Loading...
4 results
Search Results
Now showing 1 - 4 of 4
- Anthocyanin recovery from grape by-products by combining ohmic heating with food-grade solvents: phenolic composition, antioxidant, and antimicrobial propertiesPublication . Coelho, Marta; Silva, Sara; Costa, Eduardo; Pereira, Ricardo N.; Rodrigues, António Sebastião; Teixeira, José António; Pintado, ManuelaUsually, wine-making by-products are discarded, presenting a significant environmental impact. However, they can be used as a source of bioactive compounds. Moreover, consumers’ increasing demand for naturally nutritious and healthy products requires new formulations and food product improvement, together with sustainable, environmentally friendly extraction methods. Thus, this work aimed to compare ohmic heating (OH) with conventional methodology (CONV), using food-grade solvents, mainly water, compared to standard methanol extraction of anthocyanins. No significant differences were found between the CONV and OH for total phenolic compounds, which were 2.84 ± 0.037 and 3.28 ± 0.46 mg/g DW gallic acid equivalent, respectively. The same tendency was found for antioxidant capacity, where CONV and OH presented values of 2.02 ± 0.007 g/100 g and 2.34 ± 0.066 g/100 g ascorbic acid equivalent, respectively. The major anthocyanins identified were malvidin-3-O-acetylglucoside, delphinidin-3-O-glucoside, petunidine-3-O-glucoside, cyanidin-3-O-glucoside, and peonidine-3-O-glucoside. These extracts displayed antimicrobial potential against microorganisms such as Yersinia enterocolitica, Pseudomonas aeruginosa, Salmonella enteritidis, methicillin-sensitive Staphylococcus aureus, a methicillin-resistant Staph. aureus (MRSA), and Bacillus cereus. In conclusion, OH provides similar recovery yields with reduced treatment times, less energy consumption, and no need for organic solvents (green extraction routes). Thus, OH combined with water and citric acid allows a safe anthocyanin extraction from grape by-products, thus avoiding the use of toxic solvents such as methanol, and with high biological potential, including antimicrobial and antioxidant activity.
- Nanostructures of whey proteins for encapsulation of food ingredientsPublication . Ramos, Oscar L.; Pereira, Ricardo N.; Simões, Lívia S.; Madalena, Daniel A.; Rodrigues, Rui M.; Teixeira, José A.; Vicente, António A.The most current and high-level research is being taken on the use of nanoscience and nanotechnology due to its varied application in numerous fields of science. Food nanotechnology, and in particular, the development and application of bio-based nanostructures are an emerging area having a high potential to engender new products and processes in the food industry. This chapter intends to discuss whey protein-based nanostructured systems (i.e., whey protein isolate, whey protein concentrate, β-lactoglobulin, and α-lactalbumin) for encapsulation of food ingredients. These protein nanostructures have unique properties, such as a high nutritional value, GRAS nature, gelling capability, and can be easily prepared and controlled. They have also the ability to conjugate a large variety of food ingredients (e.g., antioxidants, vitamins, minerals, flavors, and odors) via amino groups or ionic and hydrophobic interactions. This behavior will prevent the degradation of sensitive bioactives, while permitting a site-specific action and controlled delivery rate due to the swelling behavior of the gel in reaction to external and physical stimuli such as temperature, enzymes, pH, or ionic strength), thus contributing to an improved bioavailability of such ingredients. The potential of whey protein nanostructures for encapsulation and controlled delivery of food ingredients will be addressed in a critical manner in this chapter. Moreover, various techniques used for their nanoencapsulation and evaluation of their stability during storage will also be discussed. The behavior and bioavailability of whey nanostructures and their associated/encapsulated food ingredients will be discussed using insights from in vitro and in vivo gastrointestinal systems together with potential cytotoxicity, cellular uptake, and allergenicity via in vitro cell lines. Finally, examples of such nanostructures applied in food matrices will be described, as well as the main challenges for their commercial use.
- Effect of whey protein purity and glycerol content upon physical properties of edible films manufactured therefromPublication . Ramos, Óscar L.; Reinas, Isabel; Silva, Sara I.; Fernandes, João C.; Cerqueira, Miguel A.; Pereira, Ricardo N.; Vicente, António A.; Poças, M. Fátima; Pintado, Manuela E.; Malcata, F. XavierThis manuscript describes the detailed characterization of edible films made from two different protein products e whey protein isolate (WPI) and whey protein concentrate (WPC), added with three levels of glycerol (Gly) e i.e. 40, 50 and 60%(w/w). The molecular structure, as well as barrier, tensile, thermal, surface and optical properties of said films were determined, in attempts to provide a better understanding of the effects of proteinaceous purity and Gly content of the feedstock. WPI films exhibited statistically lower (p < 0.05) moisture content (MC), film solubility (S), water activity, water vapor permeability (WVP), oxygen and carbon dioxide permeabilities (O2P and CO2P, respectively) and color change values, as well as statistically higher (p < 0.05) density, surface hydrophobicity, mechanical resistance, elasticity, extensibility and transparency values than their WPC counterparts, for the same content of Gly. These results are consistent with data from thermal and FTIR analyses. Furthermore, a significant increase (p < 0.05) was observed in MC, S, WVP, O2P, CO2P, weight loss and extensibility of both protein films when the Gly content increased; whereas a significant decrease (p < 0.05) was observed in thermal features, as well as in mechanical resistance and elasticity e thus leading to weaker films. Therefore, fundamental elucidation was provided on the features of WPI and WPC germane to food packaging e along with suggestions to improve the most critical ones, i.e. extensibility and WVP.
- Using ohmic heating effect on grape skins as a pretreatment for anthocyanins extractionPublication . Pereira, Ricardo N.; Coelho, Marta; Genisheva, Zlatina; Fernandes, Jean Michel; Vicente, António A.; Pintado, Manuela E.; Teixeira, José A.This study aims to obtain aqueous extracts of valuable phytochemicals, in particular anthocyanin’s, from winemaking residues by using grape skins as natural electrical conductors allowing internal heat dissipation through Ohmic Heating (OH) effect. Two different electric pretreatments were evaluated: i) using mild temperatures at 40 °C during 20 min; ii) flash heating from 40 to 100 °C in less than 20 s (no holding time). These pretreatments were followed by aqueous extraction in water at room temperature. Independently of the temperature applied, OH allowed to boost extraction levels increasing concentration of total phenolic compounds, as well as conductivity, soluble solids and red color intensity of the obtained extracts, as shown through principal component analysis (PCA). OH pretreatments at high-temperature short-time (HTST) due to the fast internal heating of grape skin structure allowed increase total concentration of anthocyanins from 756 to 1349 μg/g, with malvidin-3-O-glucoside being the main compound identified and quantified in the aqueous extracts through HPLC analysis (corresponding to about 60% of the total). These results showed that OH bring potential to be an efficient and environmentally friendly technology towards sustainable food processes.