up with unpleasant odour molecules and deactivating them. This perfume science technique was first used in Febreze, a spray used for eliminating bad odours on fabrics. By getting rid of unpleasant smells, Lenor Stayfresh helps clothes keep their just-washed fragrance and delivers real in-wear freshness.

Fortunately, a perfume allergy is a relatively rare phenomenon. For laundry detergents, our data and the available scientific information indicate that the risk of perfume allergy is extremely small and there are no reasons to be concerned about the perfume in laundry detergents.

P&G have tested laundry detergents for skin allergies (HRIPT) or skin intolerance in tens of thousands of volunteers. We have never seen any perfume allergy caused by one of our detergents. For fabric softeners, we tested over four thousand volunteers and have not noticed anything either. We have also not seen any allergic reactions from the actual use of one of our laundry products, even though they are used by millions of European consumers on a daily basis.

All our laundry products and their perfumes are formulated with the greatest care and utmost attention to safety. The perfumes are formulated taking into account our stringent internal safety standards for every ingredient, as well as safety standards set by the International Fragrance Association (IFRA) and those of the Research Institute for Fragrance Materials (RIFM). Whenever the perfume of a product changes, our scientists in charge of safety always evaluate the detailed composition and make sure there is no risk. The scientists take into consideration all available data on all ingredients as well as the various possibilities of exposure to the product, and they conduct clinical trials. P&G’s approach to assessing skin safety of its detergent products, including perfumes, has been reviewed and approved by an international group of dermatology experts from Europe, the USA and Canada. Moreover, the company has published and continues to publish papers on the subject in peer-reviewed literature (visit www.scienceinthebox.com for abstracts).

It is important to note that laundry detergents and fabric softeners are not intended for direct application on the skin. They normally only come into contact with the skin in a very diluted solution during hand washing, a habit which has become quite infrequent nowadays. The perfume exposure of a laundry detergent through hand washing is about 100 times less than with a perfumed product applied directly to the skin.

To further help physicians as well as people who are allergic to a particular perfume substance, detergent manufacturers have started to list perfume substances on their labels, when present in the product at a concentration greater than 0.01%. The labelled substances belong to a “list of 26”, selected by the European Union Scientific Committee of Consumer Products (SCCP). Industry fully supported the European regulations in force from 2005 and aim to better inform consumers on products. Cosmetic companies had already started doing this back in 2004.

In some countries, our line of laundry products may include a perfume-free variant. We do this to meet the needs of those consumers who want a perfume-free product. However the majority of consumers enjoy the benefit of a pleasant odour of fresh and clean laundry and they can safely do so.