AllPumpkin – Development of a high-quality pumpkin pulp enriched and preserved by added-value molecules from pumpkin by-products, an integrative and sustainable strategy.

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Prunus spinosa L. fruit epicarp: extraction of compounds with colouring capacity for food application

Publication . Leichtweis, Maria Gabriela; Novais, Cláudia; Pereira, Carla; Dias, Maria Inês; Carocho, Márcio; Barreira, João C.M.; Baraldi, Ilton J.; Ferreira, Isabel C.F.R.; Barros, Lillian

Prunus spinosa L. is a wild shrub with bitter and astringent fruits, also known as blackthorn. These fruits are commercially underexplored, despite presenting high amounts of anthocyanins, and the epicarp if often discarded in the production of blackthorn jams and jellies. The present study aimed to characterize the fruit epicarp and develop an anthocyanin-based food colorant, predominantly rich in cyanidin 3-rutinoside and peonidin 3-rutinoside. The extract was obtained by ultrasound-assisted extraction, a rapid and low-cost extraction procedure (Leichtweis, 2019), and it was incorporated in a typical Brazilian pastry product named “beijinhos”. The coloured products were monitored and compared to control samples (uncoloured products) in terms of nutritional, chemical, and physical properties, immediately after manufacture and after 24h, according to the typical shelf-life of this product. For that purpose, the colour parameters were evaluated using a portable colorimeter, through the CIELab spherical coordinates (L*, a*, and b*), the nutritional value was assessed following AOAC procedures, the texture was evaluated using a texture analyser, the pH using a portable pH-meter, the phenolic profile was assessed by HPLC-DAD/ESI-MS, the fatty acids composition was assessed by GC-FID, and the free sugars by HPLC-RI. The extract presented a reddish-purple hue and conferred a purple colour to the pastry product. The addition of the colorant extract did not cause changes in pH, fatty acid profile, and nutritional parameters of “beijinhos”, except in the content of free sugars, where the levels of glucose and fructose were higher when compared to the control, reflecting the profile of free sugars of this fruit epicarp. Regarding the rheological parameters, the addition of the colorant extract significantly changed the hardness, cohesiveness, springiness, gumminess, and chewiness of the coloured products, compared to the control ones. The colour analysis was performed with a portable colorimeter and the CIELab spherical coordinates (L*, a*, and b*) were obtained and calculated. The purple colour conferred by the extract has lost some intensity after 24 h, but this observation was also made for the control sample, over the 24-hour period. In general, the obtained colorant revealed a good colouring ability, without causing significant alterations in the nutritional, chemical, and physical characteristics of the food product, corroborating the applicability of this bioresidue for the development of natural additives.

2021Conference object

Open access

Natural compounds with preservative capacity obtained from by-products of pumpkin industrial processing

Publication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Pereira, Carla; Dias, Maria Inês; Pires, Tânia C.S.P.; Calhelha, Ricardo C.; Bachari, Khaldoun; Ziani, Borhane E.C.; Oliveira, Beatriz; Ferreira, Isabel C.F.R.; Barros, Lillian

The search for cheap and suitable sources of natural compounds with functional properties as an alternative for the replacement of synthetic additives is growing. Part of this occurs in the food industry, which is under pressure to offer healthier products, but still convenient and durable. However, great potential can be found inside the industry itself, once large amounts of fruits and vegetables are discarded during food processing. These wastes comprise leaves, seeds, skin, bagasse, and juices, which are rich in high value-added compounds that present functional and bioactive properties.The present work purposed to explore the by-products of pumpkin industrial processing as source of natural compounds with preservative capacity for food application. For this purpose, pumpkin peel, seeds, and fibers were evaluated. These by-products were obtained from the pumpkin varieties “Butternut squash”, “Gold nugget pumpkin”, and “Musquée de Provence” grown in Algeria. The preservative capacity of their extracts was assessed by two biological antioxidant methods, more specifically the lipid peroxidation inhibition capacity (TBRAS) and the inhibition of oxidative hemolysis (OxHLIA), and the antimicrobial assessment, tested against eight strains of bacteria, and two strains of fungi with relevance in food safety. As a first validation of safety for food application, the cytotoxicity was evaluated in a primary culture of non-tumor porcine liver cells (PLP2). Furthermore, the phenolic composition analysis was performed by HPLC-DAD-ESI/MS.The pumpkin by-products presented great preservative capacity. All samples showed microbial inhibition capacity and high antioxidant activity, especially the seeds of “Butternut squash” and “Gold nugget pumpkin”. Despite the second one did not present anti-hemolytic properties, probably due to the interference of its fat content, it presented a TBARS IC50 value lower than the control Trolox. These samples also presented better antibacterial activity than the remaining by-products, protecting against seven of the eight bacterial strains tested. All samples inhibited at least two strains of bacteria and one of two fungal strains, and none of them presented bactericidal nor fungicidal capacity, at the maximum concentration tested of 10 mg/mL. Regarding the cytotoxicity, none of the samples showed toxicity in the primary culture of non-tumor porcine liver cells (PLP2), up to the maximum concentration tested of 400 μg/mL. Interestingly, the peel of “Butternut squash” presented the most heterogeneous phenolic profile, with O-glycosylated flavonoids as the major compounds, specially isorhamnetin-O dideoxyhexosyl-hexoside ([M-H]- at m/z 769). Other type of compounds, such as citric acid ([M-H]- at m/z 191) and 4-O-(6′-O-glucosyl-4″-hydroxybenzoyl)-4-hydroxybenzyl alcohol ([M-H]- at m/z 405), have also been tentatively identified among all varieties and by-products. These results revealed pumpkin by-products as cheap and promising sources ofpreservative compounds for food application, fostering more sustainable food supply chain and promoting natural ingredients that add functional properties to the product with benefits to consumer health.

2022Conference object

Open access

Pumpkin bioresidues as sources of bioactive compounds for food application

Publication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Pereira, Carla; Pires, Tânia C.S.P.; Ferreira, Isabel C.F.R.; Barros, Lillian

According to FAO data, in Europe, almost half of fruit and vegetable production is lost or wasted [1]. Part of this occurs in the industry during processing stages of these commodities, resulting in huge amounts of waste in the form of peels, seeds, liquid, and molasses [2]. Nevertheless, these residues are rich in organic matter, phytochemicals, and compounds with nutraceutical properties [3]. Focusing on the valorisation of these residues, which compounds have commercial potential and aiming at promoting a circular economy, the present work focused the evaluation of the bioactive properties of the bioresidues generated in pumpkin pulp production. For this purpose, the peel, seeds, and fibrous strands of three pumpkin varieties grown in Portugal (butternut squash, common pumpkin, and kabocha squash) were evaluated in terms of antioxidant capacity, through 3 chemical (DPPH scavenging activity, reducing power and β-carotene bleaching inhibition) and 2 biological (TBARS and OxHLIA) methods. Additionally, their cytotoxicity was assessed through the in vitro sulforodamine B (SRB) assay, tested in a primary culture of cells prepared from porcine liver. Regarding the antioxidant activity evaluation, all the samples presented great antioxidant capacity, showing IC50 values ranging from about 50 times higher than the positive control, Trolox, to about 14 times lower than Trolox. The fibrous strands and seeds showed better antioxidant capacity than the peels, with the fibrous strands revealing great antioxidant capacity in the employed chemical methods, and the seeds in the biological ones. In terms of pumpkin varieties, the kabocha squash presented the best result in 3 of the 5 assays (DPPH, β-carotene, and TBARS). Regarding cytotoxicity, the effect of inhibiting non-tumour cell growth was not observed for any of the samples, even at the highest concentration (400 μg/mL), which is of great importance for considering their inclusion into foodstuff. These preliminary results showed a great potential for the exploration of pumpkin bioresidues to develop natural additives with antioxidant properties to be included in food products, fostering the circular economy.

2021Conference object

Open access

Developing a sustainable and functionalized pumpkin fruit pulp formulation using biobased preservatives: The PulpIng Project

Publication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Pires, Tânia C.S.P.; Pereira, Carla; Oliveira, Beatriz; Ferreira, Isabel C.F.R.; Barros, Lillian

The PulpIng project is committed to advancing the circular economy and promoting sustainable agro-industrial practices. To achieve this goal, the project aims to develop new pumpkin fruit pulp formulations functionalized with natural preservative extracts from pumpkin by-products. The seeds, peels, and fibers from different pumpkin genotypes cultivated in five different countries were used to obtain extracts with preservative properties. These extracts showed great antioxidant and antimicrobial capacity, as well as a diversified phenolic compounds profile. The peels proved to be the most promising by-product, being thus selected to optimize the extraction by RSM, to reach the most efficient conditions leading to preservative compounds-rich extracts. In the next step, the extracts will be incorporated into the new pulp formulations, which quality will be assessed during shelf-life. Waste and wastewater management will also be addressed. By pursuing these goals, the PulpIng project ambitions innovation and sustainability within the agro-industrial sector.

2023Conference object

Open access

Pumpkin peel phenolic extracts: optimized extraction and potential use as food preservatives

Publication . Leichtweis, Maria Gabriela; Molina, Adriana K.; Petropoulos, Spyridon Α.; Carocho, Márcio; Pires, Tânia C.S.P.; Dias, Maria Inês; Calhelha, Ricardo C.; Oliveira, Beatriz; Barros, Lillian

In the food industry, byproducts generated from food processing can be a significant source of valuable compounds that can be used for different applications, including food preservation. The aim of this study was to extract phenolic compounds from pumpkin peels of the Greek variety 'Leuka Melitis' in order to valorize this byproduct generated during pumpkin processing and promote sustainability and circular economy. Two different extraction techniques were compared: heat-assisted (HAE) and ultrasound-assisted (UAE) extraction. The extraction processes were optimized using response surface methodology (RSM) based on the Box Behnken experimental design, using extraction time, temperature (HAE) or power (UAE), and ethanol concentration in the solvent as independent variables; whereas extraction yield (dry residue) and total phenolic content (Folin-Ciocalteu method) were used as dependent variables. In addition, to validate the potential application of the obtained compounds as food preservatives, the phenolic profile (HPLCDAD-ESI/MS), the antioxidant, antimicrobial, and cytotoxic properties of the optimal extract were also evaluated. The optimization study demonstrated that UAE was more effective than HAE in both responses. This technique resulted in a two-fold increase in the concentration of phenolic compounds compared to the HAE, yielding 307 mg/g dw and 135 mg/g dw of total phenols, respectively, in the individual optimal variable conditions. In the global optimal conditions, although the UAE method required the highest power tested (400 W), it allowed the lowest extraction time (5 min) and only the use of water as solvent (0% ethanol), resulting in 1.1 g/100 g of dry residue and 120 mg/g dw of total phenols. On the other hand, the conventional extraction (HAE) facilitated energy and solvents saving, demanding only 30 °C and water as solvent, despite the increased extraction time (67 min), resulting in a yield of 0.9 g/100 g of dry residue and 106 mg/g dw of total phenols. Through the RSM, it was suggested that the ethanol concentration in the extraction solvent had the most significant impact on both dependent variables, with higher ethanol concentrations resulting in lower extraction yields, but higher phenolic content in the extracts. Regarding the experimental validation of the global optimal conditions by UAE, the results were satisfactory, since the extract presented a heterogenous profile of phenolic compounds, with six tentatively identified molecules, including three flavonoids, two phenolic acids, and one flavan-3-ol, in a total concentration of 1.525 ± 0.004 mg/g of extract. The extract revealed antihemolytic activity (IC50: 540 ± 15 µg/mL) and inhibited lipid peroxidation (IC50: 2510 ± 147 µg/mL), while it was effective against four bacteria and one fungus (at the maximum tested concentration of 10 mg/mL). Furthermore, it did not reveal cytotoxicity in a primary culture of non-tumor porcine liver cells, up to 400 µg/mL. The results of this study demonstrate the potential use of pumpkin byproducts from the food industry to obtain extracts with a high content of bioactive compounds. In addition, the study highlights the efficiency of alternative extraction techniques in reducing byproduct waste, and solvents and energy consumption, while at the same time improve the added value of pumpkin crop within the circular economy context.

2023Conference object

Open access