Optimization of edible coating with essential oils in blueberries

ABSTRACT The application of edible coatings containing natural antimicrobials is a postharvest conservation technology in fruits that have generated interest. This research aimed the determination of the edible coating composition and the concentration of essential oil that allows optimizing the physical-mechanical characteristics for its application in the conservation of blueberries. The antimicrobial activity of the essential oils of cinnamon and lemon was determined, resulting in a minimum inhibitory concentration of 0.3% in both cases. After applying the Box Behnken design of the Response Surface Methodology (RSM), the optimal treatment for edible coating with cinnamon essential oil 0.3% was determined: aloe vera gel 18.40%, gelatin 2%, and glycerol 0.055% obtaining values of 27.95% solubility, 0.90 mm of deformation and 3.34 N of breaking strength. Likewise, the same procedure was followed for the coating with lemon essential oil 0.3%, determining as optimal 23.94% aloe vera gel, 2% gelatin, and 0.05% glycerol, getting values of 28.06% solubility, 0.45 mm deformation, and 4.53 N of breaking strength. Finally, their applications in Biloxi blueberries were validated, preserving the main physicochemical and microbiological quality attributes during 28 days of storage at 2 °C, compared, to a control sample.摘要 添加天然抗菌剂的可食用涂层是当前广受关注的果品采后保鲜技术。本研究旨在确定可食用涂层的配方与精油最优浓度，以优化其物理机械性能，用于蓝莓保鲜处理。本研究测定了肉桂与柠檬精油的抗菌活性，二者的最低抑菌浓度均为0.3%。本研究采用响应面法（Response Surface Methodology, RSM）中的Box-Behnken设计，确定了添加0.3%肉桂精油的可食用涂层最优配方：芦荟凝胶18.40%、明胶2%、甘油0.055%，所得涂层的溶解度为27.95%、变形量0.90 mm、断裂强度3.34 N。同理，针对添加0.3%柠檬精油的涂层，本研究采用相同流程确定了最优配方：芦荟凝胶23.94%、明胶2%、甘油0.05%，所得涂层的溶解度为28.06%、变形量0.45 mm、断裂强度4.53 N。最后，本研究验证了两种涂层在比洛克西（Biloxi）蓝莓上的应用效果：与对照组相比，在2℃条件下储存28天期间，两种涂层均可有效维持蓝莓主要的理化与微生物质量属性。