Effect of Chitosan as an Antifungal and Preservative Agent on Postharvest Blueberry

Abstract

Preventing deterioration and extending shelf life by using natural agents remain challenges in the distribution of premium‐quality blueberry. Herein, Botryotinia fuckeliana (B. fuckeliana) was isolated from the rotting postharvest blueberry and identified, and the causal pathogen was re‐isolated from the decay blueberry to confirm Koch's postulates. Experimental results indicated that spore germination and mycelial growth of B. fuckeliana, were significantly inhibited by chitosan in a concentration‐dependent mode. Application of chitosan coating to blueberry exhibited positive effect on the changes of weight loss, firmness, total phenolics and anthocyanins, as storage time increased. Hence, chitosan may be potentially applied in food industry for controlling the decay and extending the shelf life of postharvest blueberry. Practical Applications Blueberry has received considerable attention due to its content of health promoting micronutrients and several bioactive phytochemicals. However, it is often shortened by weight or moisture loss, and fungi infection under high humidity condition resulting in sensorial and nutritional changes. This study aims to provide experimental evidence for application of chitosan in the maintenance of quality (inhibits the microbial spoilage, retards weight loss, maintains the total phenolic and anthocyanin contents) of postharvest blueberry.

An approach to improve the safety and quality of ready‐to‐eat blueberries

“…Alvarez et al () found significant differences on firmness values when compared fresh and chitosan coated blueberries by a digital penetrometer at initial time of storage. Furthermore, several works on coated blueberries shows a significant improvement on firmness retention and in some cases even an increase of it when this parameter is evaluated in a certain period of time, at a certain storage temperature, and in general by instrumental techniques (Alvarez et al, ; Jiang, Sun, Jia, Wang, & Huang, ; Sun et al, ). Odd‐odor and odd‐flavor were the most affected parameters by the biopreservatives.…”

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

“…According to our previous report (Jiang et al, ), fungal isolation from the lesions was done by transferring a representative portion of decayed blueberry surface‐sterilized with 1% sodium hypochlorite (NaOCl) solution for 2 min and rinsed in sterile distilled water. Fungi were isolated with a sterile scalpel onto PDA plates.…”

“…Blueberry is one of the most valuable fruits worldwide because of the potential health benefits and significant economic impact (Giacalone et al, ; Jiang, Sun, Jia, Wang, & Huang, ). However, it is susceptible to several fungal diseases caused by fungi, and it is a serious problem because once blueberries are infected by storage pathogens, the walls of the blueberries soften, while the pathogens will be transmitted intact to adjacent blueberries, leading significant economic loss (Yang et al, ).…”

“…In our previous study (Jiang et al, ), Botrytis cinerea ( B. cinerea ) was isolated and identified as the predominant fungal specie in blueberry in China, while some unremarkable fungi were observed and isolated from the yellowish sunken lesions of the bulbs that usually appear with B. cinerea . The identities of these isolated fungi remain unknown.…”

“…To date, chitosan and its derivatives with different molecular weights and functional groups have been well applied as biodegradable fungicides, plant growth regulators, and seed protectors (Gabriel, Tiera, & Tiera, ). The antifungal activity mechanism of chitosan is supposed to be the interaction between its cationic chain and negatively charged residues of macromolecules which are exposed on the fungal cell surface, thereby affecting cell wall morphogenesis and interfering directly with the activity of enzymes (El Ghaouth, Arul, Asselin, & Benhamou, ; Jiang et al, ; Li, Chen, Liu, Zhang, & Tang, ) . Some cationic groups such as quaternary and pyridine‐grafted chitin/chitosan derivatives exhibit higher antifungal activity than pristine chitin/chitosan (dos Santos Gabriel et al, ; Geng et al, ; Huang et al, ; Jia, Dun, Fang, Wang, & Huang, ; Qiu et al, ).…”