Browsing by Author "Pereira, Carlos Dias"
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- Characterization of a concentrated second cheese wheyPublication . Faustino, Margarida; Salsinha, Ana Sofia; Pimentel, Lígia; Alcalá, Luis; Freitas, Ana Cristina; Gomes, Ana Maria; Pereira, Carlos Dias; Pintado, Manuela
- Characterization of concentrated second cheese wheyPublication . Faustino, Margarida; Salsinha, Ana Sofia; Pimentel, Lígia; Alcalá, Luis; Freitas, Ana Cristina; Gomes, Ana Maria; Pereira, Carlos Dias; Pintado, ManuelaThe residual deproteinized whey known as second cheese whey or “Sorelho”, is a byproduct obtained from whey cheese manufacture. It is commonly obtained in small/medium scale cheese plants and, although it has little to no commercial value, it is produced in relatively high volumes, which results in a complex disposal process. Therefore, the objective of this work was to characterize the nutritional composition of two concentrated deproteinized wheys (sheep and goat), obtained through ultrafiltration/diafiltration with a 10 kDa membrane followed by freezedrying. From the nutritional standpoint, it was possible to observe that after ultrafiltration, samples were mostly comprised of protein 75-58% (w/w). Samples also exhibited a low mineral and lactose contents (1.7-3.9% (w/w) and 0.93 -69%(w/w), respectively). The fatty acid composition profile was predominantly composed of short- and medium chain fatty acids including butyric, caproic and caprylic acids, with long chain fatty acids, such as palmitoleic, rumenic, trans vaccenic, docosapentaenoic and docosahexaenoic acids being also detected in both goat and sheep Sorelho, but in the goat Sorelho the concentration was bigger of these fatty acids. When regarding the amino acids identified aspartic acid, glutamic acid, alanine and tyrosine were the most predominant amino acids found in the sheep Sorelho while in the goat Sorelho aspartic acid, glutamic acid, asparagine, threonine and valine were prevalent. Overall, these results provide some insights into Sorelhos’ potential usage as source of bioactive compounds for posterior incorporation into foods.
- Nutritional ingredients from spent brewer's yeast obtained by hydrolysis and selective membrane filtration integrated in a pilot processPublication . Amorim, Manuela; Pereira, Joana O.; Gomes, David; Pereira, Carlos Dias; Pinheiro, Hélder; Pintado, M. E.Spent brewer's yeast is a natural surplus from brewing industry. In order to up-grade this by-product, isolation of compounds has been tentatively assessed. The main objective of this work focuses on the use of ultrafiltration and nanofiltration pilot system for recovering cell compounds. Initially, yeast was autolyzed and ultrafiltered with a 10 kDa cut-off, and the two fractions obtained were hydrolyzed with Cynara cardunculus extract and nanofiltered with 3 kDa cut-off. Four fractions with different molecular weights were obtained, with protein and sugar contents ranging between 30–69% and 20–48%, respectively. Sodium and potassium were the major minerals present, whereas glutamine, glutamic acid and alanine, the most representative free amino acids. Peptide profile showed peptides with hydrophilic and hydrophobic characteristics, usually associated with biological activities, including antihypertensive and antioxidant. Thus, based on their compositions, all fractions show technological and biological potential, and can be used as nutritional ingredients in food and feed.
- Sheep’s butter and correspondent buttermilk produced with sweet cream and cream fermented by aromatic starter, kefir and probiotic culturePublication . Silva, Tânia; Pires, Arona; Gomes, David; Viegas, Jorge; Pereira-Dias, Susana; Pintado, Manuela E.; Henriques, Marta; Pereira, Carlos DiasSmall ruminant dairy products are common in some Mediterranean countries, in the Middle East and Africa, and can play a particular role in the development of rural areas. Butter has been the object of few research studies aimed at evaluating its potential as a vehicle for probiotic microorganisms. Moreover, the recovery of fermented buttermilk with functional properties can be considered an excellent opportunity to value this dairy byproduct. Therefore, the purpose of the present work was to develop different sheep butters and respective buttermilks after cream fermentation by: (1) a mesophilic aromatic starter (A); (2) a kefir culture (K); and (3) a mixture of probiotic bacteria (P). The butters and buttermilk produced with fermented cream were compared with non-fermented sweet cream (S) butter or buttermilk, respectively, regarding their physicochemical, microbiological and sensory characteristics. The adjusted production (%, w/v) obtained for butter were: S (44.48%), A (36.82%), K (41.23%) and P (43.36%). S, A and K butters had higher solids, fat and ashes contents than P butter. The probiotic butter had a total fat of ca. 75% (w/w), below the legal limits, while all others had fat levels above 81.5%. In all samples, the pH decreased and the acidity increased over 90 days of refrigerated storage. These variations were more evident in the P butter, which agrees with the highest lactic acid bacteria counts found in this sample. Differences in color between samples and due to storage time were also observed. In general, the butter samples tended to become darker and yellower after the 60th day of storage. Texture analysis showed comparable results between samples and greater hardness was observed for the P butter, most probably due to its higher relative saturated fatty acids content (66.46% compared to 62–64% in S, A and K butters). Regarding rheological properties, all butters showed pseudoplastic behavior, but butter P had the lowest consistency index (249 kPa.sn−1). The probiotic butter and the corresponding buttermilk had viable cell counts greater than 7 Log CFU/g, indicating their suitability as probiotic carriers. All products were well accepted by consumers and small, but non-significant, differences (p > 0.05) were observed in relation to the sensory parameters evaluated. In general, it can be concluded that the use of adequate starter cultures can allow the production of innovative and potentially healthier products, alongside the valorization of dairy byproducts, improving the income of small-scale producers.