Effect of Drying Methods and Ultrasonication in Improving the Antioxidant Activity and Total Phenolic Content of Apple Pomace Powder

Abstract

Although extrusion is a promising process to develop ready to eat cereals and snacks, thermal treatment to raw material during extrusion results in degradation of phenolic compounds. Therefore, an approach was made to enhance the total phenolic content (TPC) and antioxidant activity (AA) of apple pomace (AP) prior to extrusion process. In this study, AP powder was naturally fermented (F) for 12 h and then was subjected to ultrasonication (U) at various conditions [25, 37, and 50 µm ultrasonication amplitude (UA) for 1, 2, and 3 min of ultrasonication time (UT)]. AP was then dried in oven (O) and microwave (MW), separately and thus four drying methods, i.e. O F -O U , O F -MW U , MW F -O U , MW F -MW U were used in combinations. Full factorial design was used for experimental plan and results were analyzed using statistical software. It was observed that drying method significantly affected the TPC and AA of AP powder followed by UA. UT did not have any significant effect on TPC, and AA. Maximum TPC, and AA observed for the AP powder dried in MW after fermentation and ultrasonication (MW F -MW U ) at 50 µm UA for 3 min UT were 372.98 mg GAE/100g DW, and 729.67 µmol TE/100 g DW, respectively. MW F -MW U drying exhibited a more prominent disrupted and porous structure of AP powder compared with that of O F -O U drying.

Effect of sequential treatments of fermentation and ultrasonication followed by extrusion on bioactive content of apple pomace and textural, functional properties of its extrudates

“…Candrawinata et al . (), and Lohani & Muthukumarappan () also reported high correlation between TPC and AA of AP.…”

“…Our comprehensive literature review revealed that in the past few years, ultrasound assisted extraction of phenolic compounds from AP has been extensively investigated (Grigoras et al, 2013;Candrawinata et al, 2014) but application of the fermentation followed by ultrasonication to enhance phenolics as well as functional properties in AP is limited. Even though Lohani & Muthukumarappan (2015) found a significant (P < 0.05) increase in TPC and AA of AP after fermentation followed by the ultrasonication and microwave drying, more levels of the fermentation time (FT), ultrasonication parameters (intensity, time) and microwave power (MWP) are needed to be explored. Therefore, keeping in view above facts, the objective of this study was to investigate the influence of sequential treatments of fermentation and ultrasonication followed by microwave drying on TPC and AA of AP.…”

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

“…So, considering the solvents, the present outputs fitted to Arunachalam et al (2011) Candrawinata et al (2014) found that an increasing temperature permitted an increasing extraction of total phenols, thus an increasing antioxidant activity. As aside results, Lohani and Muthukumarappan (2015) proved that the interaction effects between two independent variables mainly reduce the derived result. For instance, looking at the drying method (DM) and ultrasonication amplitude (UA) effects on apple pomace separately, they reported 6788.3334 and 1876.8693, respectively; while the interaction (DM*UA) leaded to 1594.1769 µmol TE/g.…”

“…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 accordance with Lohani and Muthukumarappan (2015), compare to raw material, dried products exhibit higher phenolic compound extracts. For example, the fresh exhibited 3.125 versus 3.5 mg GAE/g for the dried apple pomace at 50 o C. Furthermore, they found that, when the product is fermented then dried, it exhibits higher total phenols extracts.…”

“…Thus B. aethiopum is richer than apple pomace for total phenols. 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).…”