Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels

Noemi Caruggi, Mara Lucisano, Aberham Hailu Feyissa, Saeed Rahimi Yazdi, Mohammad Amin Mohammadifar*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21% higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40% less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.
Original languageEnglish
JournalFood Biophysics
Volume14
Issue number3
Pages (from-to)249-259
ISSN1557-1858
DOIs
Publication statusPublished - 2019

Keywords

  • Ohmic heating
  • Acid milk gels
  • Preheat treatment
  • Rheology
  • Texture

Cite this

Caruggi, Noemi ; Lucisano, Mara ; Feyissa, Aberham Hailu ; Rahimi Yazdi, Saeed ; Mohammadifar, Mohammad Amin. / Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels. In: Food Biophysics. 2019 ; Vol. 14, No. 3. pp. 249-259.
@article{b420b8e1a75142638689a5555a944fd6,
title = "Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels",
abstract = "This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21{\%} higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40{\%} less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.",
keywords = "Ohmic heating, Acid milk gels, Preheat treatment, Rheology, Texture",
author = "Noemi Caruggi and Mara Lucisano and Feyissa, {Aberham Hailu} and {Rahimi Yazdi}, Saeed and Mohammadifar, {Mohammad Amin}",
year = "2019",
doi = "10.1007/s11483-019-09578-y",
language = "English",
volume = "14",
pages = "249--259",
journal = "Food Biophysics",
issn = "1557-1858",
publisher = "Springer New York",
number = "3",

}

Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels. / Caruggi, Noemi; Lucisano, Mara; Feyissa, Aberham Hailu; Rahimi Yazdi, Saeed; Mohammadifar, Mohammad Amin.

In: Food Biophysics, Vol. 14, No. 3, 2019, p. 249-259.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Effect of Ohmic Heating on the Formation and Texture of Acid Milk Gels

AU - Caruggi, Noemi

AU - Lucisano, Mara

AU - Feyissa, Aberham Hailu

AU - Rahimi Yazdi, Saeed

AU - Mohammadifar, Mohammad Amin

PY - 2019

Y1 - 2019

N2 - This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21% higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40% less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.

AB - This study aimed to describe the effects of ohmic heat treatment (OHT) of milk on the formation and properties of acid milk gels. The influence of voltage gradient (25, 40, 55 V/cm), holding time (2, 16, 30 min), and final temperature (45, 65, 75, 85 °C) on rheological properties and particle size distribution was measured during the gelation process. Texture properties and syneresis of the samples were evaluated at the end of the gelation process. Scanning electron microscopy (SEM) micrographs of the acid milk gels were also taken at pH 4.6(i.e., pI or Isoelectric point of casein). Results indicated that oscillatory time sweep tests were more accurate than particle size measurements in detecting gelation onset. Complex modulus values of the final gel showed that OHT of the milk at 25 V/cm and holding at 85 °C for 16 min gave rise to a 21% higher structural strength compared to when using the conventional heat treatment (CHT) where temperature was 85 °C and holding time and come up time were 30 and 20 min respectively. In other words, by using the OHT milk, the same gel strength as that of CHT 85 °C sample was obtained by spending 185 min instead of 328 min incubation time (i.e., 40% less time). Higher voltage gradient lowered the final gel strength when temperature and holding time kept constant at 85 °C and 16 min respectively. Results indicated that the gel firmness enhanced and the amount of syneresis decreased when CHT was replaced by OHT in the manufacturing process. SEM revealed that the protein matrices of ohmic heating samples appeared to be more compact and denser with smaller pore size than observed in the conventional gel. Results indicated that OHT of milk successfully improves the quality of acid milk gels and obviate the need for increasing dry matter concentration or using additives.

KW - Ohmic heating

KW - Acid milk gels

KW - Preheat treatment

KW - Rheology

KW - Texture

U2 - 10.1007/s11483-019-09578-y

DO - 10.1007/s11483-019-09578-y

M3 - Journal article

VL - 14

SP - 249

EP - 259

JO - Food Biophysics

JF - Food Biophysics

SN - 1557-1858

IS - 3

ER -