Federica Castellani

A rapid high-performance liquid chromatography-tandem mass spectrometry assay for unambiguous detection of different milk species employed in cheese manufacturing.

The aim of the study was to investigate the possibility to differentiate the 4 most important species in Italian dairy industry (cow, buffalo, sheep, and goat), applying a bottom-up proteomic approach to assess the milk species involved in cheese production. Selective peptides were detected in milk to use as markers in cheese products. Trypsin-digested milk samples of cow, sheep, goat, and buffalo, analyzed by HPLC-tandem mass spectrometry provided species-specific peptides, some of them recognized by Mascot software (Matrix Science Ltd., Boston, MA) as derived from well-known species specific proteins. A multianalyte multiple reaction monitoring method, built with these specific peptides, was successfully applied to cheeses with different composition, showing high specificity in detection of species involved. Neither aging nor production method seemed to affect the response, demonstrating that chosen peptides well act as species markers for dairy products.

Dietary supplementation with dried olive pomace in dairy cows modifies the composition of fatty acids and the aromatic profile in milk and related cheese

This study aimed to evaluate the effect of dietary integration of dried olive pomace (DOP), a by-product of olive oil separation, on nutritional and aromatic properties of milk and cheese. Twenty dairy cows were divided into 2 groups that were balanced for milk yield, parity, and days in milk. The control group was fed a conventional diet (20 kg of dry matter/head per day), whereas the experimental group (EG) received the conventional diet supplemented with DOP as 10% of dry matter. During the trial, milk yield was recorded and the samples of milk, cheese, total mixed rations, and DOP were collected and analyzed to determine the chemical-nutritional composition and aromatic profile. Atherogenic and thrombogenic indices were calculated on the basis of the fatty acid (FA) profile of milk and cheese. Data were analyzed according to the mixed model for milk yield and chemical composition, including cows nested within treatment as a random effect, whereas the general linear model was used for the analysis of cheese parameters. Differences were assessed by Tukeys test. The EG diet had a lower content of palmitic, stearic, and linoleic acids and a higher level of oleic acid compared with the control. Dietary DOP integration did not affect milk yield and composition with the exception of protein content, which was greater in EG and significantly affected by diet and period. Instead, period was found to be significant for fat and casein in both groups. Dietary supplementation with DOP modified the FA profile of milk and cheese. There was a decrease in short- and medium-chain FA, but significance was achieved only for palmitic acid. The stearic, isomer trans of oleic (in particular vaccenic acid), oleic, and isomer trans of linoleic acids significantly increased. Monounsaturated FA increased in EG milk and cheese and saturated FA were significantly lower, whereas no difference was marked between the groups regarding level of polyunsaturated FA. Supplementation with DOP reduced atherogenic and thrombogenic indices and increased conjugated linoleic acid in both milk and cheese. The free fatty acids, ketones, lactones, esters, and phenylalanine catabolites were increased in raw milk, whereas only leucine metabolism was affected by diet in pasteurized milk cheese at both 1 and 30 d of ripening. The present results pointed out that DOP supplementation may improve the nutritional and nutraceutical properties and modify the aroma of milk and derived cheese.

Effect of diet supplementation with Ascophyllum nodosum on cow milk composition and microbiota

Iodine deficiency remains a major public health concern in many countries, including some European regions. This study aimed at understanding the effect of a supplement of marine alga Ascophyllum nodosum as a iodine fortifier in the cow diet, on the compositional and microbiological quality of milk. The results obtained in this work indicated that the dietary inclusion of A. nodosum exerted significant effects on cow milk composition. In particular, it increased iodine content and reduced the quantity of free amino acids without modifying the free fatty acid content. From a microbiological point of view, statistically significant differences were found in presumptive mesophilic lactobacilli, mesophilic lactococci, and Pseudomonas spp. counts. Based on a culture-independent method, milk obtained after dietary inclusion of A. nodosum harbored the highest number of Firmicutes (e.g., Lactococcus lactis) and the lowest number of Proteobacteria (e.g., Pseudomonas). In addition to changes in bacterial population, diet supplementation with A. nodosum changed the catabolic profiles of the milk community, according to Biolog Ecoplate (Biolog Inc., Hayward, CA) results. The results of this study suggest that the dietary inclusion of the marine alga A. nodosum led to an improvement of the iodine content in milk, and to a modification of its microbiota with a positive effect on milk hygiene and transformation.

Lipolytic volatile compounds in dairy products derived from cows fed with dried olive pomace

The study was aimed at evaluating the effects of dietary supplementation with dried olive pomace in dairy cows on the development of lipolytic volatile compounds in raw milk and cheese. Twenty dairy cows, homogeneous for milk yield, parity and days in milk, were randomly assigned to a basal diet (CON) and a conventional diet integrated with dried olive pomace (DOP) as 10% of dry matter. After 60 days of treatment, raw bulk milk of CON and DOP groups was sampled and used to produce cheese that was sampled at 1, 7 and 30 days of ripening. Volatile compounds were analyzed by the SPME-GC/MS technique. Dietary treatment influenced C6, C8, C10 and C12 free fatty acids, the short-chain ethyl and methyl esters, many of ketones and γ- and δ-lactones in raw milk. Cheese showed main differences between groups after 7 days of aging. Levels of methyl decanoate and ethyl esters of even fatty acids from C4 to C14, as well as 2-heptanone, 6-dodecen-γ-lactone, octanal and some C9 secondary lipolytic catabolites such as 8-nonen-2-one, 2-nonanone and 2-nonenal were higher in DOP cheese. The γ-dodecalactone, δ-octalactone, 2-octenal and 1-hexanol were higher in the experimental cheese at 30 days of ripening. DOP dietary integration in feeding operations of dairy cows may modify the evolution of volatile compounds derived from lipolysis in milk and cheese toward moldy and peach notes. A sensory evaluation of these changes will be necessary to understand the consumer acceptability that represents an important feedback to drive dairy industry choices.