Effects of irradiation and drying treatment on the quality of semi-dried shrimp | |
| Author | Apiporn Adulpichit |
| Call Number | AIT Thesis no.PH-00-14 |
| Subject(s) | Irradiated shrimp Shrimps--Drying |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science |
| Publisher | Asian Institute of Technology |
| Abstract | The optimum moisture content and salt content in semi-dried shrimp was determined to meet the consumer's acceptance. The application of irradiation at 2 and 4 kGy were used on semi-dried shrimp (sample which was produced commercially using combination of sun drying and mechanical batch drying) for improving microbial safety and storage stability. Rotary dryer with different high temperatures (90, 110, 130 °C) was conducted to investigate the effect of drying rate, qualities of product and energy consumption. For energy conservation test, the different levels of recirculated air (10 ± 1, 25 ± 1, 40 ± 1 %) were also examined. All products from different production techniques (irradiation, rotary dryer and recirculated rotary dryer) were sampled and compared the qualities. The results showed that 35% moisture content and 7% salt content were acceptable by panelists. For irradiation, irradiated samples at 2 and 4 kGy obtained microbial load of 7.00 * 101 and 6.00 * 101 CFU/g of samples and yeast and mold number for both samples were less than 10 CFU/g. In other hand, unirradiated sample showed microbial load 1.34 * 103 CFU/g and yeast and mold 1.00 * 102 CFU/g. The irradiated sample at 4 kGy had higher TBA-value than irradiated sample at 2 kGy and unirradiated samples. The a-value representing redness of both irradiated samples showed lower value than unirradiated sample (p<0.05). However, there was no significant difference on all sensorial properties between unirradiated and irradiated samples (p>0.05). During storage time, the TBA-value of all samples increased with redness value reducing and textural hardness increase. Irradiation at 2 and 4 kGy could extend shelf-life of semi-dried shrimp to 5 and 7 weeks respectively while unirradiated sample had storage life of only 10 days. For rotary dryer, the higher temperature at 130° C provided the faster drying time of 2.38 hours with energy saving of 1.425 kg of liquid petroleum gas. The product from rotary dryer had more a-value representing redness and less L-value representing brightness than the commercial sample. All samples from rotary dryer had higher score in term of appearance and overall acceptability when compared with the commercial one. The recycling air at 40 ± 1 % could provide the semi-dried shrimp with the most energy saving (0.774 kg). Comparing all products from different production technique's, semi-dried sample from rotary dryer had lower microbial load than commercial product but had higher load than irradiated product. From sensory evaluation, dark red semi-dried shrimps from rotary dryer gave the better appearance and overall acceptability than the other products. |
| Year | 2000 |
| 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 | Postharvest and Food Process Engineering (PH) |
| Chairperson(s) | Athapol Noomhorm; |
| Examination Committee(s) | Jindal, Vinod K. ;Rakshit, Sudip K.; |
| Scholarship Donor(s) | Asian Institute of Technology (partial scholarship); |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2000 |