Microwave-assisted extraction of phenolic acids and flavonoids and production of antioxidant ingredients from tomato: a nutraceutical-oriented optimization study

The production of natural extracts requires suitable processing conditions to maximize the preservation of the bioactive ingredients. Herein, a microwave-assisted extraction (MAE) process was optimized, by means of response surface methodology (RSM), to maximize the recovery of phenolic acids and flavonoids and obtain antioxidant ingredients from tomato. A 5-level full factorial Box-Behnken design was successfully implemented for MAE optimization, in which the processing time (t), temperature (T), ethanol concentration (Et) and solid/liquid ratio (S/L) were relevant independent variables. The proposed model was validated based on the high values of the adjusted coefficient of determination and on the non-significant differences between experimental and predicted values. The global optimum processing conditions (t=20 min; T=180 ºC; Et=0 %; and S/L=45 g/L) provided tomato extracts with high potential as nutraceuticals or as active ingredients in the design of functional foods. Additionally, the round tomato variety was highlighted as a source of added-value phenolic acids and flavonoids.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support to CIMO (PEst-OE/AGR/UI0690/2014), REQUIMTE (UID/QUI/50006/2013 - POCI/01/0145/FERDER/007265), J. Pinela (SFRH/BD/92994/2013) and L. Barros (SFRH/BPD/107855/2015); FCT/MEC and FEDER under Programme PT2020 for financial support to LSRE (UID/EQU/50020/2013), and to QREN, ON2 and FEDER (NORTE-07-0162-FEDER-000050); to the Xunta de Galicia for financial support for the post-doctoral researcher of M.A. Prieto

Optimization of microwave-assisted extraction of hydrophilic and lipophilic antioxidants from a surplus tomato crop by response surface methodology

Tomato is the second most important vegetable crop worldwide and a rich source of industrially interesting antioxidants. Hence, the microwave-assisted extraction of hydrophilic (H) and lipophilic (L) antioxidants from a surplus tomato crop was optimized using response surface methodology. The relevant independent variables were temperature (T), extraction time (t), ethanol concentration (Et) and solid/liquid ratio (S/L). The concentration-time response methods of crocin and β-carotene bleaching were applied, since they are suitable in vitro assays to evaluate the antioxidant activity of H and L matrices, respectively. The optimum operating conditions that maximized the extraction were as follows: t, 2.25 min; T, 149.2 ºC; Et, 99.1 %; and S/L, 45.0 g/L for H antioxidants; and t, 15.4 min; T, 60.0 ºC; Et, 33.0 %; and S/L, 15.0 g/L for L antioxidants. This industrial approach indicated that surplus tomatoes possess a high content of antioxidants, offering an alternative source for obtaining natural value-added compounds. Additionally, by testing the relationship between the polarity of the extraction solvent and the antioxidant activity of the extracts in H and L media (polarity-activity relationship), useful information for the study of complex natural extracts containing components with variable degrees of polarity was obtained.The authors are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support to CIMO (PEst-OE/AGR/UI0690/2014), REQUIMTE (UID/QUI/50006/2013) and J. Pinela (SFRH/BD/92994/2013); to FCT/MEC and FEDER under Programme PT2020 for financial support to LSRE (UID/EQU/50020/2013), and to QREN, ON2 and FEDER (Project NORTE-07-0162-FEDER-000050); to the Xunta de Galicia for financial support for the post-doctoral researcher of M.A. Prieto

Valorisation of tomato wastes for development of nutrient-rich antioxidant ingredients: A sustainable approach towards the needs of the today's society

Nutrient-rich antioxidant ingredients were produced from tomato fruit wastes using a microwave-assisted extraction (MAE) process. Different conditions of extraction time (t), temperature (T), ethanol concentration (Et) and solid/liquid ratio (S/L) were combined in a circumscribed central composite design and optimized by response surface methodology. The model was statistically validated and used for prediction in the experimental range. Under the global optimal MAE conditions (t = 20 min, T = 180 °C, Et = 47.4% and S/L = 45 g/L), it was possible to obtain an extraction yield of 75.5% and ingredients with high levels of sugars, proteins, phenolics, and flavonoids, and interesting antioxidant properties measured via ABTS[rad] + scavenging activity and oxidative haemolysis inhibition assay (OxHLIA). The antioxidant capacity of the extracts was lower compared to the one of commercial food additives. However, the sustainably developed ingredients may be used in the fortification and functionalisation of food, as well as for incorporation in feed products. Industrial relevance This study addresses current needs of the agri-food sector, namely the recycling of plant wastes and production of valuable extracts for the food/feed industry. A MAE process was developed and optimized to maximize the recovery of nutrients and antioxidants from tomato fruit wastes. The optimum processing conditions established in this study allowed a high extraction yield and reduced solvent consumption. MAE can be considered as a sustainable alternative to conventional extraction methods. These findings will contribute to promote a more sustainable bioeconomy in the agro-food sector.info:eu-repo/semantics/publishedVersio

Valorização de produtos de montanha pela utilização de tecnologias de processamento não convencionais

Os vegetais embalados prontos a comer têm tido uma crescente aceitação por parte do consumidor por atenderem aos requisitos contemporâneos de conveniência, segurança e salubridade. O crescimento deste setor tem levado à introdução de novos produtos e à adoção de tecnologias de conservação mais eficientes, seguras e sustentáveis [1]. O consumidor procura também alimentos com características organoléticas diferenciadas das dos alimentos habitualmente consumidos diariamente. A recuperação do uso de Rumex induratus Boiss. & Reut. (azedas) e Nasturtium officinale R. Br. (agrião) poderá responder a esta procura, aliando garantia de qualidade e inovação. Visto a maioria dos tratamentos convencionais ser ineficaz em assegurar segurança sem comprometer a qualidade, e dada a preocupação em torno dos agentes químicos vulgarmente utilizados, a irradiação de alimentos e o embalamento em atmosfera modificada têm emergido como alternativas seguras e eficazes [1-4]. Neste sentido, este estudo teve como objetivo avaliar a eficácia de diferentes atmosferas de embalamento e de diferentes doses de radiação ionizante na conservação da qualidade destas espécies durante o armazenamento refrigerado. O uso sustentável de produtos vegetais para a recuperação de biomoléculas ou produção de ingredientes funcionais de valor acrescentado é uma estratégia útil que pode ajudar a enfrentar os desafios societais deste século. Atualmente é originada uma grande quantidade de resíduos de tomate (Lycopersicon esculentum Mill.) fresco durante as várias etapas do seu ciclo produtivo, desde a cultura até ao armazenamento e venda [5]. Estes resíduos são ricos em licopeno e vitaminas, mas também em compostos fenólicos [6,7]. Estes compostos bioativos estão envolvidos na prevenção de várias patologias humanas e são de elevada importância para a indústria alimentar, farmacêutica e cosmética. Visto os métodos convencionais utilizados para a extração destas biomoléculas apresentarem várias desvantagens, novas tecnologias mais eficientes e sustentáveis têm vindo a ser adotadas. Neste sentido, este trabalho teve como objetivo otimizar as condições de extração assistida por tecnologia micro-ondas de antioxidantes hidrofílicos e lipofílicos e dos ácidos fenólicos e flavonoides maioritários da variedade de tomate redondo utilizando a metodologia de superfície de resposta (RSM)