A UN team will try to transport more than 51,000 tonnes of wheat stored in the Red Sea Mills after finally reaching the centre on Tuesday, but sources warned much of the supplies have already rotted.
The World Food Programme and other organisations had said that the wheat stored in the mills was in danger of rotting and gave priority to reaching the damaged supplies.
Officials said the mills could feed 3.7 million Yemenis a month in a country where 14 million are on the verge of famine.
The Houthis have made the mill inaccessible for at least six months, adding to fears that the wheat would be inedible.
Col Wathah Al Dubaish, a spokesman for the joint forces in Hodeidah, inspected the mills on Tuesday and said that a large amount of the wheat stored in the mills was rotten.
Col Al Duabish the mill had the smell of rot and the colour of the wheat had changed.
But Stephen Anderson, the programme's director in Yemen, said the grain could be "reconditioned".
“We finished our preliminary evaluation," Mr Anderson said. "It was the first time we visited.
"We are in the process of preparing a report to recommend further action. Some of the grain needs to be reconditioned and repairs are needed, such as cleaning the milling facilities."
The programme has called for sustained access and safe passage to the mills.
"The wheat is infested with weevils, which is something we anticipated," programme spokesman Herve Verhoosel said. "We need to fumigate the wheat. We didn’t see any evidence of water damage to the wheat, which is a good sign.
"The silos show evidence of damage from the fighting but there is no serious structural damage. There is one silo with WFP wheat, which shows evidence of serious fire damage, which is the silo that was hit in late January."
The generators appear to be in a good condition and more than 30,000 litres of diesel remains, he said.
With the lack of access to the mills, the programme has been relying on other wheat stocks and imports by sea and overland from Oman, Mr Verhoosel said.
During a UN donor conference for Yemen in Geneva this week, it was said that 80 per cent of the Yemeni population needs urgent humanitarian assistance.
Col Al Dubaish said the logistics of transporting wheat that is still usable could prove dangerous.
“The UN de-mining expert Stephen Hock, a member of the UN team visited the facility, was shocked when he saw the big amount of mines planted in and around it," he said.
"He said in all his work trips, he has never seen so many mines planted in such a horrible way."
But Mr Anderson said that the road leading to the mills was de-mined and accessible to the UN and the programme's team.
He said the road leading north, which is under Houthi control, could still be dangerous.
Hodeidah has been under the control of the rebels since shortly after the war broke out.
They have refused to adhere to a complete withdrawal from the city, as agreed to by the warring sides in December, and continue to attack areas within the city despite the UN presence.
“We found more than 3,000 landmines planted in and around the mills facility,” Col Al Dubaish said.
The team from the programme will work on supply routes from the mills to the rest of Yemen despite complications caused by clashes and faction-controlled checkpoints.
Col Al Dubaish said the team was forced to bunker down in the mills during the visit as Houthis began shelling sites controlled by the National Resistance around the mills.
The civil war continues to fragment the country, restricting the delivery of aid to many of the communities most in need of assistance.
Although the mills remained in the National Resistance's control, the Houthis, who control the roads leading north to Sanaa, have refused access to the UN.
More than 100,000 citizens have been stranded in Hajjah province, north of Hodeidah, amid clashes between tribesmen and the Houthis.
Families in other parts of the country are internally displaced and too detached to receive humanitarian aid.