Some said the factory would lose around 115 tonnes of coffee over the three days and possibly more as the machinery had to be wound down from Thursday night and takes days to re-start.
One source said the plant was 'running out of coffee' and that the packing function had worked at 20 per cent capacity because of insufficient supplies of coffee.
And they claimed JDE was covering full time employees with temps which, they said, was unlawful.
JDE said: "During last week’s 72-hour strike, our priority was to keep the factory running in a way that protects everyone’s health and safety - anyone running equipment will be (sic) skilled labour that is officially trained and qualified to do so.
"The various unsubstantiated allegations made regarding production and losses are incorrect – we are not able to share any further commercially sensitive information. We are confident we can continue to supply our products through the planning that has taken place.”
JDE has issued a Section 188 notice - known as 'fire and rehire' - to 291 members of staff in a bid to make them accept new contracts to save the company money. JDE says it needs to reset manufacturing in Banbury to make the factory competitive. However Unite the Union said in a press statement last week that Banbury workers were being singled out and that their Dutch counterparts were not being subjected to 'fire and rehire' pressures.
Unite says Banbury workers have been told to accept pay cuts of up to £12,000 a year or be sacked. JDE says the £12,000 loss only applies to a handful of employees.
One source told the Banbury Guardian: "The deadline for signing the contracts has passed and workers are supposed to be working their 12 week notice. JDE haven't issued the 12 week dismissal notice they were supposed to after May 17 because sacking 250 people would leave the factory incapacitated.
"It is understood that management were shocked so many people didn't sign up but it's not surprising as the new, inferior terms and conditions will lose them money, change their work shifts and affect pensions."
The source said that after the next strike - a 24-hour stoppage this Saturday, June 5 - JDE will have 'easily' lost £30m in coffee production. They said the loss of the defined benefit pension JDE is removing is a traditional 50-year-old pension system at the factory that is being replaced to save the company £5m a year.
"People don't realise how important and much the Banbury plant makes. It also impacts Germany, Russia, France and Holland as Banbury sends coffee globally. They aren't ramping up production at other EU plants because they can't make it like Banbury does . Even a director from Germany said they rely heavily on Banbury to supply their coffee."
After Unite the Union advertised an open letter to factory bosses, a JDE spokesperson said: “We were surprised to see the open letter containing a number of allegations that have been previously refuted by the business. Financial impacts on associates will depend on individual situations – for example, the £12,000 loss quoted only applies to a handful of associates. The current proposals see the majority gain financially with compensation for those who are financially impacted.
“Last week, we put forward proposals to the union that would enable us to work together with a view of de-escalating industrial action and reaching mutual agreement. Disappointingly, the union were unwilling to de-escalate industrial action to enable further negotiations. Therefore, we have no choice but to move forward to the next stage to provide clarity for our associates.
“We have been talking to Unite and our associates since 2019 about resetting working practices that have not changed in decades. Our fundamental issue is that we are not competitive compared to other factories. Our proposals do not include any redundancies and there is a role for everyone.
“We fully appreciate these changes may be difficult for some of our associates. We don’t propose them lightly but we strongly believe they are needed to secure a future for Banbury.”
A national campaign to outlaw use of 'fire and rehire' tactics is due to be launched on June 14 outside the coffee factory with Labour MP Barry Gardiner in attendance along with TV, press and broadcast media.