Evaluation of Turkish shallot genetic resources for morphological, biochemical and sensory properties

Abstract

Shallots, a subspecies of onion, are considered gourmet and are particularly preferred in French and Asian cooking. Their unique taste and aroma, especially after being caramelized through heat treatment, increases their importance for boutique restaurants and specialized cuisines. This study examined the morphological, biochemical, and sensory properties of seven generatively propagated shallot genotypes (GMSY-2, GMSY-3, GMSY-4, GMSY-5, GMSY-6, GMSY-7, GMSY-8) and one vegetatively propagated shallot genotype (GMSY-1) in 2021 and 2022. Sixteen morphological and 15 biometric features of the International Association for the Conservation of New Plant Varieties were used in characterization. Total phenolic content, total antioxidant capacity, total monomeric anthocyanin and pyruvic acid contents were determined as biochemical markers. The data were evaluated with hierarchical clustering (HCA) and principal component analysis (PCA) methods. With sensory analysis, genotypes were compared in terms of pungency, aroma, crunchiness, smell, consumption preferences, and perceptibility of the epidermis membrane. Results showed that leaf waxiness, bulb shape, shape of the bulb base, tendency to split into bulblets, main color of dry skin, and time of harvest maturity may be utilized to discriminate shallot genotypes. As biometric characteristics, head weight varied between 21.67 and 93.82 g, and the smallest heads were obtained from the GMSY-1 genotype while the largest heads were obtained from GMSY-7. The water-soluble solid contents of the genotypes showed significant variation (2.35%–9.50%), with the highest being determined in GMSY-2, GMSY-3, and GMSY-1, respectively, while the lowest was found in GMSY-8. According to the HCA results, four different main groups were formed in terms of biochemical and sensory characteristics. As a result of PCA, it was seen that the total variation consisted of the first two principal component axes, and the variation between biochemical contents and genotypes was 79.00%. The findings for the sensory analysis evaluation criteria highlighted the GMSY-8 genotype as promising.