Composition and Aroma Compounds of Ragusano Cheese: Native Pasture and Total Mixed Rations

S. Carpino,1 S. Mallia,1 S. La Terra,1 C. Melilli,1 G. Licitra,1,2 T. E. Acree,D. M. Barbano,4 and P. J. Van Soest 

1- CoRFiLaC, Regione Siciliana, 97100 Ragusa, Italy
2- Dipartimento di Scienze Agronomiche, Agrochimiche e delle Produzioni Animali, Catania University, Via Valdisavoia 5, 95100 Catania, Italy
3- Department of Food Science and Technology, Cornell University, Geneva, NY 14456
4- Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853
5- Department of Animal Science, Cornell University, Ithaca, NY 14853


Raw milk from 13 cows fed TMR supplemented with native pasture and from 13 cows fed only TMR on one farm was collected separately 4 times with an interval of 15 d between collections. Two blocks (14 kg each) of cheese were made from each milk. The objective was to determine the influence of consumption of native plants in Sicilian pastures on the aroma compounds present in Ragusano cheese. Milk from cows that consumed native pasture plants produced cheeses with more odor-active compounds. In 4-mo-old cheese made from milk of pasture-fed cows, 27 odor-active compounds were identified, whereas only 13 were detected in cheese made from milk of total mixed ration-fed cows. The pasture cheeses were much more rich in odor-active aldehyde, ester, and terpenoid compounds than cheeses from cows fed only total mixed ration. A total of 8 unique aroma-active compounds (i.e., not reported in other
cheeses evaluated by gas chromatography olfactory) were detected in Ragusano cheese made from milk from cows consuming native Sicilian pasture plants. These compounds were 2 aldehydes ([E,E]-2,4-octadienal and dodecanal), 2 esters (geranyl acetate and [E]-methyl jasmonate), 1 sulfur compound (methionol), and 3 terpenoid compounds (1-carvone, L(-) carvone, and citronel-lol). Geranyl acetate and (E)-methyl jasmonate were particularly interesting because these compounds are released from fresh plants as they are being damaged and are part of a possible plant defense mechanism against damage from insects. Most of the odor-active compounds that were unique in Ragusano cheese from pasture-fed cows appeared to be compounds created by oxidation processes in the plants that may have occurred during foraging and ingestion by the cow. Some odor-active compounds were consistently present in pasture cheeses that were not detected in the total mixed ration cheeses or in the 14 species of pasture plants analyzed. Either these compounds were present in other plants not analyzed, created in the rumen or in cheese after the pasture-plant material had been consumed, or the compounds were lost in the method of sample extraction used for the plant analysis (i.e., steam distillation) versus the solid-phase microextraction method used for the cheeses. This research has demonstrated clearly that some unique odor-active compounds found in pasture plants can be transferred to the cheese.

Keywords: pasture, Ragusano cheese, aroma

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D.M. Barbano

Prof. Northeast Dairy Foods Research Center, Department of Food Science, Cornell University, (USA)