Wspólnotowy Serwis Informacyjny Badan i Rozwoju - CORDIS

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

The aims of this section of the BIOCLA project were i) to study the change in CLA content from goat milk to cheese according to different technologies, ii) to evaluate the sensory properties of CLA-rich cheeses, and iii) to manufacture goat cheeses, enriched in CLA, for clinical evaluation in human volunteers (see ETIP 36846 and 36847). Three successive studies have been conducted to choose an adequate combination of feeding strategies and processing methods for production of CLA-rich cheese with acceptable sensorial quality.

During the first study, five diets have been used: three diets with high forage:concentrate ratio (HF), without or with linseed oil (LO, 4 % of diet dry matter, DM), this latter diet being supplemented or not with vitamin E; one diet with low forage:concentrate ratio (LF) supplemented with LO and vitamin E; one HF diet supplemented with extruded linseeds (ELS). Bulk milks obtained from these diets contained between 0.3 and 3.3% CLA in total fatty acids (FA) and have been pasteurized and transformed in 3 types of cheeses: lactic ripened cheese (St Maure type), lactic spread cheese, and soft cheese (camembert type). Cheese fat oxidation level was always weakest with the diets containing vitamin E, giving evidence of the antioxidant effect of vitamin E. The effects of cheese technologies were small, with increases in C10:0, C12:0 and C14:0 percentages and decrease in oleic acid, in cheese compared to processed milk. Very few changes were observed for polyunsaturated FA, including CLA.

The sensory properties of cheeses were characterised at half shelf-life (30 days):
- By a trained panel (8-10 experts) for the 15 cheeses coming from the five different diets (appreciation of the intensity of 22-26 descriptors of odour, flavour and texture on a linear continuous scale from 0 to 10). Low scores were observed for the goaty and the yeasty flavours with the spread technology.

- By 60 French consumers for 12 of the 15 cheeses (except those from the LF+LO+vitamin E diet), with a global appreciation from very bad (note 1) to very good (note 7). The cheeses were considered by the consumers as medium or good enough, ranking in order spread < ripened lactic < soft cheese, without significant effect of dietary lipid supplementation.

During the second study, CLA-rich milks were obtained from two HF diets with a high level (7 % of diet DM) of either LO or sunflower oil (SO). They were pasteurized and manufactured in 3 types of cheeses: two St. Maure types (one traditional, and one industrial ripened lactic cheese), and one high-fat spread cheese, made from either fresh or frozen curd. The high level of lipid supplementation resulted in very high CLA levels (up to 5.1% of total FA), but also in defects of flavour, especially with LO. This phenomenon could be amplified in high-fat spread cheese. Freezing had no effect on the FA profile (including CLA).

During the third study, goats were fed a HF diet supplemented, or not, with SO and vitamin E, in order to maximize CLA in the milk, and simultaneously to minimize the oxidation of cheese fat and the risk of flavour defects. The cheeses were manufactured from 1 to 8-month stored frozen curd, into high-fat spread cheese. This allowed to yield goat cheeses for the clinical trial in Italy (see ETIP 36846 and 36847), with CLA content of 0.3% or 3.9% of total FA for control or CLA-rich goat cheese, respectively, and with acceptable flavour (as evaluated by two different panels in France) despite a decrease in sensorial quality with curd ageing, particularly for CLA-rich cheese.

In conclusion, these results provide novel information on strategies to produce CLA-enriched goat dairy products that could be marketed as a functional food per se. Furthermore, CLA enriched-milk could be a valuable ingredient for the manufacture of new healthy goat products.

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Reported by

Institut National de la Recherche Agronomique (INRA)
Clermont-Theix Research Centre, Herbivore Research Unit,
63122 Saint Genes Champanelle
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