2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx
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| date | 2024-02-14 |
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| id | 15342 |
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| internalnotes | Sila masukkan subject wajib Dissertations, Academic. Terima kasih... |
| originalfilename | 15342_f2e6314c20a0f64.pdf |
| person | Abubakar Abdullahi Lema |
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| spelling | 15342 https://intelek.unisza.edu.my/intelek/pages/view.php?ref=15342 https://intelek.unisza.edu.my/intelek/pages/search.php?search=!collection3 General Document Malaysia Library Staff (Top Management) Library Staff (Management) Library Staff (Support) Terengganu Faculty of Bio-resources & Food Industry English application/pdf 1.5 216 Server storage Scanned document Universiti Sultan Zainal Abidin UniSZA Private Access Universiti Sultan Zainal Abidin SAMBox 3.0.10; modified using iTextSharp™ 5.5.10 ©2000-2016 iText Group NV (AGPL-version) 2024-02-14 15342_f2e6314c20a0f64.pdf 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx Hibiscus sabdariffa Roselle Postharvest Deterioration Abubakar Abdullahi Lema Copyright©PWB2025 Roselle (Hibiscus sabdariffa) is a fast-growing shrub and commonly found in Malaysia. It is harvested for its calyx which is known for its high antioxidant and anthocyanin. However, the calyx experiences early postharvest deterioration (PD) inevitably caused by handling, making processing calyces become challenging without diminishing their quality. Anthocyanin confers antioxidative properties and protects against stress but its instability is a persistent issue. This study aimed to determine biochemical changes of roselle calyx during PD, ascertain the influence of various drying techniques on the physicochemical and nutritional value of roselle calyx, isolate and characterize microorganisms linked with PD and characterize anthocyanin as a potential PD biomarker for roselle calyx. PD was induced on freshly harvested roselle calyx. Non- enzymatic antioxidants including total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) were determined. Accordingly, enzymatic antioxidant activities such as catalase (CAT), guaiacol peroxidase (GP), ascorbate peroxidase (APX) and other enzymes were measured. Calyx dried with different drying techniques was subjected to physicochemical and proximate analysis. 16s rRNA and ITS gene sequencing were utilized to identify bacteria and fungi from deteriorated calyx respectively. High performance liquid chromatography (HPLC) was performed to generate profile of anthocyanin and its pH, light, colour and thermal stability were determined. The non-enzymatic and antioxidative enzymes were found to be high at early stage of deterioration and decreased in the later stage. Parallel to TAC which decreased during the deterioration course, TPC also decreased significantly from 487 to 60.9 mg/L GAE/g similarly there is significant decrease in TFC from 213 to 15 mg/ml/QE/g. Also, antioxidative enzyme activities were significantly reduced up to 2 to 30-fold. CAT activity revealed significant decreased from 9.8 to 5.2 mmol/protein/min, GP activity decreased significantly from 18 to 4 µmol/protein/min and APX activity also decreased significantly from 32.61 to 0.95 µmol/protein/min. Freeze-dried (FD) calyx shown to be the best drying method as to have a higher TPC, TAC, ash, fibre and protein content but with lower fat and moisture content than sun- and oven-dried calyx. The contaminated microorganisms were identified as Enterobacter hormaechei, Providencia vermicola, Providencia huaxiensis, Aspergillus uvarum, Meyerozyma guilliemondii and Meyerozyma amylolytica. The microbes did not only contaminate but contributed to secondary deterioration of the calyx. The anthocyanin characterized was cyanidin-3-glucoside and it was found stable at pH 1-4 and in the dark condition. The colour of the extract in the acidic pH remains relatively stable at temperature up to 70 °C. The antioxidative enzymes were expressed as a result of stress-induced degradation and anthocyanin was shown to activate these enzymes. HPLC revealed cyanidine-3-glucoside as the main anthocyanin in roselle calyx and it was shown to be stable at a lower pH and moderately heated condition. Ultimately, this study suggests anthocyanin could be a potential deterioration biomarker and also provides an insight into the biochemical changes during PD in roselle calyx. Dissertations, Academic Sila masukkan subject wajib Dissertations, Academic. Terima kasih... Hibiscus Sabdariffa Thesis |
| spellingShingle | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| state | Terengganu |
| subject | Hibiscus sabdariffa Dissertations, Academic |
| summary | Roselle (Hibiscus sabdariffa) is a fast-growing shrub and commonly found in Malaysia. It is harvested for its calyx which is known for its high antioxidant and anthocyanin. However, the calyx experiences early postharvest deterioration (PD) inevitably caused by handling, making processing calyces become challenging without diminishing their quality. Anthocyanin confers antioxidative properties and protects against stress but its instability is a persistent issue. This study aimed to determine biochemical changes of roselle calyx during PD, ascertain the influence of various drying techniques on the physicochemical and nutritional value of roselle calyx, isolate and characterize microorganisms linked with PD and characterize anthocyanin as a potential PD biomarker for roselle calyx. PD was induced on freshly harvested roselle calyx. Non- enzymatic antioxidants including total phenolic content (TPC), total flavonoid content (TFC) and total anthocyanin content (TAC) were determined. Accordingly, enzymatic antioxidant activities such as catalase (CAT), guaiacol peroxidase (GP), ascorbate peroxidase (APX) and other enzymes were measured. Calyx dried with different drying techniques was subjected to physicochemical and proximate analysis. 16s rRNA and ITS gene sequencing were utilized to identify bacteria and fungi from deteriorated calyx respectively. High performance liquid chromatography (HPLC) was performed to generate profile of anthocyanin and its pH, light, colour and thermal stability were determined. The non-enzymatic and antioxidative enzymes were found to be high at early stage of deterioration and decreased in the later stage. Parallel to TAC which decreased during the deterioration course, TPC also decreased significantly from 487 to 60.9 mg/L GAE/g similarly there is significant decrease in TFC from 213 to 15 mg/ml/QE/g. Also, antioxidative enzyme activities were significantly reduced up to 2 to 30-fold. CAT activity revealed significant decreased from 9.8 to 5.2 mmol/protein/min, GP activity decreased significantly from 18 to 4 µmol/protein/min and APX activity also decreased significantly from 32.61 to 0.95 µmol/protein/min. Freeze-dried (FD) calyx shown to be the best drying method as to have a higher TPC, TAC, ash, fibre and protein content but with lower fat and moisture content than sun- and oven-dried calyx. The contaminated microorganisms were identified as Enterobacter hormaechei, Providencia vermicola, Providencia huaxiensis, Aspergillus uvarum, Meyerozyma guilliemondii and Meyerozyma amylolytica. The microbes did not only contaminate but contributed to secondary deterioration of the calyx. The anthocyanin characterized was cyanidin-3-glucoside and it was found stable at pH 1-4 and in the dark condition. The colour of the extract in the acidic pH remains relatively stable at temperature up to 70 °C. The antioxidative enzymes were expressed as a result of stress-induced degradation and anthocyanin was shown to activate these enzymes. HPLC revealed cyanidine-3-glucoside as the main anthocyanin in roselle calyx and it was shown to be stable at a lower pH and moderately heated condition. Ultimately, this study suggests anthocyanin could be a potential deterioration biomarker and also provides an insight into the biochemical changes during PD in roselle calyx. |
| title | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| title_full | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| title_fullStr | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| title_full_unstemmed | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| title_short | 2024_Effect of Storage Time, pH Temperature and Light on Biochemical and Biomarker Changes to Control Postharvest Deterioration of Roselle (Hibiscus Sabdariffa) Calyx |
| title_sort | 2024_effect of storage time, ph temperature and light on biochemical and biomarker changes to control postharvest deterioration of roselle (hibiscus sabdariffa) calyx |