| Title: | The conversion of pistachio and walnut shell waste into valuable components with subcritical water |
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| Authors: | ID Čolnik, Maja (Author)
ID Irgolič, Mihael (Author)
ID Perva, Amra (Author)
ID Škerget, Mojca (Author) |
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| Files: |  processes-12-00195.pdf (1,95 MB)
MD5: 88066EB64E587DD72A4F5F893EB2F26E
 https://www.mdpi.com/2227-9717/12/1/195
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| Language: | English |
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| Work type: | Article |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | FKKT - Faculty of Chemistry and Chemical Engineering
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| Abstract: | Pistachio and walnut shells accumulate in large quantities as waste during food processing and represent a promising lignocellulosic biomass for the extraction of valuable components. Subcritical water technology was used as an environmentally friendly technique to study the extraction of active ingredients and other valuable degradation products from walnut and pistachio waste. Subcritical water extraction (SWE) was carried out under different process conditions (temperature (150–300 ◦C) and short reaction times (15–60 min)) and compared with conventional extraction using different organic solvents (acetone, 50% acetone and ethanol). The extracts obtained from pistachio and walnut shell waste are rich in various bioactive and valuable components. The highest contents of total phenols (127.08 mg GA/g extract at 300 ◦C for 15 min, from walnut shells), total flavonoids (10.18 mg QU/g extract at 200 ◦C for 60 min, from pistachio shells), total carbohydrates (602.14 mg TCH/g extract at 200 ◦C for 60 min, from walnut shells) and antioxidant activity (91% at 300 ◦C, for 60 min, from pistachio shells) were determined when the extracts were obtained via subcritical water. High contents of total phenols (up to 86.17 mg GA/g extract) were also determined in the conventional extracts obtained with ethanol. Using the HPLC method, sugars and their valuable derivatives were determined in the extracts, with glucose, fructose, furfurals (5-hydroxymethylfurfural (5-HMF) and furfural) and levulinic acid being the most abundant in the extracts obtained by subcritical water. The results show that subcritical water technology enables better exploitation of biowaste materials than conventional extraction methods with organic solvents, as it provides a higher yields of bioactive components such as phenolic compounds and thus extracts with high antioxidant activity, while at the same time producing degradation products that are valuable secondary raw materials. |
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| Keywords: | pistachio shells, walnut shells, subcritical water extraction, conventional extraction, waste biomass, valuable compounds, sugars, furfurals |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Submitted for review: | 17.12.2023 |
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| Article acceptance date: | 14.01.2024 |
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| Publication date: | 16.01.2024 |
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| Publisher: | MDPI AG |
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| Year of publishing: | 2024 |
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| Number of pages: | 18 str. |
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| Numbering: | Vol. 12, iss. 1, [article no.] 195 |
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| PID: | 20.500.12556/DKUM-93524  |
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| UDC: | 66.02 |
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| ISSN on article: | 2227-9717 |
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| COBISS.SI-ID: | 181523459 |
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| DOI: | 10.3390/pr12010195 |
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| Copyright: | © 2024 by the authors |
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| Publication date in DKUM: | 01.07.2025 |
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| Views: | 166 |
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| Downloads: | 11 |
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| Metadata: |    |
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| Categories: | Misc.
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