Production and characterisation of reduced-fat and PUFA-enriched Burrata cheese.

Burrata is an Italian fresh 'pasta filata' cheese made from cow's milk and cream that is rapidly spreading in Europe. It has very high caloric content, and a technological protocol was developed for producing a reduced-fat type and fortifying it with polyunsaturated fatty acids (PUFA) of vegetable origin. A satisfactory reduced-fat prototype was obtained by using a 14% fat cream, which was specifically developed by diluting double cream with a suspension of carob seed flour. The composition of the new cheese changed with respect to the control, but the sensory characteristics were not impaired. Moisture increased from 62·6 to 68·4%, fat on dry matter decreased from 59·1 to 34·7%, and the caloric content decreased from 1060·8 to 718 J/100 g. Proteolysis and lipolysis were not affected by the technological modifications: after 7 d storage, the electrophoretic pattern of caseins and the free fatty acids profile of experimental and control cheeses were not significantly different. Fortification of reduced-fat Burrata with PUFA was obtained by using two commercial formulates available at a compatible price with the current economic values of the cheese. The two formulates derived from flaxseeds and Carthamus tinctorius oil and allowed enrichment in C18 :3 : n3 (α-linolenic acid, ALA), and 9cis,11trans- and 10trans,12cis- conjugated linoleic acid (CLA), respectively. Fortification was easy to perform under a technical point of view, but the negative sensory impact limited fortification at a maximum of 7·0 mg g-1 fat ALA and 6·8 g-1 fat CLA.

Complex role of monoacylglycerols in the oxidation of vegetable oils: different behaviors of soybean monoacylglycerols in different oils.

The relationship between fatty acid composition of oils and their oxidative stability in the presence of monoacylglycerols was investigated. Purified vegetable oils were added at increasing amounts (0.5, 1, 2, and 3%) of monoacylglycerols obtained from purified soybean oil and submitted to an oven test (60 °C for 18 days). The obtained results showed a generally antioxidant effect of monoacylglycerols, with remarkable differences among oils. The antioxidant effect was significantly higher in less unsaturated oils, such as palm and olive oils. Among the more unsaturated vegetable oils, peanut and sunflower oils showed an almost linear slowdown of oxidation, slightly less pronounced in sunflower oil, which was the most susceptible to oxidation due to its high content of linoleic acid. A peculiar trend was highlighted for soybean oil, where the antioxidant effect of high amounts of monoacylglycerols was opposed to a pro-oxidant effect observed up to 1%.

Diacylglycerol isomers in extra virgin olive oil: Effect of different storage conditions.

An experimental investigation was carried out with the aim to investigate on the isomerisation of 1,2-diacylglycerols to 1,3-diacylglycerols as a function of the storage conditions, as well as to identify indices useful to evaluate the freshness of the oils. Two oils derived from two different cultivars (Coratina and Ogliarola barese) were stored for two years as follows: in bottles at dark; in clear glass bottles at light; in green glass bottles at light; in bottles at dark, the latter subjected to repeated opening and samplings to simulate domestic use. The obtained results evinced that during the storage period a significant increase in the 1,3-isomers was observed due to an isomerisation from the 1,2 to the 1,3 isomeric form, consequently the 1,3/1,2 ratio increased in both oils. The covariance analysis of the data showed that the isomerisation of diacylglycerols, taking place during time, was affected by the type of oil, probably due to the different initial hydrolysis level, but was not affected by the storage conditions. Among the parameters considered, the total diacylglycerols/1,3-diacylglycerols ratio could be used as freshness index of extra virgin olive oil, since it is not affected by either oil or storage conditions.

Effect of the type of oil on the evolution of volatile compounds of taralli during storage.

Baking process leads to a huge quantity of newly formed volatile compounds, which play a major role in developing the flavor of the final product. The aim of this work was to investigate on the evolution of the volatile profile of taralli as a function of both the kind of oil used in the dough and the storage time. The volatile compounds from the taralli were extracted by headspace solid-phase microextraction and analyzed by gas-chromatography/mass spectrometry (GC/MS). Forty-four volatile compounds were identified in taralli, most of which produced by thermically induced reactions occurring during baking process, such as volatiles deriving from Maillard reaction and/or sugar degradation and lipid oxidation. The results obtained demonstrated the essential role played by the type of oil on the formation and on the release of volatile compounds. The volatile compounds significantly increased during storage and their individual levels were in most cases significantly lower in taralli made with extra virgin olive oil than in those made with refined oils. Finally, the taralli made with extra virgin olive oil, compared with those prepared with other vegetable oils, showed to be more resistant to oxidation, probably due to the presence of natural antioxidants.

Influence of the different oils used in dough formulation on the lipid fraction of taralli.

An experimental investigation was carried out to evaluate the quality of taralli as a function of the type of oil used in their dough formulation. To this end, 4 types of oil (extra virgin olive oil, olive oil, olive-pomace oil, and refined palm oil) were utilized to prepare taralli to investigate on the lipid fraction degradation and evaluate the taralli acceptability by consumers. The data obtained pointed out that taralli manufactured with extra virgin olive oil were significantly more appreciated than those made with refined oils due to their visual appearance and odor. Moreover, with respect to the other kinds of oil, the use of extra virgin olive oil led to significantly lower values (P < 0.05) of specific absorption at 232 and 270 nm (K(232) and K(270) , respectively) and of triacylglycerol oligopolymers. It also proved to present a much lower content in oxidized triacylglycerols and diacylglycerols than olive-pomace oil and refined palm oil, respectively. Furthermore, trans fatty acid isomers were absent in taralli made with extra virgin olive oil but were constantly present in those produced with refined oils.

Effects of monoacylglycerols on the oxidative stability of olive oil.

BACKGROUND: The study of pro- and anti-oxidant compounds is important for their influence on the shelf-life and nutritional value of food. The aim of this research was to evaluate the activity of monoacylglycerols (MAG), obtained by partial saponification of a purified olive oil, added in increasing amounts to the same oil and submitted to the Rancimat test and oven test at 60 °C. Besides routine analyses, high-performance size exclusion chromatography analysis of polar compounds was performed. RESULTS: The addition of MAG led in all cases to a significant slowdown of the oxidative processes. These trends were more evident as the oxidation went on. The purified oil added with 30 g kg(-1) of MAG after 9 days of oven test at 60 °C presented a level of oxidative degradation significantly lower than the control after only 4 days. CONCLUSION: The data showed a marked antioxidant effect of MAG in purified olive oil, contrary to what has been observed by other authors, who noticed either a pro-oxidant or a non-antioxidant activity of these compounds in soybean oil. A different behaviour of MAG during oxidation could depend on the different fatty acid composition of the oil matter they are added to.

Influence of processing and storage time on the lipidic fraction of taralli.

An experimental investigation was carried out to evaluate the influence of processing and storage time on the lipidic fraction of taralli. The data obtained pointed out that the kneading phase caused a significant increase of the oxidized triacylglycerols and triacylglycerol oligopolymers, primary and secondary oxidation compounds, respectively, accompanied by a significant decrease of the content of polyunsaturated fatty acids. The successive baking step caused the degradation of a part of the oxidized compounds to volatile substances, as confirmed by the p-Anisidine values, whereas the storage time determined a further significant increase of the level of oxidized triacylglycerols. Finally, the level of diacylglycerols, monoacylglycerols, and free fatty acids, indicative of hydrolytic degradation, did not show significant changes. The principal component analysis allowed one to clearly distinguish among samples obtained through processing conditions.

Improving virgin olive oil quality by means of innovative extracting biotechnologies.

Three major virgin olive oil varieties (Dritta, Leccino, and Coratina) extracted by a modern centrifugation system aided with a new plant enzyme preparation (having prevalently pectolytic activity) were characterized. These oils showed a clearly enhanced quality standard, owing to higher levels of some important minor components (phenolics, volatiles, tocopherols, carotenes, and chlorophylls) and to frequently lower concentrations of oxidized triglycerides and diglycerides. The oils were therefore characterized by lower susceptibility to oxidation and longer shelf life, and their flavor, aroma, and color features appeared to be significantly improved. The saponifiable fraction was practically not affected as the enzymatic effects involved only the membranes of the oil droplets, where the nonglyceridic compounds are essentially located.

Fate of oxidized triglycerides during refining of seed oils.

The evolution of oxidized triglycerides (ox-TG) during industrial refining was studied in soybean, sunflower, peanut, and corn oils. The analytical techniques used were silica gel column chromatography and high-performance size exclusion chromatography. The decrease in ox-TG during refining (42.3% on average) was accompanied by an increase in triglyceride oligopolymers (TGP). The inverse correlation between the two lipid groups suggests that the decrease in ox-TG during refining was due in part to the occurrence of polymerization reactions. An inverse correlation was also found between the percentage sum of ox-TG + TGP and percent TGP, indicating that a part of the ox-TG also underwent degradation or transformation reactions. On average, almost 58% of the ox-TG remained unchanged during refining and, of the rest, about half was involved in polymerization reactions and half in degradation or transformation reactions.