Effect of drying temperature on polyphenolic content and antioxidant activity of apricots

Abstract

This study was carried out in order to check for the influence of drying parameters on the phenolic compounds and antioxidant activity on two apricot cultivars (Pelese and Cafona) using two sets of air drying temperatures: (1) air temperature at 55°C; (2) air temperature at 75°C. Whole fresh and dried fruits were assessed for: phenolics, ascorbic acid, antioxidant activity and redox potential (all parameters were calculated on a dry matter basis). Analysis of data shows that the decrease in chlorogenic and neochlorogenic acid in Cafona cultivar is higher at the lower drying temperature. Catechin showed the same behaviour of hydroxycinnamic acids in both cultivars, while the decrease in the other compounds was significantly more marked in the sample dried at 75°C. The antioxidant activity increased significantly in Cafona fruits and this increase was confirmed by a diminution of the redox potential.

Drying Temperature Effect on Total Phenols and Flavonoids Content, and Antioxidant Activity of Borassus aethiopum Mart Ripe Fruits’ Pulp

“…The observed gap was just 0.0033 g GAE/l (9.966 mg GAE/g), meaning 6.6%. Madrau et al (2009) o C a large variety of mushrooms, extracted them in aqueous ethanol, and the highest extract of total phenols was 15.8 mg GAE/g. Herein, the least extraction was 0.1083 g GAE/l (327.066 mg GAE/g) in DW+Meth.…”

“…At high temperature, following Madrau et al (2009) remarks, the PPO enzymatic reaction doesn't occur because of a relative short exposure time. In addition, Lohani and Muthukumarappan (2015) indicated that the phenolic compounds can be liberated by heat treatment, and moreover, Jeong et al (2004) came to the conclusion that phenols should have different bound status along with plant species.…”

“…In fact, at high drying temperature, the covalent bound in phenolic compounds can be cleaved (Lohani & Muthukumarappan, 2015). Many authors reported that an increase drying temperature leads to an increase total phenolic extract (Wood et al, 2002;Jeong et al, 2004;Ruenroengklin et al, 2008;Madrau et al, 2009). However, Rajha et al (2014) mentioned that, at high drying temperature, when the product reaches a constant weight, meaning it can't release any more water, we should stop heating; otherwise the excessive heat leads to a degradation of polyphenols.…”

“…Thus, the extraction mode was a main effect for total flavonoids content assessment at 40 o C, whereas it wasn't for other products. The announced PPO enzymatic reaction by Madrau et al (2009), occurring during the long exposure at low temperatures may not affect flavonoid compounds in B. aethiopum Mart mature pulp, since they are still available. Or, maybe our drying method which consisted in a thin layer of fibrous pulp in the oven leaded to a quick dry to reach the stable weight, so that the phenomenon was eschewed.…”

Drying and pickling on phenols, capsaicinoids, and free radical-scavenging activity in Anaheim and Jalapeño peppers

“…), were retained 64 and 62.5%, respectively, after sun-drying (Table 1). During the drying process, enzyme activity remains high for long periods of time when temperature is maintained among 55-60°C, whereas many enzymes are inactivated after short periods of exposure to temperatures of 75-80°C (MADRAU et al, 2009). Caffeic acid is susceptible to decarboxylation reactions, which can be promoted by either thermal conditions or enzymatic action through decarboxylases to generate vinylphenols (RIZZI & BOEKLEY, 1992).…”