Effect of high-humidity hot air impingement blanching on photochemical degradation kinetics (red pigments and ascorbic acid) and antioxidant capacity changes (2,2-diphenyl-1-picrylhydracyl, DPPH and total antioxidant capacity) of red pepper during 6-month storage at ambient temperature in dark was investigated. Ultrastructure of raw and blanched samples was also observed using a transmission electron microscope (TEM). Blanching followed by drying resulted in 63-85% and 33-59% reduction in red pigment and ascorbic acid content, respectively. The antioxidant capacity of samples was found to increase after drying. After 6-month storage, further breakdown of red pigment and ascorbic acid was observed. The red pigment degradation followed the first-order reaction kinetics; untreated samples displayed the most red pigment loss, while the Weibull model described well the ascorbic acid degradation kinetics. Ultrastructure observations explained why over-blanching can cause serious phytochemical degradation. The current findings indicate proper blanching pretreatment prevents phytochemicals degradation of dried pepper during storage.
Keywords: 5-Hydroxymethylfurfural (PubChem CID: 237332); ABTS (diammonium salt) (PubChem CID: 5360881); Antioxidant capacity; Ascorbic acid (PubChem CID: 54670067); Blanching pretreatment; Capsaicin (PubChem CID: 1548943); Capsanthin (PubChem CID: 5281228); Capsorubin (PubChem CID: 5281229); DPPH free radical (PubChem CID: 2735032); Degradation kinetics; Paprika (PubChem CID: 11980947); Red pepper; Red pigment; Storage; Weibull model; Zeaxanthin (PubChem CID: 5280899); β-Cryptoxanthin (PubChem CID: 5281235).
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