Many well-known names, including Yoplait, Weetabix, Jil Sander, Jimmy Choo, 7 for all Mankind and Tommy Hilfiger have passed from the hands of their corporate or other owners into those of private equity firms.

The reason is simple: established brands offer the buyer the comfort of a long and predictable history of sales and cash flow and the prospect of increased profitability.

"What attracts private equity investors to mature brands is the opportunity to make money, not develop a brand," says Julian Kynaston, chairman of Propaganda, the brand and communication consultant.

The downside is that good brands command a higher price and there is always the risk of overpaying.

That is not the case with so-called orphan brands, which have typically been undermarketed and allowed to languish before being sold by their corporate parents.

Private equity firms that believe the brands can do better under new ownership stand to make high returns if they can breathe new life into the company.

The key is paying an acceptable price and devoting the right resources to management, marketing and distribution.

"Orphan brand products usually have extremely attractive margins as well as strong consumer franchises and cashflows," says Charles "Chuck" Esserman, president and chief executive of TSG Consumer Partners, a private equity firm specialising in consumer products. "So you start with that and then there is the opportunity to substantially increase sales because the product has not been an area of focus."

Over the years big corporations have shed many famous brands with long histories - from Spic and Span household cleaner to Close-up toothpaste - to focus on the brands that are number one or two in their category. For private-equity firms, sitting on tens of billions of dollars raised in the boom years, opportunity abounds.

An attractive orphan brand, says Mr Esserman, is "one with a strong customer franchise, attractive margins and underlying growth opportunities".

In 2004, TSG, then known as The Shansby Group, sold Medtech Holdings to GTCR Golder Rauner, another private equity firm. Medtech's product line of "unwanted brands" included Compound W wart remover and Cutex nail polish remover.

"We identified early on the opportunity to acquire orphan brands from large consumer companies, at reasonable prices, and then build value," Mr Esserman says.

GTCR, in turn, merged Medtech with Spic and Span and later added Bonita Bay Holdings. It renamed the consolidated orphans Prestige Brands. Last year GTCR took Prestige public and more than trebled its investment in its portfolio company.

The Mauna Loa Macadamia Nut Corporation is another example of a revitalized orphan brand. TSG bought Mauna Loa for Dollars 40m in September 2000, increased sales by an average of 30 per cent a year and in 2004 sold the company to Hershey Foods, the chocolate maker, for Dollars 130m.

When TSG invested in the brand it was losing Dollars 10m a year. The company installed a new executive team, partnered with management to eliminate unprofitable items, expanded the product line, redesigned the packaging and widened distribution. When TSG sold Mauna Loa, it had annual sales of about Dollars 80m.

Reviving older, established brands relies on the equity that remains from decades of marketing support.

"If you can get something that is underappreciated or ignored and do all the things needed to revive the business you can get an extraordinary return on investment," says John Howard, chief executive of Bear Stearns Merchant Banking, an institutional private equity fund.

In 1998 BSMB and a management group bought Aeropostale, an under-performing clothing retailer, from Federated Department Stores, owner of Bloomingdale's and Macy's. At the time it was generating about Dollars 100m in sales - now it is approaching Dollars 1bn.

"What it needed was loving attention," says Mr Howard. BSMB later exited the company through the public markets.

In 2004 BSMB took public New York & Company, an orphan cast off by Limited Brands, whose chains include The Limited and Victoria's Secret. Investors paid Dollars 105m for an initial public offering of a quarter of the shares - roughly twice what Bear Stearns had paid for that stake just two years before when it bought the clothing retailer for Dollars 193m.

In the case of New York & Co, BSMB changed the original name from Lerners as the brand had lost its resonance with consumers. "We created a new brand out of ashes of an old one that didn't work anymore," Mr Howard says.

Private equity firms are good at cutting costs and improving operating margins, and can often breathe new life into brands.

One of the keys to their success is that the firms give management equity in the new company. "There is a certain magic that comes from empowering managers," Mr Howard adds.

Cyrus Jilla, head of Bain & Company's European consumer products practice, says private equity has several advantages over corporate bosses when it comes to reviving brands, including the ability to attract top-notch talent.

Orphan brands generally do not attract the best talent in the company, he says, but private equity firms can often find skilled management teams because of their vast management networks and the high compensation they offer.

Not all well-established - albeit flawed - brands can be revived, however. If all else fails, a brand can simply be killed off with any promising products moved to another category.