Comparative volatile compounds and primary metabolites profiling of pitaya fruit peel after ozone treatment

Abstract

BACKGROUND: Ozone treatment can effectively inhibit fruit decay in many fruits during postharvest storage. However, little information is available for pitaya fruit. RESULTS:Ozone treatment significantly reduced the decay rate and induced the enzyme activities of peroxidase and polyphenol oxidase, and also reduced the levels of reactive oxygen species. In total, 103 metabolites were detected and changed the content after ozone treatment, including 54 primary metabolites and 49 aromatic compounds. After significance and importance analysis, 37 metabolites were important. Some metabolites were induced by peel senescence to respond to senescence stress, including D-fructose, D-glucose, mannose, inositol, galactonic acid, ethanedioic acid and stearic acid. Some metabolic products of peel senescence were reduced by ozone treatment, including D-arabinose, glucaric acid, galacturonic acid, 1-hexanol, senescence and decay, including malic acid, succinic acid, pentenoic acid, eicosanoic acid, 2-hexenal, hexanal, 2-heptenal, 4-heptenal, 2-octenal and nitro m-xylene. CONCLUSION: Ozone treatment significantly reduced decay and prolonged shelf-life without reducing fruit quality. In total, 37 metabolites might play an important role in ozone delayed fruit decay. 4-ethylcyclohexanol, -linalool, palmitoleic acid and 2-hydroxy-cyclopentadecanone. Some metabolites induced by ozone treatment might play a vital role in delaying the RESULTS AND DISCUSSION Decay rateDuring the postharvest storage, fruit decay is the main factor leading to fruit loss. In pitaya fruit, decay generally occurs near the pedicle and then the disease spot expands gradually, which results in a fruit shelf-life of only 7-10 days at 25 ∘ C. To test the effect of ozone in pitaya, we screened the concentration J Sci Food Agric 2019; 99: 2610-2621

Comparative metabolites profiling of harvested papaya (Carica papaya L.) peel in response to chilling stress

“…Then, GC–MS analysis was conducted using GC–MS system (GC‐MS‐QP2010 Plus) with the DB‐5MS stationary phase fused‐silica capillary column (30 m × 0.25 mm i.d., 0.25 μm, Agilent Technologies Inc). The parameters and searching databases (NIST05 and NIST databases) for mass spectra were also used according to our previous research . Three biological replicates were conducted.…”

“…Organic acid metabolism is closely related to flavor and fruit response to stress during storage . Moreover, ascorbic acid content increased in papayas during ripening .…”

“…Though the primary metabolites were universal in peel and pulp (Table S1), they might play different roles in pulp and peel. Importantly, the primary metabolites in fruit peel play important roles in fruit response to stresses . However, few studies reported the effect of low temperature on the changes of primary metabolites in papaya peel.…”

“…Primary metabolites analysis was conducted according to the method described by Wu et al . with ribitol as an internal standard.…”

“…The parameters and searching databases (NIST05 and NIST databases) for mass spectra were also used according to our previous research. 19 Three biological replicates were conducted.…”