Studies on the hygienic quality, biogenic amines content and histamine-forming bacteria in salted mackerel products

• Main Authors: Shiou-wen Chiou, 邱秀雯
• Other Authors: Tsong-ming Lee
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/24407317082515537540

碩士 === 大仁科技大學 === 食品科技研究所 === 100 === Abstract To probe into hygienic quality and risk of histamine poisoning of salted mackerel products selling in markets, this research collected 35 salted mackerel products from traditional markets and supermarkets in seven areas in Taiwan, carried out investigation on hygienic quality, biogenic amines contents, and isolation of histamine-producing bacteria. Outcomes of research showed that contents of pH, salinity, water activity, Total volatile basic nitrogen, Aerobic plate count, Coliform, and Escherichia coli in salted mackerel samples were 5.13-8.56, 0.17-16.70%, 0.75-0.99, 6.80-133.73 mg/100 g, 2.6-8.68 log CFU/g, < 3-448 MPN/g, < 3-230 MPN/g respectively; samples collected in Kaohsiung had higher salinity, ash contents, and TVBN in average which were 5.09%, 5.81%, 39.73 mg/100 g respectively while water content and water activity were 62.16%, 0.93% respectively which were the lowest in average among all samples. In addition, there were 14 samples (40%) that had Aerobic plate count exceeded limitation (6.4 log CFU/g) of Food Sanitation Standards, there were 2 samples (6%) of E. coli exceeded limitation (below 50 MPN/g) of Food Sanitation Standards which indicated low hygienic quality of partial salted mackerel selling in markets. The outcomes of analyzing biogenic amines contents of samples indicated histamine contents were within range of ND-154.22 mg/100 g, there were 5 samples (14%) with histamine contents exceeded U.S. Food and Drug Administration (FDA) histamine contents limitation (5.0 mg/100 g) for sea foods, and there were 2 samples (5%) with histamine contents even exceeded hazard actuating quantity (> 50 mg/100 g). Additionally, for histamine-producing bacteria isolation, 5 strains of high histamine-producing bacteria were sifted from samples, identified by 16S rDNA series analysis of PCR amplification strain, we found two of them were Raoultella ornithinolytica and the other three were Morganella morganii. To understand the interference in growth and production of high histamine-produced bacteria under different temperatures and salinities, we implanted 5.0 log CFU/mL of isolated high histamine-produced bacteria R. ornithinolytica and M. morganii into TSBH cultivation liquid of different salinities (0.5%, 1.5%, 3%, 5%, 10%). We analyzed bacteria growth and histamine production over samples under 4°C and 37°C cultivation. The results showed that under 37°C cultivation, growth of histamine could be suppressed effectively when salinities above 3% whereas the growth of bacteria and histamine could not be suppressed effectively when salinities of cultivation liquid were 0.5% or 1.5%. Growth of histamine-produced bacteria was postponed and production cumulation of histamine was little under 4°C cultivation. Added approximately 5.0 log CFU/g of strong histamine-produced bacteria R. ornithinolytica, and M. morganii in salted mackerel of 3% salinity to simulate contamination of salted mackerel by histamine-produced bacteria, stored in different temperatures and durations to investigate how histamine related hygienic quality varies in flesh of fish. From outcomes we acknowledged that both 4°C for 12 hours and 37°C for 24 hours of cultivation caused TVBN contents raised and exceeded early rotten level (25 mg/100 g) rapidly. By analyzing results of growth of histamine-produced bacteria and histamine production indicated bacteria experienced storage under 15°C, 25°C, and 37°C grew fast, after 12 hours of storage under 25°C and 37°C, 48 hours of storage under 15°C, all histamine productions exceeded the poisoning hazard level (50 mg/100 g). Histamine-produced bacteria grew slow (<1 mg/100 g) under 4°C storage environment, the cumulation of histamine was insignificant. Besides, adopted -20°C, 8 weeks of frozen storage while analyzing strains count of samples, we found that bacteria counts neither increased nor decreased, that indicated R.ornithinolytica and M. morganii were dormant under -20°C low temperature. We then put 8 weeks frozen fish under 25°C to simulate room temperature de frozen, sampling at different times (0, 6, 12, 24, 48 hours) analyzing count of histamine-produced bacteria and histamine productions, outcomes indicated that after 12 hours de frozen under 25°C room temperature, histamine-produced bacteria grew rapidly and exceeded limitation of food sanitation standards (6.4 log CFU/g), TVBN reached early rotten level (25 mg/100 g), histamine cumulation exceeded toxicity hazard level (50 mg/100 g) raised by U.S. Food and Drug Administration