1. Introduction
Passion fruit belongs to the Passifloraceae family and it is distinguished by its taste and nutritional properties (Corrêa et al., 2016; Cheok et al., 2018; He et al., 2020; Viganó & Martinez, 2015; Cesar et al., 2022). Among the substances contained in passion fruit are dietary fiber, minerals, vitamins, pectin, antioxidants, flavonoids and other bioactive compounds (Corrêa et al., 2016; He et al., 2020; Biswas et al., 2021; Viganó & Martinez, 2015). Systematized information on chemical and biological activity of different parts of passion fruit could be found in the mini-review article by He et al. (2020); in the work by Viganó & Martinez (2015), the composition and extraction techniques of phytochemicals were considered. Passion fruit can be processed and consumed as juices, dehydrated products, jams, jellies, marmalades, etc. (Biswas et al., 2021); and large amounts of waste are released during processing, including peels and seeds (Corrêa et al., 2016; dos Reis et al., 2018; He et al., 2020; Viganó & Martinez, 2015). Constituent characteristics and functional properties of passion fruit seeds were summarized by Kawakami et al. (2022); possible applications of seed oil were considered by Cesar et al. (2022). According to Cheok et al. (2018), passion fruit peels and seeds account for about 45%-52% and 1%-4% of the total fruit, respectively. Due to the larger amount of peels, they are utilized to a greater extent than the seeds (Cheok et al., 2018).
To the best of the author’s knowledge, there is still no published review in the English-language scientific literature in which the opportunities for the valorization of passion fruit waste were considered in general terms. Therefore, the purpose of this review is to present some recent highlights regarding the valorization possibilities of passion fruit waste.
2. Brief bibliographic overview
The current review has been prepared using only scientific publications in English indexed in the most authoritative international databases (Scopus, Web of Science, PubMed, Google Scholar); book chapters were not considered at all and were not included.
This review does not aim to cover, compile and describe all available scientific production in the above databases under the keywords “passion fruit waste”, but aims to systematically summarize and highlight, with the help of the descriptive approach, only some major research tendencies regarding valorization aspects about possibilities of passion fruit waste. Scientific articles that remained for technical or other reasons beyond the scope of the current review paper could be included in a subsequent updated review.
Among the selected publications after the literature survey was done, it is noticeable that the author teams in just over half of them are entirely Brazilian or individual members of international author teams are Brazilian. This confirms what has been stated in almost all the articles about who are the leading passion fruit growers worldwide and about the importance of passion fruit as an agricultural crop. In one-third of the publications used here, the number of authors is five or more.
The intention of this paper was to give an overview and to provide a general framework on the stated subject, not to retell statements, conclusions, generalizations done by other authors that can be found in their respective works.
In Table 1 the scientific publications cited in the present review paper were systematized by some main words contained in the title and their percentage share.
The most common words were “peel/peels”, pre sented in just over a quarter of the titles used here; in second and third place were the words “seed/seeds” and “waste/wastes”, respectively, which confirms what was stated in the article by Cheok et al. (2018) that the peels were utilized to a greater extent than the seeds. This was also shown by the present descriptive study: in most of the research studies, the object of investigation was the peels.
Next were the terms “rind/rinds”, the simultaneous presence in the title of the words “waste/wastes” and “peel/peels”, followed by “by-product/by-products”, “shell”, “residue/residues”, “pericarp”. The words “bark/barks”; “epicarp”; “mesocarp”; “flavedo”; “albedo”; “valorization”; “waste/wastes” and “rind/rinds”; “waste/wastes” and “shell”; “waste/wastes” and “seed/seeds”; “waste/wastes” and “residue/residues”; “waste/wastes” and “utilization”; “peel/peels” and “by-product/by-products”; “peel/peels” and “albedo”; “peel/peels” and “seed/seeds”; “peel/peels”, “by-product/by-products” and “valorization”; “rind/rinds” and “albedo”; “skin”, “by-product/by-products” and “utilization”; “seed/seeds” and “residue/residues”; “seed/seeds”, “residue/residues” and “utilization”; “seed/seeds” and “utilization”; “by-product/by-products” and “valorization” were included in almost one percent of the titles, respectively.
3. Passion fruit waste valorization highlights
The performed descriptive literature review gave reason to conclude that the main areas of valorization of passion fruit waste can be grouped into several main directions, which the author of this review considered appropriate to be systematized and presented in Figure 1.
It is clear from the Fig. 1 that the main directions for valorization of passion fruit waste, which are being worked on in modern conditions, are: determination of composition, isolation of chemical compounds and characterization of biological activity; development of adsorbents for the removal of various pollutants; attempts at embedding and application in food systems; use in animal nutrition; as well as some other areas of valorization.
The articles used in this review paper were systematized by valorization aspects and some main highlights were presented in Table 2.
Valorization highlights | Waste used | Reference | |
Chemical compounds and bioactivity characterization | Soluble dietary fibres; high methoxyl pectin | Peel | Abboud et al., 2020 |
Enzymes production | Rinds | Zilly et al., 2012 | |
β-glucosidases production | Peel | Almeida et al., 2015 | |
Xylanase production | Peel | Martins et al., 2018 | |
Seed oil: physical and chemical characterization | Seeds | Malacrida & Jorge, 2012 | |
Supercritical CO2 extraction of seed oil assisted by ultrasound | Seeds | Barrales et al., 2015 | |
Polar lipids of seeds oil extracted by supercritical CO2 | Seeds | Arturo-Perdomo et al., 2021 | |
Oil extraction | Seeds | Pereira et al., 2017 | |
Oil extraction | Seeds | Surlehan et al, 2019 | |
Oil quality | Seeds | Regis et al., 2015 | |
Oil quality | Seeds | Antoniassi et al., 2022 | |
Dietary fibres: pectin and (hemi)cellulose | Peels | Bussolo de Souza et al., 2018 | |
Physicochemical composition | Pericarp | Canteri et al., 2010 | |
Essential oils | Shells and seeds | Chóez-Guaranda et al., 2017 | |
Carotenoids extraction | Peel | Chutia & Mahanta, 2021 | |
Fiber pectin | Waste | Contreras-Esquivel et al., 2010 | |
Flour: physico-chemical characterization | Peel and albedo | da Silva et al., 2019a | |
Production of flour by drying | Peel and albedo | da Silva et al., 2019b | |
Production of functional flour | Residues | Lima et al., 2018 | |
Flour: development and characterization | Peels | Macedo et al., 2023 | |
Flavonoids and pectin extraction | Rind | de Souza et al., 2018 | |
Flavonoid extraction | Peel | da Silva Francischini et al., 2020 | |
Flavonoid content of ethanol and ethyl acetate extract | Peel | Aisyah & Ngibad, 2022 | |
Pectin | Albedo | de Aguiar et al., 2019 | |
Pectin and phenolics - simultaneous extraction, physicochemical properties, and antioxidant activity | Peel | Huo et al., 2023 | |
Albedo flour; pectin content | Rind | de Oliveira & de Resende, 2012 | |
Antioxidant polyphenolic compounds extraction | Seeds | de Santana et al., 2017 | |
Phenolic compounds extraction | Rinds | Pereira et al., 2021 | |
Pericarp fractions characterization | Rind | Talma et al., 2019 | |
Antioxidant properties | Peel | Wong et al., 2014 | |
Antioxidant activity | Peel | do Nascimento et al., 2016 | |
Extraction methods - antioxidant activity | Seed | Ahmad & Malik, 2023 | |
Phenolic compounds - antioxidant activity | Peel and seed | da Costa et al., 2023 | |
Lipids and antioxidants | Seeds | Reis et al., 2020 | |
Seeds oil as a source of fatty acids and bioactive substances | Seeds | dos Santos et al., 2021 | |
Physicochemical and technological properties | Peel | Duarte et al., 2017 | |
Physicochemical and antioxidant evaluation | Peel and seed | dos Reis et al., 2018 | |
Anthocyanins | Epicarp | Ghada et al., 2020 | |
Anthocyanins extraction | Peels | Liu et al., 2018 | |
Anthocyanins extraction | Peel | Herrera-Ramirez et al., 2020 | |
Anthocyanins extraction | Rind | Liu et al., 2021 | |
Mesocarp flour in flexible films | Mesocarp | Nascimento et al., 2012 | |
Cellulose nanocrystals as drug carrier | Peels | Wijaya et al., 2017 | |
Ag- and Au-nanoparticles: antibacterial and catalytic activities | Peels | My-Thao Nguyen et al., 2021 | |
Cellulose nanofibers; immobilization of trypsin | Stalks | Rodríguez-Restrepo et al., 2020 | |
Extraction and biological activity | Seeds and seed cake | Oliveira et al., 2016 | |
Antibacterial activity | Pericarp | Nugraha et al., 2018 | |
Some chemical and bioactive investigations | Peel and seed | González et al., 2019 | |
Pectin for edible coating | Rind | Inayati et al., 2018 | |
Pectin extraction | Peel | Kliemann et al., 2009 | |
Pectin extraction | Peel | Kulkarni & Vijayanand, 2010 | |
Pectin extraction | Rind | Canteri et al., 2012 | |
Pectin extraction | Peel | Seixas et al., 2014 | |
Pectin extraction | Peels | Liew et al., 2016 | |
Pectin extraction | Peel | Vasco-Correa & Zapata Zapata, 2017 | |
Pectin and cellulose extraction | Peel | Phan & Ngo, 2020 | |
Novel pectin polysaccharides | Peel | Teng et al., 2022 | |
Antioxidant activity of seeds oil | Seeds | Krambeck et al., 2018 | |
Stilbenes (piceatannol and resveratrol) in seeds oil | Seeds | Krambeck et al., 2020 | |
Aromatic oil | Seeds | Leão et al., 2014 | |
Seeds and oil: chemical characteristics | Seeds | Silva et al., 2015 | |
Isoorientin | Rinds | Zeraik et al., 2012 | |
Bioactive compounds extraction | Rinds | Viganó et al., 2016 | |
Bioreduction of carbonyl compounds | Barks | Machado et al., 2008 | |
Adsorbents | Adsorption of Pb, Cr, Cu | Shell | Campos-Flores et al., 2018 |
Adsorption of Cr (III) | Shell | Campos-Flores et al., 2019 | |
Removal of Pb and Cr | Peels | Castañeda-Figueredo et al., 2022 | |
Removal of Cu(II), Cd(II), Pb(II), Ni(II) | Shell | Chao et al., 2014 | |
Adsorption of Pb(II) | Skin | Gerola et al., 2013 | |
Eriochrome black adsorption | Peel | de Oliveira Brito et al., 2019 | |
Methylene blue removal | Peel | Pavan et al., 2007 | |
Adsorption of methylene blue | Peel | Pavan et al., 2008a | |
Methylene blue adsorption | Peel | Pavan et al., 2008b | |
Removal of methylene blue and methyl violet | Peel | Lin et al., 2022 | |
Food systems | Flour in drinkable yogurt | Peels and seeds | de Toledo et al., 2018 |
Peel flour in dietary cookies | Peel | Garcia et al., 2020 | |
Peel flour in biscuits | Peels | Weng et al., 2021 | |
Peel flour in cookies | Peel | Sampaio et al., 2022 | |
Dark chocolate | Seeds | Yeo & Thed, 2022 | |
Meat products preservation | Peels | Ramli et al., 2020 | |
Animal feeding | Meat quail | Pulp waste | de Barros Júnior et al., 2020 |
Quail in the laying phase | Waste from pulp extraction | Pereira et al., 2020 | |
Some other valorization aspects | Peel flour: bibliometric analysis | Peel | Florêncio et al., 2020 |
Activated carbon | Seed | de Almeida et al., 2021 | |
Activated carbon for methylene blue removal | Seeds | Vieira et al., 2022 | |
Fe and N dual doped catalyst | Peels | Zhang et al., 2023 | |
Production of solid biofuels by torrefaction | Peel | da Silva et al., 2022 | |
Sunscreen products | Seed | Lourith et al., 2017 | |
UVB-protection | Peels | Fang et al., 2023 | |
Effect of 3% purple passion fruit seed extract cream on facial skin aging | Seed | Muslim et al., 2023 | |
Peel flour in starch bioplastics | Peel | Moro et al., 2017 | |
Biochar | Shell | Hu et al., 2021 | |
Biochar production by microwave-assisted wet co-torrefaction | Shell | Lin & Zheng, 2021 | |
Ratiometric fluorescent molecularly imprinted sensor for tetracycline detection | Peels | Sun et al., 2021 | |
Fat content prediction | Seed | Viyona et al., 2019 | |
Dehydration of thin-layer foods: semiempirical models | Peels | Vega-Castro et al., 2023 | |
Potential use as biomass | Exocarp | Suárez Rivero et al., 2018 | |
Biodiesel from seed oil | Seed | Kariuki et al., 2012 | |
Waste peel as a catalyst for biodiesel production | Peel | Tarigan et al., 2022 | |
Cellulase production to obtain biogas | Peel | Silva et al., 2019 | |
Biochemical evalution | Rinds | Barbalho et al., 2012 | |
Corrosion inhibition | Shell | Fan et al., 2022 | |
Seed oil encapsulation | Seed | Oliveira et al., 2017 | |
Micro-encapsulation of peel powders rich in polyphenols | Peel | Kobo et al., 2022 | |
Pectin as a substrate for the cell growth | Peels and bagasse | Locatelli et al., 2019 | |
Substrate for pigment production | Peel | Silva et al., 2021 |
The largest was the valorization direction (more than two-thirds of the articles cited here), dedicated to the study of the chemical composition of passion fruit waste, the extraction of various compounds from them and the evaluation of their biological activity with the aim of their potential further application as functional components for various industrial purposes. The author is of the opinion that it is completely explainable and understandable that this valorization direction was the most extensive and that the largest number of studies have been devoted to it, because before outlining specific guidelines for practical application and utilization of waste resources, it must first to be determined and known their chemical composition. The presence of various valuable components in passion fruit waste necessitates the development and application of various techniques for their extraction, isolation, as well as determination of their content.
Almost one-tenth of the research focused on the possibilities of using passion fruit waste as adsorbents for the removal of various inorganic and organic pollutants from water. In the works used here, the adsorption mechanisms and the efficiency of the adsorption process with respect to both metal ions and organic dyes presented in various aqueous media were studied and discussed.
The opportunities and challenges of incorporating passion fruit waste components into food systems after appropriate processing was the next area of research. The author of the present review believes that this is a very interesting and promising direction of valorization in which investigations could be intensified.
The number of studies using passion fruit waste in animal feed was surprisingly small. One possible reason for this may lie in the fact that such researches (including non-English-language ones) were indexed in other scientific databases not used in this review.
The areas united here under the term “other valorization aspects” were quite diverse and include the development of activated carbon, biochar, biofuels, etc. In this way, the scope of research on the potential application of passion fruit waste is greatly expanded, and the advantages, effectiveness and challenges of each of the developed and proposed methods are indicated.
As this paper presented only the general framework for the directions regarding the valorization aspects of passion fruit waste, and did not consider in detail one specific area of potential application itself, quantitative data from the individual articles cited here were not compared and commented on.
4. Current and future challenges
The possibilities and prospects for possible valori zation of passion fruit waste for non-food purposes can be seen as a perspective and promising direction. Of particular importance is the creation, development and implementation of easily biodegradable materials from environmentally friendly waste resources, which will significantly reduce the accumulation of fruit waste and limit its harmful environmental impact if it is not managed properly.
The challenges could be deepening the research regarding the possibilities and prospects for the possible use of passion fruit waste in animal nutrition, as well as the inclusion of individual valuable components of these waste resources in food systems. In order to be developed first on a laboratory scale, and at a later stage implemented on a larger scale, such products must be categori cally proven and established to be safe for the health of consumers. This necessitates conducting in-depth intensive interdisciplinary research in the long term. It would be interesting and useful to periodically conduct surveys on consumer awareness of the possible marketing of products containing passion fruit waste components, to study and track consumer attitudes, their propensity and willingness to consume such products, as well as researching user satisfaction and establishing the opinion of consumers about these products after their use.
5. Conclusions
It can be concluded that the numerous intensive studies that were being carried out worldwide, regarding the possibilities of valorization of passion fruit waste, prove in an indisputable way the importance and relevance of the subject considered in the present review. Among the promising areas of potential application could be the creation and development of readily available, affordable, environmentally friendly materials and products for non-food purposes. From the point of view of the development of products with potential application for food purposes, the first priority should be given to the safety of consumers, which should be demonstrated in a clear, definite, indisputable and unequivocal way. Last but not least, after establishing and proving the safety of the products, is to investigate and analyze consumer attitudes regarding their receptivity and propensity to use such products.