Cedenco Foods said it is "business as usual" even though a company owned by its US owner has filed for protection under US bankruptcy law.

Cedenco has the largest tomato processing factory in the Southern Hemisphere in Echuca in Victoria. It is one of New Zealand's biggest vegetable processors, with two Gisborne factories, a processing plant at Whakatu in Hawke's Bay and a business in Ohakune.

On Thursday, SK Foods LP said it was preparing to start voluntary Chapter 11 bankruptcy. Under this kind of bankruptcy companies continue to trade.

Both SK Foods and Cedenco are owned by a Sayler Family Trust in the United States, according to New Zealand Cedenco manager Richard Lawrence.

Cedenco used to be listed on the share market. In 2001 SK Foods bought a 55 percent stake, acquiring shares from Brierley Investments and others, and in 2003 moved to full ownership.

"We do operate completely separately with separate banking, governance and management," said Mr Lawrence.

"It is business as usual for Cedenco. It has been a pleasing year, coming after two very difficult years, and we are forecasting a much better result against budget."

It was unfortunate that SK Foods was caught up in a situation that Mr Lawrence considered a "perfect storm".

"There is the ongoing federal investigation (into SK Foods and senior management, including bribery allegations), as well as a global bank industry crisis where banks are risk adverse to renewing loans."

Mr Lawrence said all Cedenco suppliers, employees and customers would be unaffected by what was happening with SK Foods.

SK Foods LP is a privately-held company with operations in Kings, Colusa, Monterey, Solano and Yolo counties, with more than 400 full-time employees and 2500 seasonally-employed workers.

"This was a difficult but necessary decision," said SK Foods chief executive Scott Salyer.

"We have been focused on realigning our operations and improving our execution, and this filing will relieve the immediate pressure from our creditors and provide us time for an orderly exploration of our strategic alternatives, including a sale."