| Summary: | 碩士 === 國立高雄海洋科技大學 === 水產食品科學研究所 === 106 === High pressure processing (HPP) is an emerging non-thermal technology that can achieve food safety. The principle advantages of the HPP process is an expanded shelf life due to the inactivation of pathogen. Histamine fish poisoning is a worldwide food-borne intoxication caused by the consumption of seafood containing high histamine contents. This study was to determine the effects of HPP treatments on inhibitory effects of histamine-forming bacteria (HFB) such as Morganella morganii and Photobacterium phosphoreum, and resistance variations were detected between HFB in phosphate buffer, in tuna meat slurry. In addition, the changes of aerobic plate count (APC), total volatile basic nitrogen (TVBN), pH value and histamine contents in tuna meat after HPP treatment during storage at different temperatures (4℃ and 15℃) were evaluated.The objective of this study will assess the HPP potential for the preservation and reduction of histamine hazard and risk on tuna meat. The result showed that HFB subjected to HPP in phosphate buffer solution and homogenous solution of tuna meat, and their bacterial counts decreased with increasing pressure level and holding time. However, HFB had a higher D value in the homogenate of tuna meat compared with that in the phosphate buffer, indicating that the HFB were more resistant to pressure in the homogenized of tuna meat. Under the same pressure conditions, M. morganii had a higher D value than P. phosphoreum. This result indicates that M. morganii is able to withstand high pressure treatment for a longer time than P. phosphoreum.
The APC of raw tuna meat after HPP treatment (200, 300, 400, 500, and 600 MPa for 5 min) decreased with increased pressure from 5.97 log CFU/g (control) to 2.15 log CFU/g (600 MPa). In color of tuna meat, L* value (lightness) increased significantly with increased pressure, whereas a* value (redness) was significantly reduced with increased pressure. In general, the HPP treatment significantly delayed the APC, TVBN and histamine increase in tuna meat stored at low temperature (4 or 15 oC). However, the APC and TVBN levels were retarded, and histamine production was completely inhibited in HPP samples (>400 MPa) stored at 4 oC. In addition, the HPP treatment significantly delayed the HFB count, TVBN and histamine increase in tuna meat inoculated with HFB (M. morganii and P. phosphoreum) and stored at low temperature (4 or 15 oC). However, the TVBN and histamine levels were retarded, and HFB growth was completely inhibited in HPP samples (>450 MPa) stored at 4 oC. In summary, this result suggested the tuna meat treated with HPP and stored at below 15℃ could prevent deterioration of product quality, extend shelf life, and reduce histamine hazard and risk.
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