Browsing by Author "Silva, J. L. da"
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- Microalgae hydrolysates as functional ingredientsPublication . Cunha, S. A.; Nova, P.; Silva, J. L. da; Pintado, M. E.Microalgae have been used in food and cosmetic industries due to their richness in compounds with high biological value, such as proteins, essential amino acids, vitamins and minerals [1]. Several microalgae contain high protein content, similar to other common protein sources such as meat and soybean [1], making them a promising source of bioactive peptides. Bioactive peptides are inert inside proteins but can show several interesting properties when isolated [2]. Antioxidant, antihypertensive, antidiabetic, anticancer, anti-inflammatory and anti-aging are some properties that can be found described in bioactive peptides. Bioactive peptides may be more easily absorbed by the gastrointestinal tract than the intact protein, which allied with their potential bioactivities make them interesting for the development of functional foods, with health benefits for the consumer. Hypertension is one of the main causes of cardiovascular diseases, which can lead to heart attack or stroke. Angiotensin-converting enzyme (ACE) is involved in blood pressure regulation, thus inhibiting it can help to control high blood pressure. Thus, this research aimed to produce water soluble hydrolysates rich in proteins and bioactive peptides, with antioxidant and anti-hypertensive potential, from the five microalgae species Chlorella vulgaris, Nannochloropsis oceanica, Tetraselmis sp., Scenedesmus obliquus and Phaeodactylum tricornutum. The five microalgae species were submitted to an enzymatic hydrolysis (one of the most described methods for producing bioactive peptides) with a cellulase and a subtilisin protease, using previously optimized methods. Prior to the enzymatic hydrolysis, C. vulgaris was submitted to an acid hydrolysis, using a weak and food-grade acid. The anti-hypertensive potential was evaluated by the hydrolysate’s ability of inhibiting ACE. Previous studies [3] showed that C. vulgaris and S. obliquus hydrolysates stood out with the higher antioxidant potential. All the hydrolysates demonstrated anti-hypertensive potential by showing an IC50 lower than 500 μg protein/mL for ACE inhibition (Table 1). Thus, production of peptide hydrolysates from microalgae may represent an interesting approach for the development of sustainable, natural functional ingredients to be used to prevent hypertension on the consumers by incorporating it in food matrices.In conclusion, the enzymatic hydrolysis of microalgae allowed to produce hydrolysates with antioxidant and anti-hypertensive potential. Further studies should be done to confirm the anti-hypertensive ability after the gastrointestinal digestion of the hydrolysates. If the bioactivity is maintained, these hydrolysates may be incorporated in food matrices as functional ingredients, contributing to the development of functional foods with antioxidant and anti-hypertensive benefits for the consumers.
- Production, characterization and ultrafiltration of bioactive extracts derived from the microalgae Senedesmus obliquusPublication . Cunha, S. A.; Castro, R. de; Coscueta, E. R.; Silva, J. L. da; Pintado, M. E.Algae are very abundant worldwide and contains compounds with high biological value, such as proteins, amino acids, antioxidants. It is noteworthy that some algae species contain protein levels similar to meat, soybean and milk. Micro and macroalgae have been studied as a source of bioactive compounds, such as bioactive peptides, with properties of interest for humans and animals. In vitro, enzymatic hydrolysis is one of the most described methods for producing peptides. Thus, in this work the microalgae Senedesmus obliquus was used with the goal of producing water soluble extracts rich in proteins and bioactive peptides. The Senedesmus obliquus used showed 45.7% of protein, 9.1% of lipids, 15.6% of carbohydrates and 15.8% of fibers. Extracts were produced from the microalgae by enzymatic hydrolysis, using ultrapure water as the solvent. First, the mixture was incubated at 50ºC for 2h with a cellulase to weaken the cellular wall and help releasing proteins. Secondly, the mixture was incubated with a protease at 40ºC for 2h, to hydrolyse the proteins into smaller peptides. One half of the produced extract was fractionated by ultrafiltration in a Tangential Flow Filtration System (Cogent μScale) using a cut-off of 3KDa. The protein content was determined by Kjeldahl, the antioxidant activity was determined by ORAC and ABTS assays and anti-hypertensive property was determined by the inhibition method of Angiotensin-I converting enzyme (iACE). The hydrolysis strategy resulted in high levels of hydrolysis with a yield of 52% of soluble protein. The biological activity of non-fractionated extract showed ORAC and iACE results of 530 μmol TE/g of extract and an IC of 200 μg protein/mL, respectively. The showed ORAC results of 597 μmol TE/g of extract. So, due to its protein richness and interesting bioactivities, Senedesmus obliquus extracts may have potential to be used in food and cosmetic industries.