When I prepare roast beef at home, it's never as good as the one prepared with a rotisserie. What is the difference between a roast beef cooked in a rotisserie, and a regular oven?
Dry and even heat. There is still a difference, even with the same cut of meat and using a roasting rack to avoid roasting the cut in its juices: meat on a rotating skewer will be exposed to uniform heat. If you set the temperature of a home oven to 350°F, the top of the roast will be exposed to that temperature, but the bottom, in line of sight to the heat source, will be much hotter.
Commercial rotisserie ovens also cook the meat by convection and use the heating elements to create the outside crust. As the meat roasts, it becomes darker and absorbs more of the radiant heat from the roasting coils. So the outside ends up getting overcooked unless the roasting coils are carefully controlled, which is kind of hard to do. In a convection oven the temperature is constant around the roast.
Additionally, the roast done on a spit is going to lose less juice because of the rotating action. As gravity is pulling the juices downward the meat is rotating so what would have been the bottom is now becoming the top, thus the juices can't run out as easily.
Is that really true? If the roast is being heated to at least 60C (i.e., medium-rare range), then the juices it loses are due to the denaturing of collagen. I'd be surprised if the force of gravity alone could counteract the squeezing of the proteins. Even if the rotation did prevent moisture loss, the rotation speed would have to be finely tuned to the size of the roast: too slow and gravity will pull out moisture, too fast and centrifugal force will also pull out moisture. Or maybe that's why organizations like the Confrérie de la Chaîne des Rôtisseurs exist... ;-) Apr 28, 2011 at 12:55
More even crust around the whole surface.
If you are roasting in a pan, the meat is likely sitting either it's own juices or in some other liquid. Even if you are flipping it over halfway through, the top and bottom are stilling spending half their time wet. Roasting a turning spit, the whole exterior gets exposed to the same amount of dry radiated and convective heat.