TY - JOUR
T1 - Optimization of microwave-assisted hydrothermal extraction of homogalacturonan-rich, low methoxyl pectin from discarded garlic peels
T2 - Comparative macromolecular and functional analysis with conventional extraction
AU - Gonzalez-Serrano, Diego J.
AU - Benmebarek, Imed E.
AU - Hadidi, Milad
AU - Bechtner, Julia D.
AU - Martinez, Mario M.
AU - Cabañas, Beatriz
AU - Moreno, Andres
N1 - Publisher Copyright:
© 2025 The Authors
PY - 2025/10
Y1 - 2025/10
N2 - This study explored the extraction of pectin from garlic peels and its potential application as a food hydrocolloid due to its liquid-holding, emulsifying, thickening, and gelling properties. A Box-Behnken optimization of microwave-assisted hydrothermal extraction (MAHE) was performed to examine the effects of pH, temperature, and irradiation time on pectin yield (PY), galacturonic acid concentration (GalAC), degree of methylation (DM), and degree of acetylation (DA). Low methoxyl (36.1% DM) and low-acetyl (0.9% DA) pectin (MAHEP) were obtained at optimal MAHE conditions, achieving a high GalAC (74.9%) and a notable PY (14.5%). Following MAHE optimization, a 2-h conventional heat extraction (CE) was conducted under the same temperature, pH, and ratio. Pectin obtained through CE (CEP) demonstrated a lower PY (12.1%) but maintained a high purity level (67.1%) and exhibited higher DM (46.6%) and DA values (1.1%). Both MAHEP and CEP were rich in homogalacturonan (HG) domains (83.6–92.2% HG ratio) but differed in DM, thermal degradation behavior, and functionality. CEP showed excellent water retention (9.0 g/g) and thickening properties (2.5 Pa s at 4% w/w and 1 s−1), whereas MAHEP excelled in emulsifying stability (85–99% under all conditions tested) as well as gelling performance (G' > G″ for all frequencies tested at 4% w/w). This study highlights the potential of garlic peels as a source of two distinct pectic polysaccharides with high purity and functional versatility. It also provides insights into how the extraction system influences pectin structure and functional behavior.
AB - This study explored the extraction of pectin from garlic peels and its potential application as a food hydrocolloid due to its liquid-holding, emulsifying, thickening, and gelling properties. A Box-Behnken optimization of microwave-assisted hydrothermal extraction (MAHE) was performed to examine the effects of pH, temperature, and irradiation time on pectin yield (PY), galacturonic acid concentration (GalAC), degree of methylation (DM), and degree of acetylation (DA). Low methoxyl (36.1% DM) and low-acetyl (0.9% DA) pectin (MAHEP) were obtained at optimal MAHE conditions, achieving a high GalAC (74.9%) and a notable PY (14.5%). Following MAHE optimization, a 2-h conventional heat extraction (CE) was conducted under the same temperature, pH, and ratio. Pectin obtained through CE (CEP) demonstrated a lower PY (12.1%) but maintained a high purity level (67.1%) and exhibited higher DM (46.6%) and DA values (1.1%). Both MAHEP and CEP were rich in homogalacturonan (HG) domains (83.6–92.2% HG ratio) but differed in DM, thermal degradation behavior, and functionality. CEP showed excellent water retention (9.0 g/g) and thickening properties (2.5 Pa s at 4% w/w and 1 s−1), whereas MAHEP excelled in emulsifying stability (85–99% under all conditions tested) as well as gelling performance (G' > G″ for all frequencies tested at 4% w/w). This study highlights the potential of garlic peels as a source of two distinct pectic polysaccharides with high purity and functional versatility. It also provides insights into how the extraction system influences pectin structure and functional behavior.
KW - Garlic by-product
KW - Homogalacturonan
KW - Hydrocolloids
KW - Pectin
KW - Process optimization
UR - http://www.scopus.com/inward/record.url?scp=86000723055&partnerID=8YFLogxK
U2 - 10.1016/j.foodhyd.2025.111324
DO - 10.1016/j.foodhyd.2025.111324
M3 - Journal article
AN - SCOPUS:86000723055
SN - 0268-005X
VL - 166
JO - Food Hydrocolloids
JF - Food Hydrocolloids
M1 - 111324
ER -