• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文学位 >Effects of Product Structure, Temperature, Water Activity, and Storage on the Thermal Resistance of Salmonella Enteritidis PT 30 in Low-Moisture Foods
【24h】

Effects of Product Structure, Temperature, Water Activity, and Storage on the Thermal Resistance of Salmonella Enteritidis PT 30 in Low-Moisture Foods

机译：产品结构，温度，水分活度和贮存对低水分食品中肠炎沙门氏菌PT 30耐热性的影响

获取原文
获取原文并翻译 | 示例
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The elevated and dynamic thermal resistance of Salmonella on/in low-moisture foods is an emerging challenge for the food industry. Therefore, the overall goal of this study was to improve the validation process for low-moisture foods by providing new knowledge about the effects that product structure and water activity have on Salmonella thermal resistance in or on low-moisture foods. The specific research objectives were: (1) To quantify the effect of inoculation protocol on the thermal resistance of Salmonella Enteritidis PT 30 in fabricated low-moisture foods (almond, wheat, and date products), (2) To evaluate the effects of long-term storage on the survival and thermal resistance of Salmonella Enteritidis PT 30 on almonds, and (3) To develop Salmonella thermal inactivation models that account for the effects of product structure, temperature, and water activity (for almond, date, and wheat products).;For pre- and post-fabrication protocols, samples were inoculated before and after product fabrication. Salmonella exhibited greater thermal resistance on almond and date products (almond meal, almond butter, and date paste) inoculated using the pre-fabrication method as compared to the post-fabrication method. However, the opposite was true for wheat products (meal and flour). Differences in the food product composition may have contributed to these findings. Based on these results, the pre-fabrication method was chosen for all further experiments in this dissertation.;In the long-term storage study, Salmonella populations decreased by ∼3 log CFU/g after 103 weeks of storage. However, Salmonella thermal resistance did not significantly change during long-term storage.;Primary (log-linear and Weibull) and secondary (Bigelow-type) inactivation models for Salmonella were fit to isothermal inactivation data from eight different products, accounting for product structure (kernels/pieces/meal/flour/butter/paste), temperature (70-90°C), and water activity (0.25-0.65 aw). Overall the log-linear model was the most-likely-correct model, and the Bigelow-type secondary models therefore were incorporated into the log-linear model.;Among all products, Salmonella was most heat resistant in 0.25 aw almond meal (D80°C = 75.2 min), and least resistant in 0.65 aw date paste (D80°C = 0.7 min). Decreasing aw increased thermal resistance. Additionally, Salmonella thermal resistance was generally greater on fabricated than whole products. However, these differences were relatively small for wheat products. Salmonella resistance on fabricated wheat products actually was lower than on wheat kernels at 0.45 and 0.65 aw. Variability in some of these effects across products might be attributable to compositional factors (e.g., sugar or moisture content), temperature-induced shifts in sorption isotherms or physical properties, or variable effects of particle sizes and microenvironment within the fabricated products.;Overall, the primary-secondary inactivation models fit the various data sets well (RMSE from 0.51 to 1.08 log) and therefore are potential tools to predict Salmonella thermal inactivation for these products. Ultimately, this dissertation shows that low-moisture process validation protocols should account for inoculation methods and specific product structures, both of which can significantly affect process outcomes.
机译：沙门氏菌在低水分食品上/中的较高的动态热阻是食品工业的新兴挑战。因此，这项研究的总体目标是通过提供有关产品结构和水分活度对低水分食品中或低水分食品中沙门氏菌耐热性的影响的新知识，来改善低水分食品的验证过程。具体的研究目标是：（1）量化接种方案对人工制作的低水分食品（杏仁，小麦和大枣产品）中肠炎沙门氏菌PT 30耐热性的影响，（2）评估长期食用的影响。沙门氏菌肠炎沙门氏菌PT 30在杏仁上的存活和耐热性的长期储存，以及（3）建立沙门氏菌热灭活模型，该模型考虑了产品结构，温度和水分活度（杏仁，大枣和小麦产品）的影响）.;对于制造前和制造后的方案，在产品制造之前和之后都要对样品进行接种。与预制方法相比，沙门氏菌在用预制方法接种的杏仁和大枣产品（杏仁粉，杏仁黄油和大枣酱）上显示出更高的耐热性。但是，小麦产品（粉和面粉）则相反。食品成分的差异可能导致了这些发现。根据这些结果，本文选择了预制方法进行所有进一步的实验。在长期保存研究中，在保存103周后，沙门氏菌种群减少了约3 log CFU / g。但是，沙门氏菌的耐热性在长期存储过程中并没有显着变化。；沙门氏菌的主要（对数线性和Weibull）和次要（Bigelow型）灭活模型适合来自八个不同产品的等温失活数据，这说明了产品结构（内核/块/膳食/面粉/黄油/糊状物），温度（70-90°C）和水分活度（0.25-0.65 aw）。总体而言，对数线性模型是最可能正确的模型，因此将Bigelow型次级模型纳入了对数线性模型。;在所有产品中，沙门氏菌在0.25 aw杏仁粉（D80° C = 75.2分钟），在0.65 aw枣糊中的最低电阻（D80°C = 0.7分钟）。减小aw会增加热阻。另外，沙门氏菌的耐热性通常在制成品上要比整个产品高。但是，对于小麦产品，这些差异相对较小。实际上，在0.45和0.65 aw时，人造小麦产品的沙门氏菌抗性低于小麦粒。整个产品中的某些影响的差异可能归因于组成因素（例如，糖或水分含量），吸附等温线或物理性质的温度诱导变化，或加工产品内颗粒尺寸和微环境的变化影响。初级-次级灭活模型非常适合各种数据集（RMSE从0.51到1.08 log），因此是预测这些产品沙门氏菌热灭活的潜在工具。最终，本文表明，低水分工艺验证协议应说明接种方法和特定的产品结构，这两种方法均会显着影响工艺结果。

著录项

  • 作者

    Limcharoenchat, Pichamon.;

  • 作者单位

    Michigan State University.;

  • 授予单位 Michigan State University.;
  • 学科 Engineering.;Food science.;Agricultural engineering.
  • 学位 Ph.D.
  • 年度 2018
  • 页码 229 p.
  • 总页数 229
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号