No abstract

Effect of olive oil in dairy cow diets on the fatty acid profile and sensory characteristics of cheese

Staphylococcus aureus, Salmonella spp., Listeria monocytogenes and Escherichia coli O157:H7 are the most frequent potential pathogens associated with milk or dairy products in industrialized countries and are therefore the main microbiological hazards linked to raw milk and raw cheese. This review summarizes the scientific information about outbreaks related to foodborne pathogens in dairy products and highlights the increasing application of molecular approaches to detect and identify the bacteria responsible for these outbreaks. Molecular techniques have facilitated the rapid detection and identification of foodborne pathogens, which has been crucial for current surveillance and outbreak control.

The study aimed at determining the antioxidant effect of natural extracts on the oxidative quality and color variation of rainbow trout fillets during storage at 4 °C. The fillets were marinated and samples from the belly flap area and Norwegian quality cuts were used for lipid oxidation determination while the dorsal region was used for color measurements. The fillets were marinated with the different treatments: 470 mg l-1 of oregano extract, 6.84 ml l-1 of quillaia extract, 7.2 ml l-1 of rosemary extract and 2 ml l-1 of a synthetic antioxidant. Maximum TBARS (Thiobarbituric acid reactive substances) values of belly flap and Norwegian quality cuts occurred at five and six days of storage, respectively. The susceptibility of treatments to lipid oxidation in decreasing order was: control>quillaia>oregano>rosemary>synthetic antioxidant. An increase in lightness (L*) and redness (a*) were observed for rosemary and quillaia extracts when compared to control samples. Marinates with natural antioxidants may be an alternative for extending shelf-life of trout fillets at least during the first six days of storage at 4 °C.

We used a multivariate chemometric approach to differentiate or associate retail bovine milks with different fat contents and non-dairy beverages, using fatty acid profiles and statistical analysis. We collected samples of bovine milk (whole, semi-skim, and skim; n = 62) and non-dairy beverages (n = 27), and we analyzed them using gas-liquid chromatography. Principal component analysis of the fatty acid data yielded 3 significant principal components, which accounted for 72% of the total variance in the data set. Principal component 1 was related to saturated fatty acids (C4:0, C6:0, C8:0, C12:0, C14:0, C17:0, and C18:0) and monounsaturated fatty acids (C14:1 cis-9, C16:1 cis-9, C17:1 cis-9, and C18:1 trans-11); whole milk samples were clearly differentiated from the rest using this principal component. Principal component 2 differentiated semi-skim milk samples by n-3 fatty acid content (C20:3n-3, C20:5n-3, and C22:6n-3). Principal component 3 was related to C18:2 trans-9,trans-12 and C20:4n-6, and its lower scores were observed in skim milk and non-dairy beverages. A cluster analysis yielded 3 groups: group 1 consisted of only whole milk samples, group 2 was represented mainly by semi-skim milks, and group 3 included skim milk and non-dairy beverages. Overall, the present study showed that a multivariate chemometric approach is a useful tool for differentiating or associating retail bovine milks and non-dairy beverages using their fatty acid profile.