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  • A new vision for agri-food waste from bell pepper (Capsicum annuum L.) production: a potential source of bioactive compounds
    Publication . Baessa, Jozias Domingos da Veiga; Fernandes, Ângela; Pires, Tânia C.S.P.
    Agri-food waste and loss has become a pressing and urgent problem with notable environmental and economic consequences. Among various sectors, the fruit and vegetable industry, particularly the bell pepper industry, stands out as a major contributor to food waste and by-products. This industry generates substantial amounts waste, which presents an opportunity to showcase the potential of the circular economy through valorization of bio- waste. Over the past two decades, there has been a concerted effort to study the biochemical composition of various natural matrices, aiming to discover new functional compounds. Among these, the bell pepper has emerged as a particularly interesting vegetable, in terms of its nutritional value and its biochemical characteristics. However, a significant quantity of waste is generated during production, which is considered an excellent source of bioactive compounds of high interest. These waste fruits and their by-products, namely stalks and seeds, contain a wide range of phytochemicals, including capsaicinoids, phenolic compounds, carotenoids, and vitamins, which exhibit important biological activities such as antioxidant, antimicrobial, and anti-inflammatory. These bioactive compounds hold promise for utilization in food, cosmetic and pharmaceutical industries. Therefore, the valorization of agri-food waste has become an area of great interest in biotechnology and innovation, with beneficial effects not only for the environment but also for the economy and the population. In this sense, the present study aimed to evaluate the proximal and biochemical composition of waste-green, orange, and red fruits of Capsicum annuum L. Additionally, the bioactive potential of the fruit, stalk, and seed hydroethanolic extracts obtained from the waste- colored bell peppers was equally assessed. Moisture, ash, protein, fat, carbohydrate, and energy contents were determined following official AOAC analysis methodologies. The quantification of free sugars was performed using a HPLC-RI system, organic acids by UHPLC-DAD, fatty acids by GC-FID and volatile organic compounds by a GC-MSD system. The phenolic composition of waste- colored bell peppers was determined by HPLC-DAD-ESI/MS. Furthermore, different biological activities (antioxidant, cytotoxicity, antimicrobial) were analyzed through different in vitro assays. Overall, the proximal and chemical assessment revealed that carbohydrates were the predominant macronutrient in the analyzed samples, with fructose standing out as the main free sugar in two different waste-colored bell peppers (orange and red), whilst glucose was the main present free sugar in green bell peppers. Four organic acids were identified in the samples, of which oxalic acid was presented greater content in orange and red bell peppers, whilst malic acid was the most abundant in green bell peppers. Regarding fatty acids, fifteen compounds in total were identified being palmitic acid, linoleic acid, and α-linolenic acid present in major quantities, verifying the prevalence as well of PUFAs. In the assessment of phenolics, twenty- two compounds were identified in waste-colored bell peppers including seven phenolic acids, fourteen flavonoids and one stilbene. Moreover, the analysis of volatile organic compounds revealed the presence of thirty-four compounds, including eight heterocyclic compounds, seven acids, six esters, three alcohols, two amines, two alkanes, one acetal, one aldehyde, one ether, one glyceride, one ketone, one ketose. Concerning the bioactive properties assessment, the extracts of stalks, fruits, and seeds revealed antioxidant capacity, with extracts from waste-green bell peppers presenting the best result (0.36±0.01 mg/mL, 0.44±0.02 mg/mL, and 0.21±0.01 mg/mL, respectively). All the extracts demonstrated no cytotoxicity activity at the maximum concentration tested (GI50>400μg/mL). Fruit extracts demonstrated superior antibacterial activity when compared to extracts of stalks and seeds with best results identified against food contaminants Y. enterocolitica, B. cereus, S. aureus (MIC = 5 mg/mL), and clinical isolates E. faecalis and MRSA (MIC = 5 mg/mL). Furthermore, all the extracts revealed no bactericidal effects for any bacteria up to the maximum concentration tested (MBC>10 mg/mL). In the antifungal activity assessment, the fungal strain A. brasiliensis was the most susceptible to the tested samples, especially against the extracts of the fruits, with waste-red bell pepper demonstrating superior inhibitory effects (MIC = 1.25 mg/mL). Moreover, all the extracts showed no fungicidal effects for both fungal strains up to the maximum concentration tested (MFC>10 mg/mL). In general, this study aimed to valorize waste-colored bell peppers as natural source of bioactive compounds that can be exploited by different industries, through their conversion into value-added products, contributing simultaneously to the implementation of circular economy guidelines.
    2024Dissertação de mestrado Acesso restrito Ver mais