Food and tobacco giant RJR Nabisco Inc. took a big bite out of its debt troubles by selling its Del Monte processed foods business to an investor group headed by Merrill Lynch & Co. for $1.475 billion in cash, company officials said Monday.

The Del Monte sale is part of a continuing program to cut the enormous debt that resulted from Kohlberg Kravis Roberts & Co.'s $25-billion leveraged buyout of the company early this year.

Lenders who financed the buyout gave RJR Nabisco until February, 1990, to reduce the debt by $5.5 billion and an additional six months to bring the total cut to $6 billion. Monday's announcement brings RJR Nabisco to within $600 million of the February requirement.

"We are now up to $4.9 billion," said David Kalis, an RJR Nabisco spokesman. "We're almost home. . . . We don't expect any more major divestitures--by major I'm talking in the mega-billions."

In addition to Merrill Lynch, other investors include Del Monte senior management, Kikkoman Corp. of Japan and Citicorp Capital Investors Ltd. In addition to its investment, Kikkoman has agreed to purchase a variety of Del Monte's assets in the Far East, RJR Nabisco said.

The processed foods business has been for sale for several months, analysts say, with Citibank as the major would-be buyer.

"But Citicorp had to reduce its equity stake . . . because the Federal Reserve Board had rules limiting banking investments in non-financial companies," said Kurt Feuerman, analyst for Drexel Burnham Lambert. "That was the major roadblock. Merrill Lynch stepped in fairly recently when it was decided that Citibank could not have a larger equity portion."

Will Retain Parts

The sale announced Monday includes Del Monte Foods USA, Del Monte Foods Europe, the company's processed foods businesses in Mexico, the Caribbean and the Far East, and Del Monte's pineapple operations in the Philippines and Kenya.

Not sold were Del Monte/Aylmer Canada, Del Monte's processed foods business in Venezuela and Nabisco food businesses in Latin America, which were managed by Del Monte.

RJR Nabisco's sell-off campaign was made necessary when Kohlberg Kravis Roberts took control of the company last February in the biggest corporate buyout in history. In a leveraged buyout, a company is bought with borrowed money, and its own assets are used as collateral. The debt is paid off through cash generated by the firm and the sale of assets.