Food fraud in several value chains including meat, fish, and vegetables has gained global interest in recent years. In the meat value chain, substitution of high commercial-value meats with similar cheaper or undesirable species is a common form of food fraud that raises ethical, religious, and dietary concerns. The presence of undeclared species could also pose public health risks caused by allergic reactions and the transmission of food-borne or zoonotic pathogens. Measures to monitor meat substitution are being put in place in many developed countries. However, information about similar efforts in sub-Saharan Africa is sparse. In this study, we used PCR coupled with high-resolution melting (PCR-HRM) analysis targeting the three mitochondrial genes, cytochrome oxidase 1 (CO1), cytochrome b (cyt b), and 16S rRNA, to detect species substitution in meat sold to consumers in Nairobi, Kenya's capital city. Out of 107 meat samples from seven common livestock animals (cattle, goat, sheep, pig, chicken, rabbit, and camel), 11 (10.3%) had been substituted. Of 61 samples sold as beef, two were goat and one was camel. Of 30 samples sold as goat meat, four were mutton (sheep) and three were beef. One of nine samples purchased as pork was beef. Our results indicate that PCR-HRM analysis is a cost and time effective technique that can be employed to detect species substitution. The combined use of the three markers produced PCR-HRM profiles that successfully allowed the distinction of species. We demonstrate its utility not only in analysis of raw meat samples, but also of cooked, dried, and rotten samples, meat mixtures, and with the use of different DNA extraction protocols. We propose that this approach has broad applications in authentication of meat products and protection of consumers from food fraud in the meat industry in low- and middle-income countries such as Kenya, as well as in the developed world.

中文翻译：

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通过线粒体PCR产品的高分辨率熔解分析，肉类价值链中的物种替代

近年来，包括肉，鱼和蔬菜在内的多个价值链中的食品欺诈行为已引起全球关注。在肉类价值链中，将高商业价值的肉类替换为类似的廉价或不良品种是食品造假的一种常见形式，引起了伦理，宗教和饮食方面的关注。未声明物种的存在还可能造成由过敏反应和食源性或人畜共患病原体的传播引起的公共健康风险。许多发达国家已经采取了监测肉类替代的措施。但是，关于在撒哈拉以南非洲开展类似工作的信息很少。在这项研究中，我们针对3个线粒体基因，细胞色素氧化酶1（CO1），细胞色素b（cyt b）和16S rRNA使用了PCR和高分辨率熔解（PCR-HRM）分析，检测肯尼亚首都内罗毕出售给消费者的肉中的物种替代。在七种常见牲畜（牛，山羊，绵羊，猪，鸡，兔子和骆驼）的107种肉样品中，有11种（占10.3％）被替代。在出售为牛肉的61个样品中，有两个是山羊，一个是骆驼。在以山羊肉出售的30个样品中，有四个是羊肉（绵羊），三个是牛肉。作为猪肉购买的九个样本之一是牛肉。我们的结果表明，PCR-HRM分析是一种成本和时间有效的技术，可用于检测物种替代。三种标记物的组合使用产生了PCR-HRM图谱，该图谱成功地区分了物种。我们不仅证明了其在分析生肉样品中的效用，而且还对煮熟，干燥和腐烂的样品，肉混合物，并使用不同的DNA提取方案。我们建议在肯尼亚等低收入和中等收入国家以及发达世界的肉类工业中，这种方法在肉类产品的认证和保护消费者免受肉类食品欺诈方面具有广泛的应用。