Nanolaminated edible coating with layer-by-layer (LbL) deposition of biopolymers to enhance the shelf life and in situ effects on strawberry | |
| Author | Adhikari, Manita |
| Call Number | AIT Thesis no.FB-20-01 |
| Subject(s) | Biopolymers Antimicrobial polymers |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Food Engineering and Bioprocess Technology, School of Environment, Resources and Development |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ;no.FB-20-01 |
| Abstract | Edible coatings, being eco-friendly and economic feasible have recently been explored to reduce postharvest loss of fruits. This study aimed at the development and characterization of nanolaminate coating with layer by layer (LbL) deposition of biopolymers and its evaluation in the quality and the shelf life of strawberry. The optimization of bio-polymeric nanolaminate coatings with various concentrations of biopolymers and number of layers was conducted using response surface methodology. The concentrations of biopolymers and the number of layers had no significant effect (p > 0.05) on water vapor permeability of the film. The chitosan concentration (2% w/v) was fixed whereas pectin varied (0.25%, 0.5% and 1% w/v) with number of layers (n = 9). The optimized conditions was used to coat the low density polyethylene film alternatively in a LbL sequence and water vapor permeability was found as 1.85x10-9 , 1.63x10-9 and 1.26 x 10-9 gm-1 h -1Pa-1 . Furthermore, the assemblage of layers n = 9 was characterized by Fourier infrared spectroscopy. The spectrums of layers n = 9 assemblage with fixed concentrations of chitosan and varied concentration of pectin on the film reveals the main changes in the range of 1800-1600 cm-1 indicating the strong interactions between chitosan and pectin. The zeta potential of polyelectrolytes solutions was also evaluated. The chitosan was positive while the pectin showed negative charge. The nanolaminated coating n = 9 layers with optimized concentrations of chitosan and pectin was further applied on test fruit (strawberry). The shelf life was evaluated during nine days in terms of weight loss, firmness, pH, total soluble solids, titratable acidity, color, browning and total microbial count. Coated fruit significantly delayed changes in weight loss, firmness and external color throughout the storage time compared to uncoated fruit. Application of nanolaminate coating was effective in reducing the enzymatic activities and lowered rate of browning was observed for coated fruit by the 9th day of storage. With the increase in the storage, pH and TSS increases whereas TA decreases. Microbiological growth was significantly reduced in coated fruit and till 3rd day no growth of yeast and mold was observed in coated fruit whereas the uncoated fruit was attacked by fungi on the very first day of storage. The sensory parameters were significantly (*p < 0.05) maintained by the coated fruit |
| Year | 2020 |
| Corresponding Series Added Entry | Asian Institute of Technology. Thesis ; no.FB-20-01 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Food, Agriculture and Natural Resources (Former title: Department of Food Agriculture, and BioResources (DFAB)) |
| Academic Program/FoS | Food Engineering and Bioprocess Technology (FB) |
| Chairperson(s) | Anal, Anil Kumar; |
| Examination Committee(s) | Loc Thai Nguyen;Bora, Tanujjal; |
| Scholarship Donor(s) | Royal Thai Government;Her Majesty the Queen’s Scholarships (Thailand); |
| Degree | Thesis (M. Sc.) - Asian Institute of Technology, 2020 |