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

Abstract

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.

Effect of Gum Arabic and Starch-Based Coating and Different Polyliners on Postharvest Quality Attributes of Whole Pomegranate Fruit

“…The coating solutions consisting of gum Arabic (0.5% w/v) (Sigma-Aldrich, Johannesburg, South Africa), maize starch (0.5% w/v) (Chem. lab suppliers Co., Johannesburg, South Africa), glycerol (1% v/v) (Sigma-Aldrich, Johannesburg, South Africa), tween 80 (0.05% v/v) (Sigma-Aldrich, Johannesburg, South Africa) and lemongrass oil (3% v/v) (Umuthi Botanicals, Wilderness, South Africa) were prepared in 1000 mL mill-Q water according to optimization procedure conducted by Kawhena et al [49]. The solutions were continuously stirred at low heat (25 • C) for 1 h on a hot plate magnetic stirrer (Spinot, Tarsons, New Delhi, India).…”

“…All treatment combinations are summarized in Table 1. Weight loss was determined according to Kawhena et al [49] using an electronic weighing balance (ML3002.E, Mettler Toledo, Zurich, Switzerland). For each treatment combination, the weight of ten randomly selected fruit was continuously measured during storage, and weight loss was calculated using the following Equation (1):…”

“…Depending on the physiology of specific fresh fruit and the storage conditions, different edible coatings can be applied, including polysaccharides and their derivatives, proteins, fats and combination or composites [42][43][44]. Several studies have demonstrated the efficacy of edible coatings to minimize weight loss and decay incidence in different pomegranate cultivars during cold storage [45][46][47][48][49]. Similar results have also been reported for edible coating applications in fruit types, such as citrus [50], avocado [51], melon [52], passion fruit [53] and pineapple [54].…”

“…For instance, De Reuck et al [58] found that application of chitosan coating and biorientated polypropylene packages on 'Mauritius' and 'McLean's Red' litchi, resulted in the best overall fruit quality compared to uncoated control or biorientated polypropylene packages alone. Recently, Kawhena et al [49] showed that gum Arabic and maize starch-based coatings reduced weight loss in 'Wonderful' pomegranate packaged in Xtend ® polyliners during 42 d of cold storage (5 ± 1 • C) and 5 d at ambient temperature (20 ± 0.2 • C). Beyond similar research, there is limited information on the effect of edible coatings without plastic packaging on the quality attributes of pomegranate fruit during cold storage.…”

The Effect of Whey Protein-Based Edible Coatings Incorporated with Lemon and Lemongrass Essential Oils on the Quality Attributes of Fresh-Cut Pears during Storage

“…Lemon essential oil, used as a food additive or favouring agent, is extracted from Citrus lemon and its main components are limonene, valencene and ocimene [15]. Lemongrass essential oil is a natural mixture of different compounds such as terpenes, alcohols, aldehydes, ketones, carboxylic acids, and others found to exhibit antimicrobial activity against different types of microorganisms [16] and can be used as an active ingredient in edible coatings. Kapetanakou et al [17] observed the positive effect of using sodium alginate coatings incorporated with cinnamon essential oil (0.3% and 0.9% v/v) as a natural active compound on the fungal growth and ochratoxin A production in coated apple and pears.…”