Generation of food-based chlorination disinfection byproducts (F-DBPs) during food processing

据估计，美国每年有7600万人因食物而患病，用含有高剂量氯消毒剂的洗涤水清洗农产品正变得越来越重要。然而，氯可以与产品中的生物分子反应，形成可能致癌的氯化副产品。这项研究将确定这些氯化副产品，重点是那些留在农产品中，直到消费者食用。这项研究将量化生菜、胡萝卜、西红柿、苹果和鸡肉在农产品包装设施中使用含氯洗涤水处理时产生的副产品。这项研究的成功完成将产生可用于制定氯剂量指南的结果，以控制食源性疾病，同时将癌症风险降至最低。这些结果还将有助于维持对食品中这些潜在致癌副产品的出口。与受污染农产品有关的食源性疫情加剧了加工设施中食品消毒的重要性。然而，众所周知，氯与有机物反应产生卤化消毒副产物(DBP)，通常是有毒的，甚至是致癌的。食品加工过程中氯化DBP的形成可能比饮用水中更显著，因为食品加工过程中氯(~300毫克/L)和有机前体的含量可能高出100倍。虽然食品安全目前侧重于病原体，但这一益处必须与DBP形成的潜在健康影响相平衡。这项研究的目标是表征食品中氯与氨基酸酪氨酸和色氨酸以及不饱和脂肪酸反应产生的DBPs，不饱和脂肪酸是食品中与氯高度反应的四个主要生物分子群中的两个。这项研究的中心假设是，氯化最初会形成卤化酪氨酸、色氨酸和脂肪酸卤代醇生物分子，在长时间的氯化过程中会释放出可溶的副产物。与饮用水加氯相比，食品洗涤的氯接触时间较短(~15分钟)，有利于这些基于生物分子的初始副产品相对于可溶副产品的更高产量。中心假设的推论是，基于生物分子的副产品将留在食物中，而可溶的副产品将分配到洗涤水中。将通过比较不同系统中可溶副产品和初始生物分子氯化副产品的产量来测试这些副产品，这些系统包括：1)模型蛋白质和甘油三酯，2)在与食品消毒相关的条件下处理的生菜、胡萝卜、西红柿、苹果和鸡，以及3)从食品洗涤设施采集的样品。将测定基于氨基酸和脂肪酸的副产物的细胞毒性效力，并将其用于归一化食品中这些副产物的测量浓度，以便与之前对饮用水中DBP毒性的评估进行比较。这项研究给社会带来的好处包括通过支持一名非裔美国研究生的论文研究扩大对STEM的参与，通过REU项目让未被充分代表的少数族裔本科生参与进来，以及让一名高中科学教师和未被充分代表的高中生参与暑期研究。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With an estimated 76 million illnesses attributable to food per year in the US, rinsing produce with washwater containing high doses of chlorine disinfectant is becoming increasingly important. However, chlorine can react with biomolecules in the produce to form chlorinated byproducts that are potentially cancer-causing. This research will identify these chlorinated byproducts, focusing on those that remain in the produce until eaten by consumers. The research will quantify byproducts formed when lettuce, carrots, tomatoes, apples and chicken are treated with chlorine-containing washwater under conditions used in produce packing facilities. Successful completion of this research will produce results that can be used to develop guidelines for chlorine doses that control foodborne illness while minimizing cancer risk. The results will also help maintain produce exports to countries concerned about these potentially cancer-causing byproducts in food.Foodborne outbreaks linked to contaminated produce have heightened the importance of food disinfection in processing facilities. However, chlorine is known to react with organic matter to produce halogenated disinfection byproducts (DBPs) that are often toxic and even carcinogenic. Chlorinated DBP formation during food processing may be more significant than in drinking water, because food processing can involve 100-fold higher levels of both chlorine (~300 mg/L) and organic precursors. While food safety currently focuses on pathogens, this benefit must be balanced with the potential health impacts of DBP formation. The goal of this research is to characterize DBPs produced in foods from reactions of chlorine with the amino acids tyrosine and tryptophan, and unsaturated fatty acids; two of the four major biomolecular groups in food which are highly reactive with chlorine. The central hypothesis of this research is that chlorination will initially form halogenated tyrosines, tryptophans, and fatty acid halohydrin biomolecules, and soluble byproducts can be released during prolonged chlorination. The shorter chlorine contact times of food washing (~15 min) compared to drinking water chlorination (days) will favor higher yields of these initial biomolecule-based byproducts relative to the soluble byproducts. The corollary to the central hypothesis is that biomolecule-based byproducts will remain in food while soluble byproducts will partition to the washwater. These will be tested by comparing the yields of soluble byproducts and initial biomolecule-based chlorination byproducts in various systems including: 1) model proteins and triglycerides, 2) lettuce, carrots, tomatoes, apples, and chickens treated under conditions relevant to food disinfection, and 3) samples collected from food washing facilities. The cytotoxic potencies of the amino acid- and fatty acid-based byproducts will be determined and used to normalize measured concentrations of these byproducts in foods for comparison to previous evaluations of DBP toxicity in drinking water. Benefits to society resulting from this research include broadening participation in STEM through support of the dissertation research of an African American graduate student, engagement of under-represented minority undergraduates through an REU program, and the involvement of a high school science teacher and underrepresented high school students in summer research.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.