Browsing by Author "Tlehema Gwandu Umbayda"

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Chitosan enriched with ZnO–nanoparticles fabricated using Synadenium glaucescens (Pax) aqueous leaf extract maintains postharvest quality of banana
(Applied Food Research, 2024-09) Alinanuswe Joel Mwakalesi; Tlehema Gwandu Umbayda
Applications of edible coatings containing metallic nanoparticles for the preservation of post-harvest fruit quality have emerged as one of the most preferable strategies because of their enhanced antimicrobial properties. In the current study, zinc oxide nanoparticles were synthesized using Synadenium glaucescens leaf extract and added to chitosan for the post-harvest quality preservation of banana. The synthesized zinc oxide nanoparticles (ZnO- SydlNPs) were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), elemental dispersive x-ray (EDX) and X-ray diffraction (XRD) techniques. The nanoparticles were found to form large particles due to aggregations of small particles of an average size of 11 ± 4 nm. The coating so- lution containing a mixture of chitosan and zinc oxide nanoparticles exhibited higher antimicrobial effects against Escherichia coli, Staphylococcus aureus, Puccinia asparagi and Candida albicans compared to chitosan. The inhibition diameters of chitosan and chitosan-ZnOSydlNPs against E. coli were 6 and 15 mm, respectively. Similarly, the average inhibition diameters of chitosan, chitosan-ZnOSydlNPs (0.1%) and chitosan-ZnOSydlNPs (0.3%) against Staphylococcus aureus, Puccinia asparagi and Candida albicans were 10 ± 2, 15 ± 0.5 and 16 ± 3 mm, respectively. The banana coated with chitosan-ZnOSydlNPs solutions exhibited higher titratable acid (maleic) than control and chitosan-coated samples. Additionally, banana coated with chitosan-ZnOSydlNPs lms showed lower total soluble solids, weight loss and ripening index compared to chitosan-coated and control samples. The ndings from the current study indicated that ZnOSydlNPs incorporated in polymeric materials (chitosan) could serve as a potential preservative of post-harvest qualities for banana and related fruits.
Novel edible coating based on Macadamia Nut oil and chitosan to maintain the antioxidant and physical properties of tomato fruits
(Applied Food Research, 2024-06) Tlehema Gwandu Umbayda; Anthony Daniel Funga; Alinanuswe Joel Mwakalesi
Innovative approaches for extending the shelf life of tomatoes are required due to increased postharvest losses of climacteric-fruits. The use of edible coatings is recently considered as a promising approach due to their non- toxicity and affordability properties. The coatings form physical barriers that alter the internal atmosphere of the fruit and slow down a ripening process. The inuence of an edible coating comprising of chitosan and macadamia nut oil on the antioxidant and physical properties of tomato fruits is reported. The antioxidant and physical qualities of tomato fruits were investigated using different coating solutions. Various concentrations of macadamia nut oil, ranging from 1 % to 2.5 %, were used as independent coating solutions. Additionally, another set of coating solutions was prepared by mixing macadamia nut oil in the same concentration range (1 % to 2.5 %) with 1 % w/v chitosan. The tomatoes were dipped into the coating solutions and stored under a post- harvest shed (23.8–30 ◦ C, 65.8–97.5 % RH) for 20 days to monitor total phenolic content, total avonoid con- tent, ascorbic acid content, color, percentage weight loss, decay percentage, and shelf life after every 5-days interval. The results showed a signicant difference (P < 0.05) between coated and uncoated tomato samples. The coated tomatoes showed the signicant retention of total avonoid content, total phenolic content, hue angle and red-green (a*) compared to uncoated tomatoes. On contrast, the decrease of decay, weight loss, the lightness (L), blue-yellow (b*), chroma, and ascorbic acid content was lower for coated compared to control tomatoes. The ndings indicated that 1 % macadamia nut oil exhibited the highest retention of antioxidant and physical properties, and lowest decrease in ascorbic acid content from 0.014 mg/100 g on the 5th day to 0.0096 mg/100 g on the 20th day was observed. Thus, the ndings from this study suggest that the macadamia nuts can serve as a cheap and low-cost source of edible oil suitable for prolonging the shelf life of tomatoes and related fruits.
Synergistic effect of macadamia nut oil and Chitosan coatings on physicochemical characteristics of tomatoes during storage
(John Wiley & Sons Ltd, 2025-10) Tlehema Gwandu Umbayda; Anthony Daniel Funga; Alinanuswe Joel Mwakalesi
A signicant portion o globally produced ruits are lost between the armer and consumer, necessitating solutions like natural edible coatings or preservation due to their low cost and less toxicity. Tis study aimed to assess whether the combination o macadamia nut oil and chitosan posed synergistic eects on physicochemical properties o tomato ruits or the macadamia nut oil alone. A completely randomized design (CRD) with eight treatments was employed: S1 (control), S2–S4 (combined macadamia nut oil and chitosan coating), S5–S7 (macadamia nut oil coating), and S8 (chitosan). Te experimental setup was conducted over 20 days at rerigeration (4°C) and postharvest shed conditions (23.8°C–30°C, 65.8%–97.5% RH). Te coating solution made up o a combination o 2.5% v/v macadamia nut oil and 1% w/v chitosan showed signicant dierences (p ≤ 0.05) in slowing down the changes in pH rom 3.95 to 4.3, total chlorophyll content rom 0.19 mg/100 to 0.12 mg/100 mL, and lipid peroxidation rom 13.5 to 19.71 meq/kg. Moreover, coating solutions made by macadamia nut oil alone, especially with 1% v/v, showed the smallest increases in total soluble solids (SS) and total sugar content, and also they exhibited the smallest decreases in titratable acidity (0.64 to 0.08 g/L), ripening index (5.78 to 84.74), total carotenoids (17.02 to 24.585 μg/g), and rmness (355 N to 130 N). Comparative analysis indicated that 1% v/v macadamia nut oil had higher mean dierences (p < 0.05) or most physicochemical parameters than coating solutions comprising 2.5% v/v macadamia nut oil and 1% w/v chitosan. However, this nding highlighted that the combination o macadamia nut oil with chitosan oers a synergistic eect on specic crucial parameters (pH, total chlorophyll content, and lipid peroxidation) compared to macadamia nut oil alone. Further studies could investigate the an- timicrobial eect o tomatoes treated with a combination o macadamia nut oil and chitosan.