Authentication of organic pork and identification of geographical origins of pork in four regions of China by combined analysis of stable isotopes and multi-elements

doi:10.1016/j.meatsci.2020.108129

Meat Science

Volume 165, July 2020, 108129

https://doi.org/10.1016/j.meatsci.2020.108129 Get rights and content

Highlights

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Stable isotopes and multi-elements in conventional and organic pork were analyzed.
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Organic pork was authenticated well by stable isotopes and multi-elements analysis.
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Pork origin was verified by stable isotopes and multi-elements analysis.

Abstract

The purpose of this study was to verify that the organic status of pork purchased in the markets from four different regions of China can be authenticated by the combined analysis of stable isotopes and multiple elements. Four stable isotope ratios (δ¹³C, δ¹⁵N, δ²H and δ¹⁸O) and the concentrations of seven elements (K, Na, Mg, Ca, Fe, Cu and Se) were determined in organic and conventional pork samples from four locations of China. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyze stable isotope ratios and multi-element concentrations in pork. Based on the limited database of analytical values, the methodology would be potentially able to confirm whether a sample of pork came from the region and organic status it claimed. These results provide a possibility for authenticity of organic agricultural products from a large scope such as a province even a country.

Introduction

A safer and healthier diet is greatly demanded in China since people's dietary patterns have undergone a huge change in recent years, with the economic development and improvement of people's living standards. Organic food is becoming increasingly popular in most countries including China (Grebitus, Yue, Bruhn, & Jensen, 2011). Unlike conventional food, organic food is free from conventional feedstuffs, including genetically modified or synthetic feed, animal by-products, synthetic fertilizers (Smith-Spangler et al., 2012) and growth promoters. There is also welfare for animals producing organic food, for example, organic animals have some living space and free time outdoors (Karwowska & Dolatowski, 2013).

Special cultivation methods of organic food lead to a higher cost than conventional food (Capuano, Boerrigter-Eenling, van der Veer, & van Ruth, 2013). The high cost and an increasing demand for organic food make it the target of fraud (Chung, Park, Yoon, Yang, & Kim, 2014). Therefore, it is important to establish a reliable method to distinguish between organic and conventional food. At present, many investigations have been reported on the discrimination of organic products from conventional agricultural products, including milk (Erich et al., 2015), vegetables (Laursen, Schjoerring, Kelly, & Husted, 2014), beef (Zhao et al., 2013), and chicken (Zhao, Lv, & Yang, 2015). Pork is popular among consumers in China because of its good quality, high nutritional value and low price, which makes it a topical subject to study the composition of pork from a health perspective (Reig, Aristoy, & Toldra, 2013). However, there are not many reports about the authenticity of organic pork so far. Our research group has achieved good results in identifying organic pork from conventional pork under strict experimental conditions by measuring stable isotope ratios (Zhao, Yang, & Wang, 2015) or multi-element concentrations (Zhao, Wang, & Yang, 2016). Nevertheless, some studies have shown that stable isotopes or mineral elements in pork are also related to geographical origin (Woo-Jin et al., 2018). As far as we know, there are only a few reports verifying the organic status of pork from different geographical origins by analyzing stable isotopes and/or mineral elements.

In the present experiment, we aimed to investigate the following issues: (1) Could organic pork be distinguished from conventional pork collected from the same region? (2) Since geographical origin affects stable isotopes and mineral elements in pork, could geographic origins of commercial organic or conventional pork be identified? (3) Could organic pork samples of different geographical origins in the Chinese market be distinguished from conventional ones? (4) Based on the above research, could key factors for identifying organic pork samples in the market be screened, and an organic pork model be established for China's main pork brands? By answering these questions, this research is expected to provide a practical protocol for identification of organic pork samples in the scope of a province even a country.

Section snippets

Sample information

According to the information on the package labels, the purchased organic pork was produced from four cities of China (Chengde, Anqing, Chifeng and Changchun) (Table S1). Organic pork from Chengde was certified by the National Organic Program of the US Department of Agriculture, and organic pork from Anqing was certified by Hangzhou Wantai Certification Co., Ltd. Organic pork from Chifeng was certified by EU Organic Certification, and organic pork from Changchun was certified by Beijing Wuyue

Differences of stable isotopes between organic and conventional pork

As shown in Fig. 1, four stable isotope ratios (C, N, H and O) of conventional pork and organic pork from four cities of China (Chengde, Anqing, Chifeng and Changchun) were compared. In all the four places, the δ¹³C value range of conventional pork samples was from −18.4‰ to −15.1‰, while that of organic pork samples was from −17.2‰ to −14.7‰. It could be seen that the δ¹³C value of conventional pork in the same area was generally lower than that of organic pork. According to the results in

Discussion

Stable isotope technology is innovative and plays an increasingly important role in determining the authenticity of animal-sourced foods for producers and control agencies (Camin, Bontempo, Perini, & Piasentier, 2016), for example, using the isotope detection technology to identify the origin of wheat (Luo et al., 2015) or authenticate organic chicken (Zhao, Lv, & Yang, 2015). However, there are still some issues with this technology for food traceability and authenticity. On one hand, the

Conclusion

In this study, four stable isotope ratios and seven mineral elements in pork were determined to identify the geographical origins of pork and authenticate possible organic status. The ratio of the nitrogen stable isotope in organic pork in the four market of China was found higher than that in conventional pork from the same area, while the ratio of the carbon stable isotope and the concentrations of seven mineral elements (K, Na, Mg, Ca, Fe, Cu and Se) of organic pork were found lower than

Declaration of Competing Interest

None.

Acknowledgements

This study was supported by the National Key Research and Development Program of China (2016YFD0401205) and China Agriculture Research System (CARS-35).

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¹: Yan Zhao and Ting Tu contributed equally to this work.

View full text

Authentication of organic pork and identification of geographical origins of pork in four regions of China by combined analysis of stable isotopes and multi-elements

Highlights

Abstract

Introduction

Section snippets

Sample information

Differences of stable isotopes between organic and conventional pork

Discussion

Conclusion

Declaration of Competing Interest

Acknowledgements

Food Chemistry

Analytica Chimica Acta

Food Chemistry

Food Chemistry

Food Chemistry

Food Chemistry

Food Chemistry

Food Chemistry

Meat Science

Trac-Trends in Analytical Chemistry

Food Chemistry

Meat Science

Food Chemistry

Food Chemistry

Food Chemistry

Agriculture Ecosystems and Environment

Meat Science