He used his creative skills to build markets for new products such as Ban roll-on deodorant at Bristol-Myers, Cran-Apple juice for the Ocean Spray cooperative, and Manwich canned sloppy joe sauce for Hunt-Wesson.
His tuition for Hamilton College was covered by a wealthy relative who expected him to become a clergyman, but the advent of World War II led Gelsthorpe to enlist in the United States Navy in 1942 following his graduation with a degree in philosophy and English literature.
During action in the Mariana Islands, Gelsthorpe was awarded service stars for his efforts to protect fellow soldiers who were being attacked by Japanese troops; he left the Navy as a lieutenant.
Largely selling a seasonal product, consumed at Thanksgiving and Christmas, the cooperative had been facing declining sales that resulted from warnings issued in the late 1950s about potentially cancer-causing chemicals sprayed on the cranberries.
[6] Working together with Sylvia Schur of Creative Food Services, Gelsthorpe was able to oversee the development of several brand extensions, including its blockbuster Cranapple and other fresh and frozen fruit juice mixes, as well as a cranberry-orange relish.
He oversaw the expansion of the company's narrow product variety with the introduction of single serving Snack Pack shelf-stable puddings, Manwich sloppy joe sauce, and Skillet Dinners.