A contribution to the promotion of biodiversity and production of Creole avocado: Study of the thermal and phase properties of the oils extracted from its peel, pulp and seed

Abstract

In this work, a study on the thermal and phase properties of the oils extracted from the peel, pulp and seed of Creole avocado (Persea americana var. drymifolia), was carried out, as a contribution to the knowledge of this important native variety of Mexico, to support and stimulate its greater cultivation, production and consumption and promote biodiversity. The oils from the three portions of the fruit were extracted with hexane, and their yields, composition, and chemical, thermal, and phase properties were analyzed using official analysis techniques, FT-IR spectroscopy, gas/mass chromatography, TGA and DSC. The results showed that the peel, pulp and seed of this fruit constituted 8.93, 58.1 and 31.1%, by mass, of the fruit, with oil yields of 6.07 ± 0.85, 34.91 ± 3.26 and 1.00 ± 0.19% (bs)., respectively, and saponification values of 173.59 ± 8.39, 163.28 ± 2.50 and 181.74 ± 12.73 mg of KOH/g of oil. The oils had predominantly unsaturated FAs, with oleic being the majority in the peel (45.52%) and pulp (42.58%) oils, and linoleic in the seed (23.31%). The TGA showed several stages of decomposition of the samples, with an initial stage that removed volatile compounds present in this avocado variety at initial temperatures below 120°C and initial decomposition temperatures of the TG mixture of the oils at 290.4, 220 and 150°C for the peel, pulp and seed, respectively. The DSC analysis showed the S/L phase transitions and the predominance of the liquid phases at temperatures in the ranges typical of environmental and body conditions.