Changes in physical properties, chemical and elemental composition and antioxidant capacity of pomegranate (cv. Ruby) fruit at five maturity stages

This study was conducted to investigate the physical and compositional changes as well as antioxidant properties of pomegranate fruit (cv. Ruby) at five distinct maturity stages between 54 and 139 days after full bloom (DAFB). Physico-chemical properties such as fruit mass, size, juiciness, colour, total soluble solids (TSS), pH, titratable acidity (TA), individual organic acids and sugars, and phenolic composition were investigated. Mineral element concentrations were determined using inductively coupled plasma optical emission spectrometry (ICP-OES) while total antioxidant capacity was measured by DPPH scavenging activity (DPPH) and ferric ion reducing power (FRAP). Results showed that major compositional changes in fruit are developmentally regulated. Significant increases in total soluble solids (TSS), sugars (glucose and fructose) and anthocyanins composition, coupled with significant decline in titratable acidity (TA), organic acids and total phenolics occurred with advancing maturity. Principal component analysis (PCA) showed that fruit at advanced maturity stages (132 and 139 DAFB) were characterized by intense peel and aril pigmentation and better juice quality. PCA results also showed that peel and aril colour attributes and indices of sugar/acid ratio (TSS/TA and BrimA index) could be useful measures of fruit maturity and ripeness for ‘Ruby’ pomegranate cultivar, and therefore might be suitable for the development of reliable fruit maturity index to assess fruit optimal maturity.

Phytochemical contents of pomegranate ‘Ruby’ arils at different maturity stages. Total phenolics and flavonoids contents (A); total gallotannins content (B). GAE-gallic acid equivalents; CAE-Catechin equivalents. Mean ± S.E. presented, different letter(s) on bars indicate statistically significant differences (P < 0.05).Figure optionsDownload as PowerPoint slideHighlights
► We quantify major compositional changes in pomegranate fruit.
► We examine changes in antioxidant capacity at different maturity levels.
► Increasing maturity will increase sugars and anthocyanins.
► Increasing maturity will lead to decline in organic acids and total phenolics.
► We recommend potential indices of fruit maturity and ripeness.