Chitosan extraction from seafood waste and its potential application in production and postharvest horticulture
This research was conducted to transform seafood waste, particularly shrimp shells, into a chitosan source as a high-value safe input in horticulture. The chitosan extraction process involved the removal of protein, mineral and color from shrimp shells, followed by removal of the acetyl group from the molecular chain of chitin. Shrimp shell samples were deproteinized with 5% NaOH, demineralized with 3% HCl, and decolorized with 0.315% sodium hypochlorite. Deacetylation was performed using ›40% NaOH. From this process, chitosan yield was about 25%. The chitosan product had a moisture content of 11.3%, 0.65% total ash, 96.6% solubility, degree of acetylation 78% and viscosity 1536 mPa s. Chitosan solution at 1% was prepared for preharvest and postharvest application. Chili was used as a test crop for the preharvest application, which was done by spraying the leaves to runoff with 10 or 20 mL of 1% of the chitosan produced, starting at 20 days after transplanting, and every 5 days thereafter. For comparison, commercial 1% chitosan (imported product from Thailand) applied at 20 mL per 10 L water and unsprayed control plants were included. Plants receiving no treatment served as control. Other recommended cultural management practices were followed. Chitosan-sprayed plants were generally of better health, with less disease incidence than the control plants, which were affected by virus, stem rot and fruit rot diseases. The locally produced chitosan at 20 mL per 10 L water caused comparable responses as the imported chitosan in hastening flowering, increasing plant height, and increasing yield. The local chitosan was relatively more effective, increasing yield more than 4-fold, while the imported product increased yield by about 3-fold relative to the control. For postharvest application, mature green mango was the test produce, and was coated with 1% local chitosan; this was compared with coating with vegetable oil and without coating. Fruit were then stored at ambient (25-32°C or Coolbot cold chamber, 13°C). Chitosan coating retarded fruit yellowing, based on b* values, under both ambient and cool conditions. It did not markedly affect weight loss, softening, total soluble solids or titratable acidity. Coolbot storage was very effective in reducing weight loss and delaying ripening processes. The results show the potential of chitosan application as a component management strategy in production and postharvest horticulture.
Tong, S., Sophal, L., Samoeun, B., Buntong, B., Kong, T. and Acedo, A.L. (2017). Chitosan extraction from seafood waste and its potential application in production and postharvest horticulture. Acta Hortic. 1179, 9-14
value addition, preharvest spray, postharvest coating, chili, mango