Fatty acid composition in avocado by-products: Effect of rootstock and variety

The cultivation of avocado (Persea americana) has experienced remarkable growth in the Canary Islands in recent decades, becoming a crop of increasing economic and agronomic relevance. This expansion has been further reinforced by the recent recognition of Canary Islands avocado with a Protected Geographical Indication (PGI), which highlights not only its production value but also its distinctive sensory identity and quality. In this context, the valorization of avocado by-products has gained increasing attention as part of circular bioeconomy strategies. Peel and seed, often considered waste, represent a promising source of valuable compounds, including lipid fractions with potential functional applications. Therefore, the main objective of this study was to determine the fatty acid content in peel and seed from Hass and Lamb Hass avocados using Duke 7 and Toro Canyon as rootstocks. Fruits were harvested between September 2023 and January 2024 and selected at a commercial maturity stage corresponding to 24% dry matter.

The results revealed a clear influence of rootstock on fatty acid composition, strongly dependent on the variety. In Hass, the Toro Canyon rootstock significantly enhanced fatty acid content in peel by-products compared to Duke 7, with increases ranging from approximately 1.8- to 2.4-fold. In contrast, no significant differences were observed in seed extracts. Notably, higher levels of palmitic, palmitoleic, oleic, and linoleic acids were detected, with oleic acid exhibiting the greatest increase (≈2.4-fold) in peel by-products. These findings suggest a greater capacity of Toro Canyon peel by-products to promote lipid accumulation in this variety. In Lamb Hass, however, the rootstock effect was less pronounced and more variable. In some cases, peel by-products from Duke 7 showed higher levels of certain fatty acids, particularly palmitic and palmitoleic acids (≈1.8-fold), while only minor differences were observed for oleic acid and negligible differences for linoleic acid. These results indicate a different physiological response compared to Hass.

When comparing varieties under the same rootstock (in both by-products), Hass showed higher fatty acid contents than Lamb Hass under Toro Canyon, whereas under Duke 7, the differences between varieties were reduced, resulting in more similar lipid profiles. Overall, these findings highlight a significant rootstock × variety interaction, with Hass being more influenced by rootstock selection—particularly under Toro Canyon—while Lamb Hass exhibited a more stable and less responsive behavior.

From an application perspective, these results are highly relevant, as avocado by-products have been identified as promising sources of bioactive lipids. Previous studies have demonstrated their potential for developing functional ingredients, including lipid extracts with antioxidant and biological activity. The presence of key fatty acids such as oleic, linoleic, and α-linolenic acids further supports their nutritional and technological value.

In this context, the fatty acid profiles observed in this study reinforce the potential of avocado peel and seed as sustainable raw materials for food, nutraceutical, and cosmetic formulations. Their exploitation not only contributes to generating high-value products but also supports circular bioeconomy approaches aimed at reducing agro-industrial waste and improving the sustainability of avocado production systems.