Active taste compounds in juice from oranges symptomatic for Huanglongbing (HLB) citrus greening disease

Authors: DALA PAULA, BRUNO - Universidade Federal De Minas Gerais; RAITHORE, SMITA - Former ARS Employee; Manthey, John; Baldwin, Elizabeth - Liz; Bai, Jinhe; ZHAO, WEI - Former ARS Employee; GLORIA, M. BEATRIZ - Universidade Federal De Minas Gerais; Plotto, Anne

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/29/2018
Publication Date: 2/20/2018
Citation: Dala Paula, B., Raithore, S., Manthey, J.A., Baldwin, E.A., Bai, J., Zhao, W., Gloria, M., Plotto, A. 2018. Active taste compounds in juice from oranges symptomatic for Huanglongbing (HLB) citrus greening disease. LWT - Food Science and Technology. 91:518-525.
DOI: https://doi.org/10.1016/j.lwt.2018.01.083

Interpretive Summary: This research presents data of unknown secondary metabolite compounds that contribute to increased sourness, bitterness and astringency in orange juice made with fruit infected by the Huanglongbing (HLB) or greening citrus disease using high performance liquid chromatography (HPLC) combined with sensory evaluation (LC-taste). Previous research showed that limonoids and flavonoids such as polymethoxylated flavones, played a role in orange juice bitterness. In the present work, multiple levels of fractionation resulted in subfractions with taste activities that did not contain any limonoids or flavonoids. Instead, these subfractions were composed of hydroxycinnamic acid derivatives, suggesting this group of compounds also contribute to sourness, bitterness and astringency of orange juice affected by HLB.

Technical Abstract: Citrus greening disease, also known as Huanglongbing (HLB), compromises the quality of citrus fruit and juice, causing increased bitterness, metallic taste, astringency and a burning mouthfeel. The chemical basis responsible for these changes remains largely unknown other than the roles of the bitter limonoids, limonin and nomilin, and of flavonoids that may cause astringency. A combination of chemical and sensory analyses was used to identify bitter components in HBL-affected orange juice, and comparisons were made with juice from healthy fruit. The results showed that there were statistical differences in pH, total acidity (TA), soluble solids content (SSC), SSC/TA, total sugars, organic acids, secondary metabolites and sensory characteristics between healthy and HBL-affected orange juices. Nonvolatile juice compounds were fractionated using fast centrifugal partition chromatography and semi preparative HPLC. Some fractions were described as bitter, but did not contain limonoids, polymethoxylated flavones (PMF) or hesperidin, and, instead, were overwhelmingly composed of hydroxycinnamates, indicating that these compounds might also be involved with this sensory attribute.