Chemical composition and structure of different types of macroparticles (specks, spots) and microparticles (microcrystals) present in hard and extra-hard cheeses were investigated. Light microscopy revealed that the small hard specks had the structure of crystalline tyrosine, as confirmed by amino acid analysis. Spots showed a complex structure, including several curd granules, cavities, and microcrystals, and were delimited by a dense protein layer. Spots contained less moisture and ash than the adjacent cheese area, and more protein, including significantly higher contents of valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine. Microcrystals were observed by light and electron microscopy and analyzed by confocal micro-Raman. Among others, calcium phosphate crystals appeared to consist of a central star-shaped structure immersed in a matrix of free fatty acids plus leucine and phenylalanine in free form or in small peptides. A hypothetical mechanism for the formation of these structures has been formulated.

New insight on crystal and spot development in hard and extra-hard cheeses : Association of spots with incomplete aggregation of curd granules / P. D'Incecco, S. Limbo, F. Faoro, J. Hogenboom, V. Rosi, S. Morandi, L. Pellegrino. - In: JOURNAL OF DAIRY SCIENCE. - ISSN 0022-0302. - 99:8(2016 Aug), pp. 6144-6156. [10.3168/jds.2016-11050]

New insight on crystal and spot development in hard and extra-hard cheeses : Association of spots with incomplete aggregation of curd granules

P. D'Incecco;S. Limbo;F. Faoro;J. Hogenboom;V. Rosi;L. Pellegrino
2016-08

Abstract

Chemical composition and structure of different types of macroparticles (specks, spots) and microparticles (microcrystals) present in hard and extra-hard cheeses were investigated. Light microscopy revealed that the small hard specks had the structure of crystalline tyrosine, as confirmed by amino acid analysis. Spots showed a complex structure, including several curd granules, cavities, and microcrystals, and were delimited by a dense protein layer. Spots contained less moisture and ash than the adjacent cheese area, and more protein, including significantly higher contents of valine, methionine, isoleucine, leucine, tyrosine, and phenylalanine. Microcrystals were observed by light and electron microscopy and analyzed by confocal micro-Raman. Among others, calcium phosphate crystals appeared to consist of a central star-shaped structure immersed in a matrix of free fatty acids plus leucine and phenylalanine in free form or in small peptides. A hypothetical mechanism for the formation of these structures has been formulated.
calcium phosphate crystal; cheese ultrastructure; electron microscopy; free amino acids; hard and extra hard cheeses; animal science and zoology; food science; genetics
Settore AGR/15 - Scienze e Tecnologie Alimentari
2016
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/439214
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