An improved method for determining free amino acids by RP-HPLC/DAD with o-phthalaldehyde derivatization: Method evaluation in beers and wines

Rapid methods for amino acid determination are desired to reduce running times, and the main factors involved in the rapid separation of these compounds in HPLC are the columns, solvents, and gradient. The present study refers to a method optimization to rapidly analyze 19 amino acids in RP-HPLC/DAD with pre-column derivatization using o-phthalaldehyde. To evaluate the method's robustness, Indian Pale Ale-IPA beers and wines from the San Francisco Valley-SFV and Chapada Diamantina-CHD, Brazil, were analyzed. The method showed acceptable linearity (R2 > 0.992), precision (CV < 3.96%), recovery (74.2-113%), detection limits (<0.56 mg/L), and quantification limits (<3.62 mg/L) and separation gradient in 18.5 min. IPA beers were discriminated from wines by arginine, asparagine, tryptophan, alanine, phenylalanine, and tyrosine contents. Furthermore, CHD wines were discriminated from SFV wines by asparagine, glutamine, arginine, cystine, tyrosine, and leucine. In conclusion, a rapid method for amino acid determination was optimized and validated for wines and beers.

Arbuscular mycorrhizal fungi decrease Meloidogyne enterolobii infection of Guava seedlings

Guava (Psidium guajava L.) production is prominent in the irrigated fruit growing area of Brazil. However, the parasite Meloidogyne enterolobii (a phytonematode) has caused a decrease in guava production. Arbuscular mycorrhizal fungi (AMF) are known to be beneficial to plants; however, their ability to protect plants against nematodes such as M. enterolobii remains poorly known. This study aimed to monitor M. enterolobii infection in guava seedlings inoculated with three AMF species. After AMF inoculation, the seedlings were grown in sterile soil for 60 days before inoculation with 2000 M. enterolobii eggs. Plant growth parameters, mycorrhizal colonization and the number of Meloidogyne in the roots were determined over time (30 and 60 days after Meloidogyne inoculation). The AMF enhanced guava seedling growth, and reduced the amount of Meloidogyne in the roots at 30 and 60 days after nematode inoculation, indicating that these AMF species could serve as biocontrol agents of M. enterolobii in guava cultivation.