Supermarket giant Tesco has been forced to change the packaging on its cartons of orange juice after a schoolboy spotted a grammatical error.

Albert Gifford had just sat down for breakfast when he saw that his carton of juice boasted it was made with the "most tastiest" oranges.

The 15-year-old, from Shepton Mallet, Somerset, wrote to the supermarket chain to complain, suggesting they change the wording to "tastiest" or "most tasty".

When he did not receive a reply from Tesco the teenager wrote a letter to the Daily Mail, which was printed last week.

The following day Albert received a reply from Tesco promising to correct the packaging.

The schoolboy wrote: "I woke up one Thursday morning a few weeks ago thinking the day would be like any other.

"Sitting down for breakfast as usual, I picked up a carton of Tesco orange juice – and noticed it described itself as 'most tastiest'. 'Most tastiest'? Surely not? It could be 'most tasty' or simply 'tastiest', but never 'most tastiest'.

"That's just wrong, and I was so astonished, especially as Tesco is such a large company, that I almost started pouring the orange juice on to my Weetabix.

"My mum stopped me just in time, but when I told her about Tesco's 'most tastiest' orange juice, she was just as surprised.

"I've since discovered that Tesco also describes its apple juice as the 'most tastiest', and, I suspect, its range of other juices, too.

"I considered what to do, and after some thought, I walked to my local Tesco and went up to the checkout. I looked at the assistant, thought for a second, and asked for a book of six stamps so I could write to Tesco's customer services.

"Later that day I posted a polite letter pointing out the mistake, and for the next few weeks I rushed home after school, beside myself with the anticipation of a receiving a reply.

"But every day I came home to a doormat with only the occasional leaflet urging me to buy this furniture or those clothes, but nothing from Tesco. I was devastated the mighty supermarket chain hadn't even acknowledged my existence.

"Still, I told myself every night: 'Don't worry, it'll come tomorrow.' Finally, I decided instead to write to the press to share my surprise at Tesco's command of English – or lack of it – with the rest of the country when, lo and behold, a letter arrived the next day, apologising for the mistake and assuring me it would be corrected when the packaging was re-printed.

"I don't think supermarket packaging should be wholly responsible for teaching young people English grammar – but I can't help thinking that 'every little helps'."

Albert is taking his GCSEs this summer and hopes to go university to study medicine.

A Tesco spokesman said: "I'm sorry that there's a grammatical error on our Tesco Pure Smooth Orange Juice packaging.

"Our design team checks all packaging very carefully before it's used on any of our products, and we carry out regular reviews, but apparently we overlooked this mistake.

"I've told our team about this and they will correct the error when the packaging is reprinted."