Changes in total phenolic and flavonoid content and antioxidative activities during production of juice concentrate from Asian pears (Pyrus pyrifolia Nakai)

Abstract

The total phenolic and flavonoid content and antioxidative activities during production of pear juice concentrate (PJC) from two cultivars, Hwasan and Niitaka, were investigated. The main processing steps in PJC production are washing, pressing, pasteurization, clarification, filtration, evaporation, and packaging. Total phenolic and flavonoid content of end-product PJC from Niitaka decreased by 53.11 and 46.47%, respectively, while those from Hwasan decreased by 55.46 and 36.09%, respectively, compared to the phenolic and flavonoid content of original fresh fruit. DPPH radical-scavenging activities, reducing power and nitrate radical-scavenging activities showed a similar tendency as total phenolic and flavonoid content; that is, they decreased in juice concentrate made from both cultivars. Also, antioxidant activities of press cake waste (skin and seeds) from Niitaka and Hwasan pears were higher than fresh pears. In conclusion, antioxidant levels were significantly affected during processing of PJC, especially during the pressing step in which press cake waste retains the seeds and skin.

Effect of 1-methylcyclopropene (1-MCP) application and periodic cold storage on ripening of “Bartlett” pear during ambient shelf life periods

“…Total phenols were estimated according to the method of Jiang et al, (2016). Phenols were extracted in 80% ethanol and estimated on the basis of their reaction with an oxidizing agent phosphomolybdate in Folin‐Ciocalteu reagent under alkaline conditions.…”

Halo-fluorescein for photodynamic bacteria inactivation in extremely acidic conditions

“…70-72). Compared with the common operations in juices production (e.g., thermal treatment, concentrate, and storage) [43][44][45][46] , the changes of the antioxidants by photodynamic sterilization with TIF were comparable or lower (Supplementary Table 9). It should be noticed that only 10-20 min of light irradiation (once) was employed for all the above photodynamic sterilization investigations.…”

Formation of Amadori compounds in LIGAO (concentrated pear juice) processing and the effects of Fru-Asp on cough relief and lung moisturization in mice

“…The total phenolic concentration was determined using the Folin–Ciocalteu reagent and the total flavonoid concentration was measured using the aluminum chloride colorimetric method. 16 Soluble protein was determined by Coomassie Blue G-250 staining. Vitamin C was determined volumetrically by using the 2,6-dichlorophenol-indophenol reagent.…”