Modulating temperature and pH during subcritical water extraction tunes the molecular properties of apple pomace pectin as food gels and emulsifiers

TY - JOUR

T1 - Modulating temperature and pH during subcritical water extraction tunes the molecular properties of apple pomace pectin as food gels and emulsifiers

AU - Yilmaz-Turan, Secil

AU - Gál, Teodóra

AU - Lopez-Sanchez, Patricia

AU - Martinez, Mario M.

AU - Menzel, Carolin

AU - Vilaplana, Francisco

N1 - Publisher Copyright: © 2023 The Authors

PY - 2023/12

Y1 - 2023/12

N2 - This study explores the cascade extraction of polyphenols and pectins from apple pomace and their potential application as food emulsifiers. The extraction of polyphenols was achieved by a simple method using ethanol and resulted in remarkable antioxidant activity. Pectic polysaccharides were sequentially extracted (5, 10 and 15 min) using subcritical water at two different temperatures (120 °C and 140 °C) and three different pH conditions (pH 3.0, 5.0 and 7.0). Acidic pH resulted in higher pectin yields when combined with higher temperature, whereas neutral conditions were less selective towards pectin. Pectin with different branching patterns could be isolated by tuning the process conditions. Linear homogalacturonan (HG) was preferentially isolated at milder conditions, whereas more branched rhamnogalacturonan (RG-I) populations required longer extraction times. Subcritical water enabled the extraction of pectins with different degrees of methoxylation (DM) depending on the extraction pH, which enabled the production of pectin acid gels with varying rheological properties. Low DM pectin was directly recovered from apple pomace at lower pH, eliminating the need for its conventional derivatization from high DM pectin. The emulsifying properties of two apple pomace pectin fractions with high and low methoxyl content were compared; the pectin with higher methoxyl content showed higher emulsifying capacity and stability. This study demonstrates that the relative abundance of the different pectic domains and the methoxylation of pectin can be controlled by subcritical water extraction, which has important implications for the valorization of pectic-rich agricultural wastes into valuable food ingredients.

AB - This study explores the cascade extraction of polyphenols and pectins from apple pomace and their potential application as food emulsifiers. The extraction of polyphenols was achieved by a simple method using ethanol and resulted in remarkable antioxidant activity. Pectic polysaccharides were sequentially extracted (5, 10 and 15 min) using subcritical water at two different temperatures (120 °C and 140 °C) and three different pH conditions (pH 3.0, 5.0 and 7.0). Acidic pH resulted in higher pectin yields when combined with higher temperature, whereas neutral conditions were less selective towards pectin. Pectin with different branching patterns could be isolated by tuning the process conditions. Linear homogalacturonan (HG) was preferentially isolated at milder conditions, whereas more branched rhamnogalacturonan (RG-I) populations required longer extraction times. Subcritical water enabled the extraction of pectins with different degrees of methoxylation (DM) depending on the extraction pH, which enabled the production of pectin acid gels with varying rheological properties. Low DM pectin was directly recovered from apple pomace at lower pH, eliminating the need for its conventional derivatization from high DM pectin. The emulsifying properties of two apple pomace pectin fractions with high and low methoxyl content were compared; the pectin with higher methoxyl content showed higher emulsifying capacity and stability. This study demonstrates that the relative abundance of the different pectic domains and the methoxylation of pectin can be controlled by subcritical water extraction, which has important implications for the valorization of pectic-rich agricultural wastes into valuable food ingredients.

KW - Apple pomace

KW - Emulsifier

KW - Food waste

KW - Gelling properties

KW - Pectin

KW - Subcritical water

UR - http://www.scopus.com/inward/record.url?scp=85166971471&partnerID=8YFLogxK

U2 - 10.1016/j.foodhyd.2023.109148

DO - 10.1016/j.foodhyd.2023.109148

M3 - Journal article

AN - SCOPUS:85166971471

SN - 0268-005X

VL - 145

JO - Food Hydrocolloids

JF - Food Hydrocolloids

M1 - 109148

ER -