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FP5

BIOCLA Résumé de rapport

Project ID: QLK1-CT-2002-02362
Financé au titre de: FP5-LIFE QUALITY
Pays: Italy

Optimisation of processing methods for production of CLA-enriched hard cheese

With the aim to develop CLA-rich dairy functional foods, several experiments were carried out using sheep and cow milk with different levels of CLA and using different production technologies.

Experiment 1 - With the aim to optimize the production technology to obtain the best CLA recovery from sheep milk, the partitioning of CLA into different products and by-products during the manufacture of Pecorino Sardo and Ricotta cheeses has been assessed. The vaccenic and rumenic acid contents in milk, ripened cheeses and whey were similar.

Experiment 2 - PDO Pecorino Sardo and Ricotta cheeses were manufactured from ovine milk having a low (18mg/g fat, low CLA milk) and a high (25mg/g of fat, high CLA milk) level of rumenic acid using two different rennet types: a liquid rennet which does not contain lipolytic enzymes and a rennet paste which on the contrary is characterised by an high level of the lipolytic enzymes. The effect of the rennet type on the vaccenic and rumenic acids partitioning into cheese at different ripening time (24-old cheese, 2M, 4M, 6M and 8M-old cheeses) and by-products such as ricotta cheese, whey and scotta whey was assessed. The rennet type did not affect the content of vaccenic and rumenic acids in ripened cheese from both high and low CLA-milk.

Experiment 3 - PDO Pecorino Sardo and Ricotta cheeses were manufactured from milk without treatment (control milk) and from milk with homogenized cream. The cream homogeneisation brought some problems in the structure of the cheese. The particles of the curd had a poor cohesivness and in fact the paste of cheese tended crumbling. Gross composition was not affected by the treatment whereas a ripening effect was found for all determined parameters. FA composition also was not influenced by cream homogenisation, on the contrary several FA (like vaccenic acid and CLA) content changed significantly during ripening. The vaccenic and rumenic acids partitioning into different products (1 day and 30, 60, 90, 180 days old cheese) and by-products (ricotta cheese, whey and scotta whey) was not significant influenced by cream homogenisation.

Experiment 4 - PDO Pecorino Sardo cheese were manufactured from bulk ovine milk using a liquid calf rennet. liquid calf rennet + esterase-lipase from Rhizomucor miehei and liquid calf rennet + esterase-lipase from Rhizopus oryzae. No significant effect was found in cheese gross composition related to the treatment and, as expected, a ripening effect was observed for these parameters. With reference to the FA profile, only butyric acid content in cheese was significantly influenced by the treatment. Ripening time significantly influenced several FA as oleic and linoleic acid.
Experiment 5 - PDO Pecorino Sardo cheese were manufactured from bulk ovine milk using a natural whey culture and a freeze-dried culture (CO-02 Hansen). The results showed that gross cheese composition was not affected by treatment. On the contrary a ripening effect was observed for all parameters except for pH value. The use of different lactic cultures did not significantly influence the FA profile in cheese. As reported for the experiments above, a significant effect of ripening was found for several FA as oleic, linoleic and linolenic acid as far as CLA.

CLA-enriched cheese has also been manufactured with CLA-enriched bovine milk from supplementation trials (1. sunflower oil anbd 2. sunflower and linseed oils). Product manufacture was not affected by the elevation of the CLA levels in the cheese milk and sensory or compositional properties of the product were not affected during ripening. Elevated CLA levels were maintained in the cheese during the ripening period.

In conclusion the results demonstrate that the level of beneficial FAs in cheese depends form that of the milk. All studied technological parameters have not allowed enhancing the level beneficial FAs in the final products.

Informations connexes

Contact

Antonio PIRISI, (Research Scientist)
Tél.: +39-079-387277
Fax: +39-079-387277
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