Linus' big business scheme in the film is to make a flexible, strong, super-plastic out of sugar cane. The plastic is even sweet to the taste… which is truly odd. Who wants a sweet tasting shampoo bottle?
You could see the plastic's sweetness as a sign of Linus' hidden goodness; he comes off as inflexible and bullying and awful—a "cold businessman." But beneath that hard exterior there's a dude who wants even his plastic to be sweet.
You could also, though, see the sugary plastic as a symbol of the film itself. Sabrina is a formulaic rom-com in a lot of ways; a mass-produced Hollywood piece of "plastic." In fact, critics of the time were quick to note that Sabrina was anything but original.
But they also noted that it was the movie's total sweetness that made it awesome. Take it from the NY Times original review:
Even though autumn is scheduled to arrive at 9:56 A. M. today and the musical theme for the occasion may be "September Song," the sunshine of summer was pouring into Broadway yesterday and the air was full of the tender and magical strains of "La Vie en Rose." At least, it was in the vicinity of the Criterion Theatre, where Billy Wilder's "Sabrina" was put on public display, with the sweetly bewitching Aubrey Hepburn and Humphrey Bogart in principal roles. (Source)
There you have it: all the news that's fit to print about Sabrina's sweetness.