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Why do seeds and fruits build up fats as they ripen?

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Synthesis of palmitate — Fat Palmitic acid is one of the most prevalent fatty acids occurring in the oils and fats of animals; it also occurs naturally in palm oil. It is generated through the addition of an acetyl group to multiple malonyl groups connected by single bonds between carbons. This structure forms a saturated acid—a major component of solid glycerides.

Seeds and fruits build up fats during the late stages of the ripening process as a way to store energy. In their unripe state, these plant parts primarily contain sugars and starches, which are converted by enzymes into fatty acids and glycerol as the plant matures.1

This synthesis serves a vital biological purpose:
* Energy Reserve: In seeds, fat acts as a concentrated energy reserve for the embryo to support it during germination. Fats are more energy-dense than carbohydrates, providing roughly nine kilocalories per gram compared to four for carbohydrates.23
* Nutrient Storage: Through the process of double fertilization, plants create nutrient-rich tissues like the endosperm or cotyledons, which store these fats alongside proteins and other materials to ensure the survival of the developing plant.45

While the function of fat in seeds is clearly linked to fueling the embryo, the presence of large quantities of fat in certain fruits is less easily explained, as much of this energy may be lost or consumed before the seed germinates.2