Giovanni Piredda

Effects of sheep α s1 -casein CC, CD and DD genotypes on milk composition and cheesemaking properties

The effects of sheep alpha s1-casein CC, CD and DD genotypes on milk composition and cheese yield were studied. Processed bulk milk was collected from three groups of 15 ewes, carrying alpha s1-casein CC, CD and DD genotypes. CC milk was higher in casein content than CD or DD milk (+3.5 and +8.6% respectively), and had a higher protein: fat ratio and a smaller casein micelle diameter. In addition, DD milk had a significantly lower alpha s1-casein content. The main differences were in curd formation: CC milk had better renneting properties. Cheesemaking trials, carried out in a pilot plant, showed that CC milk had better cheesemaking characteristics than DD milk, while CD milk was intermediate. Both 1 d old and fully ripened cheeses had different fat: dry matter ratios and alpha s1-I-casein electrophoretic mobilities: these were lower for DD cheese. As a consequence, these genotypes could be considered as markers of milk and/or cheese quality.

SPME/GC-MS Characterization of the Volatile Fraction of an Italian PDO Sheep Cheese to Prevalent Lypolitic Ripening: the Case of Fiore Sardo

A specifically aimed SPME/GC-MS method has been assessed in order to describe the volatile fraction of intense flavoring cheeses like Fiore Sardo PDO, a prevalent lipolytic ripening sheep cheese from Sardinia, Italy. A DVB/CAR/PDMS 50/30 µm fiber and a 3-min exposure time showed to be the best compromise between the possibility to extract compounds with a wide range of polarity and molecular mass and the need to avoid competition and displacement effects among analytes. The volatile compound profile of Fiore Sardo PDO sheep cheese was largely characterized by carboxylic acids (about 68% of the total area of recognized peaks), whereas esters (14%), ketones (9%), and alcohols (8%) represented other abundant classes of low molecular weight species. A number of low-smelling threshold trace compounds were also identified as likely contributors of aroma of the Fiore Sardo PDO cheese.

A survey on the milk fatty acid composition of forty dairy sheep flocks in Sardinia

Abstract A survey was carried out to monitor milk fatty acid (FA) composition during two years (2003 and 2004) on forty dairy sheep flocks, fed pasture based rations, in 5 macro pedoclimatic areas of Sardinia, featured by different i) soil type, (granitic, G; basaltic, B and alluvial, A) ii) average annual rainfall (low, L, 500-600 mm/year; high, H, 600-800 mm/year). Milk FA profile was strongly influenced by year. In particular milk linolenic acid (LN), CLA (conjugated linoeic acid) and PUFA (polyunsaturated fatty acids) levels increased (by 25, 30 and 14%, respectively, P<0.01) whereas the atherogenicity index (AI) decreased (by 8%, P<0.01) in all areas in 2004 as compared with 2003. Pedoclimatic area affected milk fatty acid composition (P<0.01). In both years milk from AL farms showed the highest levels of LN, CLA and PUFA. AI was lower in BH and GH in year 2003 and in BH, AH and GL in 2004.

Dietary Conjugated Linoleic Acid-Enriched Cheeses Influence the Levels of Circulating n-3 Highly Unsaturated Fatty Acids in Humans

n-3 highly unsaturated fatty acids (n-3 HUFA) directly and indirectly regulate lipid metabolism, energy balance and the inflammatory response. We investigated changes to the n-3 HUFA score of healthy adults, induced by different types and amounts of conjugated linoleic acid (CLA)-enriched (ENCH) cheeses consumed for different periods of time, compared to dietary fish oil (FO) pills (500 mg, each containing 100 mg of eicosapentaenoic and docosahexaenoic acids—EPA+DHA) or α-linolenic acid (ALA)-rich linseed oil (4 g, containing 2 g of ALA). A significant increase in the n-3 HUFA score was observed, in a dose-dependent manner, after administration of the FO supplement. In terms of the impact on the n-3 HUFA score, the intake of ENCH cheese (90 g/day) for two or four weeks was equivalent to the administration of one or two FO pills, respectively. Conversely, the linseed oil intake did not significantly impact the n-3 HUFA score. Feeding ENCH cheeses from different sources (bovine, ovine and caprine) for two months improved the n-3 HUFA score by increasing plasma DHA, and the effect was proportional to the CLA content in the cheese. We suggest that the improved n-3 HUFA score resulting from ENCH cheese intake may be attributed to increased peroxisome proliferator-activated receptor alpha (PPAR-α) activity. This study demonstrates that natural ENCH cheese is an alternative nutritional source of n-3 HUFA in humans.

Physico-chemical, colorimetric, rheological parameters and chemometric discrimination of the origin of Mugil cephalus ' roes during the manufacturing process of Bottarga

The aim of this work was to measure the physico-chemical and the colorimetric parameters of ovaries from Mugil cephalus caught in the Tortolì lagoon (South-East coast of Sardinia) along the steps of the manufacturing process of Bottarga, together with the rheological parameters of the final product. A lowering of all CIELab coordinates (lightness, redness and yellowness) was observed during the manufacture process. All CIELab parameters were used to build a Linear Discriminant Analysis (LDA) predictive model able to determine in real time if the roes had been subdued to a freezing process, with a success in prediction of 100%. This model could be used to identify the origin of the roes, since only the imported ones are frozen. The major changes of all the studied parameters (p < 0.05) were noted in the drying step rather than in the salting step. After processing, Bottarga was characterized by a pH value of 5.46 (CV = 2.8) and a moisture content of 25% (CV = 8), whereas the typical per cent amounts of proteins, fat and NaCl, calculated as a percentage on the dried weight, were 56 (CV = 2), 34 (CV = 3) and 3.6 (CV = 17), respectively. The physical chemical changes of the roes during the manufacturing process were consistent for moisture, which decreased by 28%, whereas the protein and the fat contents on the dried weight got respectively lower of 3% and 2%. NaCl content increased by 3.1%. Principal Component Analyses (PCA) were also performed on all data to establish trends and relationships among all parameters. Hardness and consistency of Bottarga were negatively correlated with the moisture content (r = -0.87 and r = -0.88, respectively), while its adhesiveness was negatively correlated with the fat content (r = -0.68).

Effect of different forage species supplemented with two carbohydrate sources on short and medium chain fatty acids in sheep milk

Abstract Sixty four Sarda dairy sheep fed with diets based on fresh forage were allocated to eight groups to evaluate the effect of corn or beet pulp based supplementation on milk fatty acid composition. Four forage species were compared: annual ryegrass (RY, Lolium rigidum Gaudin), sulla (SU, Hedysarum coronarium L.), burr medic (BM, Medicago polymorpha L.), and garland, a daisy forb, (CH, Chrysanthemum coronarium L.). The supplements were iso-nitrogenous but differed in carbohydrate composition consisting either of 60% (DM) of corn (concentrate C) or 40% sugar beet pulp (concentrate BP). The supplementation was iso-energetic (500 and 530 g/d, respectively). Overall during winter period (growing stage of the forages) SU and RY groups showed higher levels of atherogenicity index and C16:0. In winter period BP outperformed C for palmitic acid. In spring AI showed a trend similar to that of winter. Moreover C concentrate gave a better level of AI and myristic acid than BP. This study confirms that forage species and, to a lesser extent, carbohydrate source in the supplement markedly affect mediumchain FA profile and hence atherogenicity index in sheep milk.