Comparative characterization of avocado (persea americana) pulp oils and seed powders from selected varieties across different locations and seasons in Uganda

Abstract

This study characterized the physicochemical properties of avocado pulp oils and the nutritional as well as anti-nutritional composition of seed powders from selected varieties (Reed, Hass, Fuerte, Semil 34) cultivated across the different locations in the Lake Victoria Crescent Agro-ecological zone and seasons in Uganda. Analysis of pulp oils revealed significant variation influenced by genotype, environment and seasonal factors. Reed oil exhibited the highest acid values (0.54–0.67 mg KOH/g), suggesting greater susceptibility to lipolysis, whereas Hass oil showed the lowest acid values (0.30 mg KOH/g); indicating enhanced stability. Iodine values, reflecting the degree of unsaturation, were elevated in Reed and Fuerte oils, especially during the first season, reaching up to 88.81 mg I₂/g, while Hass displayed notable seasonal fluctuations. Peroxide values ranged from 2.02 to 3.27 meq O₂/kg, with Hass consistently maintaining the lowest levels, signifying superior oxidative stability. Saponification values peaked in Reed oil (up to 212.66 mg KOH/g). Fatty acid profiling highlighted Hass oil as richest in oleic acid (47.88%) and linoleic acid (15.44%), contributing to its nutritional value. Seed powder analysis demonstrated substantial genotype-environment interactions affecting composition. Protein content varied between 3.0% and 5.9%, while dietary fibre peaked at 13.87% in Fuerte during the first season. Amylose and amylopectin contents responded variably to seasonal and varietal factors; Hass maintained consistent amylose levels (~29%), and Semil 34 showed minimal changes in amylopectin. Starch content increased in Semil 34 and Fuerte during the second season, suggesting adaptive metabolic responses. Tannin concentrations rose in the second season, likely due to stress-induced metabolite accumulation. Mineral profiling revealed considerable amounts of potassium (350-410 mg/100 g), calcium (120-150 mg/100 g), and magnesium, underscoring the potential of avocado seed powders as valuable nutritional resources. These findings emphasize the intricate influence of genetics and environment on avocado oil and seed quality, offering pointers for industrial, nutritional and functional food application