Document Details
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Document Type |
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Thesis |
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Document Title |
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Development and assessment of functional chitosan-based edible coatings to maintain shelf life quality of banana fruit تطوير وتقييم أغلفة قابلة للأكل معتمدة على الكيتوزان للحفاظ على جودة ثمار الموز خلال فترة العرض |
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Subject |
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Faculty of Meteorology, Environment and Arid Land Agriculture |
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Document Language |
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Arabic |
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Abstract |
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Bananas are among few fresh fruit that are available to the consumers throughout the year worldwide and considered as functional fruit due to their high nutritional and healthiness properties. However, the climacteric nature of bananas leads to rapid ripening process, quality deteriorate and a relatively shorter shelf life (SL) at ambient conditions following harvest and ethylene treatment. The ultimate aim of the production, handling and distribution of fresh fruit is to satisfy consumers need. To maintain quality and extend the SL of post-climacteric bananas, several experiments were conducted to evaluate the effects of some natural edible coat formulations based on chitosan (CT) solution alone or loaded with natural antioxidant compounds on regular quality attributes, antioxidant compounds, free radical scavenging capacity (FRSC) (DPPH IC50 value) and antioxidant and hydrolytic enzymes activities of two bananas cultivars during ripening at SL conditions (20 ± 2 ºC and 60-70% RH). First experiment was carried out to evaluate the effect of dipping treatments in CT at 0.15 and 1%, gallic acid (GA) at 0.075 and 0.15%, and CT/GA formulation (equal volumes of 2.0% CT and 1.0% GA solutions were mixed) at 25, 50 and 75 ml l on Sukkari bananas during 13 days of SL. The results of this study showed that weight loss, peel color index in most of the treatments, total soluble solids (TSS) concentration, TSS/acid ratio, and FRSC of fruit peel increased while, membrane stability index (MSI) of peel tissues, pulp firmness, and titratable acidity (TAC), total phenols (TPC), total flavonoids (TFC) and vitamin C concentrations decreased during SL. As overall, all rates of CT/GA and GA decreased weight loss and maintained higher pulp firmness than control during SL. CT/GA delayed ripening as reflected by lower peel color index especially at medium and high rates and showed higher MSI at all rates after 6 and 13 days of SL. All treatments of CT, GA and CT/GA showed lower TSS than control. TAC was higher at high rates of CT, GA and CT/GA treatments than control. TSS/acid ratio was lower at high rate of CT, low rate of GA and at all rates of CT/GA than control. High rates of CT and GA, and medium and high rates of CT/GA retained higher TPC than control. While, TFC, vitamin C and FRSC of fruit peel were not affected by the applied treatments. α-amylase activity showed higher values during SL compared to initial and was not affected by the applied treatments. Xylanase, polygalacturornase (PG) and polyphenoloxidase (PPO) activities were higher after 6 than 13 days of SL while, peroxidase (POD) activity was higher after 13 than 6 days of SL. Low rate of CT, high rate of GA and medium rate of CT/GA lowered xylanase activity than control. All treatments, except for high rate of CT/GA, lowered PG activity compared to control. CT at high rate showed higher POD activity than control only after 13 days of SL, while GA at both rates lowered POD activity during SL. CT and GA at high rates and CT/GA at low and medium rates lowered PPO activity after 6 days while, GA and CT/GA at all rates showed higher activity of this enzyme after 13 days of SL. In the current study, an experiment was conducted on Grand Nain bananas to evaluate the effect of postharvest dipping treatments in CT at 0.25 and 1% alone or CT at 0.25% loaded with trans-resveratrol (TR) (CT/TR) at 0.00183 and 0.00365%, or tannic acid (TA) (CT/TA) at 0.25 and 0.5% on quality and biochemical changes during 7 days of SL. Weight loss, peel color and browning indices, in most treatments, increased while, MSI of peel tissue, pulp firmness, b* and chroma values decreased during SL. TSS concentration increased until day 5 and then decreased afterwards but showed much higher values than initial. TAC and L* values, in most treatments, were lower at day 7 than day 2 while, TSS/acid ratio and a* values was higher, in most treatments, at day 7 than day 2 during SL. pH remained stable until day 5 then increased afterwards. Vitamin C of pulp and TPC, TFC, FRSC and enzyme activity both in peel and pulp greatly varied during SL. CT at low rate showed lower PPO activity both in peel and pulp and higher PG activity in peel than control. However, CT at high rate showed lower peel color, b* values and PPO activity both in peel and pulp and higher MSI, TAC, pulp TPC, peel PG activity and pulp POD activity than control. CT/TR at low rate showed higher MSI, peel TFC and pulp TPC and lower pulp FRSC, pulp xylanase activity and PPO activity both in peel and pulp than control. However, CT/TR at high rate delayed ripening (especially until day 5) as indicated by lower peel color index, higher pulp TPC, TFC both in peel and pulp and peel POD activity and lower peel PPO, pulp xylanase and PG activities than control. CT/TA at low rate showed lower vitamin C concentration, pulp FRSC and PG and xylanase activity in pulp and higher pH, MSI, TFC both in peel and pulp, pulp TPC and peel POD activities than control. CT/TA at high rate delayed ripening as reflected by lower color index, higher pH, pulp TPC, peel TFC and peel POD activity as well as lower PPO both in peel and pulp and pulp PG activities than control. Scan electronic microscopy (SEM) images after 3 days of SL revealed that control treatment showed irregular and compact morphology while, CT at low rate showed regular morphology with reduced porous coat. However, SEM image of CT at high rate showed more rough morphology coat with appearance of CT agglomerates. SEM images of CT/TR and CT/TA both at high rates showed less porous with smooth morphology compared to other treatments. Additional experiment was conducted to investigate the response of ‘Grand Nain’ bananas to postharvest dipping treatments in CT at 0.25 and 1%, CT at 0.25% loaded with γ-aminobutyric acid (GABA) (CT/GABA) at 0.103 and 0.206%, or ascorbic acid (ASA) (CT/ASA) at 1 and 2%. Weight loss, peel color index, and browning index, TSS/acid ratio, a* values and TPC both in peel and pulp, in most treatments, increased while, pulp firmness, TAC, L* and b* values and MSI, chroma and PPO activity in peel, in most treatments, decreased during SL. TSS increased until day five then decreased afterwards. pH, vitamin C concentration and peel xylanase activity remained relatively stable, in most treatments, during SL. FRSC and α-amylase activity both in peel and pulp and xylanase activity in pulp were lower, in most treatments, at day 7 than day 2, while PG and POD activities both in peel and pulp were higher, in most treatments, at day 7 than day 2 during SL. CT at low rate showed higher TAC and PG activity in peel and lower PPO activity both in peel and pulp than control. However, CT at high rate showed lower L*, b* values and PPO activity both in peel and pulp and higher MSI, TAC, pulp TPC and PG activity in peel than control. CT/GABA at low rate showed higher pulp TPC and peel TFC and lower FRSC in pulp, PPO and xylanase activities both in peel and pulp and PG activity in pulp than control. However, CT/GABA at high rate showed higher TFC both in peel and pulp and TPC in pulp and lower L*, a* values, FRSC in pulp and PPO activity in peel than control. CT/ASA at low rate showed higher MSI and peel TFC and lower L* and a* values, PG and PPO activity both in peel and pulp than control. However, CT/ASA at high rate showed higher TAC, TFC both in peel and pulp and POD in peel and lower peel color, L* values, and PG and PPO activity in pulp than control. According to the SEM images of edible coat formed on fruit surface after 3 days of SL, CT at low rate showed regular morphology with small porosity compared to control in which irregular morphology was observed. While, increasing CT level from 0.25 to 1% lead to formation of rougher coat with agglomerated CT. CT/GABA at high rate showed voids, cracks and shrinkage morphology with small porous size whereas, CT/ASA at high rate revealed the formation of coat with small porous size morphology without voids and cracks. As overall, Sukkari seems to be better storable than Grand Nain bananas as it retained more green color, and higher firmness, MSI, acidity, vitamin C and FRSC but, lower TFC and TPC than Grand Nain after 5 to 6 days of SL. It is noticed that, the color stage 5 was reached after 5 to 6 days in both cultivars at which quality attributes such as TSS, acidity and firmness where at the acceptable level for fruit consumption with still recognizable level of antioxidant compounds. In conclusion, CT/GA at medium or high rates retained more green color, firmness, MSI and TPC, and decreased weight loss, TSS and PG activity of Sukkari bananas during 6 days of SL compared to control and could be recommended to extend SL of bananas. With the respect of Grand Nain bananas, high rates of CT/TR, CT/TA and CT/ASA treatments delayed ripening and maintained better quality until 5 days of SL than control. However, the incorporation of TR or TA, GABA or ASA in CT matrix at the used concentrations showed unexpectedly relatively less efficiency in delaying ripening and maintaining quality of Grand Nain bananas. Incorporation of such antioxidant compounds at higher concentrations in the CT matrix are suggested for future studies. Such information might be beneficial for postharvest technologist, nutritionists and consumers. |
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Supervisor |
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Prof. Dr. Mohamed A. Awad |
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Thesis Type |
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Doctorate Thesis |
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Publishing Year |
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1440 AH
2019 AD |
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Co-Supervisor |
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Prof. Dr. Adel D. Al-Qurashi |
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Added Date |
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Tuesday, January 29, 2019 |
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Researchers
| مد عرفان علي | Ali, Md Arfan | Researcher | Doctorate | |
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