The aim of this study is to determine fungal infestation of onion bulbs during storage in sack and on its antioxidant properties.
The fungal infestation of onion bulbs during storage in sack shows that five fungi each were isolated from the onion bulbs during storage in sack at day zero and day seven respectively while at day fourteen, six fungal infestations were isolated from the onion bulbs during storage in sack. A total of sixteen fungi infested the onion bulbs during storage in sack. The fungi belong to four genera and six species of fungi infested the onion bulbs during storage in sack.
Aspersillus niger and Aspersillus flavus were the most frequently isolated fungi with 31.25% each followed by Fusarium oxysporum and Aspergillus fumigatus with 12.50% each while Penicillium chrysogenum and Rhizopus stolonifer recorded 6.25% each. The antioxidant analysis of onion extract after storage in sack for 14 days recorded at all concentrations, show that the antioxidant property of the onion extract at day zero and day 7 was higher than that of 14. The inhibition of free radical DPPH at day zero and 7 were 29.92 %, 49.21%, 69.29%, 70.07% and 47.63% while at day 14, the percentage (%) of inhibition of free radical DPPH were 29.33 %, 49.02%, 69.01%, 69.77% and 47.21%.
Healthy, undamaged onion bulbs which have been dried in the field should be stored in dry, well ventilated stores. This will reduce growth and development of fungal pathogens and minimize storage rots. Therefore, A. cepa and its constituents could be of therapeutic value in disorders such as aging, anti-inflammatory, and wound healing processes where radical scavenging activity can be of therapeutic value.
Table of Contents
1.0 Introduction
1.1 Background of the Study
1.2 Aim of the Study
1.3 Objectives of the Study
2.0 Literature Review
2.1 Uses of Allium cepa
2.2 Post-harvest losses in onion
2.3 Microorganisms Associated with Onion Spoilage in Nigeria
2.4 Antioxidant effects of A. cepa
2.5 Antimicrobial activity
3.0 Materials and Methods
3.1 Study Area
3.2 Materials used and Sterilization
3.3 Collection of Samples
3.4 Storage of Onion Bulb in Sack Bag
3.5 Preparation and sterilization of media
3.6 Assessment of Fungal Infestation of the Onion bulb during Storage
3.6.1 Preparation of pure cultures of fungal isolates
3.7 Identification of fungal isolates
3.8 Determination of Frequency of Occurrence of Fungal Isolates
3.9 Preparation of Onion Extract
3.10 Determination of antioxidant Properties of Onion
3.10.1 DPPH Free radical scavenging assay
3.10.2 Measurement of reducing power of the crude extracts of Onion Bulb
3.10.3 Determination of antioxidant activity of crude extracts of the Onion
3.11 Statistical Analysis
4.0 Results
4.1 Fungal Infestation of Onion Bulbs during Storage in Sack
4.2 Frequency and Percentages of Fungal Infestation of Onion Bulbs
4.3 DPPH radical scavenging activity of Fungal Infested Onion Bulbs during Storage in Sack
5.0 Discussions and Conclusion
5.1 Discussions
5.2 Conclusion
5.3 Recommendation
Research Objectives and Core Themes
This study investigates the fungal infestation of onion bulbs stored in sacks over a 14-day period and evaluates how these infestations influence the antioxidant properties of the onions. The research aims to identify prevailing storage-associated fungal pathogens and determine their impact on the nutritional quality, specifically the free radical scavenging potential of the bulb extracts.
- Identification of fungal species infesting onion bulbs during sack storage.
- Evaluation of fungal load and infestation frequency over time.
- Analysis of the antioxidant capacity of onion extracts using DPPH assays.
- Assessment of the correlation between storage duration and antioxidant degradation.
Excerpt from the Book
1.1 Background of the Study
The onion (Allium cepa L.) is an important vegetable crop in Nigeria based on consumption and economic value to farmers. The crop is grown for its bulbs which are used daily in every home for seasoning and flavouring of foods. Onion is a valuable ingredient in the diet due to its content of sugars, vitamins and minerals (Ole et al., 2014). The crop is grown mainly in the north, during the dry season (October to April). The onion farmers in Nigeria almost always store, their onions after harvest for one to five months to ensure a continual supply through seasons when fresh produce is unavailable. Bulb rots are a common cause of onion loss during storage.
Fungi, especially moulds are important pathogens of fruits and a vegetables particularly under tropical and sub-tropical conditions (Adebayo and Diyaolu, 2013). The importance of storage rots includes reduction in the quantity and quality of onion which affects the market value (Dogondaji et al., 2015). Other important consequence often overlooked, is mycotoxin contamination of the affected material (Muhammad et al., 2014).
Biological effects attributed to onions have been commonly ascribed to the volatile sulfur-containing compounds, such as thiosulfinates, mainly responsible for the characteristic taste, aroma and lachrymatory effects (Krest et al., 2012). These compounds are formed from cysteine sulfoxide precursors and the effect of the enzyme alliinase which is released from cell vacuoles when tissues are damaged (Ioku et al., 2011). However, these volatile products are highly unstable and recently, attention has been focused on the effects of phenolic compounds, such as flavonoids, which are more stable (Fossen et al., 2011). Onion is known for being a good natural source of
Summary of Chapters
1.0 Introduction: Provides an overview of the agricultural and economic importance of onions in Nigeria, while highlighting the significant post-harvest challenges posed by fungal bulb rot.
2.0 Literature Review: Explores existing knowledge regarding the medicinal and nutritional benefits of Allium cepa, common storage methods, and the specific microbial agents responsible for spoilage.
3.0 Materials and Methods: Details the experimental design, including sample collection, microbiological techniques for fungal isolation, and analytical procedures for assessing antioxidant activity.
4.0 Results: Presents the primary data concerning the identification of fungal isolates found on stored onions and the corresponding quantitative findings from the DPPH antioxidant assays.
5.0 Discussions and Conclusion: Interprets the experimental outcomes, relates them to existing scientific literature, and provides final conclusions along with recommendations for minimizing storage losses.
Keywords
Allium cepa, Fungal infestation, Storage rot, Antioxidant properties, DPPH assay, Phenolic compounds, Aspergillus niger, Post-harvest loss, Food security, Mycotoxins, Fungal pathogens, Sack storage, Nigeria, Phytochemicals.
Frequently Asked Questions
What is the primary focus of this research study?
The study investigates the impact of post-harvest storage (specifically in sacks) on fungal infestation of onion bulbs and evaluates the resulting changes in their antioxidant properties.
Which key fungi species were identified in this study?
The research identified several fungi, most notably Aspergillus niger and Aspergillus flavus, which showed the highest frequency of occurrence, as well as Fusarium oxysporum, Aspergillus fumigatus, and Penicillium chrysogenum.
What is the main research question or goal?
The primary goal is to determine the extent of fungal infestation on stored onion bulbs and assess whether these infestations significantly diminish the beneficial antioxidant capacity of the onions over a 14-day storage period.
What scientific methods were employed to achieve these objectives?
The study utilized standard microbiological methods such as the blotter technique for isolating fungi and established chemical analysis protocols like the DPPH radical scavenging assay to measure antioxidant activity.
What does the main body of the research address?
The main body covers the identification and quantification of fungal pathogens, followed by a comparative analysis of the antioxidant inhibitory percentages of onion extracts taken at day zero, seven, and fourteen of storage.
Which keywords define the core themes of this work?
Common themes include Allium cepa, Fungal infestation, Post-harvest loss, Antioxidant properties, and specific storage management practices.
How does storage time affect the antioxidant properties of the onions?
The results indicate that the antioxidant properties of onion extracts were higher at day zero and day seven compared to day fourteen, suggesting that prolonged storage and increased fungal infestation negatively correlate with antioxidant efficacy.
Are the findings of this study consistent with global agricultural research on onions?
Yes, the findings support existing global reports stating that fungal pathogens are a major cause of post-harvest deterioration in stored vegetables and underscore the necessity of improved storage conditions to preserve nutritional quality.
- Arbeit zitieren
- Bamidele Ijigbade (Autor:in), 2022, Fungal infestation of onion bulbs during storage in sack and on its antioxidant properties, München, GRIN Verlag, https://www.grin.com/document/1312514
