News

A novel method to identify animal species in complex or adulterated processed meat products has been developed by Chinese researchers, which combines a cytochrome oxidase I (COI) mini-barcode with next-generation sequencing (NGS).  A universal primer based on 140 sequences from 51 edible animal species was designed. A mixture of 12 species raw meat samples (beef, water buffalo, pork, sheep, chicken, partridge, grass carp, silver carp, blue scad, tile fish, pomfret, and prawn) were identified both with the clone sequencing and also with the mini-barcode (136 bp) sequence combined NGS method. The NGS method was superior in accuracy, sensitivity, and detection efficiency compared to the clone sequencing method, The edible animal species were identified both in the mixed raw samples and 7 heavily processed food products (different meatballs - beef, pork, fish, and shrimp), 'modified' beefsteak, sausages, and Chinese sausages. Moreover, some unlabelled species and dubious contamination were also detected as well, leading to stringent cleaning procedures.

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Quantitative DNA methods are used to detect and measure common wheat adulteration of durum wheat pasta. Italian and Argentinian researchers have validated a method for common wheat adulteration using Fourier transformed infrared spectroscopy (FT-IR) and chemomentrics. The dataset used to calibrate this infrared method was from 300 samples of both Italian and Argentinian durum wheat pasta analysed by an ELISA (enzyme-linked immunosorbent assay) method with common wheat adulteration ranging from less than 0.5% to 28%. These samples were analysed by both near- and mid-infrared spectroscopy (FT-NIR, FT-MIR) and the performance results were compared. The spectra were then analysed by two chemometric methods  - Partial-Least Squares Discriminant Analysis (PLS-DA) and Linear Discriminant Analysis (LDA). The first LDA and PLS-DA models grouped samples into three-classes, i.e. common wheat ≤1%, from 1 to ≤5% and >5%; while the second LDA and PLS-DA models grouped samples into two-classes using a cut-off of 2% common wheat adulteration. The accuracy of the validated models were between 80 and 95% for the three-classes approach, and between 91 and 97% for the two-classes approach. The three-classes approach provided better results in the FT-NIR range, while the two-classes approach provided comparable results in both spectral ranges. These results indicate the method could provide a rapid and inexpensive way of determining common what adulteration in durum wheat pasta.

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As the novel coronavirus pandemic shuts down businesses globally and sends countries into lockdown, the disruptions are threatening to cut off supply chains and increase food insecurity.

"Supermarket shelves remain stocked for now," the Food and Agriculture Organization of the United Nations (FAO) said in a report released late last month. "But a protracted pandemic crisis could quickly put a strain on the food supply chains, a complex web of interactions involving farmers, agricultural inputs, processing plants, shipping, retailers and more."

The issue, however, is not food scarcity -- at least, not yet. Rather, it's the world's drastic measures in response to the virus.

Border closures, movement restrictions, and disruptions in the shipping and aviation industries have made it harder to continue food production and transport goods internationally -- placing countries with few alternative food sources at high risk.

Airlines have grounded thousands of planes and ports have closed -- stranding containers of food, medicine, and other products on tarmacs and holding areas, said the UN Conference on Trade and Development on March 25.

Heightened instability in global food supply will affect the poorest citizens most, warned the UN's Committee on World Food Security (CFS) in a paper last month.

Even private companies and organizations have called for immediate action to address the looming food catastrophe.

"Governments, businesses, civil society and international agencies need to take urgent, coordinated action to prevent the COVID pandemic turning into a global food and humanitarian crisis," said an open letter to world leaders from scientists, politicians, and companies like Nestle and Unilever.

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Commercial starches such as corn starch and potato starch are widely used as ingredients by industry and consumers. In China, the most common commercial types of starch are potato, sweet potato, cassava, corn, and wheat, but cassava starch is the cheapest of all the starches. Chinese researchers have developed a rapid and accurate quantitative detection method using droplet digital PCR (ddPCR) technology to identify cassava adulteration in commercial starch products.The ddPCR analysis showed that the weight of cassava (M) and cassava-extracted DNA content had a significant linear relationship—the correlation coefficient was R² = 0.995. The developed method was tested by analysing 50 commercial starches (30 sweet potato, 12 potato, and 8 corn starch). Eleven of the 30 sweet potato starch samples were adulterated with cassava starch, and one sample has just over 37% cassava starch, also 5 out of the 12 potato starches were adulterated and 2 out of the 8 corn starches were adulterated. 

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Cibus Analytical will commercialise research completed at IGFS, Queens University Belfast, and will not only offer a laboratory testing service, but also innovative, portable testing tools to allow customers to rapidly test for food authenticity and safety across global supply chains. The £0.57 million seed funding has been led by QUBIS, the commercialisation arm of Queen’s University, and also involves a number of investors with a range of backgrounds from the food sector and support from Innovate UK. Cibus Analytical was founded by IGFS researchers Prof Chris Elliott, Dr Terry McGrath, Dr Simon Haughey and Mrs Pamela Galvin-King. 

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Chinese researchers have applied an electronic nose (E-nose) system to detect beef adulteration with pork. The E-nose system uses a colourimetric sensors, which give different colours with different volatile compounds emmitted by the meat, the resulting coloured pattern is analysed by image analysis before and after exposure to the meat sample. The resulting signals are then analysed chemometrically to predict both qualitatively and quantitatively, the adulteration of beef with pork. This system was tested using samples of raw minced beef and pork mixed at different levels from 0%  to 100%  adulteration at 20%  increments. The system was able to accurately identify adulteration and give good quantitative correlation.  Read the article and the full paper.

UK meat plants and abattoirs, like many other sectors, are suffering a shortage of personnel during the Covid-19 crisis. However, the shortage is not just for operators in the plants, but also there is insufficient supervision by official veterinarians (OVs) and meat hygiene inspectors (MHIs) because of Covid-19 related sickness. In the face of these challenges the FSA, which has responsibility for meat hygiene, has drawn up contingency plans to try and deal with this situation. Measures include transferring qualified staff from other roles back to inspection, and bringing some qualified staff out of recent retirement. There is also the possiblitity to relax certain rules on inspection to ease the burden in meat plants and abattoirs.

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Cocoa botanical and geographical origin and the primary processing applied (i.e. 'fermentation') at the beginning of the supply chain characterise the quality of cocoa beans and influence the finished chocolate.  Therefore, authenticity markers of cocoa beans could verify their origin in the supply chain, and establish a compositional link between the raw materials and finished chocolate, and enhance traceback. In this study, Dutch researchers examined the retention and loss of compositional signatures from cocoa beans to chocolate. The compositional signatures chosen were VOCs (volatile organic compounds), elemental and stable isotope signatures. These were determined in cocoa beans from 10 different origins and 11 corresponding chocolates by high sensitivity-proton transfer reaction-mass spectrometry (HS-PTR-MS), inductively coupled plasma-MS (ICP-MS) and isotope ratio-mass spectrometry (IR-MS), respectively. The volatile fingerprints provided mostly information on the origin and primary processing traits of the raw cocoa beans in the chocolates. VOCs that are relevant and robust markers include: acetic acid (m/z 61), benzene (m/z 79), pyridine (m/z 80), 2-phenylethanol (m/z 123), and maltol (m/z 127). On the other hand, the elemental and stable isotope characteristics are more indicative of the cocoa content and added ingredients, although Fe, Cr, and Cd are possible elemental markers for origin. 

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Authenticating nut and nut products is not only important to prevent adulteration, but also has safety implications for allergy sufferers. Spanish researchers have developed a method using HPLC-FLD (high performance liquid chromatography with fluorescence detection) combined with chemometrics (partial least squares discrimination - PLS-DA) to produce non-targeted fingerprints to authenticate ten species of nuts, as well as detect and quantify adulterations with hazelnut and peanut in almond-based products (almond flour and almond custard cream). A satisfactory global nut classification was achieved with PLS-DA. Paired PLS-DA models of almonds with their adulterants were also evaluated, producing a classification rate of 100%. 

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The δ¹³C and δ¹⁵N isotopic ratios  are important in the investigation of food authenticity and fraud. Previous studies in Brazil on targeted foods revealed  that many of them were adulterated; mislabelled or even fraudulent. Hence to improve future authenticity studies, Brazilian researchers have determined baseline values of δ¹³C and δ¹⁵N in 1245 food items and 374 beverages; most of them made in Brazil. The average δ¹³C and δ¹⁵N values of C3 plants, C4 plants, plant-based processed foods, meat (including beef, poultry, pork and lamb), meat products, and beverages (including beer and wine) are all given in the paper. Because cattle are grass fed, and chickens and pigs fed on soya and maize, C-C₄ constitutes a large proportion of fresh meat, dairy products, as well as meat products. Also cane sugar and maize predominate as ingedients, and hence there is a large proportion of C-C4 in plant-based processed foods.

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Karen Everstine (Descernis) and Selvarani Elahi (LGC) have written an update on the Food Authenticity Network giving a good overview of its achievements since it formation nearly 5 years ago in response to the 2013 horsemeat incident. Read the article here

Determining the geographic origin of coffee beans is more challenging with roasted coffee beans, and is useful if it can be performed on the product available to the consumer. US researchers analysed the concentrations of 44 trace elements in 53 samples of roasted Arabica coffee beans (Coffea arabica) from 21 different countries. Although trace elements are not volatilised at roasting temperatures, the absolute elemental concentrations of coffee beans vary through different degrees of roasting (from green through dark roasts). The study analysed trace element ratios to evaluate concentration-related differences among beans from different origins. By comparing the distributions of 1892 element ratios for each of the  countries, the study demonstrated that many of the world’s coffee-producing regions can be distinguished from other regions of the world on the basis of element ratios.

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The March 2020 Foods Journal has a special issue on “Food Authentication: Techniques, Trends and Emerging Approaches” consisting of  12 articles (11 original research articles and 1 review), which focus on the development and application of analytical techniques and emerging approaches in food authentication. The research papers cover the authentication of foods with high commercial value, such as olive oil, Iberian ham or fruits, among others. The review examines the potential of matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) as a valuable technique to determine small metabolites in food tissue sections without requiring purification, extraction, separation or labelling. It can be used not only to identify the composition of foods, but also to investigate among other applications, their geographical origin for improved traceability, food safety and breed enhancement. 

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In our March 2020 Newsletter on page 8 there was a call for new Centres of Expertise. Originally, the closing date for proforma applications was the end of March. In view of the disruption caused by the Covid-19 situation, the deadline for new applications has been extended until the end of April. I would encourage any laboratory which is either specialist or general in authenticty methodology, especially with an agent or base in the UK, to consider applying.

Gas chromatography techniques are routinely used to detect key lipids (e.g., triacylglycerols) to assess milk origins and to detect foreign milks in bovine milk. However, such approach requires several sample preparation steps and a dedicated laboratory environment, precluding a high throughput process. In order to simplify sample preparation and speed of analysis, UK researchers developed a novel and simple method without organic solvent extractions for the detection of bovine and non-dairy milks based on lipids fingerprint by routine MALDI-TOF mass spectrometry. The method was tested using mixtures of bovine with either soya or coconut milks in the range of 0-100% additions. Marker ions specific to each type of milk permitted a reproducible and cost effective approach to milk analysis, which is suitable to qualitatively typify milks and potentially their adulteration.

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This pilot study used SIRA (stable isotope ration analysis) and trace element analysis to verify the organic status of pork purchased in the markets from four different regions of China. 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 the four locations of China. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used to analyse stable isotope ratios and multi-element concentrations in pork. Discrimination between the organic and conventionally reared pigs was based mainly on δ¹⁵N as the marker for organic feedstuffs. Using the limited database of analytical values, the methodology would potentially be able to confirm whether a sample of pork came from the region and organic status it claimed. 

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This study examines fraud vulnerability in the Dutch food service sector; identifies underlying fraud vulnerability factors; and studies the differences in fraud vulnerability between casual dining restaurants, fine dining restaurants and mass caterers for four product groups. Vulnerability was assessed by an adapted SSAFE food fraud vulnerability assessment, tailored to the food service sector. Fifteen food service operators were assessed, and were rated high vulnerability for 40% of the fraud indicators, which is much higher than food manufacturers, wholesalers and retailers assessed in a previous study. In particular, there was more opportunities for fraud and fewer controls were noted. The overall fraud vulnerability was determined more by the type of food service operator than by the type of food product. Hence casual dining restaurants were assessed as being the most vulnerable, followed by fine dining restaurants. Mass caterers were assesed as the least vulnerable operators to fraud, because they had more adequate controls in place.

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Because of its higher price, goats milk is vulnerable to adulteration by cheaper cows milk. A rapid method based on β-carotene as a marker for cows milk, but absent in goats milk, has been developed using Raman and Infrared spectroscopy with chemometrics. The application of PLSR (partial least squares regression) to the two spectrocopic methods was the most successful giving an good correlation coefficient of validation (R² value > 96) and an accurate determination of β-carotene content and percentage in spiked milk.

Read the abstract here