Valorisation of Camellia sinensis branches as a raw product with green technology extraction methods

This work deals with the study of tea stalks from pruning debris using environmental friendly extraction technology to offer new healthy properties. In the manufacturing tea industry, tea trees require to be pruned every year and most of their remains are discarded as a waste with no economic value. Microwave aqueous extraction and pressurized hot water extraction process (autohydrolysis) were used to recover bioactive compounds from the tea branches. Operating at a fixed solid: liquid ratio (1:15), the effect of the maximum heating temperatures from 140 to 220 °C was studied. Liquid extracts were analysed for total phenolic, oligosaccharides, protein, mineral and heavy metals content, as well as for antioxidant capacity. The antitumoral possibilities were also determined for selected samples. The obtained results indicated that both processes could be used as an alternative to recover bioactive compounds from tea wastes, although microwave-assisted extraction allowed saving time when compared with autohydrolysis processing. The temperature exhibited a relevant effect on the total phenolic content and antioxidant capacity, decreasing with the microwave treatment and increasing with the autohydrolysis temperature. The obtained extracts could be adequate for incorporation in food and non-food fields.Ministerio de Economía y Competitividad | Ref. IJCI-2016-27535Ministerio de Ciencia, Innovación y Universidades | Ref. RYC2018- 024454-

Seasonal and spatial compositional variation of the red algae Mastocarpus stellatus from the Northern coast of Portugal

This study focusses on the valorization of the red seaweed Mastocarpus stellatus, collected in the Northern coast of Portugal, as a natural source of high value compounds due to its beneficial properties. An annual monitoring of the seaweed was performed by determining its lipids, ash, carbohydrates, phycobiliproteins, total phenolic compounds, antioxidant capacity and carrageenan from three different rocky shores located in the north of Portugal. The results showed a seasonal and spatial variability of the studied compounds between October 2018 and September 2019 depending on the climatic variables of temperature, precipitation, and solar radiation. The most productive season coincided with the warmest months, except for carbohydrates and phycobiliproteins, which were promoted in the colder season. The spatial variation also could be explained by the proximity to water channel discharges at the sampling sites. Complementary studies on the carrageenan fraction were conducted in one of the shores due to the high biopolymer content, to determine their carrageenan proportion between the summer and winter period and establish their rheological capabilities for the formulation of gelling matrices. The extracted biopolymers exhibited typical structural and viscoelastic characteristics of kappa/iota-hybrid carrageenans, suggesting notably differences depending on the harvest season, which is critically relevant to define future applications.Agencia Estatal de Investigación | Ref. RYC2018-024454-IXunta de Galicia | Ref. ED431F 2020/01Fundação para a Ciência e a Tecnologia | Ref. UIDP/04423/2020Fundação para a Ciência e a Tecnologia | Ref. UIDB/04423/2020Universidade de Vigo/CISU

Extracción de compuestos valiosos de fuentes agrícolas y macroalgas rojas para desarrollar nuevos geles

Durante el programa de doctorado se plantea llevar a cabo la revalorización de deshechos de origen vegetal considerados de nulo o bajo valor económico, caracterizarlos y proporcionarles nuevos usos y aplicaciones. Para el cumplimiento de este objetivo general, se propone la determinación de su composición, capacidad antioxidante, su potencial bioactivo y funcionalidad como agente gelificante, para ser utilizados en la industria de la alimentación, medicina, farmacología o cosmética. Se utilizarán tecnologías extractivas de bajo impacto ambiental a diferentes condiciones, como son los microondas, autohidrólisis y ultrasonidos o la combinación secuencial de alguna de ellas para optimizar la recuperación de compuestos de interés presentes en la materia prima. La idea principal es crear nuevos productos que mejoren la calidad de vida, a través de tecnologías verdes, minimizando el uso de material, utilizando la menor energía posible y maximizando su eficiencia.Durante o programa de doutoramento proponse realizar a revalorización de residuos de orixe vexetal considerados de cero ou baixo valor económico, caracterizalos e dotalos de novos usos e aplicacións. Para o cumprimento deste obxectivo xeral, proponse determinar a súa composición, capacidade antioxidante, o seu potencial bioactivo e a súa funcionalidade como axente gelificante, para ser empregado na industria alimentaria, farmacéutica ou cosmética. Utilizaranse tecnoloxías extractivas de baixo impacto ambiental en diferentes condicións, como microondas, autohidrólise e ultrasóns ou a combinación secuencial de calquera deles para optimizar a recuperación de compostos de interese presentes na materia prima. A idea principal é crear novos produtos que melloren a calidade de vida, a través de tecnoloxías verdes, minimizando o uso de material, empregando a menor enerxía posible e maximizando a súa eficiencia.During the doctoral program it is proposed to carry out the revaluation of waste of plant origin considered of zero or low economic value, characterize them and provide them with new uses and applications. For the fulfillment of this general objective, it is proposed to determine its composition, antioxidant capacity, its bioactive potential and functionality as a gelling agent, to be used in the food, medicine, pharmacology or cosmetics industry. Extractive technologies with low environmental impact will be used at different conditions, such as microwaves, autohydrolysis and ultrasound or the sequential combination of any of them to optimize the recovery of compounds of interest present in the raw material. The main idea is to create new products that improve the quality of life, through green technologies, minimizing the use of material, using the lowest energy and maximizing its efficiency.Xunta de Galicia | Ref. ED431C 2018/47Ministerio de Economía y Competitividad |Ref. RTI2018-096376-B I00Hijos de Rivera S.A.U. Centro de Desarrollo Tecnológico Industrial (CDTI) | Ref. IDI-20180987Universidade de Vigo | Ref. 21-EST-

Ultrasound-assisted extraction of high-value fractions from fruit industrial processing waste

This work deals with the valorization of fruit industrial processing waste pretreated with two dehydration methods, air oven and lyophilization. Ultrasound-assisted extraction using a sonication probe was selected to recover the high-value fractions. A battery of experiments following a Box–Behnken design was planned to evaluate the effect of the ultrasound amplitude, extraction duration, and temperature on the yield, protein content, phenolic content, and antiradical capacity of the soluble extracts. Operating at a fixed frequency (24 kHz) and solid:water ratio (1:15), the models predicted (significance degree >95%) the maximum extraction conditions of 69.7% amplitude, 53.43 °C, and 12 min for conventionally dehydrated fruit waste. Under these processing conditions, 52.6% extraction yield was achieved, with a protein content of 0.42 mg/g, total phenolic content of 116.42 mg GAE/g, and antioxidant capacity of 44.95 mg Trolox/g. Similar yields (53.95%) and a notably higher protein content (0.69 mg/g), total phenolic content (135.32 mg GAE/g), and antioxidant capacity (49.52 mg Trolox/g) were identified for lyophilized fruit waste. This treatment required a longer dehydration pretreatment duration (double), higher ultrasound amplitude (80%), and higher extraction temperature (70 °C), but shorter extraction time (4 min). These outcomes highlighted the important impact of the dehydration method on the valorization of the tested waste, with conventional drying saving costs, but the lyophilization procedure enhancing the bioactive features of the waste.Ministerio de Ciencia, Innovación y Universidades | Ref. RYC2018-024454-IXunta de Galicia | Ref. ED431F 2020/0

Formulation and thermomechanical characterization of functional hydrogels based on gluten free matrices enriched with antioxidant compounds

Native starch from potatoes and hybrid carrageenans from the red alga Mastocarpus stellatus have been used as gluten-free gelling matrices to obtain functional hydrogels. The enrichment of gelling matrices with antioxidant compounds from natural sources is an increasing market trend. In this context, this work is aimed at the formulation and thermo-rheological characterization of functional hydrogels using potato starch from agro-industrial waste and kappa–iota hybrid carrageenans extracted from the above seaweed, enriched with antioxidant compounds from different agro-industrial products, such as waste coming from the pruning of green tea and two varieties of hops used in the brewing industry. Environmentally friendly technologies such as microwave hydrodiffusion and gravity, microwave-assisted extraction, ultrasounds and autohydrolysis were used for the recovery of antioxidant compounds. The results point out that functional hydrogels based on potato starch and hybrid carrageenans with a wide range of viscoelastic features can be achieved, with the particularity of being suitable for people with celiac disease. The incorporation of selected antioxidant extracts from vegetable by-products involved the drop (about tenfold) of the viscous and elastic properties of the formulated gels. The sequential combination of the above treatments could even further expand the thermo-rheological properties of formulated hydrogels, with potential application in functional foodstuffs and novel gluten-free goods.Xunta de Galicia | Ref. ED431F 2020/01Ministerio de Ciencia, Innovación y Universidades (España) | Ref. RTI2018-096376-B-I00Ministerio de Ciencia, Innovación y Universidades (España) | Ref. RYC2018-024454-

Green extraction of phenolic compounds from Perle Hallertau and Nuggets hop pellets

Operation conditions to recover and quantify active compounds from Perle Hallertau (PH) and Nuggets (N) hops, following a sequential combination of ultrasound and microwave assisted ethanolic extraction were studied. Ultrasound treatment (55 °C, 60% ethanol, 30 minutes) allowed extracts with phenolic contents of 160.43 mg GAE/g extract and ABTS radical scavenging capacity equivalent to 400.24 mg Trolox/g extract for PH. Optimal conditions for N were found at 55 °C, using 60% ethanol for 120 minutes (98.80 mg GAE/g extract) and 55 °C, 40% ethanol for 180 min (370.00 mg Trolox/g extract). The remaining solids were further processed under ethanolic microwave extraction (130–190 °C, 5 minutes) with the optimal results obtained at 190 °C for PH (77.11 and 98.67 mg GAE/g extract) and N (226.96 and 368.72 mg Trolox/g extract). Results obtained provided hops pellets as a rich source of active compounds that could be suitable for food and no food industry applicationsMinisterio de Ciencia, Innovación y Universidades | Ref. RYC 2018-024454-

Pressurized hot water extraction and bio-hydrogels formulation with Aristotelia chilensis [Mol.] Stuntz leaves

Aristotelia chilensis is a plant rich in phenolics and other bioactive compounds. Their leaves are discarded as waste in the maqui berry industry. A new application of these wastes is intended by the recovery of bioactive compounds using pressurized hot water extraction with conventional or microwave heating. Both technologies have been selected for their green character regarding the type of solvent and the high efficiency in shorter operation times. Extractions were performed in the temperature range 140–200 °C with a solid/liquid ratio of 1:15 (w:w). The extracts’ total phenolic content, antioxidant capacity, and saccharides content obtained with both heating methods were measured. Additionally, the thermo-rheological properties of the gelling matrix enriched with these extracts were analyzed. Optimum conditions for lyophilized extracts were found with conventional heating, at 140 °C and 20 min extraction; 250.0 mg GAE/g dry extract and 1321.5 mg Trolox/g dry extract. Close to optimum performance was achieved with microwave heating in a fraction of the time (5 min) at 160 °C (extraction), yielding extracts with 231.9 mg GAE/g dry extract of total phenolics and antiradical capacity equivalent to 1176.3 mg Trolox/g dry extract. Slightly higher antioxidant values were identified for spray-dried extracts (between 5% for phenolic content and 2.5% for antioxidant capacity). The extracts obtained with both heating methods at 200 °C contained more than 20% oligosaccharides, primarily glucose. All the formulated gelling matrices enriched with the obtained extracts displayed intermediate gel strength properties. The tested technologies efficiently recovered highly active antioxidant extracts, rich in polyphenolics, and valuable for formulating gelling matrices with potential applicability in foods and other products.Xunta de Galicia | Ref. ED431G2019/06Ministerio de Economía y Competitividad (España) | Ref. RYC2018–024454-IXunta de Galicia | Ref. ED431F 2020/0