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Cited by 3Proteins in Food SystemsFood and Agricultural SciencesProbiotics and Fermented Foods

Characterization of a traditional ripened cheese, Kurdish Kope cheese: Proteolysis, microstructural, and rheological characteristics

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Esmaeilzadeh, Peiman, Mizani, Maryam, Ehsani, Mohammad Reza, Givianrad, Mohammad Hadi·2025·Journal of Food Science
DOI 10.1111/1750-3841.70107
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Abstract

This study explored the primary and secondary proteolysis reactions in Kope cheese made from raw sheep milk, revealing significant biochemical and structural changes throughout the ripening process. The ripening index and proteolysis depth increased significantly (p < 0.05) during the ripening period. Electrophoresis results indicated that by the end of ripening, 44.7% of αs1-casein and 70.2% of β-casein residues remained intact, reflecting progressive protein breakdown. The low-molecular-weight protein-to-casein ratio rose from 0.12 to 0.40, signifying intensified proteolysis over time. Analysis of the ethanol-soluble fraction's peptide profile showed two prominent peaks between 40 and 50 min and a single major peak between 20 and 25 min, demonstrating the formation of specific peptides during maturation. Free amino acid analysis revealed higher concentrations of glutamic acid, leucine, and lysine in Kope cheese, signifying a rich profile of flavor-enhancing compounds. Principal component analysis classified the cheeses into three distinct ripening categories: (1) Young-ripened cheese (37-67 days) with low proteolysis intensity; (2) Mild-ripened cheese aged 67-127 days, characterized by the lowest mean storage modulus (G') value (576 KPa); (3) Old-ripened cheese (127-187 days) displaying significant proteolysis intensity and a comparatively low G' value. Scanning Electron Microscopy (SEM) imaging revealed dramatic structural changes during ripening. Initially, the cheese had a compact and rough texture, which evolved into an open, crumbly structure by the end of the ripening period. These changes corresponded with the biochemical processes of proteolysis and the resulting textural softening.

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  • Valine, leucine, isoleucine, tyrosine, phenylalanine, histidine, and arginine increased in concentration as protein breakdown and hydrophobic peptides increased during ripening.

    “In contrast, valine, leucine, isoleucine, tyrosine, phenylalanine, histidine, and arginine, which are associated with bitterness, increased in concentration as protein breakdown and hydrophobic peptides increased during ripening (Esmaeilzadeh et al., 2025).”

    From Impact of lactic acid bacteria coculture on the quality characteristics of goat cheese during ripening (2025) · cites this paper as Esmaeilzadeh et al., 2025

    Section 3.3.2 reports increasing proteolysis during ripening, and the 70% ethanol-insoluble peptide section reports more hydrophobic-zone peaks in older cheese and links large hydrophobic peptides to bitterness. Section 3.4 reports that total free amino acids rose, then fell, then rose again; it does not establish that all seven listed amino acids increased or that those amino acids were associated with bitterness. Page numbers were not available in our copy. (LLM, conf=0.86)

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Research works printed but not linked: 8

  1. Bontinis, T. G., Mallatou, H., Pappa, E., Massouras, T., & Alichanidis, E. (2012). Changes in lipolysis, proteolysis, and volatile profile of Xinotyri cheese made from raw goat's milk. Bulletin of the International Dairy Federation, 87, 414-428.
  2. Elsamani, M. O. (2023). Kinetics of free amino acid profile in various levels of NaCl concentration of cheese protein whey. Journal of Chemical Health Risks, 13(6), 2023-2030.
  3. Hassas, B., Nateghi, L., & Lavasani, A. S. (2019). Investigation of physicochemical, microbial and sensory properties of low-fat jug cheeses containing β-glucan powder and ethanolic extract of menthe longifolia. Iranian Food Science & Technology Research Journal, 15(1), 181-198.
  4. Hemmatian, M., Aminifar, M., & Attar, F. (2015). Characterization of Poosti Cheese, a traditional raw sheep cheese during ripening: Physicochemical, microbial and micro-structural aspect. Nutrition and Food Science Research, 2(2), 39-48.
  5. Hayaloglu, A. A., Topcu, A., & Koca, N. (2011). Principles of cheese science. In A. A. Hayaloglu & B. Ozer (Eds.), Cheese analysis (pp. 489-562).
  6. Michaelidou-Koniordou, A. M. (1997). Protein hydrolysis during ripening of Feta cheese [Doctoral dissertation, Aristotle Univer- sity].
  7. Mashak, Z., & Rooshani, J. (2019). The survey of chemical and microbial characteristics of traditional Koozeh-Cheese (Koopeh) in Kurdistan province. New Findings in Veterinary Microbiology, 2(1), 67-80.
  8. Nateghi, L. (2020). Evaluation the possibility of producing low-fat Cheddar cheese containing sesame and walnut powder during storage. Electronic Journal of Food Processing and Preservation, 11(2), 1-18.

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Authors
Esmaeilzadeh, P., Mizani, M., Ehsani, M. R., & Givianrad, M. H.
Affiliations
Islamic Azad University, Science and Research Branch (IR)
Corresponding author
Mizani, Maryam
ORCID
Venue
Journal of Food Science
Publisher
Wiley
Published
2025-04
Volume
90
Issue
4
Pages
e70107-e70107
ISSN
  • 0022-1147 (ISSN-L)
  • 1750-3841
DOI
10.1111/1750-3841.70107
OpenAlex
W4409343527
Cited by
3
References
41
Citations by year
2026: 2 · 2025: 1
FWCI
1.43
Type
journal article
Language
en
Open access
Licence
onlinelibrary.wiley.com/termsAndConditions#vor (vor, 8 d)
Locations
  • Journal of Food Science (publishedVersion)
  • PubMed (publishedVersion)
Topics
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Proteins in Food Systems
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Food and Agricultural Sciences
  • Life Sciences › Agricultural and Biological Sciences › Food Science › Probiotics and Fermented Foods
Keywords
sheep cheese, casein hydrolysis, αs1-casein, β-casein, free amino acids, cheese microstructure, cheese texture, storage modulus, cheese ripening
MeSH terms
Amino Acids, Animals, Caseins, Cheese, Food Handling, Milk, Rheology, Sheep, Taste, Proteolysis

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