Genomic relationship and physiochemical properties among raw materials used for Thai black garlic processing

Abstract

Raw materials used for black garlic (BG) processing were collected from the major garlic production areas in Northern Thailand. Five of those were identified as of Thai origin (accession G1–G5), and accession G6 was of the Chinese variety. They were initially analyzed for varietal differences using morphological characteristics and genetic variation. Fresh materials from each accession were dried to the same moisture content (55%–60%) and BG processed at 75°C, 90% relative humidity (RH) for 15 days. Thereafter, physiochemical and chemical profiles were analyzed and compared. The dendrogram from random amplified polymorphic DNA fingerprints grouped G2, G3, G4, and G5 as closely related while G1 and G6 were out-groups. Prior to BG processing, the pH of fresh garlic was approximately 6.3 and decreased to 3.7, thereafter. The contents of chemical properties were independent with genotypes. BG processing improved phenolic, flavonoid, and antioxidant but the content of thiosulfinate was minimized in all BG samples. Overall, result indicated that garlics grown in Northern Thailand were genotypically variable. BG processing altered physical and chemical appearance, and these changes were independent with the genotypes.