Physical properties, biochemical and antioxidant contents of new promising Tunisian almond genotypes: Traits stability, quality aspects and post-harvest attributes

Abstract

The specific approach of any fruit tree genetic resources preservation program depends undoubtedly on the valorization of the autochthonous germplasm with noticeable traits related to quality and adaptation to harsh climatic conditions. In this context, pomological and biochemical properties of 15 chance seedling almond genotypes, 11 old local Tunisian cultivars and 5 foreign introductions from different origins were studied in order to evaluate possibilities for their commercial and industrial valorization features. Parameters with high discriminating values were more related to kernel weight and width, shelling percentage, oleic and linoleic acids, tocopherols, sugar and protein contents. On the other hand, oil and protein contents were highly variable between genotypes, ranging respectively from 42.6 to 61 % and from 14.5 to 28.3 % of the total kernel dry weight. Main fatty acids ranged between 5.9–7.5 % for palmitic acid, 60.3–76.5 % for oleic acid, and 13.4–28.9 % for linoleic acid. The range of variation of tocopherols, was large for α-tocopherol (208.3–629.2 mg kg−1oil) and for γ-tocopherol (2.8–21.9 mg kg−1oil). Although the physical performances of the kernels for some accessions were in general low, their interesting chemical composition offers the possibility of many alternative uses which could improve their marketable value. In addition, some genotypes were singled out as the most promising for varied commercial finalities. ‘Porto’ and ‘Blanco’ were characterized by high stable total sugar and sucrose contents. Moreover, ‘Blanco’ had the highest α-, γ- and δ-tocopherol contents. ‘Guernghzel’, ‘Ras Bouma’ and ‘Forme en Poire’ were a rich source of protein while ‘Mahsouna’ and ‘Achaak’ may be a potential source for almond oil extraction. All of the understudied ‘K.Friji1’, ‘Bouchouka’ and ‘Forme en Poire’ oils had powerful antioxidant effects due to their high α-tocopherol content. ‘Sahnoun’ and ‘Zahaaf’ presented valuable oil with high oleic acid content. Thus, newly identified genotypes with high performances compared to the introduced cultivars represent a very promising base for breeders to generate new local almond cultivars with high quality kernel and oil that might be used for edible and industrial purposes.