Risk assessment of aflatoxin B1in ‘egusi’ melon seeds (Citrullus colocynthis)

2018 ◽  
pp. 493-506 ◽  
Author(s):  
M.B. Adeyemo ◽  
L. Jacxsens
2020 ◽  
Vol 19 (2) ◽  
pp. 223-231
Author(s):  
David Morakinyo Sanni ◽  
Catherine Joke Adeseko ◽  
Samuel Olufemi Bamidele

Polyphenol oxidase (PPO) is an enzyme that is responsible for the enzymatic browning of fruits and vegetables. This is generally undesired process and need to be prevented in food technology. PPO from seeds of Citrullus colocynthis was purified, the physicochemical properties such as effects of pH and temperature, substrate specificity, effects of inhibitors and cations on PPO activity and the kinetic parameters for four substrates namely, catechol, L-DOPA, gallic acid and tyrosine, were determined. The purification steps resulted in 41-fold with 10 % yield, and the optima pH and temperature values for PPO from C. colocynthis were found to be pH 7.0 and 60 °C, respectively using catechol as substrate. About 9 % enzyme initial activity was retained after 60 min of incubation at 80 °C, and the apparent molecular weight was determined as 42 kDa by partially denaturing SDS-PAGE. PPO activity was inhibited by ascorbic acid, SDS and certain divalent (Ca2+, Zn2+, Mg2+ and, Fe2+) and monovalent (Na+) metal. Moreover, purified enzyme solution showed diphenolase activity toward catechol, gallic acid, L-DOPA and monophenolase activity toward tyrosine, therefore, tyrosinase was identified as the only one PPO in C. colocynthis seeds. This study revealed the use of temperature above 80 °C to inhibit PPO activity during processing and storage of melon seeds.


2020 ◽  
Vol 47 (4) ◽  
pp. 74-82
Author(s):  
S. O. Olufeko ◽  
A. B. Omojola ◽  
O. A. Ogunwole

Effects of cooking on proximate, phytochemicals and selected vitamins composition of melon and walnut were investigated in this study. Melon Seeds (MS) and Walnut Seed (WS) weighing 500 g each were obtained from open market and each was halved into two. One half o was boiled for one hour and oven dried at 60 C for 48 hours till constant weight was attained to obtain treated melon seed and treated walnut seed, respectively. The other halves were left un-cooked and were labelled uncooked melon seed and uncooked walnut seed, respectively. In MS, cooking reduced the crude protein, crude fibre and ash compositions but increased the moisture and ether extracts contents significantly (p<0.05). In WS, cooking reduced the crude protein and crude fibre but increased the ether extracts and moisture significantly (p<0.05) without any effect on ash contents (p>0.05). Aside from flavonoids which increased (p<0.05), other phytochemicals in MS were significantly reduced by cooking (p<0.05). Also, there were reduced tannins, steroids, terpenoids and alkaloids. The phytates and flavonoids increased significantly (p<0.05) while saponins composition remained significantly unaffected (p>0.05) by cooking. Ascorbic acid and tocopherol in MS as well as â-carotene and ergosterol contents were not affected significantly (p>0.05) by cooking. However, the â-carotene of 0.16 and ergosterol of 0.57 in raw MS reduced significantly (p<0.05) to 0.13 and 0.25 mg/kg, respectively by cooking. Also, tocopherol and ascorbic acid with respective values of 69.40 and 4.41 mg/kg in WS were lowered significantly (p<0.05) by cooking to 58.65 and 3.95 mg/kg, respectively. Processing reduced antinutrients in melon and walnut seeds and improve their nutrient sources.


Author(s):  
Cajethan U. Ugwuoke ◽  
Agatha A. Asogwa ◽  
Chinyere R. Okwo ◽  
Francis M. Onu ◽  
Godwin E. Eze ◽  
...  

Background: Egusi melon production is declining, even though the crop plays a significant role in the well-being of farmers. Few farmers that grow the crop do not allow adequate spacing and seed rate which compels the crop to produce flourishing vegetative parts without producing many fruits. The study was therefore, aimed at determining the effect of planting distance and seed rate on the growth and yield of egusi melon. Methods: A split-plot design which was replicated thrice was adopted to carry out the study during 2018 and 2019 planting seasons. Twenty-four plots were made and were randomly assigned to eight treatment groups with each replicating thrice. The egusi melon seeds were sown in four different seed rates of one seed/hole, two seeds/hole, three seeds/hole and four seeds/hole and four different spacing of 30cm × 50cm, 45cm × 70cm, 60cm × 60cm and 60cm × 90cm respectively. Analysis of variance was used to analyze the data collected and was tested at 0.05 level of probability. Result: The number of leaves/plant, branches/plant, flowers/plant, fruits/plant and fruit weight (g) were significantly higher in egusi melon planted at 60cm × 90cm. Furthermore, the parameters measured were significantly higher in egusi melon planted at 1 seed/hole. 


Author(s):  
Chuku, E. C ◽  
Chika, B ◽  
Nmom, F. W

Antifungal property of A. paniculata on fungal isolates from Citrullus colocynthis was investigated. Citrullus colocynthis were bought from traders in a major market in Abia State, Nigeria. The melon seeds were first cleaned and disinfested by keeping them in a freezer at -50C for 7 days to kill all hidden infestations. The disinfested seeds were dried in a Gallenkamp oven at 40oC for 4 hours before they were stored in plastic sterile containers with tight lids. Fresh plant of A. paniculata was collected from botanical garden of the Rivers State University and was identified in the botany department. The leaves of the plant were shade dried and blended into fine powder. Twenty grams (20g) of the powdered leaves was extracted using methanol and ethanol. The filtrate was evaporated and the resulting crude extract was used for antifungal sensitivity test. Fungi associated with rotted C. colocynthis were identified using standard microbiological methods. The antifungal activity of the extracts was carried out using the well in agar diffusion method. In this method, 48 hours old fungal isolate was inoculated on dried Sabouraud Dextrose Agar plates in duplicates. five wells were bored using sterile 6mm cork borer on the dried seeded plates before 0.2ml of the different concentrations of 100, 50, 25, and 12.5mg/ml of the methanol extracts were transferred into the wells using sterile pipettes. Aspergillus flavus, Rhizopus arrhizus, Aspergillus niger, Rhizopus sp and Mucor sp were identified from the melon seeds. The zone diameters of methanolic extract of A. paniculata on Rhizopus arrhizus, A. niger, A. flavus, Rhizopus sp and Mucor sp were 11.50±0.71, 19.50±0.71, 34.50±0.71, 15.00±0.00 and 17.00±0.00mm, respectively. The zone diameters of ethanolic extract of A. paniculata on Rhizopus arrhizus, A. niger, A. flavus, Rhizopus sp and Mucor sp were 0.00±0.00, 16.50±0.71, 34.50±0.71, 20.50±0.71 and 0.00±0.00mm, respectively. There were significant differences (P ≤ 0.05) in the antifungal activity of the extract across the fungal isolates. The antifungal activity of the leave extracts showed that the ethanolic extract and the methanolic extract were very active on the fungal isolates and the antifungal activities of the extract was greatly influenced by the concentration of the extract, with higher concentrations of extract having high zone diameter.


1998 ◽  
Vol 62 (10) ◽  
pp. 756-761 ◽  
Author(s):  
CW Douglass
Keyword(s):  

2006 ◽  
Vol 175 (4S) ◽  
pp. 531-532
Author(s):  
Matthew R. Cooperberg ◽  
Stephen J. Freedland ◽  
David J. Pasta ◽  
Eric P. Elkin ◽  
Joseph C. Presti ◽  
...  

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