Metabolomic analysis and biological activities of guava during its different ripening stages

Abstract

The present study focused on optimizing antioxidant phenolics and flavonoids from the hydromethanolic extract of ripe guava (Psidium guajava L.) fruits (two cultivars, Arka Kiran (AK) and Arka Mridula (AM)) using Response Surface Methodology (RSM). A comparative study of pink-pulp AK and white-pulp AM was conducted during ripening stages at the post-harvest storage condition, revealing morphological, anatomical, and biochemical changes. As the ripening proressed it shiwed reduction in reduction in chlorophyll and an increase in carotenoid newlinecontent across four stages (pre-ripe, ripe, color-turn, and over-ripe) for AK and AM both over a span of eight days. In general, both fruits at the over-ripe stage exhibited dried peel, senescence spots, and fruit softening. During ripening, pink pigmentation increased in the AK pulp, and the AM pulp displayed yellow-pink appearance that eventually turned creamy yellow. As ripening progressed, AM exhibited more softening attributes than the AK. Anatomical changes included thinning of the exocarp and merging of locules. Bright-field and scanning electron microscope revealed the dissolution of the cell wall, enlargement of intercellular spaces, and irregular cell masses with leaked cytoplasmic content as the maturation progressed. In the preliminary qualitative tests, phenolics and flavonoids were detected in unoptimized extracts in the ripe stage of both cultivars. The RSM identified the optimum extraction conditions from the ripe guava fruit, and the set extraction conditions 80% methanol, 3% solute-to-solvent ratio, extraction at the elevated temperature (30-35°C), and a two-day extraction period. Under these conditions, the optimized extracts exhibited TPC as newline2907.57 ± 32.7, 3349.66 ± 122.0 mg GAE/100g dry weight (DW); TFC as 194.2 ± 5.99, 245.7 newline± 12.5 mg QUE/100g DW; and DPPH activity as 2846.8 ± 35.15, 2761.4 ± 42.0 mg AAE/100g newlineDW for AK and AM, respectively.