Browsing by Author "Kawhena, Tatenda Gift"

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    Application of dynamic controlled atmosphere technologies to reduce incidence of physiological disorders and maintain quality of 'Granny Smith' apples
    (MDPI, 2021-05-26) Kawhena, Tatenda Gift; Fawole, Olaniyi Amos; Opara, Umezuruike Linus
    The efficacy of dynamic controlled atmosphere technologies; repeated low oxygen stress (RLOS) and dynamic controlled atmosphere-chlorophyll fluorescence (DCA-CF) to control superficial scald development on ‘Granny Smith’ apples during long-term storage was studied. Fruit were stored for 2, 4, 6, 8, and 10 months at 0 °C in DCA-CF (0.6% O2 and 0.8% CO2), regular atmosphere (RA)(≈21% O2 and 90–95% RH), and RLOS treatments: (1) 0.5% O2 for 10 d followed by ultra-low oxygen (ULO) (0.9% O2 and 0.8% CO2) for 21 d and 0.5% O2 for 7 d or (2) 0.5% O2 for 10 d followed by controlled atmosphere (CA) (1.5% O2 and 1% CO2) for 21 d and 0.5% O2 for 7 d. Development of superficial scald was inhibited for up to 10 months and 7 d shelf life (20 °C) under RLOS + ULO and DCA-CF treatments. Apples stored in RLOS + ULO, RLOS + CA, and DCA-CF had significantly (p < 0.05) higher flesh firmness and total soluble solids. The RLOS phases applied with CA or ULO and DCA-CF storage reduced the development of superficial scald by possibly suppressing the oxidation of volatiles implicated in superficial scald development.
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    Application of gum arabic and methyl cellulose coatings enriched with thyme oil to maintain quality and extend shelf life of “Acco” pomegranate arils
    (MDPI, 2020-12-01) Kawhena, Tatenda Gift; Tsige, Alemayehu Ambaw; Opara, Umezuruike Linus; Fawole, Olaniyi Amos
    The effects of gum arabic (GA; 1.5% w/v) and methyl cellulose (MC; 1% w/v) enriched with thyme oil (TO; 0.25 and 0.5% v/v) on the quality of “Acco” pomegranate arils were studied. Coating treatments, namely, MC, MC + TO0.5%, MC + TO0.25%, GA, GA + TO0.5% and GA + TO0.25% were applied on arils by dipping, and evaluations were made on physicochemical and microbiological quality, phytochemicals and antioxidant capacity of arils stored (5 ± 1 ◦C, 95 ± 2% RH) for 16 days. Dipping arils in GA or MC, both containing TO (0.5% v/v) significantly (p < 0.0001) reduced weight loss and enhanced antioxidant activity (FRAP) (p = 0.0014). However, dipping arils in GA combined with TO (0.25% v/v) had the highest influence on reducing aril respiration rate compared with other treatments. Overall, results showed that application of coatings (GA + TO0.5% and GA + TO0.25%) reduced total yeast and mould and total plate counts and maintained quality up to 8 days of storage. These findings suggest that either GA + TO0.5% or GA + TO0.25% coatings have the capability to extend storage life of “Acco” pomegranate arils.
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    Formulation and application of novel bioactive edible coatings to extend storage and shelf life of pomegranate whole fruit and arils
    (Stellenbosch : Stellenbosch University, 2022-12) Kawhena, Tatenda Gift; Opara, Umezuruike Linus; Fawole, Olaniyi Amos; Tsige, Alemayehu Ambaw; Stellenbosch University. Faculty of Agrisciences. Dept. of Horticulture.
    ENGLISH ABSTRACT: The growth of the pomegranate (Punica granatum L.) fruit industry is limited by high postharvest losses along the supply chain caused by weight loss and incidence of physiological and pathological disorders. Although several postharvest technologies have been applied to reduce these losses, substantial losses still occur, causing negative financial impact on all pomegranate industry stakeholders. Therefore, the development and application of new science-based technologies to reduce postharvest losses in pomegranate fruit is a priority. The overall aim of this research study was to formulate bioactive edible coatings for pomegranate whole fruit and arils to extend storage and shelf life. In Section I, Paper 1 and Paper 2 highlighted the potential of edible coatings as a postharvest treatment for pomegranate fruit during cold storage and shelf life. Section II studies (Paper 3 and 4) applied gum Arabic and methyl cellulose coatings enriched with either thyme or lemongrass essential oils on pomegranate whole fruit and arils. Gum Arabic (1.5% w/v) coatings combined with thyme oil (0.25 or 0.5% w/v) significantly (p ≤ 0.05) reduced weight loss, microbial proliferation and maintained postharvest quality of arils for 8 days of storage (5 ⁰C and 95 ± 2% relative humidity). Similarly, gum Arabic (1.5% w/v) coating containing pomegranate peel extract (1% w/v) and lemongrass essential oil (0.1% v/v) significantly (p ≤ 0.05) reduced respiration rate and incidence of decay for 6 weeks of storage (5 ± 1 °C and 90% relative humidity). Section III (Paper 5 and 6) followed up on the results in Section II by optimizing selected coatings developed in Paper 3 and 4. In Paper 5, lemongrass essential oil was the best antifungal agent against tested microbes (Botrytis cinerea and Penicillium spp.) and the minimum inhibitory concentrations against Botrytis cinerea and Penicillium spp., were 1.5 (% v/v) and 3 (% v/v), respectively. Sodium alginate and chitosan-based coatings formulated with lemongrass essential oil (1.5 or 3% v/v) completely inhibited spore germination and reduced the decay severity of ‘Wonderful’ pomegranate during shelf life. In Paper 6, response surface methodology was used to develop an optimized coating containing gum Arabic (0.5% w/v), maize starch (0.5% w/v), lemongrass oil (3% v/v), and glycerol (1.5% v/v). In Section IV (Paper 7 and 8), the optimized coating developed in Section III was applied on whole ‘Wonderful’ pomegranate fruit and the moisture loss characteristics (Paper 7) and the effects when combined with different polyliners (Paper 8) were investigated. The optimized coating significantly (p ≤ 0.05) reduced weight loss by minimizing the rate of increase in transpiration rate. In Paper 8, the combination of coatings with Xtend® polyliners was the most effective treatment to maintain the quality of ‘Wonderful’ pomegranates during storage (5 ± 1 °C and 95 ± 2% relative humidity). Overall, this research showed that edible coatings minimized postharvest losses in pomegranate whole fruit and arils. The study provides important scientific information to assist prospective studies to develop edible coatings for other fruit types for future application at packhouse level and other food industries.
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    Optimization of gum arabic and starch-based edible coatings with lemongrass oil using response surface methodology for improving postharvest quality of whole “wonderful” pomegranate fruit
    (MDPI, 2021-04-12) Kawhena, Tatenda Gift; Opara, Umezuruike Linus; Fawole, Olaniyi Amos
    The effects of edible coatings based on gum arabic (GA) (0.5–1.5%), maize starch (MS) (0.5–1.5%), lemongrass oil (LO) (2–4%), and glycerol (GC) (0.5–1%) developed using response surface methodology (RSM) on “Wonderful” pomegranate fruit were studied. After 42 days of storage (5 1 C, 95 2% RH) and 5 days at ambient temperature (20 0.2 C and 60 10% RH), whole fruit were evaluated for weight loss (%) and pomegranate juice (PJ) for total soluble solids ( Brix), titratable acidity (% Citric acid), and antioxidant capacity. The optimization procedure was done using RSM and the response variables were mainly influenced by the concentrations of MS and GA. The optimized coating consisted of GA (0.5%), MS (0.5%), LO (3%), and GC (1.5%) with desirability of 0.614 (0—minimum and 1—maximum). The predicted values of response variables, for the coating were weight loss (%) = 5.51, TSS ( Brix) = 16.45, TA (% Citric acid) = 1.50, and antioxidant capacity (RSA = 58.13 mM AAE/mL PJ and FRAP = 40.03 mM TE/mL PJ). Therefore, the optimized coating formulation is a potential postharvest treatment for “Wonderful” pomegranate to inhibit weight loss and maintain overall quality during storage and shelf-life.