sira (12)

4353093767?profile=RESIZE_710xThe 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.

Read the full paper

Read more…

4273790207?profile=RESIZE_710xThis 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. 

Read the  abstract here

Read more…

A New Method for Exogenous Sugar Detection

4115428087?profile=RESIZE_710xSugar adulteration using carbon isotope ratio analysis by mass spectrometry is well established, but it can only be used for C4 sugar (from cane or maize) adulteration. Although a method has been developed to determine C3 sugar (from beet, most fruits or wheat) adulteration using hydrogen/deuterium isotope ratio analysis by mass spectrometry, it requires very time consuming chemical derivative preparation. The established method for C3 sugar determination has been quantitative deuterium nuclear magnetic resonance (2H NMR) measurement of ethanol derived from the sugars in the sample, which again is time consuming, and requires a normalisation process to compensate for the deuterium content of the fermentation water. Researchers at IAEA have developed a rapid method for both C3 and C4 sugar detection, which derivatises the carbohydrate's exchangeable hydroxyl-hydrogens, so that the derivative compound is sufficiently volatile to be separated and measured by a gas chromatograph coupled to an isotope ratio mass spectrometer. Feasibility of the method has been shown by measuring sugars from fruit juice and honey, but further work is required to assess the reproducibility of this method and establish its applicability for detection of undeclared addition of exogenous sugars and syrups to a range of other foods and beverages.  .

Read the abstract

Read more…

3861016247?profile=RESIZE_710xHoney is one of the most adulterated foods by addition of sugar syrups. Most if not all commercial honeys derive from the nectar of C3 plants. Sugar syrups derived from cane sugar or maize, which are C4 plants. The accepted standard method to check C4 sugar adulteration, is to determine the δ¹³C (C13/C12 ratio) by SIRA mass spectrometry.  Honeys that are tested with a δ¹³C value of -23.5 and lower are deemed to be pure. Honeys that have a δ¹³C value between -23.5 and -21.5, fall into a grey area. Honeys that have a δ¹³C of -21.5 or higher are deemed to be adulterated. However, false positives of syrup adulteration may occur if the bees have been collecting nectar from C4 plants, and hence low level adulteration is difficult to detect. This review discusses the background to testing honey by SIRA, and the limitations of this method.

Read the full review

Read more…

Analytical methods for authenticity testing of organically grown vegetables are urgently needed. Danish researchers have developed a novel assay for organic authentication based on stable isotope ratio analysis (SIRA) of oxygen in plant-derived sulphate. This method was compared with SIRA of bulk plant tissue and plant-derived nitrate to discriminate organic and conventionally grown potato, carrot, and cabbage from rigidly controlled long-term field trials and from a case study using retail potatoes. The results indicated that oxygen isotope ratios of sulphate from organic vegetables were significantly lower compared to their conventionally grown counterparts, and the values were directly linked to the fertilisation strategy. The classification power of sulphate isotope analysis was superior compared to known bulk tissue isotope markers and nitrate isotope values, and hence represents a promising new method for authentication of organic vegetables.

 Read the abstract here

Read more…

Mozzarella di Bufala Campana (MBC) is a PDO cheese produced from whole buffalo milk in specific regions of southern Italy. Due to the high price and the limited amount of buffalo milk, MBC is potentially subject to mislabelling, substitution or fraud. Italian researchers have used elemental and isotopic profiles of authentic samples of buffalo milk and the corresponding MBC samples collected in the reference area in winter and summer in an initial exploratory study. A model was developed to classify product categories for this cheese by merging MBC-PDO samples with non-PDO samples of buffalo mozzarella produced both inside and outside the reference area. Despite differences caused during processing, along with differences in the season and production area, the model was effective in distinguishing PDO and non-PDO mozzarella, particularly when non-PDO cheeses were made outside the MBC reference area.

 Read the abstract

Read more…

As the European Union has committed to only accept authenticated “sustainably sourced” palm oils, it is important to ensure that such imported oils are really from the declared source, preferably via proven analytical methods. This full review looks at the legal requirements for the traceability and authentication of palm oil, and assesses some new and emerging chemically-based technologies that should contribute to improving the monitoring of palm oil and other vegetable oil supply chains in Europe and elsewhere. 

  Read the full open access article

Read more…

This book covers the science of stable isotope measurement, sample preparation and testing of biological and geological elements. It also covers using isotopes for verification of origin and authenticity of plant based foods, fruits and vegetables, flesh foods, dairy products, vegetable oils, organic foods, alcoholic beverages, and some other miscellaneous foods. It brings the reader up to date with the latest developments in this area.

The contents and first couple of chapters can be found at: Food Forensics: Stable Isotopes as a Guide to Authenticity and Origin

Read more…

Italian researchers have measured the H, C, N and O isotopic ratios of 190 samples of different soft fruits (strawberries, raspberries, blueberries, blackberries and whitecurrants, redcurrants and blackcurrants) produced in a northern Italian region and at two sites in Romania and Poland collected over three harvest years. The different soft fruits showed a typical range for one or more isotopic parameters that can be used to verify the authenticity of the fruit species declared on the label. The δ13C and δ15N of pulp and the δ18O of juice can be considered effective tools for identifying the different geographical origin of fruit. There was a significant effect of crop cover on juice δ18O, and fertilisation practices on pulp δ15N.

Read the abstract at: SIRA of soft fruit

Read more…

This study examines the variations in isotopes and trace elements in relation to grape variety, environmental factors and provenance in order to address the wine authenticity in Cyprus. ICP-AES assessed the wines’ elemental content. SNIF-NMR and isotope ratio mass spectrometry methodologies determined in authentic and commercial wines the distribution of the naturally occurring stable isotopes of the deuterium/hydrogen (D/H) ratios and carbon (13/12C) in ethanol of wine and oxygen ratio (18/16O) in wine water. PCA (principle component analysis) highlighted the importance of grape variety and provenance, while supervised analysis pinpointed the vineyard effect and highlighted the contribution of the vintage year. These results can be incorporated to the EU Wine Isotopic Databank database providing both a guide and a tool for eventual candidatures for denomination of origin and support both Cypriot wine and winemakers. 

Read the abstract at: http://link.springer.com/article/10.1007/s12161-017-0959-2
Read more…

This paper reviews the use of SIRA of biological isotopes (H, C, O, N, S) in determining geographical origin for meat, poultry and dairy products, and production origin for seafood (wild or farmed). 

Read the full paper at : http://onlinelibrary.wiley.com/doi/10.1111/1541-4337.12219/full

Read more…

A study has been completed to look at the ratio of stable isotopes of  δ18O, (D/H)I, (D/H)II, δ13C, δ15N and 87Sr/86Sr moving from the soil, through the cultivation of grapes and their preparation at different stages into wine.  The isotopic ratio of 87Sr/86Sr does not vary significantly from grape to wine, and δ15N has been proposed as further isotopic marker for the geographical characterisation of grape products.

The paper in Food Chemistry by Caterina Durante et al is in press, but the abstract can be read at http://www.sciencedirect.com/science/article/pii/S0308814616306318

Read more…