It's a basic skill of witches and herbalists everywhere. Place the chopped leaves, stems or flowers of carefully selected herbs in a warmed pot, add boiling water, leave the mixture to steep for 10 minutes, then strain. As if by magic, the plant oils transfer to the carrier liquid and the result is an infusion that can heal or soothe. If you're lucky, it might even taste good.
If only it were that simple in the world of commercial culinary infusions.
Products enhanced with herbs, spices and fruits have become an essential part of supermarket culinary oil ranges. Tesco features 'dipping oils' with Italian herbs and with chilli and garlic in its Finest own-label range. Internet shopping service Waitrose Deliver offers basil, chilli, garlic and lemon flavoured oils, as well as olive oil infused with white truffles, among 59 online alternatives.
But the canny buyer of infused oils asks this question: have the taste and aroma come direct from a macerated herb, or has the producer taken a short cut and added a chemically extracted flavour or a nature-identical compound?
The authenticity and intensity of taste in genuine infusions -- especially those made with fresh, rather than dried, herbs -- is significantly better than their 'flavoured' counterparts. And this distinction is becoming increasingly important to manufacturers because more infused oils are finding their way into processed foods.
That is largely down to one small company, Lancashire-based SpringThyme Oils which claims to be the world's leading specialist producer. Following a management buyout and an imminent move to a new factory near Burnley, it's targeting the processing sector where already more than 70 manufacturers are apparently finding its infused oils an effective -- and cost-effective -- flavour carrier.
SpringThyme says its process (see p44) is unique, and claims that not all 'infused' oils are quite what they seem, particularly those sexy retail bottles containing sprigs of rosemary, peppercorns or dried basil. Consumers might infer that these visually appealing bits of greenery have imparted their flavour to the oil, but the flavour transfer achieved by simply sticking herbs in a bottle can be minimal, especially if the herbs are dried. If the oil has a strong taste or aroma it's more likely the flavour came out of a plastic drum.
SpringThyme has spent 10 years developing its own bulk process, which uses nothing but oil and fresh herbs, spices or fruit. The result, it claims, is a range of intensely flavoured, aromatic and 'totally unadulterated' products that bear little resemblance to artificially flavoured oils.
Working through major own-label bottlers, it has secured listings in most of the major multiples, but retail accounts for only a fifth of sales. The big opportunity is in manufacturing where infusions can fill a dual function, giving a product its required oil content and the fresh taste of herbs in one hit.
Md John Graham suggests there are several advantages in using herb-infused oils. "A fresh herb costs anywhere between £8 and £15 a kilo, whereas a fresh infused oil can be £4 to £8, depending on the ingredient and the strength. And because it's stronger, you also use less.
"The other key point is that our infused oils are derived from fresh ingredients so there's an opportunity to keep the label clean. Even in dried seasonings you often get compound flavours or anti-caking agents but with our oil there are no additives. They can be described as simply herb and olive oil. That's driving increased usage."
By supplying infusions at twice the strength of retail products, SpringThyme has also enabled manufacturers to deliver a full-on flavour hit in a less-than-3%-fat recipe dish.
The infused oils market is relatively immature. SpringThyme produced the first Marks & Spencer (M&S) retail products in 1996 and developed a sunflower oil-based range for industrial use a couple of years later. But at that time it was pursuing various different product routes -- other culinary sauces, fruit purées and even tarts and jellies for M&S -- and a lack of focus meant the opportunities for bulk oils were not fully exploited. This year's management buyout of the oils business has provided more focus and an incentive to start selling seriously.
"We're convinced this market is only in the initial stages," says sales and marketing director Ken Williams, a former consultant to SpringThyme plc who has bought into the newly-formed SpringThyme Oils Ltd along with Graham and the other employees. "We're picking up customers at the rate of two or three a month -- and we've only just scratched the surface."
Manufacturers are being offered more than 100 flavour varieties. Most are in sunflower oil, which stands up best to processing, but SpringThyme also uses olive oil and, in some cases, extra virgin olive oil. "Some customers ask us to use, say, a particular blend of oil from Tuscany," adds Williams.
This kind of fine-tuning is peculiar to processed products, where developers are always hunting for a point of difference. In retail, by contrast, there are only four significant sellers -- basil, garlic, chilli and lemon -- and of these, basil dominates. "We make 140 flavours but over 50% of what we sell is basil."
One or two new flavour combinations are starting to appear in supermarkets, but consumers are still quite conservative, and Graham predicts retailers will settle down to stocking no more than six regular varieties, using short-term 'feature flavours' to add interest. Increasingly, he sees retail as a 'shop window' to catch the eye of food technologists in the altogether bigger, more adventurous, manufacturing market.FM
HTST process means no 'stewing'
SpringThyme's infusion process uses a mix of technologies in a totally enclosed system to maximise flavour intensity while retaining the 'fresh' taste of the herb or spice.
Md John Graham explains: "Traditionally, manufacturers would chop up the herb then mix it with oil and process it in a big, sealed cooking vessel or jacket pan.
"That gives a more stewed effect because the vessel can take up to 30 minutes just to come up to temperature. Imagine a teabag. As it's brewed for longer the tea gets stronger but it also gets more bitter. Also, if you size-reduce the herbs first you don't get such good oil extraction."
In SpringThyme's method, whole fresh herb leaves and stems are combined with oil in a sealed vessel and then chopped in the oil. No heat is used at this stage so that few flavour volatiles are lost.
The herb and oil mixture is then pumped into a continuous cooker -- known as an high temperature, short time or HTST pasteuriser -- where it is rapidly brought up to temperature in less than three minutes under high pressure (6-9 bar).
The final part of the process is to remove the vegetable matter and, crucially, as much water as possible to minimise spoilage.
SpringThyme uses a bespoke, basket centrifuge to separate the water, vegetable waste and oil. Then progressive filtration to below 2 microns removes any remaining potential spores before the flavoured oil is finally blended.
"The only negative with our method is that you don't get the visible leaf or particles," says Graham, "so some customers are dropping parsley into their recipes to get that green effect."
Product destined for retail shelves is put into 1,000 litre intermediate bulk containers for trucking to own-label bottlers.
Industrial products are typically infused at double strength and distributed to processors in 15kg containers.
Buyout puts focus firmly on oils
The creation of SpringThyme Oils through a management buyout this summer sees the business truly focused for the first time in its 10-year history.
Formed by a group of disgruntled ex-Albert Fisher Group managers, including current md John Graham, the original SpringThyme plc had two distinct arms. One sold freshly made chilled ready meals direct to the public from a retail outlet in Chester; the other assembled gift packs of deli foods, including fancy bottled oils, for Marks & Spencer (M&S).
The retail business -- which pre-dated Unilever's ill-fated Rocket ready meal stores by a decade -- proved a "monumental drain on finances" and was quickly closed.
From then on, SpringThyme moved through gift assembly, to producing its own oils, then adding heat-treated fruit purées using the same technology, and eventually turning out 125,000 chilled pot desserts a week for Marks & Spencer.
But when M&S wanted to move some of the more easily made desserts to other, higher-volume producers, the SpringThyme directors decided to pull out of the sector altogether. They laid off the bulk of the workforce and once again concentrated on oils.
Now, the company's cavernous 6,503m2site in Littleborough -- an ex Allied Foods bakery -- is being sold off.
All the original directors, with the exception of John Graham, have cashed in their investments, and the newly-formed SpringThyme Oils is transferring to a modern, 2,044m2site on the outskirts of Burnley.
Here, two production lines will turn out up to 1,000t of infused product a year.