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Development of ozone-based processes for decontamination of fresh produce to enhance safety and extend shelflife.

机译：开发基于臭氧的新鲜农产品去污工艺，以提高安全性并延长保质期。

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摘要

Although good agricultural practices (GAP) and good handling practices (GHP) may reduce the incidence of pathogens in fresh produce, there is no known defense against contamination due to wildlife or surface water. Additionally, current strategies designed to minimize the risk of contamination during post-harvest operations of fresh leafy greens are not completely effective. Contaminations of fresh fruits with spoilage microorganisms also create economical losses by decreasing products shelflife. Therefore, it is necessary to develop sound mitigation strategies to minimize the health hazards associated with fresh produce.;The main objectives of the current study are to (i) enhance the safety of fresh produce in general, and baby spinach in particular, by integrating ozone-based sanitization steps into existing processing practices, while targeting Escherichia coli O157:H7 as the pathogen of concern, and (ii) to assess the feasibility of using ozone, carbon dioxide or their combinations, for reducing natural microbiota, and extending the shelf-life of strawberries.;A pilot-scale system has been successfully assembled that allows vacuum cooling and ozone treatment of fresh produce simultaneously. Combinations of vacuum cooling and ozonation (SanVac) successfully inactivated up to 2.4 log E. coli O157:H7 CFU/g spinach. Contribution of important treatment variables (ozone concentration, pressure and treatment time) to process lethality was also investigated using response-surface methodology. Parameters for the optimized SanVac process are of 1.5 g O3/kg gas-mix (935 ppm, vol/vol), 10 psig holding pressure, and 30 min holding time; these conditions achieve 1.8 log inactivation against E. coli O157:H7 with no apparent damage to quality of baby spinach.;A long-term, low-ozone process was also developed to treat fresh produce during transportation or temporary refrigerated storage. This treatment, termed "SanTrans", involves sparging moist gaseous ozone at 16 mg/kg (10 ppm, vol/vol) for up to 3 days. The process inactivated up to 1.4 log E. coli CFU/g spinach, and the optimum process resulted in 1.0 log inactivation with minimal effect on product quality. In order to maximize inactivation on E. coli O157:H7, contaminated spinach was sequentially subjected to optimized SanVac (at 1.5 g/kg for 30 min and 10 psig) and SanTrans (at 16 mg/kg) processes, using freshly-harvested, unprocessed spinach that was shipped directly from California fields. These sequential treatments inactivated 4.1 to ≥5.0 log E. coli O157:H7, depending on the treatment time. Inoculated and vacuum-cooled spinach was analyzed by scanning electron microscopy. It was apparent that vacuum-cooled leaves often contained bacterial cells throughout the intercellular spaces, compared with the non-vacuum cooled leaves.;An ozone-based treatment system was designed and constructed to enhance the storage life of fresh strawberries (Fragaria x ananassa). The O3/CO2 combination treatments showed synergistic effect in delaying mold growth and quality deterioration of the strawberries. When samples were treated with O3/CO 2 for 4 h and stored at 4°C, the initiation of visual mold appearance was delayed until the 16th day of storage; an 8-day shelflife extension, compared to untreated samples. These novel technologies are promising alternatives to conventional processes and should enhance the safety and extend the shelflife of fresh fruits and vegetables. Additionally, the new treatments should be relatively easy to integrate into existing fresh produce processes and practices.
机译：尽管良好的农业规范（GAP）和良好的处理规范（GHP）可以减少新鲜农产品中病原体的发生率，但尚无已知的防御措施来防止野生动植物或地表水造成的污染。另外，当前旨在将新鲜多叶蔬菜的收获后操作期间的污染风险降至最低的策略并不完全有效。新鲜水果受到腐败微生物的污染还会通过降低产品的保质期而造成经济损失。因此，有必要制定合理的缓解策略，以最大程度地减少与新鲜农产品相关的健康危害。；本研究的主要目标是：（i）通过整合综合来提高新鲜农产品，特别是婴儿菠菜的安全性以臭氧为基础的消毒措施已进入现有的处理方法，同时将大肠杆菌O157：H7作为关注的病原体，（ii）评估使用臭氧，二氧化碳或它们的组合减少天然微生物并扩展货架的可行性草莓的寿命。；已经成功组装了中试规模的系统，该系统可以同时进行真空冷却和新鲜产品的臭氧处理。真空冷却和臭氧化（SanVac）的组合成功灭活了2.4 log E. coli O157：H7 CFU / g菠菜。还使用响应面方法研究了重要处理变量（臭氧浓度，压力和处理时间）对处理杀伤力的贡献。优化的SanVac工艺的参数为1.5 g O3 / kg气体混合物（935 ppm，体积/体积），10 psig的保压压力和30分钟的保压时间；这些条件可达到针对大肠杆菌O157：H7的1.8 log灭活，而对婴儿菠菜的品质没有明显损害。;还开发了一种长期的低臭氧工艺来处理运输或临时冷藏时的新鲜农产品。该处理称为“ SanTrans”，涉及将湿气臭氧喷射到16 mg / kg（10 ppm，体积/体积）下最多3天。该工艺可灭活高达1.4 log E. coli CFU / g菠菜，最佳工艺可灭活1.0 log Ec，对产品质量的影响最小。为了最大程度地灭活O157：H7大肠杆菌，对污染的菠菜依次进行了优化的SanVac（1.5 g / kg，30分钟和10 psig）和SanTrans（16 mg / kg）的过程，方法是使用新鲜收获的，未经加工的菠菜，直接从加利福尼亚州的田地运来。根据治疗时间的不同，这些顺序的治疗会使4.1到5.0 log E. coli O157：H7灭活。通过扫描电子显微镜分析接种的和真空冷却的菠菜。显然，与非真空冷却的叶片相比，真空冷却的叶片通常在整个细胞间隙中都含有细菌细胞。设计并构建了一种基于臭氧的处理系统，以延长新鲜草莓的贮藏寿命（Fragaria x ananassa） 。 O3 / CO2组合处理在延缓草莓霉菌生长和质量恶化方面显示出协同作用。当样品用O3 / CO 2处理4 h并保存在4°C时，视觉霉菌的出现被推迟到保存的第16天。与未经处理的样品相比，保质期延长了8天。这些新颖的技术是常规工艺的有前途的替代方法，应能提高安全性并延长新鲜水果和蔬菜的保质期。另外，新的处理方法应该相对容易地整合到现有的新鲜农产品的过程和实践中。

著录项

  • 作者

    Vurma, Mustafa.;

  • 作者单位

    The Ohio State University.;

  • 授予单位 The Ohio State University.;
  • 学科 Agriculture Food Science and Technology.;Engineering Packaging.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 227 p.
  • 总页数 227
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 农产品收获、加工及贮藏;包装工程;
  • 关键词

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