There are two faces of Pepsi. One is the national icon, encapsulating so much of what it means to be American – everything from the soft drink with the burger and fries to the corporate behemoth unfazed by the challenge of competing with the even more fearsome Coca-Cola. The other is the global business, the company with a presence in markets from China to Chile, and with an outlook to match.

The former can be found in the eerily quiet Pepsi headquarters in suburban upper New York State. Among the Picasso paintings and Giacometti sculptures, portraits of the two founders of PepsiCo stare out into the atrium, marking their place in the industrial patriarchy of America. One, Donald Kendall, still passes his portrait every day as he comes into the office.

A few floors above sits global Pepsi, in the form of Indra Nooyi, only the fifth chief executive and chairman of the global drinks group and more than a year into her tenure. The Madras-born executive will be co-chairing Davos 2008 – this year’s gathering of the World Economic Forum that attracts world leaders, billionaires and film stars alike. As visitors view the extraordinary art collection downstairs, Mrs Nooyi talks of galvanising “the power of Davos” into attempting to solve world poverty.

“There is a tremendous amount of power in Davos,” Mrs Nooyi says. “It needs to be put to work. The NGOs, governments, companies - in partnership – we can move towards some action to improve society.”

Mrs Nooyi is not just paying lip-service to this mission. She has already met Gordon Brown a number of times and discussed with the Prime Minister at Chequers how the muscle of global corporations can be used to help the poor. “The developed world cannot just stand by and watch,” she says. “The problem is not confined to Africa. When you see the difficulties that some people face, you cannot help but ask yourself what we are doing to help this cause.”

In an attempt to highlight how the weight of global corporations could be mobilised in such a way, Mrs Nooyi had pointed out at a dinner to Tony Blair, a committed proponent of getting the corporate world involved in fighting world poverty, that around the table were executives representing a trillion dollars’ worth of capital. “I had expected him to go ‘gee whizz’. Instead, he joked that with the weakness of the dollar that was only £500 billion and that the way the pound was going . . .” That famous British sense of humour, always there when you need it in times of trouble.

While the flagging dollar is no joke for American business, Wall Street is expecting companies such as PepsiCo to weather a recessional storm well. Depressed, cash-strapped Americans can still afford a snack – a can of Pepsi or a packet of crisps. “In a slow-down, overall demand for our products doesn’t change much,” Mrs Nooyi says. “Our customers look to our products for a bit of comfort.”

Mrs Nooyi may have been joint chairman and chief executive for only 18 months, but she has spent much of her career at PepsiCo and is largely responsible for the product mix that the company boasts. Over the past ten years, Mrs Nooyi has sold off a number of businesses, such as Taco Bell and KFC, and spotted, ahead of Wall Street, the trend towards healthier eating. To respond, she engineered a deal to buy Quaker Oats for $13.9 billion and acquired Tropicana, the juice brand, for $3.3 billion.

Since she became chief executive, the share price of PepsiCo has risen as much as 26 per cent. The few critics she has on Wall Street claim that she must reduce the company’s dependence on American sales and boost international revenues, especially as many believe that the United States is already in a recession.

Mrs Nooyi is adamant that “a big transformational deal” is not on the cards, even though PepsiCo was rumoured to have been interested in a merger with Danone, the European food giant. “I don’t see one [a transformational deal] yet,” she says.

Soaring food prices and fuel costs have hit many food companies hard. Hershey, the chocolate manufacturer, was forced to issue a profit warning last year after admitting that rising raw material costs had eaten into its bottom line. Wall Street has hoped that the food squeeze, amid soaring dairy, corn and sugar prices, would trigger a wave of consolidation. Yet Mrs Nooyi disagrees that the corporate landscape for food businesses is about to change. “Consolidation is not going to address inflationary issues. This is not about scale and taking out costs. It is about the behaviour of governments, of ethanol programmes. Structural inflation is here to stay, at least for the next two to three years.”

Mrs Nooyi, who has bought a number of small “bolt-on” businesses worth about $1 billion during her tenure as chief executive, offers a warning about the perils of big, macho takeovers. “Everyone talks about a sexy deal. But the actual deal – the champagne – it’s only 10 per cent of it. It’s postmerger that counts, extracting every single dollar of synergy out of a deal. It is back-breaking work, an enormous challenge. You have to take any big, transformational deal very, very seriously.”

If her profile is high, then Pepsi-watchers have noted that she is not the first woman to have made a splash at the company. Joan Crawford, the Hollywood icon who starred in films such as Whatever Happened to Baby Jane? took a seat on the main board in 1959 after her fourth husband – Alfred Steele – Pepsi’s chairman, died. She left the company in 1973. But Mrs Nooyi is nothing if not a hands-on boss. On a recent business trip, flying over the Midwest of America, Mrs Nooyi, 52, suddenly decided to tell the pilot of the PepsiCo aircraft to stop in Indianopolis while she visited their business there. She insists that it is only through such visits that an executive can keep track of a business – and keep up with its customers.

For a company with annual sales of $35 billion, the size of a small country, does she worry in the postEnron culture that she knows every corner of her business? “They say that it is a mother’s job to worry. Well, it’s a chief executive’s job to worry ten times more. Of course I worry. But we are the world’s largest small company. There is a real ownership culture here. Every piece of it, we view as our company. If you appoint the right people, many of the worries are reduced.”

Mrs Nooyi’s style is exemplified by a simple pledge. If any customer – whether a 7/11 corner shop or Wal-Mart, the retail giant – calls her with a problem, someone will get back to them within half an hour. For larger customers, she makes the calls.

Curriculum vitae

Born: October 28, 1955, in Madras India
Education: Took a BSc in chemistry from Madras Christian College, later studied for an MBA at Yale School of Management
Career: First jobs included working for Boston Consulting group and strategy roles at Motorola and ABB. Joined PepsiCo in 1994 and became president and chief financial officer in 2001. Appointed chief executive in August 2006
Family: Married with two daughters, the elder of whom is working on Hillary Clinton’s presidential election campaign
Other Interests: Sits on the board of the Federal Reserve Bank of New York and counts Henry Kissinger as one of her friends