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- Total and sustainable valorisation of olive pomace using a fractionation approachPublication . Ribeiro, Tânia B.; Oliveira, Ana L.; Costa, Cristina; Nunes, João; Vicente, António A.; Pintado, ManuelaOlive pomace management represents a great concern to the olive oil industry. This work focused on the development of a “zero waste” strategy for olive pomace based on a fractionation approach resulting in the obtention of different value-added fractions. The physicochemical composition of edible fractions obtained (liquid and pulp) was analysed. The potential use as a solid biofuel of the non-edible fraction (stones) was evaluated. High amounts of hydroxytyrosol (513.61–625.76 mg/100 g dry weight) were present in the liquid fraction. Pulp fraction was demonstrated to be a good source of fibre (53–59% dry weight) with considerable antioxidant activity both from free and bound phenolics. The stones fraction exhibited substantial high heating values (18.65–18.94 megajoule (MJ/kg). All these results support the added value of the olive pomace fractions combining the biofuel potential from the stones fraction and the functional food ingredients’ potential both from liquid and pulp fractions. The present methodology seems to be a feasible whole valorisation approach to achieve the circularity in the olive oil sector, prioritising obtaining high over low added-value products.
- In vitro digestibility and fermentability of fructo-oligosaccharides produced by Aspergillus ibericusPublication . Nobre, C.; Sousa, S.C.; Silva, S.P.; Pinheiro, A.C.; Coelho, E.; Vicente, A.A.; Gomes, A.M.P.; Coimbra, M.A.; Teixeira, J.A.; Rodrigues, L.R.The bifidogenic potential of fructo-oligosaccharides (FOS) produced by a newly isolated strain – Aspergillus ibericus was studied. Their activity was compared to FOS produced by Aureobasidium pullulans and to a nonmicrobial commercial FOS sample (Raftilose® P95). FOS fermentability by a number of probiotic bacteria and their hydrolytic resistance to the simulated harsh conditions of the digestive system was evaluated. Aspergillus ibericus FOS sample effectively promoted probiotic bacteria growth. Overall, microbial-derived FOS promoted greater cellular growth compared to the commercial sample. FOS fermentation was both substrate and strain specific. The FOS structural differences identified may explain their distinct assimilation by the probiotics. [Fru (2→6)Glc] (possibly blastose) and a reducing trisaccharide (possibly [Fru(β2→6)Glc(α1↔β2)Fru], neokestose) were only found in microbial-derived FOS samples, while Raftilose® P95 was richer in inulobiose/inulotriose. 1- Kestose and nystose were only slightly hydrolyzed in the presence of gastric and intestinal fluid. FOS synthesized by Aspergillus exhibited great potential as food ingredients with likely prebiotic features.
- Incorporation of olive pomace ingredients into yoghurts as a source of fibre and hydroxytyrosol: antioxidant activity and stability throughout gastrointestinal digestionPublication . Ribeiro, Tânia B.; Bonifácio-Lopes, Teresa; Morais, Pilar; Miranda, Arménio; Nunes, João; Vicente, António A.; Pintado, ManuelaLiquid-enriched powder (LOPP) and pulp-enriched powder (POPP) obtained from olive pomace were incorporated into yoghurt, not only, to increase its content in dietary fibre, hydroxytyrosol and unsaturated fatty acids, but also to understand the lipids-phenolics interaction by simultaneous incorporation of olive oil. POPP (2%) and LOPP (1%) addition to yoghurt allowed fulfilling the condition of being a “source of fibre” and provided 5 mg of hydroxytyrosol and derivatives in a standard yoghurt (120 g), respectively. Yoghurts’ unsaturated fatty acids profile was positively influenced by the addition of only POPP and olive oil + LOPP or + POPP. All OP powder-fortified yoghurts exhibited higher total phenolic content and antioxidant activity than the control (p<0.05). After in vitro digestion the bioaccessibility of total phenolics (more 25.58%) and hydroxytyrosol (more 68.71%) in LOPP-yoghurts was improved by the addition of olive oil. In conclusion, OP powders´ incorporation gave additional and essential healthy properties to yoghurt.
- 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.
- Are olive pomace powders a safe source of bioactives and nutrients?Publication . Ribeiro, Tânia B.; Oliveira, Ana; Coelho, Marta; Veiga, Mariana; Costa, Eduardo M.; Silva, Sara; Nunes, João; Vicente, António A.; Pintado, ManuelaBACKGROUND Olive oil industry generates significant amounts of semi-solid wastes, namely the olive pomace. Olive pomace is a by-product rich in high-value compounds (e.g. dietary fibre, unsaturated fatty acids, polyphenols) widely explored to obtain new food ingredients. However, conventional extraction methods frequently use organic solvents, while novel eco-friendly techniques have high operational costs. The development of powdered products without any extraction step has been proposed as a more feasible and sustainable approach. RESULTS The present study fractionated and valorised the liquid and pulp fraction of olive pomace obtaining two stable and safe powdered ingredients, namely a liquid-enriched powder (LOPP) and a pulpenriched powder (POPP). These powders were characterized chemically, and their bioactivity was assessed. LOPP exhibited a significant amount of mannitol (141 g/ kg), potassium (54 g/ kg) and hydroxytyrosol/ derivatives (5 mg/g). POPP exhibited high amount of dietary fibre (620 g/ kg) associated to significant amount of bound phenolics (7.41 mg GAE/ g fibre DW) with substantial antioxidant activity. POPP also contained an unsaturated fatty acids composition similar to olive oil (76% of total fatty acids) and showed potential as a reasonable source of protein (12 %). Their functional properties (solubility, water‐holding and oil‐holding capacity), antioxidant capacity and antimicrobial activity were also assessed, and their biological safety was verified. CONCLUSION The development of olive pomace powders to apply in the food industry could be a suitable strategy to add-value to olive pomace and obtain safe multifunctional ingredients with higher health-promoting effects than dietary fibre and polyphenols itself.
- Emergent food proteins – towards sustainability, health and innovationPublication . Fasolin, L. H.; Pereira, R. N.; Pinheiro, A. C.; Martins, J. T.; Andrade, C. C. P.; Ramos, O. L.; Vicente, A. A.There is an increasing demand for alternative and sustainable protein sources, such as vegetables, insects and microorganisms, that can meet the nutritional and sensory pleasantness needs of consumers. This emergent interest for novel protein sources, allied with “green” and cost-effective processing technologies, such as high hydrostatic pressure, ohmic heating and pulsed electric fields, can be used as strategies to improve the consumption of proteins from sustainable sources without compromising food security. In addition to their nutritional value, these novel proteins present several technological-functional properties that can be used to create various protein systems in different scales (i.e., macro, micro and nano scale), which can be tailored for a specific application in innovative food products. However, in order for these novel protein sources to be broadly used in future food products, their fate in the human gastrointestinal tract (e.g., digestion and bioavailability) must be assessed, as well as their safety for consumers must be clearly demonstrated. In particular, these proteins may become novel allergens triggering adverse reactions and, therefore, a comprehensive allergenicity risk assessment is needed. This review presents an overview of the most promising alternative protein sources, their application in the production of innovative food systems, as well as their potential effects on human health. In addition, new insights on sustainable processing strategies are given.
- Antioxidant potential of two red seaweeds from the brazilian coastsPublication . Souza, Bartolomeu W. S.; Cerqueira, Miguel A.; Martins, Joana T.; Quintas, Mafalda A. C.; Ferreira, António C. S.; Teixeira, José A.; Vicente, António A.In this work, in vitro antioxidant activity of two Brazilian red seaweeds, Gracilaria birdiae and Gracilaria cornea, was characterized. The total phenolic content, the radical-scavenging activity and the antioxidant activity were determined in two solvent extracts of the algae. Liquid chromatography-mass spectrometry (LC-MS/MS) allowed identification of important antioxidant compounds. The ethanol extract of G. birdiae was found to have the highest value of total phenolic content: 1.13 mg of gallic acid equiv (GAE)/g of Extract. The radical-scavenging activity of G. birdiae and G. cornea extracts has been evaluated at different extract concentrations; the IC50 values of ethanolic extracts of G. cornea and G. birdiae were 0.77 and 0.76 mg mL(-1), respectively, while for methanolic extracts, the IC50 values of G. cornea and G. birdiae were 0.86 and 0.76 mg mL(-1), respectively. The antioxidant activities of these two seaweeds' extracts as assessed by the beta-carotene-linoleic acid assay were equally high, achieving values of beta-carotene oxidation inhibition of up to 40%. Finally, in the methanolic extracts, LC-MS/MS allowed identification in both algae of two important antioxidants: apigenin and gallic acid.
- 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.
- Κ-carrageenan/chitosan nanolayered coating for controlled release of a model bioactive compoundPublication . Pinheiro, Ana C.; Bourbon, Ana I.; Quintas, Mafalda A.C.; Coimbra, Manuel A.; Vicente, António A.Multilayer nanocoatings composed of κ-carrageenan, a sulphated anionic polysaccharide, and chitosan, a cationic polysaccharide, were produced by layer-by-layer deposition. The model cationic compound Methylene Blue (MB) was incorporated in different positions of the nanolayered coating and its loading and release behavior was evaluated. UV–VIS spectroscopy and quartz crystal microbalance analysis showed that the amount of MB loaded increased with the distance from the first layer, suggesting that the MB was able to diffuse into the κ-carrageenan/chitosan nanolayered coating and not only adhered to the surface of the layer immediately below it. For most of the tested conditions, the MB release from the κ-carrageenan/chitosan nanolayered coatings was successfully described by the linear superimposition model, which allowed concluding that MB transport is due to both concentration gradient and the polymer relaxation of the nanolayers. However, depending on temperature and pH of the medium and on the position of MB incorporated on the nanolayered coatings, different mechanisms prevail. Industrial relevance: The development of novel edible coatings with improved functionality and performance for e.g. fresh and minimally processed fruits is one of the challenges of the post-harvest industry. This work contributes to the understanding of the loading and release phenomena involved in structures at the nanoscale, which is useful for the development of bioactive compounds release systems for application in food industry. Moreover, the κ-carrageenan/chitosan nanolayered coatings represent a promising platform from which the controlled release of different bioactive compounds may be explored.
- Design of β-lactoglobulin micro- and nanostructures by controlling gelation through physical variablesPublication . Simões, Lívia S.; Araújo, João F.; Vicente, António A.; Ramos, Oscar L.β-lactoglobulin (β-Lg) is the major protein fraction of bovine whey serum and its principal gelling agent. Its gelation capacity enables conformational changes associated with protein-protein interactions that allow the design of structures with different properties and morphologies. Thus, the aim of this work was to successfully use β-Lg, purified from a commercial whey protein isolate, to develop food-grade micro- (with diameters between 200 and 300 nm) and nano- (with diameters ≤ 100 nm) structures. For this purpose, the phenomena involved in β-Lg gelation were studied under combined effects of concentrations (from 5 to 15 mg mL−1), heating temperature (from 60 to 80 °C) and heating time (from 5 to 25 min) for pH values of 3, 4, 6 and 7. The effects of such conditions on β-Lg structures were evaluated and the protein was fully characterized in terms of size, polydispersity index (PDI) and surface charge (by dynamic light scattering – DLS), morphology (by transmission electron microscopy - TEM) and conformational structure (circular dichroism, intrinsic and extrinsic fluorescence). Results have shown that β-Lg nanostructures were formed at pH 3 (with diameters between 12.1 and 22.3 nm) and at 7 (with diameters between 8.9 and 35.3 nm). At pH 4 structures were obtained at macroscale (i.e., ≥ 6 μm) for all β-Lg concentrations when heated at 70 and 80 °C, independent of the time of heating. For pH 6, it was possible to obtain β-Lg structures either at micro- (245.0 – 266.4 nm) or nanoscale (≤ 100 nm) with the lowest polydispersity (PDI) values (≤ 0.25), in accordance with TEM analyses, for heating at 80 °C for 15 min. Intrinsic and extrinsic fluorescence data and far-UV circular dichroism spectra measurements revealed conformational changes on β-Lg structure that support these evidences. A strict control of the physical and environmental conditions is crucial for developing β-Lg structures with the desired characteristics, thus calling for the understanding of the mechanisms of protein aggregation and intermolecular interaction when designing β-Lg structures with novel functionalities.