| Author | Porntip Sirisoontaralak |
| Call Number | AIT Thesis no.AE-96-13 |
| Subject(s) | Fruit--Preservation
|
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of
Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | Preservation of high-moisture pineapple stored at ambient condition (25±2 °C) was studied by applying combined treatments including mild heat treatment (blanching for 0, 30 and 60 sec. in boiling water), slight reduction of water activity with osmotic agents (sucrose and glucose), slight reduction of pH, addition of antimicrobial agent (1000 ppm of potassium sorbate), addition of antibrowning agents (sodium bisulfite, 4-hexylresorcinol and sodium ascorbate) and texture improvement by calcium chloride. The effects of these combined methods on pineapple stability were evaluated during three months of storage. For the osmotic dehydration process, effects of blanching time and osmotic agents on mass transfer were investigated. After storage, sensorial qualities of the product were evaluated. To obtain the desired Aw and pH, solutions of 22 Brix sucrose and 15 Brix glucose with pH adjusted to 3.3 was used. Microbial stability of the product was achieved under conditions wherein Aw= 0.98 and pH = 3.5 with 1000 ppm of potassium sorbate preservative added. Longer blanching time caused higher water loss and sugar gain during osmotic dehydration. Glucose treatment resulted to less weight reduction and water loss but sugar gain was not affected. During storage, pineapples blanched for 60 sec., treated with no antibrowning agent and glucose added were microbiologically spoiled. Overblanching caused softening and spoilage and the optimum duration was found to be 30 sec. Sodium bisulfite acting as enzymatic and nonenzymatic browning inhibitor is the most effective antibrowning agent compared to 4-hexylresorcinol and sodium ascorbate. Glucose as osmotic agent caused more softening and microbiological spoilage in pineapple preserved with combined methods. Calcium chloride improved the texture of preserved pineapple during three months of storage but the difference could not be detected by sensory evaluation. Sorbic acid was degraded during the storage period by microbial and chemical mechanisms. Residual sulfite level in the product was within the FDA's limitation. |
| Year | 1996 |
| 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 | Agricultural and Food Engineering (AE) |
| Chairperson(s) | Athapol Noomhorm; |
| Examination Committee(s) | Jindal, Vinod Kumar;Vincent, Jean-Claude;Rakshit, Sudip Kumar; |
| Scholarship Donor(s) | Partial Asian Institute of Technology Scholarship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 1996 |