Once picked, a pineapple stops ripening and will never get any sweeter.

Pineapples are non-climacteric fruits, a category that also includes citrus and grapes. Unlike climacteric fruits such as bananas, pears, and tomatoes, pineapples don't produce a surge in ethylene or increased cellular respiration after harvest. This means they lack the biological mechanism to continue ripening once detached from the plant.The key difference lies in how they get their sugar. Bananas and similar fruits rely on stored starch that enzymes convert to sugar over several days. Pineapples, however, receive all their sucrose, glucose, and fructose directly from the stem while still growing. Research from the University of Hawaii at Manoa shows that once harvested, the sugar content remains constant or may even slightly decrease as the fruit uses its own reserves to stay alive.When a pineapple turns yellow and softens on your counter, it's not ripening—it's aging. The shell changes color as chlorophyll breaks down, and the flesh softens because enzymes like bromelain degrade cell walls. However, the Brix level, which measures sugar concentration, stays the same throughout this process.Growers harvest pineapples at a specific maturity index, determined by shell color and total soluble solids content. The MD2 hybrid, developed by the Pineapple Research Institute in Hawaii during the 1980s, became the global standard for sweetness and quality. To get the best fruit, choose pineapples that are already fragrant and heavy for their size—they will never improve after you bring them home.