Effect of chitosan– Aloe vera coating on postharvest quality of blueberry ( Vaccinium corymbosum ) fruit

Abstract

A B S T R A C TThe present study was carried out to evaluate the effect of chitosan-based edible coatings with Aloe vera extract on the postharvest blueberry fruit quality during storage at 5 C. Firstly, A. vera fractions (pulp and liquid) were extracted from leaves and evaluated in terms of antifungal and antioxidant capacities. The choice of the most adequate chitosan and A. vera fraction concentrations to be incorporated in coating formulation was made based on the wettability of the corresponding coating solutions. Coatings with 0.5% (w/v) chitosan + 0.5% (w/v) glycerol + 0.1% (w/v) Tween 80 + 0.5% (v/v) A. vera liquid fraction presented the best characteristics to uniformly coat blueberry surface. Physico-chemical (i.e., titratable acidity, pH, weight loss) and microbiological analyses of coated blueberries (non-inoculated or artificially inoculated with Botrytis cinerea) were performed during 25 d. Microbiological growth and water loss levels were approximately reduced by 50% and 42%, respectively, in coated blueberries after 25 d compared to uncoated blueberries. After 15 d, weight loss values were 6.2% and 3.7% for uncoated and chitosan-A. vera coated blueberries, respectively. Uncoated fruits presented mold contamination after 2 d of storage (2.0 AE 0.32 log CFU g À1 ), whilst fruits with chitosan-based coatings with A. vera presented mold contamination only after 9 d of storage (1.3 AE 0.35 log CFU g À1 ). Overall, coatings developed in this study extend blueberries' shelf-life for about 5 d, demonstrating for the first time that the combination of chitosan and A. vera liquid fraction as edible coating materials has great potential in expanding the shelflife of fruits.

Starch-Based Coatings for Preservation of Fruits and Vegetables

“…Moringa plant extracts had a significant effect on the growth rate of C. gloeosporiodes, A. alternata and L. theobromae, a fact that can be closely linked to the high concentration of phenolic compounds in the tissue [58]. B. cinerea and P. expansum were better inhibited than A. niger in the presence of pulp or liquid fractions of A. vera [41]. Aloe vera gel was also effective at controlling the growth of several fungi, exhibiting the greatest efficacy against F. oxysporum.…”

“…[41] Lemongrass essential oil Colletotrichum capsici Inoculation of 10 µL of 10 5 spores/mL, before coating application CH Green bell pepper EO was found to be less effective in vivo than in vitro, but the combination of EO with CH did enhance the antimicrobial activity of the coating.…”

Selective antifungal activity of chitosan and sulfonated chitosan against postharvest fungus isolated from blueberry

“…It is well known that chitosan can interfere directly with fungal growth and activate several biological processes in plant tissues and is a potential elicitor of plant defenses (El Ghaouth et al, ). Chitosan‐based coatings have demonstrated superior effectiveness for controlling weight loss in lots of studies on blueberry, being a barrier to water transport and having antimicrobial activity (Sun et al, ; Vieira et al, ; Yang et al, ). Blueberry leaf extract incorporating with chitosan coating could maintain high nutritional value in fresh blueberries (Yang et al, ).…”

“…Chitosan-based coatings have demonstrated superior effectiveness for controlling weight loss in lots of studies on blueberry, being a barrier to water transport and having antimicrobial activity (Sun et al, 2014;Vieira et al, 2016;Yang et al, 2014). Blueberry leaf extract incorporating with chitosan coating could maintain high nutritional value in fresh blueberries (Yang et al, 2014).…”

Natural Antimicrobial Edible Coatings for Microbial Safety and Food Quality Enhancement

“…In fact, these coatings are able to reduce gas exchange between food products and the environment, which may decrease respiration rates and thereby delay ripening and senescence of fresh produce in a similar way to storage under modified/controlled atmosphere (Janjarasskul and Krochta ). Several studies have demonstrated the ability of polysaccharide‐based coatings carrying different natural antimicrobial agents to preserve quality and increase safety of many fresh and minimally processed fruits such as orange (Aloui and others ), mango (Cissé and others ), strawberry (Duran and others ), grape (Aloui and others ), blueberry (Vieira and others ), minimally processed papaya (Narsaiah and others ), fresh‐cut pineapple (Azarakhsh and others ), and fresh‐cut apple (Chiabrando and Giacalone ). Likewise, different natural antimicrobial agents mainly EOs have shown potential, when added to edible coating formulations, for prolonging the shelf life of chicken meat (Fernández‐Pan and others ; Bazargani‐Gilani and others ) and seafood products (Asįk and Candoğan ) by reducing oxygen and moisture transmission, limiting microbial contamination and discoloration, and preserving texture, color, and flavor (Gennadios and others ).…”