No abstract

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 citronellol). 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.

No abstract

The impact of presalting and nonsaturated brine on salt uptake by Ragusano cheese was determined. The study included four treatments: 1) the traditional method using no presalting and saturated brine, 2) presalting and saturated brine, 3) no presalting and 18% brine for 8 d followed by 16 d in saturated brine, and 4) presalting and 18% brine for 8 d followed by 16 d in saturated brine. Cheese blocks were weighed and sampled before brine salting (time 0) and after 1, 4, 8, 16, and 24 d of brining for each treatment. Presalting delivered 60% of the normal level of salt in the center of the block prior to brine salting without decreasing the rate of uptake of salt from either saturated or 18% brine. Use of 18% salt brine for the first 8 d of 24 d of brine salting increased the rate of salt uptake, compared with 24 d in saturated brine. The increased rate of salt uptake with 18% brine compared with saturated brine was related to the impact of salt brine on the moisture content and porosity of the cheese near the surface of the block. Brine with higher salt content causes a rapid loss of moisture from cheese near the surface of the block. Moisture loss causes shrinkage of the cheese structure and decreases porosity, which impedes moisture movement out and salt movement into the block. The use of 18% salt brine for the first 8 d delayed the moisture loss and cheese shrinkage at the exterior of the block and allowed more salt penetration.