碩士 / 國立嘉義大學 / 食品科學系研究所 / 105 / This study was aiming to investigate the effect on quality of mildly-salted dried fishery products within mildly processing period. Silver perch (900 ± 100 g) from Taiwan fishery farming and pacific saury (130 ± 20 g) from ocean fishing were chosen as raw materials and being wet salted, followed by different mildly drying methods, either sun drying (20-41°C, 45-74% RH), room temperature drying (18-22°C, 70-82% RH), or low temperature low humidity cold drying (20-21°C, 50-60% RH).
The result showed that pH of both products after light salting and drying dropped between 5.99 and 6.78, while water activity ranged from 0.915 to 0.961. Water content of silver perch and pacific saury reduced from 73.6% and 60.6% to 67.9-71.7% and 46.9-54.2%, respectively, during drying. There were no much changes in water content and water activity due to short salting and drying time. Lightness (L*) of silver perch and pacific saury decreased from 42.27 and 40.37 to 29.69-37.00 and 28.47-32.79 after processing, most severely in sun dried groups. TMA content (mg/100 g) and VBN value (mg/100 g) of silver perch increased from 1.01 to 1.26-3.10 and 10.66 to 12.57-15.59, respectively, and 2.26 to 4.66-5.57 and 8.07 to 10.39-13.90, respectively, in pacific saury during processing. TMA and VBN value were the highest in sun drying groups but total plate count (log CFU/g) did not increase in similar trend. Although total plate counts increased differently in all sample groups depending on drying method but in overall, total plate count of each group remained below 3×106 CFU/g.
Besides, TBA value (μg/g) of mildly processed silver perch and pacific saury increased from 2.14 to 3.5-6.18 and 4.87 to 7.55-10.51, respectively, specifically indicated sun drying might lead to TBA value increment. Crude lipid content of silver perch was around 1.1-2.8 g/100 g of flesh, which mainly constituted by octadecenoic acid (28.49-34.17) and palmitic acid (19.49-24.59), while pacific saury with crude lipid around 20.1 to 32.7 g/100g flesh, was majorly built up by eicosatrienoic acid (20.95-21.02) and linolenic acid (15.63-16.61). There was no significant difference in fatty acid composition among different mildly processed groups.
Crude protein content (g/100 g) of mildly processed silver perch and pacific saury were 20.6 and 18.8, respectively. Free amino acid (μg/g) of the former was mainly made up by glycine (1993-2369), alanine (1397-1958) and glutamic acid (118-212), while the later was majorly composed by cysteine acid (8491-13415), histidine (5558-8690) and alanine (1215-1991). In mildly drying, the total free amino acid and taste amino acid content increased of silver perch by autolysis enhance the fish flavor. The total free amino acid and taste amino acid content increased of silver perch by autolysis during sun drying processes. Notably that although histidine amount of pacific saury was comparably higher, no histamine was determined in all sample groups. Nucleotides and related compounds of mildly-salted dried samples mainly accumulated in IMP form. The amount (μmol/g) decreased from 8.14 to 6.60-6.97 for silver perch and 6.82 to 3.64-5.49 for pacific saury. K value of sun dried silver perch increased from 15.45% to 39.7%, while patific saury increased from 30.05 up to 62.51%. Lastly, in sensory evaluation, sample CS6 and CP4, which processed with low temperature low humidity cold drying, scored highest overall preference, 6.55 among all silver perch samples and 6.69 among all pacific saury samples, respectively.
| Identifer | oai:union.ndltd.org:TW/105NCYU5253025 |
| Creators | 黃郁雯 |
| Contributors | 黃健政 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 138 |
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