| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 101 === Ten dumpling products were collected from Taiwan and tested to determine the hygienic quality. The levels of pH, salt, ash, water content, water activity, total volatile basic nitrogen (TVBN), aerobic plate count (APC), coliforms, Escherichia coli are ranged (mean ± SD) as follows: pH value of 5.12-6.01 (5.52 ± 0.27), salt 0.34-0.56% (0.47 ± 0.07%), ash 1.22 -1.59% (1.39 ± 0.13%), moisture 57.59-73.82% (64.07 ± 5.36%), water activity 0.93-0.98 (0.97 ± 0.02), TVBN 4.39-10.97 mg/100g (7.35 ± 2.25 mg/100g), APC 5.52-8.11 log CFU/g (6.93 ± 0.72 log CFU/g), Coliform 10,150-119,950 MPN/g (31,485 ± 32,291 MPN/g) and E. coli <3 - 5,050 MPN/g (970 ± 1,642 MPN/g), respectively. Eight samples in APC levels and six samples in E. coli levels were greater than the food hygienic limit 6.47 log CFU/g and 50 MPN/g, respectively. The levels of coliform in all samples were more than 10,150 MPN/g. The results showed mostly commercially milkfish dumpling samples had poor microbiological quality. The level of each biogenic amine in all samples was less than 1.6 mg/100 g. Three histamine-producing bacterial strains, capable of producing 276.6 ppm to 561.8 ppm of histamine in trypticase soy broth supplemented with 1.0% L-histidine. Assay of multiplex polymerase chain reaction revealed adulteration rates were 50% (5/10) for pork in milkfish dumpling samples.
To elucidate the histamine-related quality in milkfish dumpling meats after being contaminated by Raoultella ornithinolytica MFS8, 5.0 log CFU/g concentration of Raoultella ornithinolytica MFS8 were inoculated to milkfish dumplings meats and stored at various temperatures. The bacterial number rapidly increased at temperature 37℃ and 25℃, and reached the highest bacterial count to 10.38±0.15 and 9.80±0.20 log CFU/g for 60 hours, respectively. Morever, the bacterial count was gradually increased to 9.27±0.09 log CFU/g for 120 hours during stored at 15℃; while 4℃ storage will retard bacterial growth. TVBN content in dumpling meats will increase slowly at temperature below 15℃ (below 20 mg/100 g) and it will rapidly increase to 25.44 mg/100 g that was greater than primary deterioration limit (25 mg/100 g). In addition, the spiked milkfish dumplings stored at 37℃ for 24 hours, 25℃ for 36 hours and 15℃ for 48 hours had histamine content greater than 50 mg/100 g suggested by U.S. FDA hazardous guideline level. However, the growth of histamine-forming bacteria and histamine production in milkfish dumpling meats were inhibited at 4℃. Therefore, this result suggested that milkfish dumpling meats mixed stuffing should promptly be stored at 4℃ below to inhibit histamine-forming bacteria growth and prevent histamine poisoning hazards.
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