The Effect of Edible Chitosan Coatings Incorporated with Thymus capitatus Essential Oil on the Shelf-Life of Strawberry (Fragaria x ananassa) during Cold Storage

Abstract

The strawberry is a fruit appreciated in the food industry for its high content of bioactive compounds. However, it is considered a highly perishable fruit, generally attacked by pests of phytopathogenic origin, which decreases its shelf-life. Normally, to diminish the losses caused by pathogenic microbes, coatings of polysaccharides in combination with natural products like essential oils are applied. In this work, we describe the effect of edible coatings from chitosan (CT) incorporating Thymus capitatus essential oil (TCEO), applied to strawberries stored under refrigeration conditions (5 ± 0.5 °C). Different concentrations of TCEO were applied to chitosan coatings, with different effects on the physical and microbiological properties of the strawberries. All the products had greater acceptance and quality than the controls, being more effective those with essential oil incorporation. It is noteworthy that all the essential oil treatments lead to an increase in the shelf-life of strawberries of up to 15 days. Scanning electron microscopy (SEM) analysis of the microstructure showed a decrease in compactness with TCEO introduction, but without compromising food preservation after 15 days. In addition, treated strawberries delayed the loss of physicochemical and antioxidant properties, due to protection against the microbial development of aerobic mesophylls, molds, and yeasts.

Effect of edible coating and antifungal emulsion system on Colletotrichum acutatum and shelf life of strawberries

“…Three types of edible coating combined with cassia oil have been shown to reduce metabolism as well as delay the increase in TSS, while the sample control was significantly higher than that of the coatings formulas showing a clearer ripe of the control sample at days 8 to 16 preserving the maturity value of the control sample increased sharply from 13.88 to 38.52, due to the fruit respiration and some fruit softening enzymes, and because they lack the protective coating against the air component. A similar result was reported by Martínez et al [14] when combining chitosan coatings with Thymus capitatus extended the shelf life of strawberries by 15 days at 5 °C. Ventura-Aguilar et al [11] indicated that the ripeness index is also affected by storage temperature as in which strawberries were stored at 5 °C for 13 days have a ripeness equivalent to the strawberry maturity at 20 °C in just 3 days.…”

“…[20] In addition, the combination with cassia oils mainly due to the presence of terpenoid compounds that could have an antibacterial effect such as carvacrol, thymol, linalool, p-cymene, β-myrcene etc. [14] Guerreiro et al [8] reported that sodium alginate combined with a higher concentration of essential oils (0.3 %) was less effective, a contrast to this study. Olivas and Barbosa-Canovas [18] also reported that chitosan by itself can reduce microbial growth.…”

Assessment of Chitosan-Rue (Ruta graveolens L.) Essential Oil-Based Coatings on Refrigerated Cape Gooseberry (Physalis peruviana L.) Quality

“…The particle size, density, viscosity, and non-volatile compounds of the emulsions were determined according to the methodologies reported previously [23,25]. Briefly, the particle size of the emulsions was tested using a laser diffractometer was used (AIMSIZER 2011, Dandong Liaoning, China).…”

“…The oil is retained in the hydrophobic region of the chitosan; therefore, CS chains must be acting as a colloidal protector through van der Waals interactions and hydrogen bonds between hydroxides and amines of the CS and ketones present in the oil. Typically, it is considered that analyzing the particle size of the emulsions allows determining the stability of the emulsion [25]. On the other hand, a smaller particle size could influence the physical and chemical properties such as the viscosity and density of the emulsions, because a higher contact surface would be available that would improve the features [23].…”

“…The incorporation of antioxidants is widespread in coatings for fresh-cut produce, as discoloration is often a significant challenge [62]. Chitosan-essential oil coatings have been probed to control antioxidant losses in several fruits [14,25].…”